The AltMill represents the pinnacle of hobby CNCing, bringing industrial level technologies to a price point and ecosystem for both beginners and advanced users.

General Specifications

  • Rigid frame and linear motion design using HGR15 linear guides and ball screws on all axis mounted to a custom-designed, machined aluminum extrusion
  • Closed loop stepper motors for over 600IPM
  • Support for 65mm and 80mm spindles and routers
  • Approximately 49″ by 49″ inch working area with a max z-height of 5.5″
  • Footprint of 59″ wide and 62″ deep
  • Inductive sensors for homing included
  • Sturdy metal legs with the ability to add 4ft wide shelving underneath

News and Updates

  • July 19 – July 26, 2024 “Photo Art Projects” Contest

    Happy Friday, everyone! Thanks for sharing your summer-themed projects made with the LongMill/AltMill. Last Week’s Winners We are happy to announce that Chuck Lalonde, Georges Côté, Brian Slevin, and Tom…

  • July 12 – July 19, 2024 “Summer-Themed Projects” Contest

    Hi everyone! Thank you for posting your film-themed projects made on the LongMill/AltMill with us. Last Week’s Winners We are happy to announce that Georges Côté, Kenneth Key, Derick Bond,…

  • Everything You Need to Know About the LongMill Spindle and Dust Shoe Kit

    Hey guys, Johann here. Ever since we announced the Sienci spindle for the Altmill, there has been a tremendous amount of interest from the community in bringing a Sienci-supported spindle…

  • July 2024 Production Updates

    Hey everyone, welcome back for our July 2024 production updates. AltMill As we alluded to in the last update, we were hoping to start shipping AltMills mid-June. However, we did…

  • June 2024 Production Updates

    Hey guys, a lot of things moving forward at Sienci Labs. So traditionally I’ve been writing production updates for pretty much every product, but I’ve realized for some things there’s…

  • Introducing the LongMill MK2.5

    For those of you that have followed us as we develop and improve our products, or read Andy’s Production Updates, you probably know the drill by now – it’s time…


Q: Will the AltMill come with the SuperLongBoard?

The AltMill will come with a specialized variant of the SLB which allows for use with a higher 48V power supply and with external driver support. Features that the SLB comes with, such as independent 4th axis control, RS485 protocol, and more, will be shared between the AltMill and LongMill.

Q: What’s the difference between the AltMill and the LongMill

The AltMill was developed to be a higher-performing machine compared to the LongMill. Our main design goal was to create a machine that had the best possible value for dollar at a higher level and pricepoint.

  1. The AltMill is larger, with a working area of 48×48 inches, whereas the LongMill comes in 12×30, 30×30, and 48×30 working areas.
  2. The AltMill is more powerful, allowing higher rapid speeds and deeper cuts. For context, the AltMill will allow for speeds over 600 inches per minute versus 160 inches per minute.

Q: What software does the AltMill come with?

The AltMill works with our free gSender software for controlling your machine. Any software that works for CAD/CAM with the LongMill also works with the AltMill.

Q: What else do I need to provide with the AltMill?

Besides the standard items we sell (machine, legs, spindle) , users will need to provide their own wasteboard (we recommend 3/4″ MDF), computer, and end mills.

Q: What accessories does the AltMill work with?

The AltMill will support accessories such as the LaserBeam, Vortex, and both the Autozero and regular touch plates.

Q: Will the AltMill come in any other sizes besides the 48×48 inch working area?

For the time being, we are focusing on developing and maturing the design of the 48×48 size. However, a successful launch and release of the AltMill 48×48 does pave the way for larger machines that could cut full sheets of wood, or smaller machines dedicated to cutting metals. We believe that the AltMill isn’t just a machine, but a new platform we can build upon for new form factors.

Q: What is the footprint of the AltMill?

The width of a fully assembled AltMill with our table legs is approximately 59″ wide and 62″ deep. Users should allow for a few inches of extra space on each side.

Q: What are the power requirements for the AltMill?

The AltMill comes with a 48V10A power supply, which can supply 500 watts of power. Users should dedicate additional power based on the spindle they choose to use, which can range from 1.5KW and above. This may require having two or three available breakers, or 220V available for your spindle.

Q: Can I add a toolchanger to my AltMill?

At this time, we do not have development or plans to release a toolchanger, but the AltMill and it’s hardware and electronics offer inputs and outputs to allow aftermarket toolchangers to be added by the user.

Q: Can I modify, update, trade-in, my LongMill to a AltMill?

No, because of the significant differences between the LongMill and AltMill, there is no path for upgrade or modification. Additionally, we currently do not have the infrastructure to support trade ins for the LongMill.