Updates to our product warranties

Over the recent months, something that our community has brought up was our relatively short warranty times for our machines, and why that was the case. To be frank, we came up with the warranty times a long time ago without too much thought and never really ended up changing or revisiting them. However with the changes to consumer expectations around machine warranty, we are addressing these expectations.

With regards to how we approached our initial warranty lengths, they were relatively short because we knew that most issues that happen with a machine typically happen within the first few months. Typically these address accidents and manufacturing defects that are caught nearly right away. However, given how rare long term issues are, we would typically help with service and replacement parts for customers after the warranty period for free or at minimal cost. Additionally, we felt that overall, the cheapest, fastest, and most effective way for us to provide support was simply to:

  • Provide documentation so that customers can fix their machines themselves
  • Provide all of the open source designs so that customers can use parts off the shelf and from other vendors
  • Order parts from us and get them quickly from our store if they want to use OEM parts
  • Have replacement parts on hand

For most of our existence, having a shorter warranty has not been a significant point of contention, because we had a strong reputation for a high standard of customer service, affordable parts, and openness of our designs which allowed customers to fix things themselves. Generally, this meant that having a short warranty didn’t actually impact the customers in the long run.

Based on our data, our cost for parts for replacement each month has been relatively low, around $1300 to $1500 per month (around 0.35% of the cost of the machine). We’ve also found that the cost of the service for our support to help with replacements is more than the cost of the parts themselves. Even if we were to increase the warranty, it wouldn’t increase our costs as we still help every customer regardless of whether they are in or out of warranty. So, our volume of technical support wouldn’t change.

Additionally, in a lot of cases, we will still provide replacement parts to customers even if they are out of warranty. So we don’t expect the volume of cost for replacement parts to increase that much either.

So why are we increasing the warranty of our machines? Well, we believe:

  • It will provide more peace of mind for customers
  • Meet expected standards for our industry
  • Align with the high quality technical support we already provide

But most importantly, we believe it will cause a fundamental shift in our thinking for our company and development in the long term. For those who have been following us, we have been a fast moving, fast developing, and innovative company. Long term planning hasn’t been one our our strong suits. Now that we’ve grown and are becoming a more mature company, and customers expect more from us and more from our products. Having a longer warranty also shifts are thinking of:

  • Did we engineer our parts and products to last a long time?
  • Can we have the resources available to help our customers through their whole journey?
  • Are we keeping track of what we have learned over the years to make our machines more reliable and long lasting?

I believe that our confidence in our engineering should be reflected in the warranty as well.

Of course, these principals have always been something important to us internally, but not strongly reflected in the warranty itself. Our warranty should reflect our confidence in how long our machines are going to last, and it also serves as our written commitment to making sure the machines are built to a high standard.

In preparation for the warranty extension, we have also been working on:

  • Updating our store with more replacement part availability
  • Tracking and analysis of our failure rates for parts
  • Looking at our QA process
  • Improving the quality of our parts

We also sat down with the team to address the purpose of what a warranty means, which includes:

  • An increased standard for durability
  • A closer analysis of the longevity of the machine, and what improvements to the design we should make to improve durability and reduce issues
  • Redefining our own confidence in our ability to produce quality machines
  • A culture of accountability for us to be helping customers through their whole journey in using our products

Additionally, there is a financial/marketing incentive. More customers are making buying decisions based on warranty. This means that we also expect an uplift in sales that will come from increasing the warranty. And based on our calculations, even if we double the number of replacement parts we need to issue, we only need to sell an extra 2-3 machines per month to cover that cost. So overall, we expect that it will only take a little extra financial benefit for us to increase the warranty period as well.

So what’s happening next?

  • All of our CNC machines sold from August 1, 2025 and onwards will retroactively have their warranty extended to be 1 year from the time of when it arrived at your door.
  • If customers have had to pay out of pocket for out of warranty service through us in the period from August 1, 2025 till today, requested technical support from us, and would have had their warranties covered with the warranty extension, we will refund them the costs through the method they originally paid or provide equivalent store credit (at our discretion).

We will review our past tickets and records and refund customers automatically if you fall into our category of customers who paid for parts out of warranty for machines shipped and arrived after August 1, 2025. If you are a customer and do not hear from us, and had to pay out of pocket for the out of warranty service, please contact us directly through our contact form.

Additionally, warranties on parts will be updated and increased on a case by case basis.

Review of data

To give some context of what is going on in the back end, we reviewed tickets from the last 60 days for the AltMill.

Here’s a look at our stats for warranty issues and tickets.

  • In the last 60 days, approximately 60.3% of issues happened within the first 120 days.
  • Increasing the warranty from 120 days to one year (365 days) means capturing approximately 92.6% of the issues, rather than 60.3%
  • Controller and motor/coupler issues (electrical) make up the majority of issues, making up 69%

Changes to expect

With all of the data analyzed, there are a few changes in the works to help us focus on new areas of improvement.

First is reviewing the designs of our key failure points, mainly with the electronics systems. We’ve observed that most of the issues come from controller/estop or motor/coupler related issues. With current development of the new SLB-EXT V2 and SLB-Lite, with more robust components and design, we expect to see a significant decrease in these issues.

We’re also reviewing our QA processes, assembly instructions, and design to improve the overall reliability of the couplers as well, which also contributes to a big part of our overall pool of issues.

We’ve also set up some processes to keep a continual eye on issues week to week to identify trends so that they can be addressed and directed to the right people within the company to resolve. This includes weekly reports and analysis of technical support tickets, review of issues on our forum and other channels, and software usage logs.

Our main goal is to continue to improve the overall performance and reliability of our products. While an update to our warranty policies is a reflection of that, I believe that continual improvement should remain the primary focus of our development and ensure that the overall experience, warranty or not, is a great as it can be.

August 2026 Production Update

Hey everyone, welcome back. Here’s August 2026 Production Update!

US/Canada Tariffs

A number of our American customers have been inquiring about the status of tariffs with the recent announcement by the U.S. government on potential tariffs being applied to Canadian products.

These tariffs are aimed to target three groups of products:

  1. Alcoholic beverages
  2. Dairy
  3. Motor Vehicles

Based on our cross-reference of all of the HS codes that are expected to be affected, we have determined that the products we are selling to the U.S. are not part of that group of HS codes. This means that we do not expect tariffs to be applied to our products.

Because the tariff situation between the U.S. and Canada is still a little bit unpredictable, we can reassure that we will handle this in one of two ways for our US neighbours.

  1. For orders that have been placed before the tariffs have been applied, we will absorb the cost of any tariffs (if there are any) and continue to ship our products as DDP. This means that any duties and tariffs will be billed directly to us and will not impact the customer.
  2. If the tariffs create a situation where it is unsustainable or not possible for us to reasonably absorb the cost, then we will communicate this to the customer and either come to another arrangement or allow the customer to cancel their order completely.

We will make an update to our policies if the tariffs end up being implemented.

Based on our experience over the last few years, and due to our CUSMCA/USMCA certification, we do not expect there to be tariffs in the future. 

Customer Support Updates

We’ve been putting a lot of work into ramping up and improving our support process.

Our new support page is now live! A few updates to this:

  • A more specific step by step process for completing tickets so that we can determine relevant vs irrelevant information
  • Built in search function to suggest articles and information that may help with the issue
  • Tracking to see which issues are the most common
  • Tracking to see how often the issues that we suggest are correct in helping the user

We also have now revamped order status tracking in our website, which allows customers to better keep track of when they expect to have their items ship. You can now enter your order information and get a list of all of the items that you ordered. Soon, we’ll have the lead times tied to each of the products, so that you can get the estimated lead time for each of the products. This will also give us a better idea on our delivery timeliness success rate, as well as more easily identify orders if we are expecting them to be delayed, so that we can communicate with the customer better.

