Everything you need to know about the spring-loaded anti-backlash nut

Hi everyone, I’m excited to share a small development, the Spring Loaded Anti-Backlash Nut! As we’ve continued to have LongMills out in the wild, we’ve recognized that the finickiness of the Delrin Anti-Backlash Nut was a pain point for our users, such as the need for adjustment on a regular basis, the potential for the adjustment screw to fall out, and improper tensioning causing jamming, especially at higher speeds.

The Spring Loaded Anti-Backlash Nut is designed to address these issues by using a set of springs to tension the nut against the threads radially, allowing smoother operation and no adjustment needed from the operator. We are now putting this out into the wild for field testing!

These nuts are drop-in replacements for any T8 size Delrin nut on the MK1 or MK2 LongMill.

Assembled Spring Loaded Nut

This new version is now available on sale and ready to ship in our store.

Flaws with the current Delrin Anti-Backlash Nut

For those who don’t know, the Delrin Anti-Backlash Nut design comes from the original Openbuilds Anti-Backlash Nut Block. At the time, this was more or less the best option for this type of hobby CNCing for T8 lead screws because it’s:

  • Inexpensive
  • Simple
  • Easy to manufacture
  • Easy to integrate
  • Low maintenance
  • Generally works pretty well

Since we were still in the early stages and didn’t have the manufacturing volume and capability to make our own designs at scale, we stuck to a lot of open-source and off-the-shelf components. As some users may have noticed, we’ve slowly been working on different innovations to improve and redevelop our own components to work better and more reliably.

The original design comes with a couple of flaws:

  • Requires constant adjustment to reduce backlash
  • Over-adjustment or incorrect assembly results in binding
  • Inconsistent resistance during its life cycle

To improve on this design, I worked on some different concepts using springs to pre-load the nuts, finally resulting in this shape:

“This design incorporates OpenBuilds, LLC design work(s) shared Open Source under the CC BY-SA 4.0 License.”  

In this design, we use two springs in the gaps to apply radial preload on the lead screw threads. This allows the two “arms” to push into the threads as it wears, automatically reducing the backlash.

According to Helix Linear, another manufacturer for anti-backlash nuts, “the radial anti-backlash nut can handle loads greater than the spring force. There is also less of an increase in required drive torque compared to an axial anti-backlash nut.”

In this design, we use two arms instead of three typically used in industrial nuts, to keep the same form factor, so that the new nut can drop in to replace the current version with no modification.

Other benefits include:

  • Zero adjustments or maintenance after installation
  • Lower potential for binding
  • Smoother, lower resistance operation

Next steps

We’ve done some initial testing with 3D-printed nylon nuts, which have pretty good results, showing basically no backlash over testing. We’ve now ordered 400pcs (100 sets) of machined Delrin nuts. Our goal is to put them available for sale for people to use on their own machines. If they work well in the field we will switch to spring-loaded nuts as the default standard in LongMill kits.

I should include a disclaimer, which is that these are still a new, unproven product, and it is still possible that in the long term they may perform worse than the original nut.

We want to put these nuts out in the field so that we can get feedback and long-term testing done to validate the design. I’m very confident that this will make an improvement to the overall experience of using the LongMill, but before we make the switch, we want to make sure that we do some real-life testing.

There may be some small tweaks we may consider making, such as adjusting the spring force and length and spacing of the arms, which may happen based on the beta testing.

For this first batch of nuts, we will collect some survey data to help understand the experience of the user. At this current stage, we only have T8-size nuts, but we may expand it to the T12 size as well.

August 2023 Production Updates

July was a bit of a slow month due to the Vancover port strike holding up shipments for us to ship LongMills in the queue. However, now that parts are back to arriving again, we’re picking back up with our regular routine.

We have a lot of news to cover, especially with the pending release and shipping of the Vortex Rotary axis and new development around the SuperLongBoard.

Want to get news like this directly in your email inbox? Make sure to sign up for our mailing list.

UPS reaches labour deal with Teamsters before strike

This July, we found out that Teamsters working for UPS were preparing for a strike in August, which would have disrupted shipments going to the US. However, UPS and Teamsters have settled on a new UPS contract which increases worker wages across the board and improved working conditions.

We are happy to hear that a resolution has been made, especially as we get into the busiest part of the season for our business.

LongMill and Extension Kit Orders

July has been a slow month for us shipping out LongMills as we have been affected by the port strike that delayed our shipment of controller boards. However, I’m happy to announce that we will receive the boards today and expect to clear the queue in the next 2 weeks.

The large majority of the pending 100 LongMill orders have been packed and are waiting to have the controller boxes done to have them shipped out.

Some LongMills waiting to be shipped

As some folks may know, we’ve continued to work on smoothing out the process of dealing with customs for shipments going to the US. Recently, we’ve been assigned a single contact with UPS to handle all of our LongMill shipments that need customs clearance going to the US. We found that some items were being miscategorized for duties and taxes, and we suspect it is because a big part of this is a manual process that causes human error. We believe that having a single contact who is familiar with the line items will speed up the clearance process with fewer mistakes.

