AltMill and LongMill Survey Results and Development Progress

Hi everyone. Thank you to everyone who took the time to fill out our survey. We received an overwhelming amount of responses which has helped us get a better understanding of what our users are looking for in a new machine. Here’s a bit of a breakdown and a report of what we learned from your responses.

General learnings

As expected, almost all of our respondents shared that they used their CNC machines for woodworking. Also as expected, almost all respondents expressed interest in increasing the working area of their machine.

I was very happy to see that most respondents use their machine actively, with the approximate per week usage for most users being 15-30 hours per week. About a third of our respondents who use a LongMill reported that they use their machine 20 or more hours per week, which suggests that many of our users use their machines in small-scale production.

As we get into larger machines, power becomes more of a concern. We initially were worried that people would not have access to 220V/240V power in their shops (at least in North America), but it appears around half of the respondents who chose to answer this question have access to 220V outlets. This indicates that we should consider supporting both 110V and 220V spindles in future machine designs.

Interest between the AltMill and the Extended LongMill


We see about a 60/40 split in overall interest between the two machines. For LongMill users who are interested in upgrading from a LongMill to an AltMill shared these common sentiments:

  • Want to have a more rigid machine, generally to be able to use spindles and cut faster
  • Want to have integrated limit switches or homing switches
  • Want to be able to handle larger projects and half sheet
  • Want more speed
  • Have some complaints about parts such as the v-wheels and delrin nuts

For LongMill users that are interested in extending the size of their machine shared these sentiments:

  • Heavily value the community support and affordablilty of the LongMill in its current state
  • Would like general improvements to rigidity and design of the machine
  • Want a way to tram
  • Improvements to the v-wheel and eccentric nut system

Many people indicated an interest in a spindle option for both the LongMill and AltMill. The AltMill will be designed and compatible with spindles. While we don’t currently recommend using a spindle with the current design of the LongMill’s Z-axis because of weight and size, one option we are exploring is to build the XZ axis assembly for the AltMill to be compatible with the LongMill. This should let us be able to share development efforts for the assembly across both machines. Allowing additional cross-compatibility between motors and electronics between LongMill and AltMill should also make it possible to upgrade more aspects of the LongMill as well.

Development progress (LongMill)


We’re excited to share that we’ve gotten our first batch of custom aluminum extrusions in for the new iteration of the LongMill. These rails were made for our prototyping and beta testing before starting a larger production batch.

We are planning on using custom extrusions for the next generation of LongMills. We’ll refer to them as LongMill MK2s (at least for now). The goal with this generation is to provide the same straightforward, rigid, and affordable machine at the current sizes that we offer, but allow us to provide extended versions of the machine.

I think it’s important to talk a bit about custom extrusions, as it is a big departure from our original angle aluminum design.

When we first started Sienci Labs, we found that using angle aluminum turned on its side provided a sturdy, simple, and affordable way to create a linear motion system. Given that aluminum angle extrusion was readily available off the shelf, we were able to create both small and large batches of rails quickly and easily, without worrying about custom tooling and MOQs. I would attribute this factor as an important reason for getting us to this stage in our company, as we were able to continue to scale our production as we continued to build more CNC machines.

Creating custom aluminum extrusion was always on our mind, but until recently, it was not feasible for us due to cost, and the volume we would need to make didn’t make sense at our scale. At today’s scale, we’ve learned some important things that justify making our own extrusions.

The first area to talk about would be the accuracy of rails over high volume. Since last year, we encountered a new problem. While all of the angle aluminum we had received in previous batches were made to high tolerances, we had received a new batch of material that varied in the length of each arm and angle, causing less than an optimal fit of v-wheels. This gave us an opportunity to look deeper into tolerances in extrusion manufacturing as well as performing additional quality checks to ensure each rail was made to a high accuracy. We also learned that it would be a reality that at high volumes, it would be important to ensure we tackle issues at the production side with our manufacturers, since we couldn’t trust them to make every rail perfectly unless we provided the correct specifications for the rails.

This lead us to make our own “custom” angle aluminum. Basically, we arranged production of the angle aluminum using a new die made specifically for us at a higher tolerance than the industry standard, as well as extruding the material at precision spec. With these changes, we were able to reduce the number of out-of-spec rails to near zero. This also set up a better understanding of the extrusion process and the process and costs involved in it. It also gave us a chance to work with the extrusion manufacturer to work out design kinks and set us up for future development.


Today, we use tens of thousands of pounds of aluminum a year to make our rails, way beyond practical MOQs for producing custom extrusion. We are able to spread the cost of the dies over the thousands of rails we produce to make it an affordable option as well. So financially and scale-wise, custom extrusion is a feasible option. So let’s talk about why custom extrusion makes sense, and some cons/downsides as well.

