Probably one of the most requested products we’ve gotten in recent years has been an auto tool changer. While the concept seems simple, the actual execution of an ATC system is extremely complex, especially as both the software and hardware must work in concert perfectly to ensure that tool changing is fast, simple and reliable. It’s taken quite a while for us to get to the point at our company to develop the engineering manpower and funding to be able to undertake such a complicated project. 

I can safely say that the ATC is by far the most technically challenging product we’ve developed, but we’re excited to share it with the world as one of the most affordable, full featured CNC spindles with an auto tool changer. We believe this paves the road towards not only mechanical and electrical advancement, but also that the development in the user experience and systems design of the software experience takes this type of product to the next level.

The ATC is a spindle with an integrated auto tool changing functionality which works with gSender to provide a seamless experience in changing tools. Users are able to load and remove tools with a press of a button (manual mode) or by ejecting and loading tools onto a rack. 

Who is this for?

The ATC was designed for users that aim to improve their productivity with their CNC machine by automating the tool changing process. We believe that the best fit for this product are users that have experience with their machine and CAM programming, and want to get into small to medium scale production. 

The ATC system is designed to be plug and play with any AltMill system, including the MK1 and MK2 2×4 and 4×4, plus the new AltMill 4×8. This makes it particularly attractive for users that want to get up and running with an ATC system as quickly as possible.

While we know that lower cost, collet-changing based ATC systems exist, we chose to focus on the ATC spindle system instead because we believe that this system will work at the level of reliability and performance that is required to our standards of being able to do hundreds and thousands of toolchanges without error.

We do also acknowledge that this product falls outside of the realm of a price point affordable to the average hobbyist, and we expect our general demographic to be folks that have higher expectations from their machine.

How does it work?

The ATC is essentially a spindle with additional electromechanical systems that allow for the change of tools controlled by the CNC controller. You can almost think of it as a spindle with extra hardware attached.

A system of pneumatic solenoids activates a piston which allows the tool to be pulled in or released during a tool change. Each end mill is mounted to a ISO20 tapered tool holder which allows the reliable interface with the spindle. As the ISO20 tool holder is a standardized design, virtually all high quality tool holders will work with the ATC.

Integration with gSender

One of the most important aspects, and what makes our ATC unique compared to nearly all other ATC systems, is the native integration with gSender. This allows functions such as:

• Automatic switching between automatic and manual tool change modes when the tool rack is removed or not detected
• Added safety features and warnings such as low pressure, tool missing and temperature
• Optimized tool loading and loading motion planning
• On-the-fly changes to tool holder position mapping
• Colour assignment in the gCode visualizer based on tool
• “Run-from-tool” functionality, which allows users to run toolpaths specific to each tool

…and more.

Engineering the ATC

The ATC comes with a series of unique engineering challenges:

• The use of low pressure air
• To have maximum reliability
• Sensor integration
• Installation and integration

Custom PCB

To integrate all of the communication and sensors into the ATC, we developed a custom PCB board that lives on board the spindle. One of the most notable features includes the LED status button, which shows the status of the spindle based on its colour, as well as allowing the user to use the button for functions like executing a manual tool change. 

Quiet Cooling System

Since we first started building spindles, we’ve felt pretty strongly that air cooled spindles are the best choice for the majority of people for these reasons:

• Watercooling relies on an external pump, which adds a significant failure point. A failed or disconnected water pump can cause the motor to overheat and in the worst of cases, the wiring to burn out. Most air cooled spindles on the other hand (although not the ATC specifically) use a mechanically mounted air impeller that drives air through the spindle to provide cooling. The ATC specifically uses an electric cooling fan to do the same job as the impeller, but uses a combination of a temperature sensor and controller to adjust the cooling and turn off the fan automatically. 
• Watercooling requires a send and return hose looped through the drag chains, requiring not only hoses but larger drag chains as well. This adds additional cost and set up complexity. 

By using a separate electric cooling fan, we are still able to get very low levels of noise, as the fan runs at a lower RPM in comparison to a mechanical air impeller. Additionally, since we can turn the fan on and off as needed, this impacts the overall noise of the spindle as well. It should be noted that the fan will primarily turn on when the spindle is running and cutting, where the sound of the spindle is masked by the sound of cutting anyway.

Installation and integration

As with all of our accessories, the ease of installation and the focus on a tool to be as plug and play as possible is critical for adoption. From our research, third party ATCs, while many exist, come with a large barrier to entry as the installation process varies significantly based on the type of machine, controller, and tool rack system the user chooses. Given the cost and difficultly of development, we’ve seen a split between ATC manufacturers and CNC manufacturers, where one company handles the resources and integration and the other builds the machine. This means the ATC manufacturers need to work out how to make their systems compatible with CNC machines they didn’t develop in the first place, which makes it more difficult to make it operate as a streamlined and optimized system.

In this ATC project, we have the opportunity to design the machine, mounting, wire management, air management, and software all as a cohesive system.