We’ve also had a lot of discussions with customers and our team in establishing better after sales support, with initiatives currently underplace to:

  • Provide maintenance kits for lubrication and replacing wear items
  • Parts available for spares and replacements
  • Updates to machine use and maintenance resource pages
  • More support videos

Lastly, it’s been mentioned to us about our warranty period for our machines. We are coordinating with the team to establish longer and improved warranty periods and support for our products.

For people wondering why our warranty is so short right now:

  • First of all, we set up this warranty system years and years ago, and we didn’t really revise it because it wasn’t something that people were talking about that much.
  • Overall, we haven’t had many issues with our warranty length because the issues are relatively rare. When we do need to send out replacements, we will typically do it for free or at minimal cost, even if the warranty period is over.
  • Practically speaking, the most issues happen within the first 30 to 60 days of ownership. It’s very rare for customers to have issues after the fact, which means that even though our warranty period is pretty short, people don’t really use the warranty after the first setup.

However, I wanted to bring this up because this is something that a couple of potential customers have been asking about. And I guess if it’s not going to impact anything to provide a longer warranty and offer additional peace of mind, then why not consider it?

Here are some things that we’ve learned:

  • The overall cost for us to provide replacements has been relatively low month over month. Based on my calculations, this is about 0.35% of the overall machine value on average.
  • Even if this were to double, the potential uplift in sales that we’d want to see in providing the longer return period, it would only need to be covered by around two or three machine sales per month.
  • Regardless of whether the customer needs to purchase a part or not, we provide the same level of service for the customers to troubleshoot and repair their machines. We expect the service we need to provide and the costs associated with it to be relatively the same.
  • We also expect that it will make it a lot easier for our team to handle repair issues because we can just issue replacement parts without having to figure out the transaction process as well.

All of which to say, it seems like we can significantly increase the warranty period while saving some costs in some areas and also with minimal impact to our bottom line. We also believe that offering the additional warranty will provide better peace of mind to customers, so from my perspective it seems like a win-win situation.

In any case, we are working on setting this up and establishing our processes, and we will also increase warranty for customers that already exist retroactively.If customers have paid for replacement parts due to warranty service that happened outside of their warranty period, then we will work with the customers to either refund them or provide them credit appropriate to their situation.

Tool Length Sensor

We recently launched the TLS in the past month to great reception. After receiving customer feedback and getting through our first batch of production here’s some updates and changes to expect:

  • Updates to the workflow in gSender
  • Ability to fine tune fast and slow find settings
  • Improved setup videos, instructions, and resources
  • Improved and streamlined packaging

Improving our Supply Chain Process

Alongside customer service and care improvements and restructuring, we are also working on improvements and restructuring to our supply chain process, with the aim to reduce delays and allow us to react more quickly to changing demand for our products. Some initiatives put into place include:

  • Automated monitoring of supply chain communication to tag and flag shipments
  • New review process for Bill of Materials for products
  • Tracking of supplier reliability and timeliness
  • Reorganization of our physical space for increased storage capacity
  • Cross departmental access to key reports to track supply and inventory
A look at the production dashboard

We are also slowly moving away from a batching system to a rolling inventory system. As our supply chain becomes more diverse, rather than building in big batches, each part will eventually be ordered as needed on an individual basis. This means that for parts like fasteners that are used in many different products, we can order them in larger quantities for multiple product lines.

You’ll likely see some changes in how we track our lead times from expected shipping month to number of weeks to ship. This gives us a more exact time when products will ship, rather than a vague date target. This will allow us to better keep track of our shipping ability and work with customers in the case of production delays.

We have also continued to grow our team on the supply chain and inventory side, with two new team members in the department and with a current search for an extra third member.

AltMill 4×8 Production

First, please note that you can check the status of your order and when it is expected to ship in the Order Status page.

AltMill 4×8 machines are expected to start shipping at the earliest on Aug 14 pending the arrival of additional rack and pinion hardware, but with assembly and processing time, most likely to start shipping between the end of August to first week of September. The remaining batch of machines in the queue are expected to clear out at the end of September. In the meantime, we are prepping parts and production to push machines out quickly once the parts arrive.

The current lead time for AltMill 4×8 is 10 weeks.

To prevent having long lead times in the future, we have about 300 machines on order for our second batch, and we expect to have about a years worth of inventory on hand. Could be less over time given that we tend to get a lot more orders as we decrease our lead times, but for now, we’ve made sure to pad our stock as much as we can.

Auto Tool Changer Production

ATCs are expected to resume shipping August 23rd, pending the arrival of a shipment of spindles around August 10. Once these spindles arrive, the remaining 58 orders in the queue will start shipping, with all current orders expected to be fulfilled by September 13.

The current lead time for ATCs is 8 weeks, so orders placed today are expected to ship early October. The lead time is due to the spindle being reviewed and modified.

Power Supply Certification

Prototyping the case for the power supply

With some things going on with CSA-related certification to do, we’ve been working on designing, developing, and testing our own power supply designs for the next iteration of our machines. During this rework, we have put sales within Ontario for the LongMill MK2.5 and AltMill machines on pause until the rework is completed. Customers outside of Ontario are not affected, and LongMill MK3 will already come with Ontario compliant power supplies.

With the development of the SLB-EXT V2, we are revising the power handling and power shutoff mechanisms away from the controller, which better complies with Ontario safety standards. Although meeting these standards are not required in many other regions, we expect this work to overall improve safety for the machines and improve safety compliance in other markets in the long run.

Current work being done now include:

  • Testing of power supplies in hot/cold conditions
  • Power draw and handling
  • Custom PCB design
  • Fuse testing and trip behavior

We now have very few (if any) LongMill MK2.5 machines, and users in Ontario and the rest of the world should expect to receive their LongMill MK3 machines in September. Ontario customers waiting on AltMills should expect to see them return for sale in November this year.

LongMill MK3

A bit more work done with the LongMill MK3 in the past month, with our focuses mostly with

  • Resource development and assembly manuals
  • Packaging design and drop testing
  • General machine testing

Many of the parts for the LongMill MK3 have now been received this month, and we are going through the setup for the assembly process.

Nikhila with our production box

We are expecting to start shipping LongMill MK3 in mid-September.

SLB-LITE and SLB-EXT V2

We are now reaching the final stages of SLB-LITE and SLB-EXT V2 development. Main work done for this month include:

  • Design and planning for testing jigs
  • Design and planning for firmware flashing
  • Testing and updates to firmware

We are also expecting new packaging and initial batches of controllers to arrive soon in preparation for our first batch of LongMill MK3 machines.

A first look at the new controller

Update on the US/Canada Tariffs for August 2026

A number of our American customers have been inquiring about the status of tariffs with the recent announcement by the U.S. government on potential tariffs being applied to Canadian products.

These tariffs are aimed to target three groups of products:

  1. Alcoholic beverages
  2. Dairy
  3. Motor vehicles

Based on our cross-reference of all of the HS codes that are expected to be affected, we have determined that the products we are selling to the U.S. are not part of that group of HS codes. This means that we do not expect tariffs to be applied to our products.

Because the tariff situation between the U.S. and Canada is still a little bit unpredictable, we can reassure that we will handle this in one of two ways for our US neighbours.

  1. For orders that have been placed before the tariffs have been applied, we will absorb the cost of any tariffs (if there are any) and continue to ship our products as DDP. This means that any duties and tariffs will be billed directly to us and will not impact the customer.
  2. If the tariffs create a situation where it is unsustainable or not possible for us to reasonably absorb the cost, then we will communicate this to the customer and either come to another arrangement or allow the customer to cancel their order completely.