Improved performance

Designing our own custom extrusions lets us create a design that is more optimal for rigidity than angle aluminum. Chris conducted dozens of simulations and tests to find the most optimal designs for the new rails. Based on the results, we can expect 2-3 times less deflection in the rail than the original design. I would note that these are simulations, and real-life results are likely to show less of a difference since the numbers do not reflect deflection from v-wheels, linear guides, and other parts in the machine.


This is especially important as we continue the development of larger versions of the LongMill since longer rails inherently have more deflection.

Ease of assembly

The new extrusions also include additional features that will make it easier to assemble and require fewer parts. For example, by including tapped holes on each face of the extrusions, users will be able to mount the rail to the gantry plate without any brackets. Each rail also has a t-slot, so all drag chain components can be mounted without additional tapped holes. Overall this will reduce the number of fasteners needed, the number of unique fasteners, as well as assembly time and complexity.

Improved scalability

Although time will have to tell, we expect that the new rails will be easier to produce at a larger scale. Since we already need to custom manufacture our own angle aluminum, lead times for both the angle aluminum and custom extrusion are the same. Since the custom extrusion requires less machining, we expect it to be slightly easier and less expensive to process the rail after it has been extruded. Also, since the rail requires less parts and a lower number of unique parts to put together the overall machine, it will save time and effort in sourcing and purchasing as well.

We are also working on cutting and tapping rails in-house, allowing us to have more flexibility in the sizes and variations in the machines we produce as well.

Less production flexibility and a step away from replicability

Since angle aluminum is a fairly universal product that can be purchased off the shelf, a determined maker should be able to replicate the rail design of the LongMill and make their own custom machine from scratch. It would be much more difficult to replicate the new custom extrusion, as the costs to produce a small number of rails are incredibly high. This, I feel, is a step away from the openness of the platform. We will continue to fully open-source the designs as we have always done, but part of the open-source movement is considering the replicability of the product. This was an important consideration when we started this development, and these are some considerations and why we made this step:

  • The number of people who make their machine from scratch is incredibly low. While there are people who use the LongMill design to make their own machine, making the designs available for this purpose serves a very small population.
  • The net benefit of having a simpler, better machine that is more easily scalable provides more benefit in our goal to make CNC accessible to beginners than to have a machine that can be made from scratch.
  • Most people who make modifications to their machines generally do it after they purchase and assemble a manufactured kit. Continuing to make the design public will continue to support people who wish to simply modify a kit
  • Building a machine from scratch generally costs more and will not perform better than a stock LongMill. We have extensively optimized the design and put an insane amount of thought and consideration to the quality of each part. Parts such as the couplers, Delrin nuts, and even the 3D printing filament are all custom made specifically for us at a higher tolerance than off the shefl components. Since we work within high volumes, we are also able to take advantange of economies of scale that do not come with buying parts in small numbers. Because of this, I believe that folks who want to build a machine from scratch would only benefit if they plan on making extensive changes to fit a specific need, or are doing it for the fun of making the machine. There are of course other designs and options that people can build besides the LongMill that lend itself in being made from scratch.

Backward compatibility

While the rails have been designed to be as backward compatible as possible, and many of the old LongMill parts can be used on the new rails, this brings up another important debate, which is “is it better to take apart and modify an old LongMill to put new parts on it, or is it better to buy a new one?” This is what I think.

First of all, if you already have a LongMill and are happy with the current size of it, I believe that keeping it the way it is and continuing to use it is the best option. While the newer versions of the LongMill will perform better, not only does the current version work well already, the extra cost to switch over parts isn’t worth the extra performance you may get. Instead, investing in other things, such as better tooling, software, and materials for projects may give a better return on investment. It should also be noted that the price of the MK2 LongMill will be higher than the current LongMill, so that we can account for changes in material prices, cost to build the machines themselves, and inflation.

If you are wanting to upgrade the machine to a larger size, then the debate gets a little more tricky. If you take apart your old LongMill to swap in new rails and lead screws, you’ll be left with a lot of leftover parts. Instead, it may make more sense to sell the LongMill and buy a whole new machine instead. So the formula would go:

(Cost to buy a larger LongMill – Price you sell your old LongMill) v.s. Price of the upgrade

I personally like the idea that instead of having this be an opportunity for a new user to scoop up a used LongMill at a discount so that they can get into the CNC hobby and prevent having a bunch of unused parts lying around. The net number of machines is one instead of two.

Of course, we will offer both an upgrade kit and full kit options to customers. These parts are interchangeable between all generations of the LongMill:

  • Motors and electronics
  • Lead screws, couplers, and nuts
  • V-wheels, fasteners, and eccentric nuts
  • XZ gantry assembly
  • Drag chains

Development progress (AltMill)

We’ve completed the baseline CAD design for the AltMill and are currently in the process of having our first prototype machined. We expect the parts to arrive in mid-November. This will be our first fully functional prototype which will be used to test performance and make design changes.


Next steps

We’ll be talking about next steps for sales and beta testing of these products. If you wish to sign up for beta testing, please fill out our survey:

LongMill/Extended version of the LongMill

We are waiting on a couple more parts to arrive to start building working versions of the LongMill MK2, at which point we’ll be contacting and working with beta testers.