One of our key accomplishments in this project was also to build a toolrack that was flexible, easy to install, and easy to remove. Given that installing and having an active toolrack reduces the working area slightly, we also wanted to optimize its footprint as well. One important feature is the ease of removing and replacing the toolrack. When users want to use the full area of their machine, users can remove their rack in seconds with two hand screws. In this mode, the ATC can be used manually, where users can press the button on the spindle to release the tool holder, and pushing the button again with another toolholder allows the tool to be secured back to the spindle.

Pricing

Users should expect to invest around $2,600 USD to $3,300 USD before tax for a complete system, including the spindle, VFD, rack, and toolholders. Users should expect to pay around $150-300 USD for an air compressor, which is needed for this system, if they don’t have one already.

• ATC 6-Tool Kit: $2,890 USD / $4,040 CAD
• ATC 12-Tool Kit: $3,340 USD / $4,670 CAD
• ATC Spindle Only Kit: $2,590 USD / $3,620 CAD

Additionally, our new “Clear Cut Dust Shoe” was specifically designed for all of Sienci Labs’ lineup of spindles, and comes standard with the ATC. This allows for tool changes to happen without any interference from the dust shoe.

Additional add-ons are available as well:

• Separate Tool-Rack: $245 USD / $340 CAD
• Single Tool Holders: $28 USD / $38 CAD
• Air Filter Regulator Kit: $80USD / $120 CAD

All available products are sold here

Air compressor compatibility

For proper operation of the ATC, users must provide a reasonable sized air compressor, with 3 CFM at 90psi or better, and 100psi minimum. The ATC spindle will only consume significant amounts of air during a tool change, but not while cutting, which keeps compressor requirements minimal.

FAQs

Some common questions are below but on Thursday, December 4, our project lead engineer Johann will be hosting a Q&A with Kevin our lead gSender software developer, and will answer any technical or work flow questions you may have. Watch for more formal announcements but you can quickly find live the streams on YouTube.

And if you haven’t already, check out what all the engineers have to say in this breakdown video:

Does the ATC work with the LongMill?

Due to weight and mounting constraints, no. The ATC is not compatible with the LongMill.

Why do I need an air compressor?

The air compressor is needed for several functions on the ATC, including supplying power to engage and disengage the tool holding mechanism, as well as providing a de-dusting function, where a blast of air is shot onto the tapered part of the tool holder to ensure that dust and debris have been removed before loading a tool.

Can I get the tool length sensor separately?

As discussed earlier, the tool rack system integrates a tool length sensor to calibrate the Z position of the tool, as well as confirm the existence of the tool itself. We will provide the tool length sensor for mounting to the machine as a separate add-on at a future date, such that LongMill and AltMill users can automate the process of finding the Z-height of their tool before cutting.

How many tools can I have set up with the ATC?

The ATC and gSender can be programmed to hold 32 tool offsets (coded into grblHAL core.) However, we believe one of the 6 or 12 position holders provides an adequate number of tools and fit within the working area of the machine.

Does the tool rack take up some of my working area from my machine?

Yes, the tool rack takes up a few inches of space in the Y direction. However, during the development of the AltMill, due to our anticipation for this to be the case, all AltMills come with some additional travel space beyond the listed capacity so that in practice, the impact is minimal. Additionally, the tool rack comes with an easy installation and removal system, which means that tool racks can be installed and removed in minutes, allowing users to get the extra space for tiling and other pass-through jobs when needed. The system intelligently detects when a rack is removed and prompts the user to swap tools when needed using the manual tool change button on the side of the spindle.

Is the ATC air cooled or water cooled?

The ATC is air cooled. We have specifically chosen to use an air cooling system to reduce the complexity of the system for the user and integrate additional functions such as automatic control over the fan, based on the spindle’s cooling needs and to provide quiet operation when not in use. A temperature sensor built into the spindle provides an additional safety mechanism to prevent overheating. 

It should be pointed out that both air cooled and water cooled systems are both designed for full duty cycles, which means that the cooling system is scaled in both systems to ensure full time use. Neither system is superior to each other with regards to performance or durability.

Is the ATC compatible with other CNC machines?

In theory, yes. We will provide mounting drawings, wiring diagrams, and schematics that may allow users with machines outside of the AltMill family to integrate the ATC into their own system. However, the use of gSender, gControl, and other Sienci specific hardware may be required to use the full capabilities of the tool. We are not providing support for third party use at this time.

Will you come out with more powerful spindles in the future?

Although we do not have specific plans for a more powerful spindle option in the future, we are expecting to work on a more powerful version, especially as we continue to develop our 4×8 line of AltMills and grow our production focused customer base.

Can I take an existing spindle motor and add the ATC parts onto it?

Unfortunately no, due to differences in the design they are not interchangeable.

Can I run the ATC on 110V power?

For the ATC to run properly, a user must provide 220V power and at least 10A. Some users may choose to get a step up transformer which can allow for the use of this spindle with 110V power outlets, but caution should be used to ensure the current capacity of your breaker is not exceeded during operation.