We will make an update to our policies if the tariffs end up being implemented.

Based on our experience over the last few years, due to our CUSMCA/USMCA certification, we do not expect there to be tariffs in the future. 

July 2026 Production Updates

Another busy June has come and gone. Welcome to our latest update!

Employee Appreciation Day

Lead Times For Major Products

AltMill 2×4 and 4x4s are now shipping quickly, typically in 2 weeks or sooner. We have stockpiled some assemblies and full machines to help keep our lead times low.

Batch 2 of 4×8 machines are now in production, and we are expecting units to start shipping in August.

All spindle kits (minus the ATC) are now shipping within 2 weeks as well. We are now in production of Batch 2 of ATCs; new orders being placed now are expected to ship in August-September.

For orders that have already been placed, please refer to the estimate provided in the month/week that you ordered the product. Please note that the lead times that are presented on the product page only refer to orders placed at that time. Your order lead time will be different if you have already placed an order in a prior month.

You can see the tabs for each month at the bottom of the sheet on the Order Status page

LongMill MK2.5s are shipping within 1 week, and LongMill MK3s are also expected to start shipping in September.

For the latest list of shipping timelines, please check out our Order Status page.

Catching up on Maintenance Stuff

The last few months have been pretty busy with new product launches, but now that we’ve gotten through all of the big things, you should expect to see a bit of cleanup on our end, including:

  • Updates and cleanup to resources and documentation
  • Updates and cleanup for open source files and documentation
  • Uploading of maintence and replacement parts on our store
  • Continued training for our customer support team
  • Continued improvement in gSender, our firmware and other parts of our ecosystem
  • Development of ancillary technologies and products, like a CNC control pendant, sensorless homing motors and vacuum workholding

I don’t think I can list every single little detail, but users should expect to see small changes come down over the next few months.

Tool Length Sensor

Although we’ve mentioned this a few times in saying that gSender fully supports a tool length sensor, and users can/have installed a tool length sensor on machines with aftermarket TLS, we have now finally made the TLS sensor available to all users.

As you may know, the Auto Tool Changer system requires a TLS system, so we designed a TLS sensor specifically for our machines and systems.

Benefits of the Sienci Labs TLS:

  • Greatly improves productivity for CNC projects that use multiple cutting tools by removing the need to manually re-zero each time the tool is changed
  • Break-away magnetic interface prevents damage to tools or machine in the event of any errors during tool length probing
  • Hardened 45HRC 4140PH probe disc ensures a durable tool probing surface and makes certain wear does not affect probing accuracy
  • Optical sensor provides high accuracy and repeatability, unaffected by temperature like other sensors
  • Flexible mounting allows the sensor to mount directly onto your AltMill or LongMill,  or other CNC other machines.*

The TLS is now available for purchase:

LongMill MK3

Last month we launched the LongMill MK3. We have continued to work on the production for the machine in anticipation of shipping in September this year. Most of our work has been in finalizing some of the mechanical design and pushing to production our fast turnaround parts.

Additionally, we have been finalizing our packaging design with plenty of destructive drop testing.

We also had a livestream to talk about LongMill MK3 engineering, design, philosophy, and more, so if you want to check that out, see below:

SLB-EXT V2 and SLB-LITE

First test cuts using the SLB-Lite
First batch of fully populated next gen SLB boards!

We have continued to make progress in the second generation of SLB-EXT controllers. We have now received another 20 units of samples in early June for continued testing. Here’s some general work

  • Continued work on the firmware configurator tool to allow for users to customize their firmware for their needs
  • Minor fixes to board design and components (namely the fit and sizing of the power connector in this case)
  • Testing of signal consistency and noise
  • Real life testing and cutting with SLB-LITE
  • Work on the expansion board for further functionality
Looking at noise on the 5V regulator

Pricing Changes to gControl Panel Computer

Due to continuing instability in the cost of processors and memory, we are again increasing the price of the gControl panel computer. We are continuing to negotiate with our suppliers, but we expect that pricing will be updated for the following batch of units.

Pricing is expected to be updated as following: USD $529 / CAD $739. Please note that timing of the change and final pricing may vary over time.

As we’ve mentioned in prior updates, we do acknowledge that the cost of the computer is high, and so we are actively working on a longer term computing solution to bring the same or similar functionality at a lower price. This is not to say that the gControl panel computer is overpriced. In fact, for a industrial level, fanless panel computer, it’s quite inexpensive, but we do recognise that not all users need such an overkill piece of hardware.

Testing the budget version of “gControl”

Sensorless Homing

In a bid to reduce component count, reduce costs, and improve overall reliability, we are currently undergoing testing and development in sensorless homing technology in conjunction with our R&D with close-loop stepper motors.

Because of a closed loop motor’s inherent ability to detect when a motor loses steps, we can also use this feature to understand when a motor has reached the limit of its travel. In a traditional machine, a separate homing sensor or switch is used, which is triggered when the machine hits a limit. However in a sensorless homing setup the motor is used to detect the limit. A closed loop motor can do this because there is an encoder and electronics inside that compare the amount of rotation the controller has commanded it to turn versus the amount it actually turned. When there is a mismatch, the motor knows that it’s “lost steps”.

To make sensorless homing work, we need to tune and program the motor to improve the sensitivity of the motor, so that it can detect contact with the machine faster and more accurately. We can do this by varying the amount of power going to the motor, the speed, microstepping, touch off distance, filtering algorithms and more. Additionally, we need to consider the mechanical structure of the contact points.

While this is a bit of a tricky thing to get right, this technology has been proven to work very well in modern 3D printers, to the degree that most 3D printers rely on this technology alone for their homing sequence.

The advantages of sensorless homing is that we remove one of the potential weak points in the machine design, which is the homing sensor. While homing sensors are extremely reliable, due to the added complexity of installing them, the wiring, and the additional hardware, we believe that reducing component count can improve the overall reliability of the machine in the long run. Additionally, while the cost of the switches are fairly low, the cost reduction in removing the ancillary hardware, instructions for installing them, configuration, and more, we believe that we can see some decent cost savings overall.

Naturally, people are going to ask if their existing machines will be able to support sensorless homing. With some generations of motors, it is possible. However this does require re-flashing the motors and may require special tools. If your machine is working well with homing switches, it’s unlikely to be practical to move to a sensorless homing system and there is no practical performance differences when both systems are working well.

Vacuum Table Development

Over the last few months, especially coinciding with the AltMill 4×8, we’ve been working on a vacuum table solution in the background. As we continue to work on more advance systems focused on more professional level applications, we naturally looked to adding a vacuum table system to our machines.

Test patters for vacuum holddown
Testing data for vacuum table designs

Most of our work is currently exploratory, trying to understand:

  • What sort of vacuum pump and architecture we should use
  • How much performance we need and how much performance we can get in different configurations
  • Potential shipping and logistics processes

Sienci Labs will be at IWF Atlanta

We will be at IWF Atlanta! We are working on the planning and logistics for coming down, but we’ll be bringing a few team members down to show case some of our cool products and chat with members of the community.

IWF Atlanta is one of, if not the largest woodworking fairs in the world.

If you’d like to attend, make sure to check out https://iwfatlanta.com

Show dates are Aug 25-28.

June 2026 Production Update

Hey everyone, welcome back to our June 2026 production update!

More Open Positions at Sienci Labs

We have a couple official positions now posted on Indeed as we continue to grow our team. With continual expansion plus the development and release of new products, we’re constantly looking for new people to join our team.