A few new design updates on the LongMill MK2 design include a focus on phasing out of using M3 bolts in the assembly process and replacing them with M5 screws, including parts such as the couplers and ACME locking nuts. We are phasing out components using M3 screws in the LongMill assembly process because they are prone to stripping the heads more easily. Eventually, a full LongMill will be able to be assembled with just one M5 Allen key and our special wrench that we provide (as well as a drill and bit to mount your LongMill to a wasteboard of course).

Some new prototypes of the assembly wrench for new hardware
New T8 locking nuts replacing the brass ACME nuts

We are also starting to use longer Z motor cables for the motors so that LongMill 48×30 kits, which are now the most popular variant, will not need a motor extension cable, simplifying the assembly process as well.

Additionally, now that the design of the LongMill MK2 has matured over the past year or so since its launch, we are moving to figure out injection molding parts for it for the first time. If you didn’t know, we 3D print several components for the LongMill MK2, including the dust shoe and feet. We found that due to the large number of feet we print, moving to injection molding would be a natural next step to reduce our need to rely on the 3D print farm, which is harder to scale production for.

We are entering into the first day of August with around 100 pending LongMill orders, but we expect to clear the queue in a week or two, after which we expect to shorten lead times again.

Vortex Rotary Axis

The last of the Vortex Rotary Axis parts have arrived at the end of July and we are now starting production and assembly!

First batch of machined parts looking beautiful
Test assembly of the Vortex kit
Switch assemblies for Y axis to rotary mode

Our team has been continuing to work on different areas of the Vortex so that when they get into the hands of our users, they’ll have everything they need to get started. This includes:

  • Thorough assembly and installation instructions. We just completed initial trials and tests of the assembly process to make sure that we provide clear instructions to make it easy to put together. We found that everything came together really easily, except for the cam clamping system for the t-track, which we are currently working on to make it less finicky. We estimate that most users should be able to put it together in about 30 minutes. Full instructions will be found on our Vortex Resources soon.
  • Video content about the Vortex. We understand that not a lot of how-to and tutorial content exists for rotary CNCing. Our video production team and the engineers are working on the next steps for creating content so that our users can learn how the Vortex works and how to use it.
  • The gSender team continues to work on completing Rotary Axis implementation into the gSender, including homing and visualization for rotary. These features will be in gSender Edge at the time of launch and will be merged into the main version of gSender down the line. You try and learn about the latest version of Edge here.

We will start to trickle out Vortex Rotary Axis kits over the next week or two as we iron out the last bits of details. We expect the first batch of kits to start shipping out at the end of this week or early next week.


LaserBeam production continues to move along smoothly, with most orders shipping out within a few days. We have stock available for the LaserBeam ready to ship now.


Work for the SuperLongBoard (SLB) continues on. The team has been able to successfully test the main functionality with excellent results. However, we found our initial tests with the onboard compute module to be unsuccessful, as the Broadcom and Rockwell-based processors used on smaller compute modules to not be powerful enough to accommodate the visualization of g-code directly onboard.

Revised SLB

While additional software development was able to make significant speed improvements, we felt that the compute module would most likely need more headroom in the future if we were to implement other features down the line such as having a camera monitoring system, which we felt would be difficult to add due to a limitation of system resources.

We have now started looking at higher power compute modules, single board computers, and other hardware that we feel would ensure that the onboard gSender experience would be smooth and seamless, as well as provide headroom for future applications. However, the downside is that higher-power computers also cost more, and while our initial budget was around $80CAD/60USD for the compute module, we expect the computers to cost somewhere around $100-$200USD depending on the specs and configuration.

That being said, since we don’t need to have certain components and other parts to support the onboard computer directly, some of the cost of the computer is offset by the lower cost of the SLB itself.

We’ve decided to split the development of the SLB into two parts, one for the board itself, which will use grblHAL, a new, more advanced firmware and all of the improved motor control and drivers, and the computer itself. This means that the computer will live off the board in one fashion or the other.

While it would have been really cool to have the whole system integrated, we believe that by dividing and conquering, we can have the main portion of the SuperLongBoard out of the development process and into production first, and focus on the computer addition after. We felt like we could tackle some of the main problems with the current LongBoard with the new controller, and that it would be better to have the improvements we’ve already developed reach users sooner rather than having everything wait on further development on the onboard computer side.

This means that users will still need to connect their computers to the board to control their machines when the first batch of SLBs release, but better communication protocols, electronics, and shielding will make the USB connection significantly more reliable than before. Andrew, our main developer on this project, assures me that unreliable connections that cause issues with some users with the current board will be a thing of the past.

This version of the SLB natively supports communication over Ethernet, as well will have onboard storage which allows for streaming onboard rather than through a cable, which will improve reliability as well.

We are making the final design changes to prepare this version of the SLB for prototype production, and we hope to have production boards available near the end of the year. If you want to learn more about the SLB, please read: https://sienci.com/2023/04/10/first-look-at-the-superlongboard/

Vortex Rotary Axis Launch Date – June 1, 2023

The Vortex Rotary Axis* will be available on June 1, 2023, at 1 PM Eastern Standard Time, where the first 300 units will be available for pre-order. We expect to ship in August 2023.

New videos and content coming out for the Vortex soon! Make sure to sign up for our mailing list, for new updates and other Sienci-related news. Subscribe to our Youtube channel where we’ll post more videos on the Vortex Rotary Axis in the new few weeks!