We’re now in the final month of the year! What a crazy year it’s been, especially with the growth of the AltMill platform, the launch of the ATC, new tools, accessories and more. We’ve seen significant growth in 2025, with our company and sales doubling from 2024.

Holiday schedule

Our offices will be closed for the holidays from Dec 25 to Jan 1, and we will reopen Jan 2, 2026.

We will continue to ship orders up to Dec 24th, however, we recommend placing orders in advance if you need them to be shipped out beforehand.

Customer service, shipping, and other company functions may be limited at this time.

ATC

The ATC has now launched!

Production is now underway, with our intial batch of parts ordered for the first 160 units. We are aiming to start shipping units in Jan 2026 based on our current schedule.

We also have a livestream scheduled on YouTube, so make sure to check that out.

AltMill 4×8

AltMill 4×8 was just launched and is currently in production as well. Most parts have been ordered, but a few major parts such as the extrusion and gear racks are going through final sample checks before full batches are ordered.

Now that the 4×8 is launched, we’re mostly in a waiting game for parts. We are slowly starting set up processes to get ready for the assembly.

AltMill 2×4 and 4×4

AltMill 2×4 and 4×4 are continuing to ship. However, we’re currently waiting on more 1.5KW and 2.2KW spindles to arrive, expected in the second week of December. This means that the machine and spindles may ship for some orders at different times. Once the spindles arrive, we are expecting to clear out of the remaining queue fairly quickly.

AutoSpin T1

We’re excited to announce that the AutoSpin T1 is now in production. We received our first production sample at the end of October and started our final set of testing. Although the performance and function of the tool met our standards, we had to get a second unit built to ensure our text and logo matched our standards for packaging and silkscreening, since they were a little bit off. However, we have checked the latest version and were able to accept it for final production.

We now have the first 2,000 units in production. We are expecting production to complete around mid-December, and we should have them arrive at our shop around the end of January.

Closed-Loop Stepper Motor Kit

A few months ago we put out a post to test the waters for interest on a closed-loop stepper motor kit. Since then we’ve received quite a lot of interest for a kit for adding CLS motors to the LongMill, as well additional inquiries to retrofit the motor and control systems on non-Sienci Labs machines.

Otherwise, we are currently wrapping up the remaining ordering of parts and finishing the resources and documentation that will be available to help users do the installation at the time of launch.

We’re excited to share that we are reaching the final stages for supply chain, testing, and resource development for a kit. We are now working on figuring out pricing as well as the potential tie in with the LongMill MK3 in development. Keep an eye out for launch info coming out in the next 3-4 weeks!

gControl Panel Computers

We’re happy to have received another batch of gControl Panel Computers, so we’re shipping out to folks who have been waiting first (roughly a month.) We are expecting to have stock until January or February. We have also ordered another batch of computers expected to arrive early next year as well.

We are experiencing a new potential issue. RAM and memory prices have skyrocketed in the recent months, with news reporting that demand for these parts have increased due to AI. Because of this, the newest batch of computers that are currently in production will ship to us without SSDs and RAM. We are hoping that the price of those components will go down early next year. If not, we will have to reconsider pricing for the computers.

Hey everyone, we have another exciting month ahead for November. I am currently on vacation, so you might not see me for the typical video update, but here’s the blog that covers everything. This post might be a bit shorter as well, but rest assured there is a lot going on. A lot of news is a continuation of prior months, so make sure to check out the previous updates to learn more.

Updated Shop Layout

We have now fully removed the floor from our main production space, opening up area to put in new racks and getting prepared to scale up production of AltMills. While our overall floorspace didn’t change, being able to use the taller racking and getting our forklift to other parts of the office will allow us to build more vertically.

A lot of stations use a system of having the assembly on the ground floor, and then materials above, which allows us to store a lot of materials for quick access. The racking is also fairly modular, allowing us to build different configurations.

Shipping Issues

We are still seeing a large volume of shipments coming back from the border, largely due to issues with customs handling. Unfortunately this means that returned orders need to be repacked and reshipped, especially if we see shipping damage.

We are continuing to work on several different things, like updating our customs documents and forms, submitting forms proactively, and working with UPS to understand where errors are happening. However, we ask that at this time – and thank you in advance – that customers are patient if shipments take a few extra days to arrive.

AltMill 4×8

The AltMill 4×8 is now available for pre-order! You can now order it on the product page. If you want to learn more about the product itself and what it stands for, make sure to read our article, Everything You Need to Know About the AltMill 4×8

In other news, we have now acquired beta testers and have started working with them for testing machines as we go into production based on our first initial sales numbers in the pre-order. Certain parts, especially parts like motors, fasteners and electronic components (which will be shared between other AltMill size variants) have been ordered earlier as part of a larger batch of components.

Most of the work with the 4×8 this past month was mostly making final design tweaks and decisions, plus lots of testing and filming in house to get marketing materials ready. This also happens to be a good time to make some new furniture around the office!