Parts that we are still working on making include:

  • Steel Gantries
  • Feet and Z axis mount
  • Thicker lead screws (for larger versions of the LongMill)

We expect the first two parts to be ready in the next 2-3 weeks, with the thicker lead screws arriving in about a month.


The prototype parts are currently in production. We will be building one single prototype and putting it through the paces. Once we’re happy with the performance of the machine, we’ll be opening up pre-orders for beta testers. We expect this to happen around the end of the year or start of 2022.

Inductive Sensor Kit now available on our store!

Hey everyone, we’re excited to announce that the Inductive Sensor Kit for the LongMill is now available!

As we talked about in our last blog post about the inductive limit switches, we had been waiting on the sensors. While the sensors were shipped out at the end of August/start of September, due to some shipping delays, the sensors took much longer than we expected. They have finally arrived, and we are able to start making and shipping out the kits.

Inductive sensors and gSender

Just a quick thank you to Garrett Fromme ( and Dana Andrews ( who have been our beta testers for the past month and a half. We sent them our first prototypes of the inductive sensor.

During the testing of the sensor system, we found a couple of interesting bugs in GRBL and gSender. First involves the coordinate system. It turns out that GRBL counts the bottom left corner in the negative space. We’ve updated the latest version of the firmware for the LongMill to change this to make it in the positive space, making it more intuitive to use the sensors. You can now update to the latest version of the firmware using the latest version of gSender. Instructions can be found in our resources.

Second is the way that the gcode sender handles moving away from a hard limit. If you were to trigger a hard limit on the machine, the machine would not let you travel in that direction any further. However, since the limit will be triggered continuously and the machine cannot move away from the limit switch, gSender has been updated to allow users to move away from a triggered switch. It is important to note that other gcode senders may not have this functionality built-in, and the sender may need to be restarted or the machine moved manually to stop the trigger.

Ordering your sensors

You can now order the kits directly on our store. We are currently in the process of assembling and packing sensors so that we can ship them to folks as quickly as we can.

What coming next?

While the inductive sensor kit is a bandaid solution to add the functionality to older versions of the LongMill, we are planning on updating the LongMill around the end of this year to provide hard mounting points for inductive sensors. This means that brackets will not be needed to install the sensors.

We will also be adding more functionality and tools to utilize the sensors further through gSender updates.

September/October Production Updates

Hi everyone. Here’s a production update for September/October 2021.

We’ve seen a small uptick in LongMill sales over the last couple of months. Overall, shipping and production have been moving along smoothly, and most of the LongMill orders have been shipping out within a few days. We’ve reached the middle of Batch 5 a little sooner than we expected, and we may start to see us run out of a few parts as we wait on parts to complete the second half of Batch 5.


Just as a side note, we build machines in batches, and Batch 5 consists of 1000 LongMills. With smaller or inexpensive parts, parts with long lead times, and parts that we need to make large quantities of to take advantage of the economies of scale, we order 1000 sets of parts. On the other hand, larger or more expensive parts, parts that have short lead times, and parts that are made locally, we produce in smaller batches. In this case, we produced 500 sets of gantries, control box parts, and rails.

It’s important for us as a business to try to time the production and purchasing for each of our components. Over-producing means having to pay for inventory that needs to sit on shelves, while under-producing means having longer wait times for completed products. We of course try to balance these things and make production as seamless as possible.

Due to the uptick in sales, we’re running out of parts sooner than we expected, which may lead to shortages of parts. Currently, we are expecting to run out of gantries in the next few days. The laser cutting for the gantries is expected to be completed on Monday, with painting and finishing of the gantries to take about 2 weeks to complete. We will be working with our manufacturers to coat the parts that we are lowest first so that we can keep production going, but regardless, you should expect the lead time to increase until the rest of the gantries are completed.

Other parts that are still in production, but are expected to arrive before we run out include:

  • Rails
  • Control boards
  • Control box parts
  • Drivers
  • Flange bearings

Expected lead times

With the gantries expected to be our bottleneck, we expect machines, once they are out of stock, to start shipping LongMills again around the third week of October.

If you are planning to order a LongMill, please check the estimated shipping date on the LongMill order page for the most accurate information.

Surging ocean freight prices and continued instability in the shipping industry

Increased consumer spending and pandemic woes have continued to cause instability in the shipping industry. Recent surges in ocean freight prices now mean that shipping products between China and North America have roughly quadrupled in price compared to the start of this year. The chart below represents a pricing index to compare shipping rates.


This of course impacts us. A reasonable percentage of parts that we use for the LongMill comes from China, so we are also at the mercy of ever-changing shipping prices.

Luckily, the LongMill is a non-commodity product with a reasonably large profit margin, allowing us to adjust to changes in fluctuation prices more easily than commodity items that have low margins, such as general household items. We have kept the price of the LongMill the same for the past two years, but inflation and current events may eventually warrant increasing our prices as well.