We also have a few positions likely to come online in the coming months as well, including people to join our engineering team for hardware and electronics, additional software developers to focus on gSender development, and an in-house CNC instructor.

If you want to reach out to us because you feel like you could be a good fit with our company, please feel free to submit through our general application form.

Changes to Website Coming Soon

Ever since our beginning, our development on our website has been shared between a few different people in the company, but we never had a dedicated web developer on the team. But now, with the recent addition to our team to work on our website, you can expect to see some updates and changes coming down the pipeline. Our main focus right now is improving the user experience on the customer service side through our Contact Us page, plus the Resources to make it easier to find information faster.

Test site
Example wireframes

LongMill MK3

The LongMill MK3 has now launched! If you want to learn more about it, read our article.

In other news, we’ve been continuing to work on a few things this month, including:

  • Continual design and testing of packaging
  • Development of the SLB-LITE
  • Machine testing
  • Dust shoe design and testing

SLB-LITE and SLB-EXT V2

Packaging samples for the SLB-EXT V2

A lot of work done on the new generation of SLBs, including:

  • New samples of the packaging
  • Testing and development of key features, such as the RGB LED support, Ethernet communication and board expansion design
  • Reliability testing with early prototypes
  • Manufacturing of key components, such as the front and back plates of the controller enclosure
Back panel samples

AltMill 4×8

As mentioned in our last update, we’re in the process of ordering another 300 machines for the new batch. Otherwise we’ve been continuing to do long term accelerated wear testing for the AltMill 4×8, essentially running the machine constantly back and forth 100,000 times at high speed and acceleration, with sudden stops and starts. For context, this is a super extreme condition and we expect no one to ever come close to running it at these conditions.

Here are some of the findings:

  • Change in backlash is essentially non-existent, under 2 thou
  • Motors heat up to 92C, which is close to the 90C limit that the gearbox can handle
  • Besides the bearing retaining ring on the gearbox starting to come loose, all other components are still at the torque they need to be

Overall, this means:

  • Under normal operating conditions, it’s unlikely for users to see any significant decline in performance or accuracy
  • Motors only heat up to their limit at the most extreme conditions
  • We can reduce the chance of the bearing retaining ring coming loose with adding some locktite during assembly. However, given that the machine was run at extreme conditions where the amount of vibration is significantly higher than normal operating conditions, we believe that this is not an issue. We will include in maintenance documentation for users to check the ring during regular maintenance. The good thing is also that when this item becomes loose, it is visually obvious, which makes it easy to address if needed.

Clear Cut Dust Shoe

When we first launched the Clear Cut Dust Shoe for the 80mm spindles, we didn’t anticipate how popular they would be. We had originally set aside around 100 dust shoes for individual sale, which were all sold within a few days. The remaining dust shoes have been set aside to include with the Spindle Kits for the LongMill and AltMill.

We are expecting some more dust shoes to come in in 2 weeks and another batch in August. We will announce very shortly when they will be available again for single purchase.

Spindle Lead Times

Spindle lead times have been long for the past few months, as we received more orders specifically for the 1.5KW spindles than we were expecting. We’re happy to announce that a new batch of spindles have come in and we are working through backlogs. Please check the orders status page for the latest lead times.

Some Interesting Proof of Concept Projects

If you’re interested in knowing what else we have going on, we have a few “proof-of-concept” projects that we worked on in the past month. These are projects that don’t have any commercial direction at the moment, but highlights our interest in pushing the technology further and could be things you may see in the future. We have a lot of different “proof-of-concepts” that we work on, but these were two that I thought were particularly cool.

Perhaps it’s also worth mentioning that when you buy stuff from us, a lot of that money goes back into R&D to develop products and updates that benefits the ecosystem as a whole, so remember that it’s not just an investment you’re making today, but it can impact what your machine and the machines of others can do in the future.

Autofeedrate

One of the challenging things with setting up a CNC for cuts is figuring out the speeds and feeds. With the implementation of “autofeedrate”, we can actively adjust the feedrate in real time based on the load on the spindle. In essence, we can take a current reading from the spindle cable and adjust the feedrate down to optimize the load on the spindle in relation to how much material it is cutting. This means that if there’s more cutting capacity that the machine can handle, it can automatically run faster. Or, and likely more important to the average user, reduce the feedrate before the spindle can stall.

In industry, this is a feature that is used to optimize feeds and speeds in manufacturing, where shaving seconds off the cycle time can result in significant cost savings in a production facility. However, the implementation of this technology can cost thousands, if not tens of thousands of dollars.

The use of autofeedrate in a hobby level setting, on the other hand, would allow users to reduce the amount of guesswork required to set feeds and speeds on their machine, especially due to differences in material, machine, and tooling differences. In essence, one of the challenging parts of providing a streamlined experience in CNCing is the fact that there are so many variables to take into account. By having an active system in monitoring load and adjusting for these factors could help optimize cuts and reduce the knowledge needed to operate a machine.

The exciting part of this technology is that the hardware and sensors needed to implement this can be done on most existing machines and are fairly inexpensive ($20-50). The software and signal processing is the more complicated and expensive part.

gSender on CM4

Up until recent months, gSender has been a fairly processor-intensive program. With recent improvements to gSender, we’ve managed significant speed and reliability improvements. However, we mostly see and expect users to run the program on full scale computers and laptops.

Kevin (one of our senior software developers), has been working on a new proof of concept we are expecting to funnel into a wider development of a more affordable control panel to control grblHAL machines.

To be frank, a solution like the gControl Panel Computer, is expensive for the average hobby user. While we see a big chunk of AltMill users buy the gControl Panel Computer, very few use it with a LongMill. I suspect this has mostly to do with the market that we are serving with the LongMill since it is a lower cost machine.

So what is the gSender on CM4? CM4 is a compute module, or a single board computer. They are generally cheaper than full size computers ($30-100), and are designed more for embedded applications and for light computing. Oftentimes, a CM4 is used as a development platform for testing before going into a full integrated computer design, as they are easy to set up and can be purchased off the shelf.

Since something like the CM4 has much less processing power than something like the N150 Intel processor found in gControl. This means gSender for CM4 needs to be optimized for that level of processing without losing functionality. This proof of concept shows the screenc apture of an optimized version of gSender designed for CM4.

One of the key things to note is the redesign of the UI, which is made to be touch screen friendly and work on smaller screens. In the long term, we expect to implement this solution into a computer that can act as an affordable controller or pendant so that users don’t need to plug in a laptop or buy a gControl for their machine.

Everything You Need to Know About the LongMill MK3

The LongMill MK3 is the successor to our past line of LongMills. Like the original LongMill, its aim is to provide a beginner friendly experience to people who are looking to get into CNCing, while providing enough power and performance to be a productive machine. The LongMill MK3 was designed to address several of the LongMill’s weak points, integrate new technologies, optimize manufacturability and ease of assembly. 

To speak frankly, we designed and we believe that the LongMill MK3 lineup represents the best entry level hobby CNC under $2000USD in terms of performance, design and customer support. We are excited to launch the LongMill MK3, as it represents a huge step forward in the hobby CNC field industry. 

Addressing Weak Points in the LongMill MK2 Design

Having shipped over 10,000 LongMills to date, we’ve experienced the impact of many of the design decisions made for our outgoing model, which has helped shape the design of the new LongMill MK3. Here are some of our learnings and takeaways.