ATC

The launch of the ATC comes this month, with some final considerations and tweaks being done in ATC development over the past 30 days. We’ve decided to move our launch date to mid-November, rather than on Oct 29th (same day as the AltMill 4×8) as we are doing final testing and refinement design work before a full launch. We need to have our bill of materials and kitting configuration decided on, as this will determine the pricing and packages we can offer for customers.

LongMill

Last month we launched a price decrease on LongMill kits across the board. We haven’t seen a big difference in sales volume, although it is present, which seems to suggest that pricing isn’t playing as big of an impact on the demand as it is currently. Perhaps this means the LongMill is due for a revision, or perhaps it means that there is less demand in this market segment in general?

Most of our efforts are in the LongMill redesign, and production isn’t quite ready yet as we wrap up development with our two larger projects, the AltMill 4×8 and ATC, but we’re currently doing some preliminary testing with the close loop steppers designed for LongMill. As we mentioned in a previous post, we are currently in consideration and progressing with offering the electronics (SLB-EXT and close loop stepper motors) in a way to allow for conversions to close loop stepper for the LongMill and other CNC machines.

While this is still a work in progress, we now have the SLB-EXT available for sale on our store. While not officially tested and supported, customers can order them on our store.

AutoSpin T1 Router

We’re excited to announce that the AutoSpin, which had been in rocky territory for the last few months with certification and supplier issues, has seen a lot of progress. I didn’t want to share too much, just in case things didn’t work out. However, we’ve hit one of the main milestones of completing certification, which means we can move towards production now, and we’ve started doing testing with our pre-production units, and if that all goes well, we will move onto production. This could mean that we’ll have AutoSpin T1 routers ready to ship in a little over 2 months.

While we are optimistic we are approaching the end of the process of launching the AutoSpin, due to the complexity of the project, we may still run into issues, and so we will not have pricing or a release date provided until we are confident that we’re able to deliver a product that is up to our quality standards, and on a firm timeline.

We’re excited to share the next member of the AltMill family with the AltMill 4×8. This has been a big collective effort to bring a well thought out, productive and affordable full format CNC machine to the hobby market. 

The AltMill 4×8 launches for pre-order on Oct 29th. Stay tuned on our email list, blog and social media for more info. We will have a series of informative videos coming out during pre-order, including an in depth feature from our engineers. Plus, we have a Live Stream Q&A with our engineers scheduled for Thursday, November 6, 7pm to 8:30pm.

What is the AltMill 4×8?

Our goal for the AltMill platform was to find the best balance between cost and performance, offering production level productivity at a price point affordable to beginners and hobbyists. The 4×8 variant takes this to the next step, allowing users to process full 4ft x 8ft sheet materials. 

The AltMill 4×8 has some similarities with the 2×4 and 4×4 sizes, but uses redesigned components to extend the Y axis travel to just over 8ft. The fundamental design of the original AltMill was scaled up to achieve high performance with a larger working area, including increased Z-axis travel and clearance.

The 4×8 format is especially important as it represents one of the most standard sizes used in professional and industrial shops, for most materials like plywood, MDF and plastics. We expect more users to focus on building a business and scaling up their work for making money with this type of machine.

Who is the AltMill 4×8 for?

The AltMill 4×8 was designed at a price point that makes it accessible to the hobbyist and prosumer user, but it has the rigidity and precision capabilities that align with production and industrial focused machines. This makes it suitable for people who are intermediate or advanced hobby CNCers intending to scale into a business; or people who are already running a business and want to supplement or augment their existing production capacity. Entry level hobbyists will need to undergo a learning curve, but luckily we have year-round support and industry-leading resources to guide users on their journey. Learn more here.

Differences Between Industrial Machines & the AltMill 4×8

Software & Programming

For the most part, the CAM processes for both types of machines remain identical. Any CAM software you use for industrial machines can be used with the AltMill. Some industrial machines have more advanced software features on the CAM side, such as version control, managing stock of materials, and distributing jobs between multiple machines. Some software may need specific machines to do these functions, whereas some software is machine agonistic. These are advanced features found on very, very high production machines.

For controlling and sending gCode to your machine, some industrial machines use a custom interface, while some use a third party interface. Common ones include UCCNC, Centroid Acorn and Mach 3. 

We offer official support for the AltMill with gSender, our free, actively developed, and powerful gCode sending software. If you’ve already used one of our other machines or used your machine with our software, you’ll already be familiar with it. 

Speed

We’ve seen a pretty wide range of advertised speeds in the industrial machine space, with rapids from a few hundred to thousands of inches per minute. There are a few practical limitations to speed. First is bit deflection. In the industrial machine, the deflection of the end mill plays the largest role in the accuracy of the cut. This is a little bit different compared to the hobby space, where deflection of the structure of the machine generally plays a bigger role. Second is material or chipload limitations, or the amount of material the end mill can pull out based on the rotational speed of the bit and travel within the material.

The productivity of a machine is also dependent on the acceleration settings. Sort of like how a drag car might go faster in a straight line, but it can’t take corners as fast as an F1 car. Machines are the same. An industrial machine may not complete a job much more quickly than a hobby CNC in practice in some cases, for projects that require a lot of acceleration and deceleration. 