*After much debate, we have decided to call the name for this new add-on the Vortex Rotary Axis

It’s been a long journey for developing the Vortex Rotary Axis, but we’re finally excited to share a launch date for our new add-on! This new product aims to make doing rotary projects like making bats, wands, furniture legs, bowling pins, and other turn-able projects with your LongMill and the Vortex.

The Vortex is unique in that not only is it a compact, precise, high-quality rotary axis we designed from scratch, but our direct integration into gSender also plans to add functionality not found in other CNC systems. Additionally, just like all our products, the Vortex will be supported by our team with high-quality tutorials and resources to make it easy to install, learn, and use your rotary axis.

The Vortex can be integrated, plug and play, in any standard LongMill CNC**, and comes with the hardware, electronics, and instructions to help you find success with CNC rotary carving!

**With the exception of the 12×12 LongMill MK1. Integration for the Vortex Rotary Axis on 12×12 machines may require moderate modification to fit.

Video Content

What is a Rotary Axis?

The Vortex Rotary Axis is an add-on created to allow users to integrate a rotary axis into their LongMill.

Most CNC routers like the LongMill use a 3-axis system, which consists of an X, Y, and Z linear motion system that is used to position bits and end mills. One of the limitations of a 3-axis system is the fact that 3-axis machines cannot make “undercuts” without flipping or material manually. Since the machine only can orient the bit vertically, there are limitations to the types of geometry it can carve.

Source: https://waykenrm.com/blogs/undercut-machining-for-cnc-machined-parts/

To address these limitations, CNC machines can come with additional degrees of motion, typically including a 4th or even 5th axis. In the case of the LongMill, a rotary axis positioned along the X direction allows the machine to turn a part as the X and Z axis can move in sync as the material turns and rotates.

On a mechanical level, the 4th axis for the LongMill will come with a chuck to hold the material as well as a series of bearings and pulleys connected to a stepper motor to rotate the material as the machine carves. This allows for users to make projects like:

  • Bats
  • Chess pieces
  • Furniture legs
  • Wands
  • Figurines
  • Busts

and more!

Production and Pricing

Each Rotary Axis will come with all of the hardware and electronics to integrate the kit into any existing LongMill CNC.

The Rotary Axis will start at:

$600CAD/$449USD – For 12×30 and 30×30 LongMills

Dimensions below.

$640CAD/$469USD – For 48×30 LongMills

Dimensions below.

The main difference between the two options is the rail track extension that allows users to mill larger items corresponding with the X-travel range on each version of the LongMill.

All options will come with a standard jaw that can hold material in several configurations:

Additionally, customers should budget purchasing rotary axis ready CAM software, such as:

  • Vectric VCarve Desktop, VCarve Pro, and Aspire ($349USD, $699USD, $1995USD)*
  • Fusion 360 ($1600/year)
  • DeskProto Multi-Axis Edition (€249.00 for the hobbyist edition, €995.00 for commercial)

*Based on our testing, we strongly suggest Vectric software for its simplicity and user friendliness.

Resources and Support

It’s important for us to stress that the Vortext Rotary Axis follows our philosophy for providing a complete product, not just hardware, but high-quality support, resources, instructions, and tutorials to make sure users are able to use their rotary axis to the fullest.

We’ve recognized that not only are affordable rotary axis options are limited in the hobby CNC space, but the resources needed to learn it also are lacking. We’ve taken the initiative to provide support through the Vortex.

Did you know that we regularly post tutorials and educational content for the LongMill on our Youtube channel? Make sure to check it out and subscribe to us if you haven’t yet!

Production Timeline

The Rotary Axis is already in production, with parts expected to complete and arrive between June and July. We are expecting a late July to mid-August shipping date. Please note that because this is a pre-order, timelines may change due to delays and unexpected circumstances. We will continue to share production updates for the Rotary Axis on a regular basis on the blog here, so that customers can sign up for our mailing list, for new updates and other Sienci-related news.

Development Timeline

Mechanical and electrical design and development of the Vortex Rotary Axis is now complete, and we are currently waiting on production parts to complete and arrive. Our engineering team is currently working on stress testing and resource development, as well as preparing for assembly, QA, and packaging for the final product.

The software development team continues to finalize the development of the software support in gSender, such as implementing new features and getting testing feedback from users of gSender Edge. We expect basic functionality to be available at time of shipping, and we will continue to add more features in future releases of gSender.


When will the Rotary Axis ship?

Production on the Rotary Axis is currently ongoing, with the first units expected to ship in Late July to August 2023. For general development and production updates, please check our Blog. Orders will ship in the order in which they are placed.

What is the between the 48in and the 30in versions?

These lengths describe the track width for the rotary axis. Customers should purchase the size that matches with the working width of their LongMill.

When do you take payment?

We take the full payment immediately. Customers may cancel their order for a full refund anytime before their order ships.

What happens when all 300 units are sold out?

Based on early demand, we’ll decide on when we’ll start building a new batch. Turnaround times to build each batch takes about 3 months, so there may be a few months wait time additional once the first 300 units are sold out.

Will I get a notification or email before my order is ready?

Yes, we’ll send you an update email to let you know that your Rotary Axis is ready to ship.

Which machines is the Rotary Axis compatible with? 