V-wheels. While V-wheels are cheap, forgiving, and generally easy to use and maintain, they come with several drawbacks. First is that they require regular adjustment. The user must maintain a specific amount of tension to ensure that there is no play in the machine movement. This level of variability leads to variance in cut quality and tolerance. The use of linear guides, more specifically the HR15 type linear guides and blocks which are also used in the AltMill does not require adjustment and inherently has very little play, allowing for a more rigid machine. This system does have a small but reasonable drawback, which is that the linear guides must be oiled regularly. However, from our experience with the AltMill, this process is simple and easy enough that the process is easier than maintaining v-wheels.

Lead screws and ACME nuts. The ACME lead screw system on initial MK1 and MK2 LongMill designs also required user adjustment. In this design, the user uses a screw to adjust for backlash in the Delrin nut threads by pushing two halves of the thread apart. This also required the user to regularly adjust as the threads would wear. With the MK2.5 design, we implemented spring loaded anti-backlash nuts to the existing lead screw system, which eliminated the need for this adjustment, as the springs would automatically take up slack as the nuts wore down. We chose to stick with the ACME lead screw system over a ball screw system, largely due to cost. A ball screw system requires additional bearing blocks and hardware, and generally does not allow us or the user to cut the rails and lead screws to different lengths to allow variations in sizes like the LongMill does. The existing lead screw system is more than precise enough for the application and allows us to keep the LongMill MK3 at a lower price point.

Open-loop steppers. Due to the nature of open-loop stepper motors, when the LongMill stalls or misses steps, the machine continues cutting, making it difficult to salvage projects. The use of closed-loop steppers means that the machine can detect when it’s lost its position, so that it can pause the cutting job and allow the user to rehome and restart the machine. Closed-loop stepper motors are generally also more efficient and can run faster with more torque, which means that we can run the LongMill MK3 faster and harder than the LongMill.

Implementing New Technologies

The development of the AltMill has allowed us to “trickle down” some of the parts and innovations into the LongMill MK3. While HR15 Linear Motion components are more expensive than v-wheels, due to the larger economies of scale, we are now able to purchase and use them for the LongMill MK3 while keeping a similar BOM price as the LongMill. 

Additionally, our work in creating and improving assembly processes allows us to utilize some of those techniques in the LongMill MK3 as well. We also are using the same types of closed-loop stepper motors and the SLB-LITE controller, which is also possible due to the high volumes of motors we are already buying for the AltMill. 

Work in features and improvements in gSender and GRBL-HAL also play a key part of the overall user experience with the LongMill MK3, including stronger integration of an independent 4th axis, auto-squaring, gcode editing, granular control of EEPROM settings, and the use of a tool length sensor. While these features are now available for legacy LongMill users, the LongMill MK3 specifically prepares the use of the machine with the new features in mind.

SLB-LITE 3D Render - Thumbnail
SLB-LITE 3D Drawing - & Ports Cables

Another key development that was created with the LongMill MK3 in mind is the AutoSpin T1 router. While we’ve been selling and recommending the Makita RT0701 for many years, we developed the AutoSpin T1 to be a successor to it by not only bringing a higher standard of quality and durability, but also the ability to control the router on-off, and speed. Overall, this allows the machine to be closer in functionality to higher end machines that use traditional spindles at a fraction of a cost. The LongMill MK3 was designed specifically with the AutoSpin T1 in mind.  

Improving Manufacturability

We’ve made significant improvements to the manufacturability of the LongMill MK3 primarily through reducing the number of unique parts and pre-assembly of certain components.

The LongMill MK3 contains approximately 30 unique components, which is a 25% decrease from the LongMill MK2. We were able to do that by:

  • Eliminating the need for rail feet by having the LongMill MK3 Y rail screw directly into the wasteboard
  • Using T12 hardware across all axis, rather than using T8 on some and T12 on others
  • Integrated mounting points for the drag chains
  • Integrated motor and sensor cables

While decreasing the bill of materials by 10 unique components might not sound like a lot, this eliminates a lot of work including supply chain and sourcing work, QA, documentation, and even resource development. We are also able to purchase larger quantities of parts, which helps improve our economies of scale and bringing the overall cost of the machine down. 

Improving Ease of Assembly

The LongMill MK3 substantially increases the ease of assembly with more of the machine assembled in house. We’ve chosen to move in this direction because:

  • It eliminates a lot of packaging, as we don’t need to individually pack items into boxes and bags
  • We can perform more QA checks through the assembly process by ensuring that parts come together with the proper fit and finish
  • Tools and processes implemented in the production and assembly of the AltMill product line allow us to speed up the process of assembly for the LongMill
  • We can reduce the amount of development needed for assembly resources
  • The time that the customer needs to assemble the machine is significantly lower

Like the AltMill line, the LongMill MK3 will be manufactured and assembled wholly in house at our shop in Waterloo Ontario, which allows us to keep a close eye on quality throughout the whole batch.

Additionally, as we mentioned earlier, there are way fewer unique parts, which means that for the parts that the user does need to self assemble, this process will be easier overall. Based on our testing, we expect users to be able to assemble and set up their machines in less than an hour, 2-3 times faster than the outgoing generation.

Competitive Landscape

Since the original LongMill launched in 2019 and especially in the past year, we’ve seen a ton of new launches for beginner friendly CNC machines, some from the Chinese market and some from the North American market. 

With CNC technology becoming more accessible and affordable, we’ve seen a lot of growth in the beginner and hobbyist market. This gives us a lot of new insights on what we think works and doesn’t work. 

A move away from belts and wheels: Earliest hobby CNC machines used belts and wheels in their motion system. While cheap, these components require adjustment and lack the rigidity that hobbyists expect today.

Pre-assembled/partially assembled machines: Users expect machines to be much easier to assemble, with most machines pre-assembled or partially assembled, requiring the user to only need basic assembly and wiring to complete the machine.

Closed-loop motors: While at the moment, most hobby CNC machines still use open-loop motors, we expect to see a shift towards more closed-loop motors for their performance advantages. As we discussed in the article about the Closed-Loop Stepper Motor Kit for the LongMill MK2 (https://sienci.com/2025/12/15/everything-you-need-to-know-about-the-closed-loop-stepper-motor-kit/), we’ve seen prices come down for the components needed for closed-loop stepper motors as they become more popular in CNC machines.

Performance Differences

With the conjunction of closed-loop steppers and thicker lead screws, we are able to push the rapid speeds of the LongMill MK3 to almost double the speeds of the MK2. 

LongMill MK2 

  • X and Y default max rapid speeds = 4000mm/min, 157IPM
  • Z default max rapid speed = 3000mm/min

LongMill MK3

  • X and Y default max rapid speeds = 7000mm/min, 275IPM
  • Z default max rapid speed = 6000mm/min, 236IPM

Rigidity

The performance of any CNC machine depends a lot on the overall rigidity. Based on our testing, we are able to see between 60 to 80% improvement in overall rigidity of the machine. This means that not only can the machine move faster, it can handle the extra power. In practice, this means shorter cutting times, cleaner results, and more reliability overall.

Comparison at 25N/5.62lbs
Positive X (thou)Positive Y (thou)
LongMill MK2 48×30 (extrapolated)710
LongMill MK3 48×304.58
Difference (thou)2.52
Difference (%)64.29%80.00%
Comparison at 50N/11.24lbs
Positive X (thou)Positive Y (thou)
LongMill MK2 48×3014.220.7
LongMill MK3 48×301011
Difference (thou)4.29.7
Difference (%)70.42%64.29%

Pricing

Pricing and sizes for the LongMill MK3 series will be approximately the same as our prior generation machines:

  • LongMill MK3 30×30 ~$1400USD or $1890CAD
  • LongMill MK3 48×30 ~ $1800USD or $2430CAD

We’ll once again be offering a bundled Beginner’s Kit, which will include the AutoSpin T1 router, an AutoZero Touch Plate, a dust shoe and some end mills, This bundle will offer savings around $100CAD/$110USD vs buying these accessories separately.