In my opinion, it’s important for customers to consider unit economics. If an AltMill costs 5x less than an industrial unit, but cuts at half the speed, then getting two AltMills might make more sense than one industrial machine.

Cost

We generally would consider 4×8 machines under $15,000 to be in the hobby range, whereas industrial machines are generally above $15,000 and can run hundreds of thousands of dollars. 

There are some industrial style CNC machines that can cost much less, typically built in China, but this generally doesn’t take into account the cost of shipping and importation, setup or modifications to work in North America which can cost more than the machine itself.

Buying Experience

Most industrial machines don’t have a single price and require the buyer to get a quote. This makes the buying process longer and harder for the average buyer to cross shop or compare pricing.

Our goal has always been to make pricing as transparent as possible. Pricing for all products are listed on the website, and shipping quotes can be automatically generated in the cart. 

Shipping

Industrial CNCs almost always need to be shipped by freight. Depending on where you’re located, it can cost hundreds, if not thousands of dollars in cost to be able to get it into your shop. Additionally, you will likely need to have some method, such as a loading dock or forklift, to be able to unload and move your machine, which adds to the cost.

The AltMill on the other hand comes in a series of 6-7 boxes, which all get shipped by courier, and can be delivered to almost any resident or shop in the world. We estimate that the shipping cost for most parts of the US and Canada to be around $300-500 USD.

Weight

As we mentioned before, the weight of the machine impacts the shipping cost and acceleration settings. Another factor to consider is the ability for the user to relocate the machine. Industrial machines weighing thousands of pounds require special equipment to move, whether it be around the shop or to a different location. Additionally, many industrial machines need a special pad or mounting to the ground for stability and safety reasons. This can cost a few thousand dollars to install if it doesn’t exist in a shop yet.

The upside of having a heavier machine is that it absorbs vibrations, which means that cuts can come out smoother and with less chatter. However, a heavier machine also requires more energy for it to move its axes. This means larger motors, bearings, and other hardware, offsetting some of the benefits of having a heavier frame.

The AltMill 4×8 weighs several hundred pounds and simply uses levelling feet to work with the typical shop or garage. This makes it easier to move around and ship. Although it may not have as much vibration dampening capacity, we believe that it provides more than enough rigidity to get clean and accurate cuts. It’s important to note that the AltMill is designed for cutting woods and plastics primarily, which is considered a fairly soft material.

Features

There are a lot of features that are found with both hobby and industrial machines, but are usually more common or standard on industrial machines. For example, automatic toolchangers and vacuum tables and hold downs are generally more common options that are built in mind for the system. 

At the moment, the AltMill ecosystem does not have every feature to match industrial systems. Some of these features can be added with 3rd party kits from other manufacturers. That being said, we’ll likely work on new features, especially for the 4×8 machines, since we expect more customers to be production focused as time goes on.

Power Requirements

The larger the machines are, the larger their power requirements typically are as well. With the AltMill, the machine itself can run off 110V power from your outlet, but we expect a lot, if not most customers will want a 220V spindle as the 110V spindles may be underpowered. If speed is not your concern and you don’t mind running your machine slower, while being able to not need any additional electrical work, the AltMill is still a great option for a budget friendly 4×8.

Because it’s expected for industrial machines to be used in industrial settings, which typically have access to 220V and even 3 phase power, industrial machines likely will use higher power input options that typical hobbyists don’t have in a home shop or similar. 

Maintenance

The more expensive and complicated a machine gets, the more likely it is to require more expensive maintenance. At minimum, all machines need proper lubrication on all moving components including the linear motion systems, power transmission, and bearings. Industrial machines may require service by a technician or specialist for maintenance and repairs.

Maintenance on the AltMill on the other hand is designed to be done by the user, which means that it can be done without the need to schedule a service. Additionally, parts for replacement are relatively inexpensive. Because there is a self assembly portion of the machine, users also get an opportunity to understand the workings of their machine better.

Engineering

The engineering of the 4×8 combines development and innovations from the other AltMill versions and adds on top of it.

Linear Rail, Rack and Rail Coupling

One of the main challenges of bringing a 4×8 form factor machine to market is getting it to the end user. Simply put, limitations to the size and weight of packages shipped through courier cannot allow linear motion components used in the Y axis to be shipped in a single piece, unlike with the 2×4 and 4×4 machines. This means that these components need to be aligned and coupled together by the user. A significant amount of engineering was done to ensure the smooth and accurate coupling of these components.

Some designs and innovations in this space include developing:

• A special bracket and process for joining the two lengths
• Adjusting the spacing between linear motion parts and tolerancing to reduce the impact of gaps in between components
• An easy to follow process to reduce assembly error 

Rack and Pinion Engineering

A big debate when it comes to choosing rack and pinion versus ball screw has revolved (haha) around the accuracy and precision differences between both tools. While ball screws can generally achieve higher precision, ball screws come with several downsides that make them less accurate over longer distances.

