Going Digital: CAM Files for the Open Source Tractor

Last year, we didn’t use any automation in our fabrication procedures. For example, check out the LifeTrac II build. We’re moving to digital fabrication this year. Our work this year will be a test case for optimizing production – to determine whether even your grandma can build industrial-grade tractors in her garage. To do this, we need your help. Read on.

We are taking the open source tractor, now in Prototype II phase, as the first test case. To create Prototype III, the first task is to take the existing LifeTrac design – full CAD in Blender (18 inch shorter version) by Will – and export it into CAM tool path files for every component –  to be cut out on our computer controller (CNC) torch table. We are using LinuxCNC as the open source control software. As we go along, we are documenting the status and needs of the open source solution for providing a robust platform for digital fabrication of economically-significant products. Our first contribution to this is the torch table, which if we develop the open source stepper motor controller, will cost $800 in parts for a 4’x8′ working area, not counting the computer and plasma cutter.The step by step procedure is proposed as follows:

  1. Export the Blender model file, which is dimensionally correct and where all the bolt holes are marked correctly – into a CAD program.
  2. Generate fabrication and CAM files.
  3. Integrate these files with LinuxCNC
  4. Develop a fabrication procedure for cutting out all the tractor parts on the torch table.
  5. Develop an assembly procedure for the completed tractor. There is a small amount of welding that goes into this.

Can you help? Here are the things that need to be done:

  1. Working with Will, myself, and the rest of the team, help us export the file to a fully-featured CAD package.
  2. Divide the machineon a part by part basis to generate full fabrication drawings, exploded part diagrams, and CAM files for every part
  3. Enlist the support of LinuxCNC leadership to serve as technical advisors to this project
  4. Produce a  step-by-step procedure for cutting the tractor parts
  5. Produce a step-by-step procedure for fabricating the tractor chassis, loader arms, and wheel mounting

If you would like to work on this hands-on at Factor e Farm, contact me or apply for a Dedicated Project Visit.

I think it’s high time to get a related digital fabrication enterprise going in Kansas City. I’ll talk to Lesa Mitchell of the Kauffman Foundation – they support local entrepreneurship for re-localization. We’re meeting on Wednesday next week.

Back to the tractor – all the wheel mounting plates and loader mounts can be torched on the CNC torch table, and so can the 4×4″ square tubing and loader arms. There is a total of 16 wheel and motor mounting plates, 4 wheel hubs, 6 cylinder mounts, 4 loader arm mounts, and hydraulic valve mounts that can be produced on the torch table – not to metion the square frame tubing and ractangular loader tubing. This constitutes the entire bolt-together frame, loader arms, and wheel drive – essentially the complete tractor to which the wheels are bolted and power cubes attached. From that point, all the hydraulics and valves  are connected, and there is the complete tractor – minus the quick attach plate for the front loader arms. That is a summary of how complicated as the tractor gets. You don’t have to worry about a transmission, because we are using direct-coupling of wheel motors with hydraulic power.

Here are some other more broad comments on the issues surrounding open source fabrication. Please add to or comment on this list. Addressing these points would help the open source fabrication and digital fabrication movement to scale:

  1. The biggest visible issue today is the absence of a fully-featured, open source CAD solution capable of producing professional fabrication drawings from 3D CAD models. Blender is a great modeling program, but it doesn’t have the capacity to generate fabrication drawings, nor is it easy to use.
  2. The biggest elephant in the room is still that there is no viable platform for scalable, open source product development that is a viable choice outside of corporate research and development . This is what the GVCS is starting to address, though still without any significant budget.
  3. Development of a scalable, open source stepper motor controller for higher power applications, so people don’t have to spend hundreds or thousands of dollars on this.
  4. Development of a scalable, high power stepper motor – so people don’t have to spend thousands of dollars on this when designing high-performance, automated industrial equipment.
  5. Development of fully featured, 6 axis robotic arm control software that integrates with LinuxCNC for the control of indusrial robots
  6. Development of fully featured software to generate toolpaths for all kinds of multiple-axis, 3D fabrication beyond 3 axis cartesian systems.
  7. Development of a full array of other productive hardware, a lot of which is on the priority list of the Global Village Construction Set.
  8. Developing an open source USB-based controller for CNC machining, so that lightweight laptops can be used for the controls.

Open-sourcing the above would allow your grandma to start a micro-factory  in her garage, and she would beat the socks of her big bully competition. It will  be beautiful when that happens, and the elephant will leave the room.


  1. Robin

    What about this stepper motor driver:

    1. Marcin

      This looks like what we need. Anyone have any experience with this? Is this a robust solution? How does this compare to the Pololu drivers?

  2. Robin
    1. Marcin

      These are unipolar controllers, we’re looking for bipolar steppers right now.

    1. Marcin

      Can we export Blender 3D into 2D dxf?

  3. Leo Dearden

    It’s great to see the push to maximum general purpose automation. That’s a good hit list for the major obstacles.

    I’m already signed up to work on #3 (the OS stepper driver).

    I have #1 (CAD package), #6 (CAM toolpath generator) and #8 (USB CNC controller) on my To Do list. I’ve got clear development pathways for all of them. Are you interested in the same deal for the development of these components too?

  4. Paul Youlten

    You need to make sure your version of Blender has the Export DXF extension. This has been bundled since Blender 2.48.

    You should be able to export your model as 3D or 2D.

    Once you have exported it you will need to tidy your plans with Qcad.

  5. drew o

    this is a bipolar stepper driver. It might not be powerful enough, but it’s a good start

  6. Bryan Bishop

    For open source CAD, I know OpenCASCADE is awful, but why not use pythonOCC? It gives you a simple python-based library for CAD manipulation. Then you can import/export files to and from Solidworks, Alibre, etc. The other advantage is that you can share your designs both as standard CAD files (not meshes), but also as raw python.

    – Bryan
    1 512 203 0507

  7. Miquel


    for #1, FreeCAD looks to be getting there. These are the latest release notes:

    I would say in a couple of releases it will start to be a contender.

    1. Marcin

      Looks promising. It shows hints of 2D fabrication drawings being produced from the 3D view. What is the exact status of fabrication drawing generation?

  8. Miquel

    @Marcin: I am asking about that in the help channels. Will report back.

  9. Miquel


    The Drawing module is currently under construction and more or less a technology preview!

    You can have a look at it here:

    1. Marcin

      Are they planning on accommodating dimension labels/arrows in the forthcoming work?

  10. Caleb

    I have SolidWorks 2007 and could take a look at making fabrication drawings if needed. But I’d like to know if someone else is already on the job.

  11. Miquel

    They answered that there are already some commands for dimensions, but are geared more towards architecture.

    He also said:
    “At the moments the my focus is on the Sketcher and PartDesign. Drawing has a low Prio, but is planed.”

    I will continue to keep an eye on the project and on every new release

  12. […] You can learn a lot more at his blog, here, and even contribute your skills to various aspects of the project (here’s one example). […]

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