Please note that pricing may change slightly at launch/production.

Production Schedule

Pre-orders are expected to open up May 26, 2026 at 11AM EST.

When pre-order opens we will share an expected shipping date, which is looking like mid-to-late August, possibly early September (at the time of this Blog). We are currently in production for 1000 units.

Stay tuned for announcements in three weeks.

 FAQs

Will I be able to upgrade my LongMill MK1, MK2, or MK2.5 to the MK3?
Practically speaking, no. The LongMill MK3 is a complete rework of the design and so the cost difference between buying a new, full machine and doing an upgrade would be negligible. 

Can I use a spindle with my LongMill MK3?
Yes, you can use the same spindle kit that we currently offer for the LongMill MK2.5 on the LongMill MK3 with essentially the same installation instructions. It should be noted that since the spindle is larger, users may lose some travel in the X.

If I buy a 30×30, can I upgrade to a 48×30 later?
Yes, we will make the parts required to increase the size of the X axis to turn a LongMill MK3 30×30 to a 48×30 available. However, we do not currently have specific plans to have them available at the time of launch.

What is the difference between the LongMill MK3 and the AltMill?
We built the LongMill MK3 with entry level/beginners on a budget in mind. The AltMill is aimed more towards pro-sumers and semi-industrial use. For a full comparison, check out our video:

Is the LongMill MK3 compatible with the Makita RT0701?
Yes it is, and all LongMill MK3s will come with a 65mm mount. Please note that you may need to use an extension cable for the Makita RT0701 to pass through the drag chains.

Does the LongMill MK3 support Sienci Labs’ accessories?
Yes, any accessories from the LongMill MK2.5 and prior will work with the LongMill MK3, with the exception of dust shoes, which have been design specifically for each machine.

Can you tile/pass sheets through the back of the machine?
Yes, just like all other LongMills, the rear of the machine is open and you can pass larger sheets through the machine. It should be noted that you may need to position or route the Y motor cable in a way to prevent interference with material if you do choose to do tiling.

Can you mount the LongMill MK3 vertically?
Yes. With the substantially stronger motors and larger lead screws, we expect essentially no performance drawbacks in mounting your machine vertically.

What will support look like for owners of LongMill MK1, MK2, and MK2.5 machines?
Support will continue to be largely the same. We have stockpiled between 3-5 years of spare components to support our users of older machines, and open source design files and specifications are available through the respective resource pages of each machine to allow users to source alternative components if necessary. Otherwise, technical support will remain the same between all of the different versions of the machine.

May 2026 Production Updates

Welcome back, it’s our May production updates! We got lots of great news for you.

Chris Thorogood Leaves Sienci Labs as CTO and Co-owner

This past April, Chris Thorogood, our CTO and co-owner left the company. You can read more about the exit here: https://sienci.com/2026/04/29/%f0%9f%91%8b-blog-post-to-say-goodbye/

More Space Expansion

Back in the March 2026 Production Update, we mentioned that we added about 2500sqft of production space to our shop. I’m excited to announce that our office expanded again this month by another 3500sqft. This includes around 2100sqft downstairs, which used to be a large boardroom to be turned into media space, where we’ll use as a dedicated filming space for the marketing team. We’re also looking to potentially host classes and events there down the line as well.

The upstairs ~1400sqft is expected to be used primarily as desk space, with some focus for the customer service team, as the space has a couple of enclosed offices, which should allow them to make and take calls in a quieter environment.

AltMill 4×8 Now Shipping

We are excited to announce that starting April 16th we started shipping the first batch of AltMill 4x8s! A huge congrats to the production and engineering team for working diligently to iron out any last minute QC issues, as well as the customer support, marketing, and resource teams for pulling together the resources for the use and assembly of the machine.

For all of the machines that have been ordered, please check our Order Status Page for estimates on when your machine will ship. We are expecting new orders for the AltMill 4×8 to ship in August, so lead times remain long for the time being. The new batch (batch 2) is expected to have 300 units.

Youtube videos on the complete assembly of the 4×8 are now out, so make sure to check those out!

ATC Now Shipping

Extra exciting news is that the ATC is now shipping as well since April 16th! Again, a huge accomplishment for all of the teams at Sienci Labs for pulling off what is probably our most complicated project to date.

Our first batch of ATCs have sold out, and we are now in production for another batch. We are expecting orders for ATC placed today to start shipping in June. We are nearly sold out on our second batch of ATCs as well. If you order in our third batch, we are expecting those to ship out Aug-Sept. Please see our latest Order Status updates for lead times.

As you may or may not know, we also designed a TLS (tool length sensor) for the ATC process, but we’ll have those for sale to accompany regular spindles as well, so keep an eye out for that. This has been a feature a lot of people have been asking for.

Videos for ATC are also now out, so feel free to check those out as well!

gSender and Firmware Updates

There is a new major release of gSender! Check out the full blog post here: https://sienci.com/2026/04/16/gsender-1-6-0-release/. gSender 1.6.0, now the latest version of gSender comes with a huge number of improvements, such as faster loading times, a built in gcode editor, and new EEPROM settings manager, but also comes with new features required for operation of the ATC and AltMill 4×8 functions. This also aligns with updates to the firmware coming out, mentioned back in January. We are shipping machines now with the new firmware to ensure ATC support, and users will be provided with resources for updating their machines to new firmware in the ATC resources.

LongMill MK3 Development

LongMill MK3 development continues to chug forward. Most of our work this past month was tweaking the design, general testing, packaging design, and planning for the resources development. As mentioned at some point in one of the updates, we are expecting to open pre-orders late May, with shipping expected to start around mid to late August. Keep an eye out for the “Everything You Need to Know About the LongMill MK3” blog releasing this week as well.

A couple of key directions we’re looking to go down at the moment include:

  • More of the machine pre-assembled in house, which means faster set up time for the end user
  • Streamlined packaging, since less bags and boxes required when parts are already assembled into units

SLB-LITE/SLB-EXT V2

Development continues to move along for the SLB-LITE and SLB-EXT V2. We have now been doing testing and troubleshooting for the new boards for the last few weeks and working on tweaking the design for the second version.

Things done this month include:

  • Design and production of pulp molds for packaging
  • Ordering of mounting bushings and other parts needed for case assembly
  • Ordering of e-stops
  • Initial test production batch of 200 PCBs, and if no issues, we’ll push for the full batch (around 1000 controllers)

Otherwise we expect to be continuing testing and design work for the new controllers into May and June.

Ontario Safety Compliance for AltMill and LongMill Machines

Hi everyone, as you guys may know, we had been working with ESA on the safety compliance for the VFDs in 2025, which was eventually completed for sales in Ontario. We are now working with ESA on the compliance for power supplies used in LongMill and AltMill products within Ontario. For customers outside of Ontario, feel free to skip this notice, as this is only limited to within Ontario. If you are within Ontario trying to make an order for the LongMill or AltMill, you may receive a notice at checkout.

Starting April 29th, we’ll be pausing sales for the LongMill and AltMill for customers in Ontario. Please read further on specific plans for each machine.

LongMill MK2.5

Given that we have a small number of machines left for the LongMill MK2.5, it’s likely that we will be clearing out of this stock before having a prepared power supply. However, the upcoming LongMill MK3 which is expected launch soon, and will be safety compliant for use and sale in Ontario.

AltMill

Since we are expecting to continue production and development of the AltMill, we have been working on a new power supply design around the safety compliance over the last few months. Based on our development timelines, we expect this to be complete around August 2026.