First is that a longer ball screw can flex more easily. Since the ball screw is only secured at each end, it means that it can bend from cutting forces. This also can be exacerbated with any whipping that happens, which can introduce vibrations and limit the speed of which the machine can move.

Rack and pinion on the other hand is mounted along the length of the rack. This means that there is much less flex in the system. 

Additionally, ball screws cannot be joined together. Due to shipping limitations, the Y-axis parts must be separated and shipped in segments. Since racks can be butted together to make longer racks, this is not a problem with rack and pinion. 

It’s also important to note that the theoretical differences between rack and pinion are more relevant in very high precision applications such as commercial vertical machining centers, and less so in the application of CNC routers, where your material and cutting tool is more likely to influence the accuracy of your parts.

Wear and Hardness Testing

We have conducted a significant amount of testing and research to ensure a high degree of longevity of the rack and pinon system. Much of this came down to understanding the effects of hardness between the rack and pinon. We’ve explored many aspects of the materials used for the rack and pinion including:

• Post processing the parts including nitriding and heat treatment
• Working with different alloys
• Adjusting the gear profiles
• Long term testing of the use of different lubrication

Pinion Tensioning System

To ensure proper meshing of the pinion to the rack, we’ve also developed our own pinion tensioning system, which allows for the pinion to have the proper preload for eliminating backlash against the rack and adjusts for wear over time. This also allows for slight misalignments and tolerances in the machine and assembly process.

Gearing

To ensure high levels of precision, the motors are geared down to increase torque and increase resolution of the motor. We found that stepper motors also have a small amount of “elasticity”, which means that when they are held stationary, they can turn very slightly when a load is applied. Given the lower friction and higher distance to rotation ratio, this effect makes a bigger impact to the precision of the machine position while it is stationary. By gearing the motor down approximately 5:1, it effectively reduces the impact of “elasticity” as well.

Spindle options

The AltMill 4×8 will work with 1.5KW, 2.2KW ER20 spindles,, and our up and coming ATC spindle and natively support a toolchanger. 1.5KW and 2.2KW spindles are identical to the ones used on the 2×4 and 4×4 except with a longer spindle cable.

ATC

For those who don’t know, we have been actively working on an ATC spindle. We’re wrapping up development and production, but here’s some details to share before we do a full announcement:

• Price: 2500USD-3000USD
• ISO20 toolholders with ER20 collets
• Capable of expansion up to 12 slots/tools
• 220V, 2.2KW
• Air-cooled via low-noise electric fan

Users must provide an air compressor and dryer (such as a desiccant dryer). The ATC has been developed specially to be compatible with most consumer grade compressors (around $300).

Our ATci is specially developed as one of the most integrated, advanced, and beginner friendly ATC systems, with features including:

• Plug and play operation, with native integration with gSender allowing easy re-mapping/selection of tools for a given job
• Advanced safety features, including integrated: pressure sensing; temperature monitoring; tool in spindle check; and tool in rack sensing to monitor the state of the spindle at all times
• Easy to remove toolrack to allow users to switch to allow passthrough/tiling operations
• Designed for quietness. Low noise cooling fans and air seal that turns off when not in operation

We are expecting to do a full announcement and launch in November.

Production Schedule

Batch 1

We are building approximately 150 AltMill 4×8 in the first batch. We expect units from this batch to start shipping mid-Feb to early March 2026. 

Pricing

Pricing for the AltMill 4×8 without a spindle will start at $7,490USD/$10,390CAD. Spindles can be purchased and configured to the user’s needs and will have different pricings.

Shipping will vary based on location, but customers should expect to pay between $300-500USD in shipping within North America.

FAQs

How much do I need to pay upfront?

A full, 100% payment for the AltMill 4×8 is required to hold your place in line. Customers may cancel and get a full refund for their machine anytime before their machine ships.

Will there be any upgrade path to a 4×8 from a 2×4 or a 4×4?

It is under consideration but it will not be a priority for us to provide an upgrade path. First, given that so many additional new components are needed to go to a 4×8, the cost difference between the upgrade kit and the full kit will not be that significant. Additionally, there is a significant overhead cost to do version tracking and ensure compatibility between machine versions that will add to the cost of the kit. It’s likely that it will be more cost effective and reduce waste if customers sell their existing machines and order a full machine. 

Eventually we will have parts available for purchase which allows us to pave the way for a potential modification or upgrade path, but this will not be available until later next year.

Are you going to make a 5x10ft AltMill?

Not until we get the 4x8ft machines out the door first. But if we get enough interest or demand, we may consider it.

Will the AltMill 4×8 work with an ATC?

We expect to have our ATC system available for pre-order closer to the end of the year. However, the ATC system will be compatible with all AltMill variants and will ship around the same time as the first AltMill 4x8s start shipping.

If you’re ordering an AltMIll 4×8 before all of the spindles are available, we recommend placing your order for one closer to when your machine is slated to ship.