The Rotary Axis is designed to be compatible with all versions of the LongMill, with the exception of the LongMill MK1 12×12, due to the track width (however it can be modified to work).

We will be providing full assembly resources for the Rotary Axis.

Although users may be able to integrate the Rotary into other hobby CNC machines, we will only be providing compatibility and support for LongMill users at this time.

How is the Rotary Axis driven?

In the current configuration, the Rotary Axis uses the X-axis and Z-axis to move along the rotational axis of the material, with the Y-axis drivers disconnected and reconnected to the Rotary Axis motor to provide rotational movement. This means that in this configuration, the system is not a full 4-axis machine, but more of a 2-axis + rotary system. Each kit will come with a switch to toggle 3-axis and rotary axis modes.

In the future, we are planning to provide full simultaneous 4th axis motion through the SuperLongBoard, expected to launch at the end of the year (at an added cost).

Does the Rotary Axis come with software?

We’ve implemented gSender to integrate the ability to control, set up, and home the Rotary Axis. Users will need to use or purchase CAM software that supports rotary carving. We recommend VCarve Desktop or VCarve Pro, as this is the software that we primarily use and do testing on.

Can I order other items alongside my Rotary Axis?

For logistical reasons, we strongly recommend users to place separate orders for the Rotary and other items. However, if you place an order for other items with the Rotary, we will ship them separately based on the stock availability of the items.

When your Rotary Axis is ready to ship, if you wish to order additional items to ship together with combined shipping, please Contact Us for assistance.

Some custom bats made on the Rotary

First look at the SuperLongBoard

Hey everyone, I’m excited to share with everyone a project that Chris and the rest of the Sienci Labs team have been working on in collaboration with Andrew and his team Expatria Technologies to develop a new CNC control board and firmware system. The SuperLongBoard (SLB for short) represents a huge step in hobby CNC technology, as it’s advanced electronics and software bring not just new features and functionality to the LongMill, but at a price point that we believe will be affordable for hobbyists.

LongMill running at 10,000mm/min and 750mm/s^2
The SuperLongBoard taking its first baby steps

What is the SuperLongBoard?

The SuperLongBoard is a next-generation control board for the LongMill CNC. This development gives access to a whole new set of features, functionality, and integrations more commonly found in industrial applications to the hobby CNC market. Some features and functionality include:

  • Full integration of gSender within the control board, removing the need for a separate computer to run the CNC
  • Advanced, programmable stepper drivers that run motors faster, quieter, and with more torque
  • Faster, more accurate motion control processing for smoother movements
  • Ability to control more than 3 axis, for full 4th and 5th axis motion control
  • Networking and file transfer with wifi and ethernet, USB port and SD card for removable storage, HDMI output for display outputs, and more
  • Standard PWM control for laser and spindle, with compatibility with industry-standard RS485 protocols for industrial-level spindle control
Rapid tests using the SuperLongBoard

Additionally, this design will have many input-output connections and ports to allow for new features and accessories to be used with the new board, effectively future-proofing your machine for years to come. Some of these features include:

  • Automatic tool changing support
  • Skew, cutter, and joint compensation
  • External wired and wireless pendant control
  • Camera and machine vision for features like failure and crash detection, auto zeroing, auto-tracing, and more

Please note that although these features are something we want to work on down the line, we currently do not have specific timelines on these features and they will not be available during launch.

You can even set up the SuperLongBoard to send messages through Slack!

The SLB is a system of two different parts working together. The first is the board itself, which contains all of the core functionality. This includes motor control, sensor inputs and outputs, and lower-level processing of g-code. Users will be able to tether this part of the controller directly to the computer using a USB cable in the same way as the original LongBoard currently used in all LongMills to control their CNC machines.

SLB takes things to the next step with the addition of an onboard compute module. The SLB has a small connection interface at the bottom of the board that allows for a compute module to be attached and replaces the computer or laptop. Users can connect a keyboard, mouse, and monitor to control all functions of the machine directly through the SLB.

The SLB can operate with and without the compute module. I expect that given the considerably low price of the compute module over a computer, around $40-80 dollars plus the cost of the monitor, keyboard, and mouse, as well as the extra speed, user experience, and reliability of an onboard system. But we are planning to allow for the board to be used in either configuration.

This control board will be backward compatible with ALL LONGMILL CNC MACHINES OF ALL GENERATIONS, which means that users can upgrade their machine’s capabilities by simply replacing the controller. All of the hardware and software will come ready to go, plug and play for all LongMill CNCs, and will have a similar form factor to the current LongBoard so that it can be integrated easily into your existing machine.

Why the SuperLongBoard?

The creation of the SLB comes with a series of motivations. The first and main motivation is our belief that at this current stage, the integration of smarter, more reliable, and more capable CNC control electronics will make the biggest improvement to the CNC user experience.

This new design will aim to eliminate many common issues universal to hobby CNC at this time, including:

  • Electromagnetic interference issues
  • Computer, compatibility, and connection-related issues
  • Resonance and driving issues restricting motor performance

With the integration of an onboard computer and far more sophisticated electronic systems, the SLB will not only be able to eliminate these issues, but it will also allow us to have better control of the hardware and software to optimize every aspect of the board and iron out bugs more easily.