In the longer term, I hope that shipping prices do stabilize. Realistically though, I expect that shipping prices will stay high in the near future, and other unexpected factors may come up, so we will have to keep our eyes peeled for that.

Batch 6 is now currently in production as well, with this batch being 1500 LongMills. By increasing our batch sizes, I hope to smooth out the supply chain and give ourselves more time and flexibility between batches.

Vectric VCarve Pro now available on our store

Hey everyone, Andy here. I’m here to announce that Vectric VCarve Pro is now available for sale on our store.

We first offered Vectric VCarve Desktop for purchase through our store after many LongMill users praised its ease of use, a wide array of resources, and powerful features that made it worth the price. Over the past year it has become one of my go-to programs for creating gcode, as it has been proven to be easy to use and come with many presets and features that I have found useful.

One very significant downside to using VCarve Desktop is its size limitation. The software limits you to projects to up to 25″x25″. This of course leaves several inches of wasted potential for LongMill users that have a 30″x30″ work area or requires users to split or tile projects. Here’s an example of one of my personal projects making a trim piece for my old Volvo out of plywood that required splitting the project into several pieces.


Vectric Pro does not have a size limitation. This, of course, comes at a price. While Desktop is priced at around $460CAD, Pro is priced at $896, a +$400 difference for the convenience of having a little extra working area and a couple of other extra features.

I still firmly believe that all new users should try out free software, as discussed in my previous article. But for advanced users who are making their bread and butter with their machines, it is easier to justify paying for software if it can save time and improve productivity. Initially, when the LongMill first was released, all of our users were new to CNC, which meant that we were focused mostly on helping beginners by focusing on supporting and recommending free and low cost software options. Now, with many users having had used the LongMill for a long time, we now have a growing community of advanced users who demand more functionality from their machines, some of which already have VCarve Pro and other paid software. So to cater to this growing community, as well as prepare for future machines such as the AltMill, which will focus on production and larger scale CNCing, VCarve Pro is now available for purchase on our website.

Just as a side note, we’ve updated the license distribution process so that all licenses get sent out automatically. This means that if you place an order for any Vectric software on our store, you will get an email with the license details right away.

Going Bigger – Announcing the Development of the AltMill and Extended Versions of the LongMill

One of the most frequently asked questions at Sienci Labs is “Can you build a bigger version of the LongMill?”. Well, I just want to assure everyone we have been actively working on the development of 1) an extended version of the LongMill and 2) the Altmill! Although we’ve been working on these projects for a couple of months now, these projects are still quite early in their development and we don’t have a ton of details to share. The purpose of this announcement is to start getting our community involved by learning what sort of machines and features folks are looking for. If you’re interested in being involved in this process, please make sure to fill out the survey.

What is the extended version of the LongMill?

Well, I guess it’s in the name. We’re working on a version of the LongMill that uses the core components of the original machine, but extends the rails and leadscrews to add more working area to the machine. The goal is to have a LongMill 30×48 or LongMill 48×48 machine. We expect to be working in a price point of around $2000-$2500 for a full extended version of the LongMill, with kits available for adapting pre-existing models of the LongMill to the larger size as well around $800 to $1000. Please note that pricing is an estimate at this point and may change.


What is the AltMill?

The AltMill is a new machine that we’ve been working on that focuses more on the more industrial/production end of the spectrum of hobby CNCing. This means linear rails and ball screws, more powerful motors, and other features that are designed for more intense CNCing. We expect to be working in a price point of around $3000-4000 for a 48×48 inch working area.



Extended version of the LongMill

We are currently in the early stages of manufacturing prototypes of the rails for the extended version of the LongMill. We will be conducting testing between October and November, to push for a December or early 2022 launch.


We are currently building to scale prototypes with wood, with plans to start producing prototypes from aluminum in the coming months. Due to the scale and complexity of the project, we expect to have working versions of the AltMill at the start of 2022 with a launch for the AltMill in mid-2022.

Beta testing

If you wish to be part of our beta testing program, please fill out the survey. You will be able to provide your information at the end of the survey.

General challenges of the project

Building larger machines also prevents new challenges. Here are some things that we’re working on addressing. We also discuss this topic specifically about the LongMill here:


Longer rails have more flex, which means that we need stronger rails to compensate. For the LongMill, we are currently working on a new rail design that improves rail rigidity while keeping overall weight down. This should help keep similar levels of overall rigidity in the machine and allow users to run their machines with the same speeds and feeds as any smaller LongMill.

The AltMill on the other hand will use stronger linear rails and bearings, as well as a solid aluminum structure to ensure a high degree of rigidity.


Our machines rely on both Y rails to be parallel with each other and perpendicular to the X rail to ensure that the machine doesn’t rack or cut out of square. With the LongMill, we can generally rely on our table mounting procedure to ensure that the machine is square, but the larger and heavier the machines become, the harder it becomes to square the machine properly.