What are the power requirements of the AltMill 4×8?

All AltMills use a 110VAC, 48VDC 10A power supply, consuming up to 500 watts. The power supply comes with a North American Standard Type B NEMA 5-15P plug.

Users will also need to account for power use from the spindle, which have separate specifications.

How big is the AltMill 4×8?

The footprint of the AltMill is approximately 114″ long x 66” wide, and over 66” tall (when including spindle height).

A lot of things are going on at Sienci Labs, and it’s time to talk about what the future looks like for the LongMill product line.

As you might know, the goal for the LongMill was to build an entry level, hobby-focused CNC machine with these characteristics:

• Price affordably
• Features that both beginner and experienced users wanted
• Large enough to do a wide variety of useful projects

A shift in the entry level market

When the LongMill first came out as a Kickstarter project in 2019, it was a radical addition to the hobby market. Not only was it significantly less expensive than some of its earliest competitors and popular machines of the time (like the Shapeoko and XCarve,) it introduced the use of leadscrews, which was (at least in our consideration) far superior to the use of belts.

Over the years, the LongMill was iterated with notable changes including:

• Transitioning to using 3D printed structural parts to metal and injected molded parts
• Custom aluminum extrusions
• Introduction of T12 based power transmission systems
• Introduction of gSender as the most advanced and intuitive hobby CNC control software
• Integration of notable accessories such as the Vortex Rotary Axis, Autozero Touch Plate, and more
• grblHAL and the SuperLongBoard, bringing next generation CNC electronics and control
• Introduction of a 4ft wide format, allowing the use of full width (4ft) sheets

Over time, we’ve seen a lot of changes in the hobby CNC landscape. The first is most hobby CNC producers going upmarket, focusing on “prosumer” machines in the $3000-6000USD range in favour of entry level machines in the sub-$2000 range. This left the LongMill as one of the only mid-format hobby CNC machines in the market.

We also saw a big wave of Chinese hobby CNC brands like Foxalien and Sainsmart enter the market, allowing users to get a taste of CNCing for a few hundred dollars. This created a big gap in the market, where users could get a very entry level CNC machine for a small amount, or move up market to a machine that could be used for small scale production for a few thousand dollars. The LongMill sits somewhere between.

Where does that leave the LongMill today? First, this presents a unique opportunity for the LongMill to combine the best of both worlds. The current design of the LongMill has not seen much change in the last 2 years. With access to new technologies and resources, we believe it’s time to implement advancements into a new version of the LongMill to make it relevant to the times.

Pricing

We will be lowering the price of the LongMill MK2.5. There is a market reason and strategic reason for this change. Over the last two years, we’ve seen a slow decline in LongMill sales. We believe that there are several factors to this, but the two main factors come down to competition and the price delta between the AltMill and the LongMill:

1. We believe that the LongMill now competes more closely with entry level Chinese hobby machines rather than North American built hobby CNC machines, and thus we should adjust pricing to reflect this. 

2. We’ve noticed the price difference between the AltMill and LongMill is small enough that most customers are choosing the AltMill instead.

The LongMill MK2.5 is still a fantastic entry-level CNC machine. We still have customers who actively use their LongMills, and regularly see examples of the MK1 versions being used on a daily basis too. We don’t know exactly how many LongMills are in the wild, but we’d estimate that there’s been nearly 10,000 shipped since the launch of the machine. However, to adapt to these external factors, we’re also making some changes.

New pricing for the LongMill MK2.5 will be available Oct 13, 2025. All machines and their variants will be reduced by $300CAD or $220USD, until supplies last.

We believe that these pricing changes make the LongMill a more competitive option in the current market, aligning with other, more direct competitors.

With regards to the strategic factor, we want to make some space for the new version of the LongMill. We’ve started prototyping some initial designs and want to start prepping for production early to mid next year. This means that we want to liquidate some or most of the existing stock of the current LongMill MK2.5.

What is the new LongMill?

In many ways, the new LongMill will be the same as the old LongMill, aiming to serve the same target demographic at a similar price point. However, the LongMill will be updated with all of the new technologies and development we’ve implemented between the LongMill and AltMill. 

We don’t have too many details to share at the moment, but keep an eye out near the end of the year for more info!

Future of the LongMill MK1, MK2 and MK2.5

Support for all prior generations will continue to be available in several different formats:

• Wear components like the Delrin ACME nuts and v-wheels will continue to be available on our store
• Cross compatibility with the SLB, motors and power supply across all generations of the LongMill will continue to allow for replacement options
• All design generations of the LongMill will continue to be open source, which allows users to fabricate their own parts if necessary
  

We expect the new version of the LongMill to have a lot of similarities and shared parts, allowing some cross compatibility. However, we don’t expect there to be a simple or affordable upgrade path for the core structure of the machine.

Final thoughts

We’re excited to navigate through this new hobby CNC landscape. We’re excited to see this market grow and new competitors come into the space. With new developments and advancements we’ve made in the AltMill line, plus everything we learned from shipping thousands of LongMills, we’re excited to bring new advancements to a new line of beginner focused, entry level CNC machines.