As some readers know, we’re also in active development of the rotary axis. The SLB will also open up more possibilities for integrating new add-ons and improving already existing add-ons such as the AutoZero touchplate and LaserBeam. Some other potential add-ons include:

  • Plug-and-play router or spindle with programmable speed control
  • Bitsetter
  • Toolchanger
  • Plasma cutter

There are no specific development timelines for these items, but the SLB will allow for better compatibility for add-ons such as the ones listed above.

Development of the SuperLongBoard

The SuperLongBoard has been in development since the Fall of 2022. We’ve received our first batch of prototype boards and have been working with Andrew to develop the firmware and software for the control boards, finalize the PCB design, and prepare them for long-term beta testing.

The development of the SLB actually comes with many different individual developments that all work hand in hand. First is the integration of grblHAL, a rewrite of GRBL that was originally designed to work on Arduino-based controllers. One of the limitations of GRBL was that since it was designed to work on low-performance microcontrollers, it has limitations on what features that could be added. Additionally, there are limitations on things like how many processes could happen at any given point and the raw speed of the processing of g-code and motor signals.

grblHAL essentially uses something called a hardware abstraction layer (HAL). The HAL is essentially like a switchboard that the GRBL core knows how to use the microcontroller to communicate with different aspects of the board, such as the spindle control, motor drivers, and networking. This means that the development of core firmware that includes all of the functionality can be developed and only the HAL needs to be adapted to each model of the microprocessor. This means that the development of grblHAL benefits the whole community since features that are developed for one controller can be implemented on other controllers almost immediately with basically no modification. grblHAL, although still fairly new, already has a fair number of plugins that can be used to add functionalities.

The next part of the development is with the gSender integration into the SLB and to use grblHAL. Since the plan is to integrate gSender directly on the compute module, we are working on optimizing it for the hardware, such as improving the general performance and UI, adding new features and functionality, and testing the speed and reliability of gSender as a whole. We’re already working on the new gSender, and you can find an early access version here.

And lastly comes the design and production of the PCBs themselves. At this stage, we’ve mostly finalized the design of the board and are making the last few touches to the design and layout. The new control board uses a larger number of components, adding to the challenge and complexity in manufacturing, but we’ve been able to work closely with PCB manufacturers for the first batch of prototypes and expect this area to come along relatively smoothly.

We are expecting to work on testing the boards in-house for the next few weeks and start beta testing in the next coming months.


At this time, we’re expecting the manufacturing and production cost of the SLB and case to cost around $100 (prices here in CAD). The compute module is expected to cost between $40 to $80 depending on the model and spec, bringing the total cost of production to around $150.

Chris and I have been talking about the pricing and how we want to figure this out, but we do have a few goals:

  1. To offer it with new LongMill machine kits with minor changes to the current price
  2. To have a simple and inexpensive upgrade path from the original LongBoard to the SBL
  3. Reduce buyers remorse for currently existing customers

Here is our tentative pricing. Please note that pricing may change and is not set in stone.

SuperLongBoard, onboard computer, and enclosure: $280CAD/$210USD

This would be the full package with everything you need to plug and play with any LongMill. This also includes the onboard computer. Users who wish to use the onboard computer will need to provide their own monitor, keyboard, and mouse.

If you want to mix and match parts, you can use the pricing estimates below:

SuperLongBoard only: $180CAD/$140USD

For users that only want to upgrade the controller, but do not have the onboard computer. This would mean that you would still need to connect a laptop or computer to your controller. This also doesn’t include the price of an enclosure, so users can either make their own or integrate it with an existing enclosure. The case for this version of the controller is not backward compatible with the original LongBoard currently used in the MK1 and MK2 LongMills.

Onboard computer: $80CAD/$60USD

The onboard compute module is essentially a Raspberry Pi CM4 or another compute module of the same form factor. There are many different versions of CM4 form factor modules, all of which have different price ranges and specs. The price points of these modules vary greatly, which means the specific cost of this will be tied to which module we decide to choose. This would be available to users who choose to start with the SuperLongBoard and decide to add the onboard computer later in the future.

Enclosure: $30CAD/$23USD

The enclosure serves to protect the controller from dust and damage, as well as provide some mounting options onto the LongMill.

What’s next?

With regard to the LongMill

Once we get the SuperLongBoard into production, customers will be able to order them from our store to upgrade their machine electronics or as the controller that ships with new LongMills.

Here is our current general plan:

  • Once the SuperLongBoard is launched, to offer the original LongBoard and SuperLongBoard as separate options. The option for the original LongBoard would be the same, and the SuperLongBoard option would be a little more expensive.
  • Once we run out of or decide to phase out the original LongBoard, all new LongMills will ship with the SuperLongBoard.
  • For existing LongMill customers, we may provide a coupon so that users who wish to upgrade to the new controller can do so at a lower cost.

Based on where we are in current development, we expect SLB available sometime in the late fall or winter of 2023.

The exact details and pricing will come later.

With regards to other CNC machines

Given how powerful and integrated the SuperLongBoard is, we expect other CNC users to want to integrate the board with their own machines. While the board itself isn’t expected to cost a lot, given the complexity of support, resources, and documentation, we expect that a significant consideration in terms of support and price point will come down to many different factors.

We do plan on releasing the board designs open source as we have done for all of our hardware and software, which means that even if we don’t provide any official support, users who want to tinker should be able to figure out how to integrate things.