Squaring and calibration tool for the LongMill

To account for this, there are a couple of options:

  • A table which uses precision cut parts to help square the machine
  • A tool or measuring device included in with the machine
  • Making the machine smaller

A table, in my opinion, offers the most precise way of keeping the machine square, which is why we are developing additional structures to support the machine that can use similar or same designs between both the larger LongMill or AltMill.

Beyond this, gSender also offers a calibration tool that will play a more integral role in working with larger machines.


Although a LongMill 30×30 fits perfectly on a 4×4 ft sheet of MDF, it is generally difficult to find sheets larger than this for mounting larger machines. One option is to cut and join multiple smaller sheets into a 5ft or 6ft square base to mount a machine on or have a pre-built bench or table that the machine mounts to, with space in the middle to put a larger wasteboard.

In terms of a 30×48 LongMill size, customers could purchase a 4×8 ft sheet and cut it down to 4×6 ft size to mount the machine to. However, 48×48 machines and the AltMill would need to use an alternative method.

In this case, having a table would also offer a good solution to this issue.


The larger a machine gets, the more power it needs. This means larger motors and drivers. This is because:

  • The parts that make up the machine that need to move are larger and heavier
  • We want to cut faster so that larger projects don’t take forever

I generally use the rule of thumb that no matter how large or small the machine is, you want the machine to be able to travel between the lowest left corner to the highest right corner in the same amount of time. So this means that the machine needs to travel faster the larger it is.

We are currently working on either using larger motors as well as optimizing the power from the stock LongMill NEMA 23 motors.

Spindle and router choices

The bigger and more powerful the machine becomes, the router or spindle power becomes a limiting factor. Although I believe that the Makita router we recommend for our LongMills should be able to handle anything for the extended versions of the LongMill, a spindle may be necessary on an AltMill. Here are some hurdles to get over with spindles:

  • They are larger and weigh more, thus needing more hardware to support on a machine
  • Have higher power requirements, which means that users will also need to make sure their workplace can support it
  • Require additional wiring, which adds additional complexity
  • Generally not available in retail, which means that we have to source a spindle manufacturer and ensure we do proper QA and testing

Seeing as spindles could be used interchangeably between the AltMill and LongMill, this opens up the opportunity to offer spindles for both machines as well.


Larger machines are larger and heavier, making it harder and more challenging to ship. The current shipping weight of the LongMill 30×30 is around 60lbs. Although fairly manageable, any heavier and larger than this, I feel would be unwieldy for the average user. Not only that, larger, heavier packages are more prone to being damaged during shipping, which is something we definitely want to avoid.

I expect our larger machines to be way bigger and heavier than this, and I estimate that weights will start to exceed 100lbs. This means either shipping the machine in several separate boxes, as well as figuring out the best way to handle the tracking and logistics on this.

Our goal is to continue to make it possible for us to ship by courier (UPS/Canada Post) to ensure that customers don’t need to worry about freighting. This should make our machines more accessible for the general public.


Because of all of the factors discussed above, larger machines cost more. As with the current LongMill, our primary goal is to provide the best possible value by lowering manufacturing costs with the most optimal designs. We do make certain decisions, some good and some tradeoffs to achieve competitive prices. Here are some examples:

  • Using standard extrusions for building tables – easy to source and build with
  • Reducing the number of variations of the machine to take advantage of economies of scale (no custom sizes) – reduces the amount of different types of support and resources we need to create as well as reduces machine complexity by not needing to design high customizability, but means customers have less choice in the size of their machine.
  • Assembly required by the customer – better understanding on how the machine works and saves costs on in house assembly labour, but would take longer for customers to get up and running

On the other hand, there are some changes that will add costs that we feel are worthwhile to spend money on:

  • Partial assembly of the AltMill to ensure proper assembly of linear motion components – we are able to create jigs and tooling to make in house assembly and calibration easier than most customers
  • Tables and other mounting options for larger wasteboards and machines – ensure proper squaring and make it easier for the user to set up their machines
  • Larger lead screws and ball screws – Although more expensive, larger screw drives are needed to prevent whip which are more apparent in larger machines

Inductive Limit Switches – Production Update

Hey everyone here’s an update on the development of the inductive limit switches for the LongMill! If you haven’t read the last post, you can read it here:

I know a lot of people are excited about this kit, and I assure everyone we’re working really hard on this. Over the last couple of weeks, we’ve been working on a couple of different things, including video and written info and content, continual testing, assembly instructions, packaging, and the supply chain for the kit. We are now waiting on our first batch of sensors and a couple of other parts to arrive from our manufacturers, and we will be starting packing and assembling the kits as soon as parts start to trickle in. All of the parts for the kit have been ordered and are expected to arrive in mid-September. We expect to start shipping kits a couple days after we’ve received all of the parts. Kits will be $60CAD or around $48USD each.