Earlier this year, we were asked by the ESA to restrict the sales of VFDs within Ontario, Canada, until we had received certification. Since then, we have been working on a design of our VFDs to certify their use. We did not have to do any further certifications for the spindle as they were already certified.

The short answer of whether an electrical product needs certification or not is yes, or more officially, complying with CSA standards qualified by UL or equivalent. Certifying a spindle and VFD system ensures:

• The system is tested to be “safe”, which takes into account factors like fire resistance, shock prevention, mechanical durability and more
• Protection against liability in the chance of an issue arising from the device
• Ability to be imported into certain regions

However, in practice, most spindles and VFDs sold in North America for hobby use do not carry a certification. In fact, based on our research, at the current moment, spindles and VFDs from Carbide 3D and PWNCNC, as well as Amazon, don’t have certifications. The only systems that carry the proper certification is Redline CNC, which describe themselves as the “industry’s first and only safety approved plug-and-play spindle kits”. 

As far as we understand, there is no specific requirement for hobby or home users to need certified spindle systems for the US*, especially if they are putting together their own systems which is why we have been able to keep selling to the US. For commercial use, insurance companies may require the electronics used to have certifications, either as a field inspection or with the use of certified equipment.

*Somewhat ironically, given that we are restricted from selling uncertified VFDs in Canada, Canadian customers have been purchasing other uncertified (perhaps less safe) spindles and VFDs instead from the US.

As a whole, I believe that it is the responsibility of the manufacturer to design and develop their products to ensure they are safe. Certification is a good representation of compliance of established standards designed by experts in the field. However, certification can cost thousands, if not tens of thousands of dollars, on top of thousands of dollars in yearly inspections needed to keep the certification active. For a full certification of a product like a VFD, we could be looking at spending around $35,000 USD, plus a few thousand dollars per year to upkeep the certification. We believe that the cost restriction is a big barrier for most manufacturers to get full certification for their products. In fact, through this process we learned that our manufacturer of VFDs had received certification for the same VFDs that we currently offer a number of years ago, but due to cost reasons, let the certification lapse. One-time certification at the scale at which we operate also prohibits us from continuously improving our product to meet the changing needs and feedback from users.

There is a secondary option, called SPE-1000, which is a field certification, where an inspector can individually inspect electronics instead. This option is more practical at lower volumes, as we simply need to pay for the inspector’s time, so that the cost to inspect units would work out to only $30 a unit. The cost for this in the short run would be less than getting a full certification.

For the short term, we will offer both certified and uncertified systems to US customers once they are available. Canadian customers will only be able to purchase certified systems. In the long run, we will likely consolidate all of the systems so that all systems will have the same hardware, and have a price difference for models with the certification. In the future when the production volume gets large enough, it may end up being more effective to move from field certification to a different certification standard.

Design Differences

The new VFD comes with several changes considering improved safety and ease of use.

Ease of use improvements:

• Pluggable spindle cable: the cable for the spindle is no longer wired in with a screw terminal but instead uses a plug on each end allowing for the user to easily connect and disconnect the cable without tools
• Pluggable AC cable: like the spindle cable, rather than needing to use a screw terminal for the plug, the NEMA 5-15P style cables. Note that this cable must be rated for 15A (these are provided in the kit)
• Pluggable RJ12 connector for controlling the spindle via RS485
• Fuse is easily accessible and swappable
• Switch allows for user to easily turn on and off their VFD

Safety related changes:

• Components are tested for fire resistance, and all bear appropriate UL/CSA safety markings
• Enclosure designed to prevent shock, with proper spacing and mechanical strength to prevent shorting
• Proper safety warnings and stickers

Customers waiting on certified VFDs

Currently we have a small number of users waiting on certified VFDs within Canada. These are either people who ordered and received a spindle kit (uncertified), or ordered but are waiting for their kits to ship, before we took it down from the store. Customers had the option to return their kits for a refund or wait until we provided the certified version.

We’re currently assembling the first 100 units for the 110V 1.5KW, some which will go to the initial customers, and the remainder will be available to Canadian customers once the batch is complete.

We are working directly with these customers to issue the replacements.

Current Production

Along with the first 100 units, an additional batch of roughly 300-400 of 110V 1.5KW VFDs, and 300-400 of 220V 2.2KW VFDs are also being lined up for production. Whatever units we have left from the first batch will be available to the general public; the other units will be available once we have an expected ship date for everything else.

Pricing

Here’s a timeline and estimated sale price for each variant. Please note these are estimates only and may change – watch for emails and social posts for formal announcements over the next few weeks

Enclosed VFD refer to the certified versions

Unenclosed VFD refer to H100/uncertified VFDs

1.5kW ER20 with unenclosed VFD – $555 USD

2.2kW ER20 with unenclosed VFD – $700 USD

1.5kW ER20 with enclosed VFD – $650 USD

2.2kW ER20 with enclosed VFD – $790 USD