Here is our current general plan:

  • Users who want to use this board for other machines will be able to purchase it from our store, but they will not receive any technical or setup support. We will provide resources that we feel will be adequate for an experienced user to use for setup. At some point, we may also set up an online community where people can help each other.
  • In the future, there may be a certain tipping point in terms of scale for us to offer specific machine support, or if a third party decides to provide support themselves.

SuperLongBoard Survey

If you want to help contribute to our development for the SLB, please feel free to do our survey!

Link to the survey: https://forms.gle/7ujAmjZ7LGwdjMjT7

Everything you need to know about 4th/Rotary axis on the LongMill (so far)

One of the common asks that users have been requesting has been adding a 4th axis or rotary axis to the LongMill. We’re now happy to share some of the work we’ve been doing to add this support to the machine. We are currently in the early stages of development for this addition but have been able to get some good results from our testing.

A survey can be found at the end of the article, where you can help us understand your needs and get feedback and comments if you wish to participate!

What are we trying to sell here?

Although things are not finalized yet, here’s a breakdown of a rotary axis kit we’re looking to develop for the LongMill. Our goal is to have a kit that allows for a plug-and-play addition of a 4th axis to any LongMill.

  • Motorized chuck and headstock, along with a mounting solution to the machine
  • Cables and switches for connecting to the LongBoard controller
  • Resources and customer support to help set up and use the kit

What is a 4th axis?

Most CNC routers like the LongMill use a 3-axis system, which consists of a X, Y, and Z linear motion system that is used to position bits and end mills. One of the limitations of a 3-axis system is the fact that 3-axis machines cannot make “undercuts” without flipping or material manually. Since the machine only can orient the bit vertically, there are limitations to the types of geometry it can carve.

Source: https://waykenrm.com/blogs/undercut-machining-for-cnc-machined-parts/

To address these limitations, CNC machines can come with additional degrees of motion, typically including a 4th or even 5th axis. In the case for the LongMill, a rotary axis positioned along the X direction allows the machine to turn a part as the X and Z axis can move in sync as the material turns and rotates.

On a mechanical level, the 4th axis for the LongMill will come with a chuck to hold material as well as a series of bearings and pulleys connected to a stepper motor to rotate the material as the machine carves.

What can it be used for?

The best way to think about 4th axis is to look at it as a computer-controlled lathe. Projects that are best suited for using a 4th-axis include making table legs, chess pieces, threads, and other mostly cylindrical objects.

Who is it for?

At this current time, we are exploring the suitability of a rotary axis as examples of practical use are limited on the market. We’ve put a link to a survey at the end of the article to help us understand the use cases of a rotary axis by asking what the community is interested in creating!

Based on our research and experience, we feel that this is best suited for early adopters and people who are wanting to tinker with the technology and can accept that at this current time, it is quite primitive. There are quite a few steps to using this add-on and the learning curve involved that may not be intuitive to folks that are mostly familiar with the typical cartesian coordinate system. Additionally, there are a lot of new software features that need to be tested and created, and we expect software bugs in the initial development of the rotary axis that may be frustrating if it’s not expected in the early stages of this product.



By far the most important aspect of the viability of this project comes down to the software since a rotary axis is useless without being able to program it. At the current time, the number of software that supports 4th axis machining is limited and the ones that we feel are best suited for this application are paid. Some options include:

  • Vectric VCarve Desktop, VCarve Pro, and Aspire ($349USD, $699USD, $1995USD)
  • Fusion 360 ($1600/year)
  • DeskProto Multi-Axis Edition (€249.00 for the hobbyist edition, €995.00 for commercial)

From our testing, Vectric’s software, in terms of functionality, ease of use, and price, is our recommended choice.

We won’t get into any specific details comparing the software today, but it’s likely that when we start to create documentation for 4th-axis programming, that it’ll be done using Vectric software.


It’s also important to specify that with the current setup, this is not a true 4th axis. Rather, this setup uses the motor control from the Y-axis, disabling the linear motion from the two motors and redirecting the power to a single motor that controls the rotary axis. At this current stage, the plan is to provide hardware that allows for switching between rotary and linear motion by connecting directly to the control board.

While this seems like a big downside because the programming of true 4th axis is quite complicated and not supported by most hobby-level software.

Users who wish to explore true 4th-axis machining will need to use a more advanced control system and sending program to control the extra axis. We are working on creating electronics and software that will support this in the future, but we are not quite ready to share these details yet.


Due to the size of the LongMill and the size of the rotary axis, users should expect to be able to cut materials up to 4.5 inches in diameter and roughly 10 inches less than the length of their X-axis. So 12×30 and 30×30 users would be able to do up to 20 inches in length and 48×30 users would be able to cut up to 38 inches in length.

The longer the material, the less stable the cutting is, since the material is only supported from each end of the machine with a chuck and headstock. Further testing will show practical speeds and feeds at different sizes.


During the development of the project, we explored using either an off-the-shelf rotary axis option or designing one from scratch. It turned out that at this stage, it would be difficult to beat the cost of an off-the-shelf option purchased in bulk since if we were to design and manufacture it ourselves, the investment into design and the high volume of custom parts we’d need to produce would make it economically unviable.