Our initial timeline for this project was to have a product released at the end of August. However, we had a minor setback due to some changes in part price and availability from one of the sensor suppliers that we initially ordered and tested samples from, so we have acquired samples from two additional suppliers, one of which we’ve fully tested and have decided to move forward with to use for production.


Some a bit more specifics that we’re working on to provide users include information about using different workspace coordinates, returning to a certain part of your job after a power outage or shutoff, and using jigs, which should add some extra tricks and functionality users can add to their machines.

Making your own

As promised in the last post, here are some instructions on making and assembling your own mounts and sensors if you prefer making your own over buying the kit from us.

Please note that these instructions are still in development, and additional resources and videos will be available for users soon. These instructions should help the general user population if they wish to make their own mounts and sensors.

Choosing sensors

The sensors we recommend using are:

Model: LJ12A3-4-Z/BX

NPN Detection

Detection distance: 2mm-4mm

Normally open

Supply Voltage: 5V* 

Choosing the correct voltage option is very important, as this particular type of sensor is more commonly available in a working voltage of 6-36V, which requires additional wiring to make work with the LongBoard. For using higher voltage sensors, you may need to use either the 12V auxiliary power from the board, 24V from the power supply, or from an external power source. That being said, I highly recommend sourcing the 5V variant of the sensor as this will make installation much more simple.

There are many variations of the LJ12A3-4-Z/BX, as well as other M12 sized barrel sensors that come in different lengths. In my experience, most seem to be more than accurate enough for this application, with a repeatability of 1 thou or better.

Most sensors also come with a set of nuts and washers, which can be used for mounting.

Making the mounts

All mounts can be 3D printed. The models can be found on our public Onshape document for the LongMill. The models can be found under Electronics -> Limit/Homing Switches. Right click on the model to export as an STL or your preferred 3D model file format.

These parts can be printed with most FDM printers. If you’re interested in reading about our 3D printing process, please check out this post. I would recommend using a higher infill for these parts since a more rigid part generally helps mounting.

All of the mounts use a pair of M3 heatset inserts. CNC Kitchen has a couple of videos on using threaded inserts on 3D printing that are awesome which talk about them in general as well as how to install them.

For our application, we found a fairly inexpensive and commonly available insert that works great. A drawing of the insert can be found below.


Here is an exploded view of the inserts.


Assembling the mounts

Here is a view of everything assembled before mounting to the machine.


And here is the exploded view:


Attaching to the machine

The mounts slide onto different areas of the machine as shown in the images below. Use the M3 screws to secure them. You will need to position the sensor to a position that lines up the tip (usually blue or orange) with the gantry you are sensing for. Loosen and adjust the mounts as necessary.


Although the sensors for our kit will come with pre-wired JST connectors with a 2.5m wire for running through the drag chain, it’s likely that off-the-shelf options will not. You will likely need to extend the wires to be able to run the wires through the drag chains.

The LongBoard comes with ports to connect limit switches via JST4 connectors or with the detachable screw terminal block. Here is a diagram of wiring the inductive sensor using the screw terminal. Note that the 5V and ground lines are shared between all of the sensors, and each black signal wire is connected to their separate axis.


More info on wiring can be found on our resources for limit switches.

Firmware settings

Once your sensors are installed you may need to update your firmware settings to enable the limit and homing functionality. A full outline of all of the related firmware settings can also be found in our resources.


I hope that this information helps some of our more ambition users who don’t want to wait to get a kit from us set up limit switches on their machine. I also hope that this will give you guys a head start in exploring all of the functionality in adding limit switches to your design. Over the next couple weeks, our team will continue developing the resources for the installation of the switches, so I highly recommend staying in tune on our social media and our blog, and check back on our resources page to check for updated resources!

LongMill limit switches coming soon

Hey everyone. One highly requested add-on for the LongMill has been limit switches. For the uninitiated, limit switches are often used on CNC machines for 1) homing the machine 2) preventing the machine from reaching the limits of its travel. If you’re interested in reading more about what limit switches are and what they can do, I recommend reading the article in the Resources.

Please note that in this post, we are using the term “limit switches” and “homing switches” interchangeably. I do understand that there is a small distinction for both, but for this application, they are basically the same.


At the beginning of LongMill development, limit switches were not a priority as a feature when focusing on beginner hobby CNCers. This primarily came down to a few factors. First was the added complexity of having limit switches, which means additional setup and assembly for the user, as well as adding to the learning curve of learning how to use limit switches. Secondly, with the LongMill set up so that crashing the machine will not damage itself, limit switches are not necessary to protect itself. For customers still adamant about having limit switches, we still provided full hardware support to plugin or wire in switches directly into the controller, which would take care of a small population of more advanced users.

For those who want to read more about community made limit switch solutions, this is a great thread to read:

We still hold our opinion that beginner users do not need limit switches with their machine to get the full functionality of the machine, and we recommend starting out without them until a better understanding of the machine and its use is achieved. However, as our community has grown and along with that their experience, more and more users are now exploring new ways to bring advanced features to their machines. Not only that, the development of our very own gSender now allows us to integrate software and hardware more closely than ever before. With these things in mind, we’ve spent some time creating our own plug-and-play solution for the LongMill.