What if I am in Ontario and want to purchase an AltMill or LongMill?

Please contact us directly for additional support as we may be able to provide you with a one off power supply for temporary use that is safety compliant or hold your order until certified power supplies are ready to ship.

April 2026 Production Updates

It’s another month, another production update!

Notes on customer service times

First off, I just wanted to mention that the last couple of months have been pretty busy on the customer service and support side of things, especially as we were coming down from our busy winter season, which meant that response times were a bit longer than usual. I’m happy to share that we did bring on another support person to our team with a lot of hands on experience being a former customer, which means we now have five full time staff for customer support, plus, some of our engineers and product management team also involved in the customer service and resource development.

We’ve now caught up on tickets and replying back on our typical timely manner.

With the AltMill 4×8, ATC, and a bunch of other stuff going through our pipeline, we anticipate our demand for support to continue to grow, so if you’re interested in joining our customer service team, feel free to share with us here: www.sienci.com/work

AltMill 4×8

Mike presents the upcoming timeline in the company townhall

We have been full swing on AltMill 4×8 production, with a bunch of stations now set up for assembly of the new machines. However, we have been delayed a few weeks, and current first machine shipping date is set at April 10th April 17th. Due to some components being off tolerance and needing rework, we are putting extra effort to make sure that the first batch of machines don’t have early stage issues. Some things that are being addressed include:

  • Pitch error on the racks
  • Tooth profile tolerances on the pinons
  • Gearbox backlash

On the bright side, we have ordered enough extra parts so that even with a higher than typical number of QA rejects, we are able to fill a substantial number of the first batch. We are also working on remaking parts to ensure that we can complete the rest of the production batch. We are building and assembling as much as we can as we work through the process in the meantime.

We are also now in production of batch 2, bringing additional considerations and QA processes to reduce potential issues and delays.

In other news, the engineers and marketing team have been working on putting together the full assembly resources and videos over the last few weeks, getting ready to post once the machines start shipping.

Filming and creating content for the assembly process
Assembled units for the gearbox and swing arm mechanisms

LongMill MK3

A lot of work/progress so far with the LongMill MK3, with most of the work done around general testing and reliability.

We have now completed a round of rigidity testing to compare between the LongMill MK3, LongMill MK2, and the AltMill. Check out the results on our blog. (TL;DR) = the LongMill MK3 is between 65-80% more rigid than the LongMill MK2, signifying a big jump in performance.

In other news, we continue to work on the development and production of the LongMill MK3. We have now ordered the majority of the components needed, with the exception of controllers and power supplies which are still in development. Based on current timelines, we expect to open up pre-orders mid-May, and start shipping in and around July.

Deflection testing on the LongMill MK3

In other news, we’re clearing out of the last set of LongMill MK2.5s . We have around 50 of the 30×30 and 50 of the 48×30 in stock, so if you are looking to get one of those machines, they’ll probably still be available for the next few weeks before we sell out.

SLB-EXT V2 and SLB-LITE

We have made a few key decisions around the SLB family of controllers. First, naming:

SLB-EXT V2: The new successor to the original SLB-EXT currently used on the AltMill. The SLB-EXT V2 is designed specifically for the AltMill and power handling of 48V.

SLB-LITE: Designed specifically for 24V architecture of the LongMill.

Wire management with the new SLB-EXT case

Our first prototype boards have been produced! We will go through initial flashing and testing of the new board over the next few weeks in April, and make revisions as needed before going into production.

First prototype boards

Additionally, new molded cable samples have been made with a nominal width of 7mm, over our current nylon sheath design with a width of 10-12mm. Why did we unify all of the cables into one mold? Because:

  • Simplifies wire management
  • Makes wiring of the machine during the assembly process more intuitive
  • Allows more space in the drag chain for additional cables and accessories

Auto Tool Changer

The ATC production is now in full swing as we get prepared to ship out existing orders. We have set up production stations to start with assembly and we are building our first units now.

Unfortunately we are continuing to work on a few straggling details in preparation for shipping, and we expect that we will begin shipping in the third week of April. Some outstanding tasks include:

  • Completion of the resources and installation guides
  • Completion of the new firmware testing

Otherwise the completion of the hardware production and assembly for the first batch of ATCs are scheduled to complete on April 10th April 17th, in tandem with the 4x8s.

I’m also excited to share that we’ve also implemented a new station with the ATC to machine some aluminum parts in house. We’re expecting to slowly integrate more parts over time that we can machine in house to give us an opportunity to stress test our machines and products, as well as give us more production flexibility or adjust designs more quickly as needed.

Nini prepping ATCs for testing
Ethan checking for Tool Rack defects with a jig
Next step is testing before shipment

Rigidity Testing on the LongMill MK3

Testing the amount of deflection a machine experiences at different loads, aka the rigidity, is a good way to predict the overall performance of a CNC machine. When it comes to using a CNC machine, two primary objectives are to make the part accurately and quickly. One major contributing factor to the precision of a part has to do with how much the end mill deflects away from the programmed path. The end mill on a more rigid machine will deflect less than on a less rigid machine given the same feeds and speeds, and thus produce a part that is more accurate. Alternatively, a user can run their machine faster while still producing a part of acceptable quality on a more rigid machine.

A diagram showing the effect of tool deflection and how it affects the geometry of a simple part

Perhaps a common example of how this affects a simple part of a CNCed design would be holes. Holes cut on a CNC machine tend to come out undersized, because the material on the walls of the hole push the machine and endmill towards the center.

It should be noted that deflection exists in all machines, it’s just a matter of how much. To improve tolerances, it’s common to do a “roughing” pass, which removes the bulk of the material, and then a “finishing” pass, which removes a small amount of material at the end, minimizing deflection to bring the part to final shape.

The state of the market & why we’re sharing results

As we discussed in one of our prior blog posts, there isn’t, as far as we can tell, a standardized method for testing machine deflection in the hobby CNC space.

We are able to glean general comparisons between our machines and other machines in the market by test results posted by other members of the community. As time has gone on, here are some of my personal opinions on why that is the case:

It’s hard to give context on what the rigidity numbers mean.

For most of the practical testing range, deflection is not visible to the naked eye. A lot of times, people will demonstrate standing on their machine as a demonstration of rigidity, maybe even standing on it while it’s cutting. This doesn’t really show how rigid the machine actually is, because you can’t see how much the machine is deflecting from a distance.

Additionally, just because a machine is bigger and heavier doesn’t necessarily mean that it has less deflection. Some areas of a machine’s design can affect the overall accuracy of the machine, even though it may seem insignificant at first glance. For example, from our comparisons between computer simulations and real life testing, we’re able to see that things like bolt tolerance and mechanical components shifting around under load can actually play a pretty big role in the overall deflection values. All this to say, you could have a super rigid machine, but have a weak or loose part of it, just that one part alone can have a major impact on the overall machine rigidity.

Rigidity is less important that we think it is.

Owning and using a CNC machine isn’t just about how rigid or fast it cuts. The whole experience is important, from the setup, assembly, software control, and overall reliability. For the average hobbyist, if a CNC project takes 45 minutes to cut instead of 30, does it really make a huge difference?

Return on investment in a higher degree of engineering requires high volumes to experience

Lastly, with us expecting to build a very high volume of CNC machines, a small design improvement affects a lot of users. For machines built at lower quantities or DIY machines, it’s cheaper and easier to over-engineer the machine rather than optimize it, since the cost of engineering time is higher than the cost of buying bigger or better components.