Additionally, the off-the-shelf option appears to be quite well-made and good value, and ubiquitous enough that customers on a budget and willing to tinker may be able to source the same or similar option and use it for their machine, rather than buying it straight from us.

We’re estimating a landed unit cost for a pre-made unit in bulk will cost around $200. Additionally, the cables and electronic hardware required would add roughly another $15-20 to the unit cost. We also may need a precision fixturing plate that may cost around $100. Once applying a margin to account for things like development cost, customer support, shipping, resources, packaging, quality control, and everything else that we need to run a business, we’d estimate a price of around $500-700CAD per unit.

Additionally, users should budget to purchase software, as at this time we do not have a recommended free software option.

Next steps

Our next step is to determine the demand and viability of providing a rotary axis option to our user base. If we see enough demand, we can start to invest more time and resources in additional work and development such as:

  • Sourcing parts to create a rotary axis kit
  • Developing new features into gSender to add 4th-axis compatibility
  • Design of hardware for mounting to the machine
  • Resource development
  • Stress and long-term testing

Our first step is to share this survey so that interested LongMill users can share their thoughts, wants, and opinions on what they want to see in a kit.

In terms of timeline, we expect to make decisions on the direction of this project by the end of January. Depending on demand, we’ll start taking pre-orders for the kit and start sourcing components. We expect the sourcing and manufacturing process to take around 2-3 months, which brings us to around April-May 2023 when users may start getting their rotary axis kits.


To participate in the survey, please click the link below. Your participation is greatly appreciated!


NEMA 23 Motor Extension Cables and Inductive Sensor Extension Cables are available on our store

Hey everyone. NEMA 23 Motor Extension Cables and Inductive Sensor Extension Cables are available on our store!

We’ve had quite a few customers ask us on assisting with relocating their controllers further away from their CNC, which involves doing some rewiring on your cables on the CNC machine. Because the LongMill MK2 48×30 needs longer cables to work with the longer X-axis rail, these cables were initially designed for that application but will work to extend those cables in general as well.

Just to note, both the motor cables and inductive sensor cables as stock is 2500mm, which should be long enough in you’re keeping your controller close to your machine as most folks do, you won’t need to order these cables.

If you want to see the jig that tests the cables 100,000 times, please check out the video below:

Everything you need to know about the AutoZero Touchplate

We’re excited to share a new product, the AutoZero Touchplate! This has been a long and complicated project that has been in progress for more than a year, with lots of design and manufacturing hurdles to get over.

Introducing the product

The AutoZero has one main purpose, to find the origin point of rectangular pieces of material. One of the main drawbacks of using conventional touch plates however is 1)the inability to use non-straight bits such as v-bits, tapered bits, and ball nose bits 2) needing to specify the size or diameter of the end mill you are using for the probing sequence.

Some higher-end touch plates can calculate the diameter of the bit to assist with probing by touching off the inner wall of the touch plate to find the distance traveled across two surfaces.

However, the AutoZero Touchplate is unique since it also offers a chamfered surface that allows the tip of v-bits, tapered bits, and ball nose bits to be used.

Lastly, we’ve made some general improvements to the new touch plates including:

  • Improved designs for touch plate wires, resulting in more reliable connection at the magnet and touch plate ends.
  • Nickel plating to help with conductivity and improved asthetic finish.
  • Integration with gSender, to make the set-up process super easy.
  • Cutout design to make removing the touchplate easy and to help visually confirm accuracy.

Pricing and availablilty

We now have around 600-700 units in stock and ready to ship. Pricing will be $120CAD/$95USD. Now to discuss the elephant in the room, these new touch plates are a lot more expensive than the original basic touch plate. There are a couple of reasons for this.

  • The cost to manufacture the touch plate itself is substantially more expensive
  • The product times for this item is very long and unpredictable
  • The AutoZero provides features not found on any other touchplates

In essence, the pricing decision for this product comes down to the fact that these are expensive to make and we can’t make a lot of them quickly.

To also make sure we’re transparent about our pricing, we’ve also compared our prices with some of our other competitors, and the pricing for this touch plate is in line with other high-end touch plates which lack the functionality of the AutoZero. In terms of a value standpoint, we believe that the AutoZero offers more than any other touch plate currently on the market.

We are hoping that we can continue to improve the design and manufacturing process of this product to bring prices down and make it more accessible to our customers. However, we feel that this pricepoint still allows us to be competitive and still provides enough profit for us to invest in research and development, as well as lowering the chance that we’ll run out of stuff (a common trend the past two years).

In terms of recommending this product, this is a very nice-to-have but absolutely not a need-to-have. The original touch plate offers a great value at $35CAD/$27USD, and has many of the same features and functionality as the AutoZero. The AutoZero is not needed for general use.

The engineering that has gone into creating this project

It’s safe to say that a lot of research, thought, and design went into this product. Here’s just a small peek at some of the things that we went through with creating the AutoZero.