Creating a limit switch solution specific to the LongMill came with several challenges.

First was the lack of foresight on providing mounting points for limit switches. This simply came down to the fact that we did not integrate mounting points on the LongMill for adding limit switches. Later versions of the LongMill did come with holes and other features that could mount sensors, however, with so many different versions of the LongMill, it would be difficult to document and provide resources for installing limit switches for every single version of our machine.

Second was the voltage support of the sensors we need to use for the limit switches. We are using a variant of the LJ12A3-4-Z sensor as our limit switches, a very common and widely used sensor. However, almost all variants of this sensor are designed for a 6-36V input voltage. Although it is possible to pull 12V power from the LongBoard, the JST 4 pin connectors already integrated into the board which was designed to be used for a plug and play solution were designed for 5V only. In hindsight, it may have been a better idea to route the 12V power to the JST connectors, but this meant that we would need to purchase 5V compatible sensors, which do exist but are more difficult to source, to be compatible with the LongBoard. Our first supplier for the sensors created the proper wiring and plug set up for the LongBoard, but unfortunately, they were only able to provide 6-36V sensors which meant that we had to start looking for a new supplier.

The new design overcomes these two challenges. First of all, the mounting hardware for the limit switches will allow users to install their sensors to any version of the LongMill, as well as allowing the flexibility to choose which side of their axis they want to mount to. For example, some users may want to home from the bottom left corner of their machine and some may want to home from the upper left corner of their machine. Users only need to move their sensor from the front of the machine and remount it to the back and specify the change in the software to make the change. Second, we have re-sourced and tested a 5V variant of the LJ12A3-4-Z sensor, which will provide proper voltage compatibility with the LongBoard. This supplier will also be providing us with the proper wiring for a plug-and-play installation of the limit switches.

We expect the kit to be ready for sale and shipping around the end of August. Each kit will come with three sensors with a plug and play wiring harness which should have an installation time of around 15-20 minutes. The price for each kit will be around $60CAD or $48USD. Additional resources and software setup support will also be provided with the kit. We’ll also be publicly releasing the designs and specs for the kit for users that want to make their own setups. Please check our blog, email, and social media for further announcements.


Today’s testing of the sensors have shown repeatably of over 1 thou which should offer a very precise way to home the LongMill.

I’m excited to see the limit switch kit in the hands of LongMill users soon and look forward to seeing the rest of the development team and the community come up with ways to utilize homing on the LongMill!

July and August 2021 Production Update

Hi everyone, this is a production update for July and August. I’m happy to announce that we are expecting the lead times for the next 400 machines to be 1 to 2 weeks (update, as of August 10, lead times for LongMills is under 1 week). For the most part, we expect most machines to ship within a few days. Any orders that are still pending shipment at the time of writing should be shipped by Tuesday of next week.

All of the parts that we were waiting on for this part of the batch have now arrived and we should not be seeing any major delays in shipping for roughly the next 8 weeks.

During part of July, we ran into some part shortages, such as with our control boards, Delrin anti-backlash nuts, and drivers. We also had a short period of time where our print farm was also shut down due to a shortage of filament. These shortages were caused primarily due to shipping delays. We’ve finally have gotten all of our parts without much issue, and can continue production.

At this point, we will be able to produce another 400 units without running into supply shortages. There are still a number of components we expect to start running out of once we ship the 400 units, including:

  • Rails
  • Gantries and other steel components
  • Control boards

We have placed orders for these items at the time or writing or are in the process of ordering these parts.

In any case, that’s our update for this month (and August). Happy making!

June Production Updates

Hey everyone, this is our June production update. For previous production updates and other company news, please check our blog.

It’s continued to be a busy month for April, but as we talked a little bit in our previous update for April/May, we have continued to shorten our lead times. We’ve taken the time to train some of our staff on new responsibilities and reorganize and plan production for the coming months. We are near the end of our run of Batch 4 machines and are starting to prepare for shipping Batch 5 in June.

In terms of COVID, Ontario has slowly seen a decrease in cases and more of our staff are becoming vaccinated. We are fortunate to have had no cases so far, and hopefully none until the end of the pandemic.

A new batch of motors, lead screws, and drag chains

Lead Times

Lead times are expected to average around 1-2 weeks for this month, however we are starting to face shortages in parts that will rely on the timely arrival to keep up with production. Some of these parts include:

  • E-stops
  • Touch plates
  • Arduinos
  • Delrin V-wheels

We expect these parts to arrive in 1-2 weeks. However, this may change if we face delays in transit. We will keep lead times updated on the product page to account for these changes.

Supply Chain

There have been some minor bumps along the way in terms of supply chain especially due to current worldwide events, but luckily with early planning and dedication from the manufacturers we work with, the supply chain process for Batch 5 has been relatively smooth.