Testing process

We built a simple testing jig using old prototype parts from the LongMill MK3. We have a force gauge on the moving gantry and the dial indicator on the other. When we turn the lead screw to push the force gauge against the router, it moves the dial indicator some amount. The more that the dial indicator moves, the more the machine is deflecting.

Getting straight to the results & comparisons

As we can see from our results below, we have around 65-80% improvements in rigidity between the LongMill MK2 to the LongMill MK3. 

(Past Data and writeup for the LongMill MK2 from 2022.)

LongMill MK3 48×30
Force Applied (N)Force Applied (lbs)Positive X (thou)Negative X (thou)Positive Y (thou)Negative Y (thou)
255.624.5589
5011.2410101112
7516.8616151718
10022.4822212425
AltMill 4×4
Force Applied (N)Force Applied (lbs)Positive X (thou)Negative X (thou)Positive Y (thou)Negative Y (thou)
255.621111
5011.242343
7516.864455
10022.487667
LongMill MK2 48×30
Force Applied (N)Force Applied (lbs)Positive X (thou)Negative X (thou)Positive Y (thou)Negative Y (thou)
102.2482.8NA3.2NA
255.62~7NA~10NA
5011.2414.2NA20.7NA
Comparison at 25N/5.62lbs
Positive X (thou)Positive Y (thou)
LongMill MK2 48×30 (extrapolated)710
LongMill MK3 48×304.58
AltMill 4×411
Comparison at 50N/11.24lbs
Positive X (thou)Positive Y (thou)
LongMill MK2 48×3014.220.7
LongMill MK3 48×301011
AltMill 4×424
Comparison at 25N/5.62lbs
Positive X (thou)Positive Y (thou)
LongMill MK2 48×30 (extrapolated)710
LongMill MK3 48×304.58
Difference (thou)2.52
Difference (%)64.29%80.00%
Comparison at 50N/11.24lbs
Positive X (thou)Positive Y (thou)
LongMill MK2 48×3014.220.7
LongMill MK3 48×301011
Difference (thou)4.29.7
Difference (%)70.42%64.29%

Expected Loads

To get an idea of what sort of loads a machine will experience in cutting:

Basic glossary

Axial engagement (AP) = depth of cut

Radial engagement (AE) = stepover/width of cut

Linear feed (VF) = feedrate

Transverse force = forces perpendicular to feed

Feed force = force needed to push the bit through the material

Axial force = up and down (in the Z axis) forces

Generic ¼” end mill

For a list of recommended feeds and speeds for our general selection of end mills, please see our guide here: https://resources.sienci.com/wp-content/uploads/2022/10/FeedsSpeedsMetric.pdf

Settings based on recommended feeds and speeds

Settings based on recommended feeds and speeds

Same settings as above but with a 6.35mm step down

Same settings as above but with a 6.35mm step down

Same settings as above but with 6.35mm step down and 6.35mm step over (full slot)

Same settings as above but with 6.35mm step down and 6.35mm step over (full slot)

We will refer to some of these values in our discussion below.

Balancing machine performance and cost

Building a machine to be rigid and powerful is easy, but making a machine rigid and powerful on a budget is hard. To optimize the design of a machine, we take many factors into account. 

Acceptable deflection

As my electrical engineering professor used to say, in science, 5 = 5, but in engineering, 5 = 5, plus or minus a tolerance, which is to say, whenever we cut out a part, we should expect some deviance in the size of that part, and we need to decide and understand how much deviance we can accept. 

In the scope of woodworking, I believe anything under 0.005” (5 thousandths of an inch) to be “very very accurate”. For context, 0.005” is 6.25x smaller than 1/32”, or about a sheet and a half paper thick. 

LongMill MK3 48×30
Force Applied (N)Force Applied (lbs)Positive X (thou)Negative X (thou)Positive Y (thou)Negative Y (thou)
255.624.5589
5011.2410101112
7516.8616151718
10022.4822212425

If we look at the range of deflection at different forces, we can determine that we should aim to keep forces to under 25N to be within the 0.005” deflection range. 

Motor power

In our testing, we also measured the maximum force that the motor can apply to each axis. On the X axis (one motor), we measured the force to be around 600N, or 135lbs. On the Y axis, 256lbs.

Each motor must resist internal machine forces, such as the friction from the lead screws, bearings, and linear guides, as well as control the inertia of the machine itself. Additionally, the motor must push the end mill through the material at varying forces.

The mean and peak feed forces from Millalyser give us an idea on what those forces are (3.8N-10.4N). Based on these calculations, the motor forces are far higher than the expected loads from cutting.

A few notes:

  • We have 1.2NM motors on all axis, which will be the same as the ones used on the LongMill MK3 in production.
  • We used a 48V power supply, instead of a 24V power supply in production

Given how much more powerful the motors are, we believe that running the machines in 24V will not make a difference in overall performance. Because the 24V power supply and SLB-LITE designed specifically for the LongMill MK3 is significantly less expensive than the 48V architecture used on the AltMill, it makes sense to go down this route.

Spindle/router power

Through our AutoSpin T1 project, we did a significant amount of testing and research around spindle and router power, even going as far as building our own dynamometer to test true power output of different routers and spindles. Millalyzer also gives us an idea on the range of power draw needed from the router, ranging from 68.6 watts to 234.8 watts. 

The green line shows that the Makita RT0701 can push around 1600 watts of power until dropping down to around 350 watts of power at 32,000RPM. A typical 1.5KW spindle progressively increases power output as the RPMs get higher.

We can ensure that the spindle or router used with the LongMill MK3 is capable enough by comparing the estimated power draw from Millalyser to our measured output line. In either case, both the Makita RT0701 or 1.5KW spindle is more than capable of producing enough power. 

Our LongMill 1.5KW spindle kit costs around $650USD versus AutoSpin T1 is around $150USD, which is a 4x difference. Users can use either option, but we believe that the AutoSpin T1 is adequate for this application with the added benefit of the lower cost.

AltMill vs LongMill MK3 comparison

As it stands, the AltMill is approximately 2-4x more rigid than the LongMill. This is largely due to:

  • Thicker and heavier structure on the AltMill
  • Higher mass of the machine on the AltMill 

If performance and rigidity is very important to you, the AltMill does provide much more in that way. 

There are some practical considerations to make when it comes to actual differences in cutting, such as:

  • This is something I learned people call the “pucker-factor”, which is that people may not be so inclined to push their machine as hard as they can because of a lack of confidence.
  • Tools have a limit to how hard they can cut because they can deflect and break as well

Overall, I expect the practical cutting performance of the AltMill to be around 2x of the LongMill MK3.

If you’re cross shopping between the LongMill and AltMill, here are the prices to consider:

LongMill 30×30 ~$1390USD or $1870CAD

LongMill 48×30 ~ $1790USD or $2410CAD

AltMill 2×4 ~ $2790USD or $3890CAD

AltMill 4×4 ~ $3160USD or $4290CAD

…so between LongMill MK3 48×30 vs AltMill 2×4, which I think is the closest comparison based on working area, the price difference is around $1000USD, or comparing the 4×4, $1370USD.

We should also note that the AltMill also requires a spindle, larger tooling, and higher power dust collection to get the maximum performance, which can increase the cost difference when comparing between total setup costs.

Conclusions

With improvements to the machine rigidity and motor power, we expect users to be able to cut much faster and reliably compared to the LongMil MK1 and MK2. A significant amount of work and consideration has been made to improve performance overall while keeping the price the same as the older generation.

While this article only covered testing around rigidity, make sure to stay tuned on discussions of other improvements for the LongMill MK3, including easier assembly, maintenance, and electronics as well!

We hope you enjoyed this report on the LongMill MK3 design and performance!