Physical design and functional improvements

Here’s an excerpt from Chris’ design documentation:

Desired Functional Improvements for V2

There are many things that the current touch plate does well but there are possibly more features that we could integrate into a newer design while retaining the existing functions:

  1. Stabilizing the touch plate when placed on stock material before & during probing
    • This can be accomplished by moving the plate’s COM (center of mass) to be further overtop the stock material, placing more of the plate’s mass overtop the stock material, or increasing the coefficient of friction between the touch plate and the stock material
    • This creates a more reliable probing operation where the plate’s position is less affected by the movement of the wire harness, the small force imparted from the bit onto the plate during the probing procedure, or by other mishaps like the user grazing their hand past the plate before running the probe sequence
  2. Probing without the need to specify end mill diameter
    • Touching off two known surfaces rather than just one can allow for bit size compensation during probing, removing an extra step for the user
    • This can be done most easily by using a circular or square cutout or extrude
    • Need to ensure that enough wall contact exists to catch the mill flute at its greatest distance from its centerline
      • With our biggest mills being ¼” and having a helix angle of 30°, the largest span between peaks, P, would be = πD * atan(90-β) ≈ 16.13mm
      • The pitch on the ⅛” bits however is about = 8.17mm
      • Smaller ⅛” bits can have a cutting length of only 12-17mm so finding the right wall height to accommodate full contact on ¼” bits but not hitting the collet nut on ⅛” bits is a close game (collet nut furthest dia = 24.98mm)
  3. Probing non-straight-style cutting tools
    • This can include v-bits, round groove bits, and tapered bits (no straight edge bits)
    • Although these geometries can be unpredictable to probe, all these bits have a cutting edge that leads down to a singular conductive tip which we could leverage to locate their XYZ positions
    • Using a very shallow geometry, we should be able to make contact only with the tool tip while still being able to infer the XY location. V-bits would require a 45° minimum for 90° v-bits and below, but tapered and round groove bits would require and even shallower tangent geometry
    • Possible probing sequence
      • Touch the bit to a top surface to find the initial Z height 
      • Using the Z height and locating the bit near the shallow geometry, touch off the bit point in two X locations and two Y locations
      • Using these 5 probed coordinates, we can locate the zero point of the cutting piece
  4. Ability to measure angling in the stock material
    • Touching off at two or more points could allow us to compensate gcode to accommodate stock material which hasn’t be mounted square to the machine
  5. Coating the aluminum to avoid any future issues with corrosion or reduced conductivity
    • Openbuilds probe leverages 2µm nickel coating

Ideal design will maintain:

  • Thin profile to not reduce z-travel needed for probing
  • High side walls for straight bits
  • Low chamfered profile for tapers and Vs
  • Same starting point for all bits
  • Bit goes to zero point once probing is complete
  • Good weight and COM distance from material edge
  • Plate places to bit rather than bit placing to plate

Over 8 different design concepts were created before landing on the current design. Here are a couple examples.

  1. Hole block

    Rough dimensions: 60x60x20mm
    Total weight: 147g
    COM from edge: X & Y= 19.89mm
  2. Leaf plate

    Rough dimensions: 60x60x20mm
    Total weight: 127g
    COM from edge: X & Y= 20.12mm
  3. Hole block

    Rough dimensions: 80x80x20mm
    Total weight: 206g
    COM from edge: X & Y= 28.04mm

Manufacturing and supply chain challenges

The new design also proved to have some design challenges as well. First of the design challenges was in creating the chamfered edge. The AutoZero uses a 170 degree chamfer at the bottom of the plate. Initial prototypes used a ball nose based 3D toolpath strategy to create the angle, but because of the scalloping, the surface was not smooth and consistent enough for use with. This was then changed to custom tooling to create the edge.

The other challenge was to get consistent nickel plating thickness. Since we were working with fairly high tolerances, the thickness of the coating and the variance in thickness would impact the overall dimensions of the block. So this meant that the manufacturer would need to control the coating thickness AND the tolerance of the milled block underneath.

And lastly, even though these parts were shipped at the end of November/early December, due to lots of shipping delays, the touch plates finally arrived just a few days ago, meaning that the transit time for these were just about 4 months.

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 (https://www.youtube.com/c/IDCWoodcraft) and Dana Andrews (https://www.youtube.com/c/BuckysCustoms) 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.

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: https://forum.sienci.com/t/homing-limit-switches/99/41

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!

1/4″ Flat Compression End Mills now available on our store

Hi everyone, I’m happy to announce that we now have 1/4″ Flat Compression End Mills available on our store! These compression bits work basically the same as our 1/8″ Flat Compression End Mills , just with a larger cutting diameter.

If you’re interested in learning more about compression bits and how they work, check out our old post about compression bits.

When I started cutting this project, I realized that I had set the depth of cut too shallow as to not get past the upcut part of the end mill. I stopped the cut and started it again after changing the gcode. I guess this is a bit of a happy accident as we can show the difference between using an upcut bit versus a downcut bit, and how it affects the quality of the edge on this particular piece of plywood.

Because on the first part of the cut, only the upcut portion of the end mill is being used, we are pulling the chips up, splintering the top surface of the material. Changing the depth of cut to 5mm engages the downcut portion of the bit, pulling the chips down and leaving a smoother edge.

For this project, I used a feedrate of 1400mm/min and a depth of cut of around 5mm. The upcut portion of this end mill is 4mm long, and as long as your depth of cut for your first pass exceeds 4mm, you will be engaging the downcut portion of the end mill.

In any case, after setting up the job properly, testing shows clean, crispy edges on both the top and bottom surface of the material!