One area that we’ve seen a large spike in prices have been with drivers and Arduinos. Due to the chip shortage, many of the components that go into the LongBoard controller have gone up in price. Most ICs that go into this production have doubled in price, and new products that we are working on that involve chips may be delayed due to the unavailability of chips. We have acquired parts for the next 500 controllers with approximately another 100 controllers in stock, but we may need to be cautious of continuing shortages for the rest of 2021.

On the topic of spiking prices, steel prices have gone up more than double since the start of the pandemic, affecting the price of gantries and other steel components that go into making the LongMill. On a lesser level, copper, tungsten carbide, and other raw materials have increased overall prices for many components as well such as E-stops and end mills. Cardboard shortages with our packaging manufacturer have also affected costs and lead times a few times over the last few months too.

Luckily due to improving processes and increasing batch sizes, we have been able to find other ways to save costs and so we don’t expect to have major changes in pricing for our products, however, it is a reality that we may need to face at some point that our company will have to account for changing material prices by increasing the prices of our products.

We have also been affected by the shipping fiascos that have been happening around the world as well. Although we weren’t directly involved in the Suez Canal crisis, we have experienced slowdown in some shipments due to this situation. At the time of writing, most of the parts that we need for Batch 5 production are in transit within Canada (by rail) or are in production with local manufacturers. A couple of parts that we are still waiting on that are in transit by sea include:

  • Router mounts
  • Couplers
  • Delrin nuts
  • 3D printer filament

The remaining components for Batch 5 are expected to arrive this month but won’t be complete for shipping until these parts arrive.


There have been a few changes in manufacturing at Sienci Labs. Here are some of the things that have been going on.

One small change is the material that we have made the ACME nuts from, switching from stainless steel to brass. Brass has shown to be easier to work with in terms of manufacturing and forming threads. In previous manufacturing batches, a portion of nuts were rejected due to rough threading that made it difficult to thread onto the lead screws. The new brass nuts are of much better quality.


As part of the transition from steel shoulder brackets and drag chain mounts, Batch 5 kits will use M8-16mm bolts instead of M8-25mm bolts to mount these parts. There is no functional change, as the longer bolts are a carryover from when longer bolts were needed on the 3D printed parts.

Next, we are switching to e-coating our gantries from powder coating. We believe that e-coating is an excellent alternative to powder coating as it provides a cleaner, more consistent surface which is important for our XZ gantry assemblies. In some of our recent batches of powder-coated steel, we were running into issues where paint contamination and dripping would either produce cosmetic defects or affect the assembly of the parts because of the unevenness of the surface. E-coating does have a thinner surface, which theoretically means that it offers less scratch resistance on parts. However, based on samples that we have been provided of our parts after being e-coated, we have seen significantly better resistance to chipping and surface quality, without much difference in scratch resistance. This change should decrease manufacturing costs while improving overall quality.


In the last batch, we switched to using M3 screws with captive washers to help keep the screws from coming loose. For these screws, we have switched from stainless steel screws to Class 12.9 alloy, which is a much stronger screw that will prevent head stripping. Head stripping has been a minor inconvenience as removing stripped screws takes a while.

We’ve added three new CR30s (3D Print Mills), a belt based 3D printer. These machines will add additional 3D printing capacity with the benefit of being able to continually print repeated parts. We are currently in the stage of testing and tuning these machines, but we expect each printer to do the work of 4 standard 3D printers, increasing our print capacity by approximately 25%.



Batch 5 comes with some very minor design changes to the LongMill.

First to mention is that motor shafts on the X and Y will be fully round. This is due to a very small number of customers reporting their motor shafts breaking off. The engineers at LDO Motors and us have confirmed that the full shafts will prevent this.


We are manufacturing a slightly modified 65mm router mount to eliminate the need to use M5-12mm screws. Because of the drill tap depth of the four mounting screws in the back of the router, shorter M5 screws were needed compared to the rest of the machine assembly. With the new router mounts, M5-25mm screws can be used on all parts of the router mount. We have also relocated the additional tapped holes that are used for mounting to the front of the mount for easier installation of accessories such as the LaserBeam.


New ACME Delrin nuts have been manufactured without the counterbore, which were an unnecessary feature for our application.


Shipping to US and Canada have been reliable overall and seems to have returned to pre-COVID speeds.

We had some delays with Canada Post shipments going to the US via US Air Parcel, so as an alternative we would recommend using UPS.

We have had several issues with customs for shipments going to Mexico this past month that are new. If you have an order that needs to go to Mexico, please let us know in case we need to make other arrangements.

What is a G-Code Sender or CNC Machine Interface?

Hey everyone. We get a lot of questions about software for CNC machines, part of which includes using a g-code sender or machine interface. If you’ve ever gotten technical support from us, there’s a good chance you might have talked to Kelly, who took some time to make this video to help answer the common questions and discuss common functionality in the software.

This video covers some of the basic features that are in g-code senders like UGS and our very own gSender.