Converting a mill to CNC

For most of the past year, [Joel] has been working on converting a manual mill to a CNC mill with the addition of a computer, brackets and stepper motors. He’s put an amazing amount of effort into his project, and the result is awesome and much less expensive than buying and shipping an old Bridgeport mill.

The project started with this mill from Grizzly. It’s a step above the small ‘hobby mills,’ but still very affordable at $1200 shipped to [Joel]‘s driveway. The work began by fabricating an enclosure for the PC and motor drivers out of an electrical panel box. The controller box includes a touch screen, keyboard and computer running Mach3 CNC software. The computer connects to a breakout board with a trio of motor drivers providing power for the stepper motors on each axis.

After a few months (good things take time), [Joel] was ready to attach the stepper motors to the axes of the mill. He’s just put up a few videos of milling copper-clad board for PCBs and surface machining ABS, viewable after the break. For a total investment that is less than finding, buying, and repairing an old industrial mill, we’ll call [Joel]‘s project a success.


  1. grovenstien says:

    Very tidy build! I am now very jelous as this is far better than my SEIG X1 CNC conversion. If anyone has the desire to convert a mill my advice is buy the biggest you can afford! There arn’t many things more satisfying than pushing the start button and watching the mill cut out your dreams!

  2. poe says:

    Impressive build.

    I wonder how it compares to off-the-shelf add-ons… once you factor in how much time and money was invested.

    • DanJ says:

      I agree. Very impressive build.

      He definitely seems to have invested a lot of time. He should work with one of the companies that productize maker designs to come up with a kit for this mill.

  3. mohonri says:

    Every time I see a hack like this, it makes me want to do it myself. Ah, but for the lack of funds…

  4. Hackerspacer says:

    “and the result is awesome and much less expensive than buying and shipping an old Bridgeport mill.”

    Except for the fact that Joel’s time is worth something and that is rarely taken into account.

  5. tjb says:

    That pesky time thing. I have about 90% of the parts needed to convert my mill, just need time to make the brackets and put it all together. Looking forward to 4 axis milling tho, XYZ plus a turntable!

  6. joel says:

    I’ve often struggled with the time issue when evaluating the real cost of a project… Fortunately in most cases (and this one especially) it’s time well spent, IMO. Also, I’ve learned so much about CNC machines in the last year that I would have missed out on if I just bought a turnkey machine.

    I remember reading in a CNC forum– if you want a CNC mill, buy one. If you want a project, build one. That’s true, but it’s an awesome project.

    @tjb- 4th axis is definitely on my list… sweet!

  7. Ulrich says:

    I am about 3/4th done with my Proxxon KT150/BFW 40/E conversion.

    Which opensource CAM software can you recommend for converting 2D/3D CAD-drawings into G-Code?

    I’ve compiled HeeksCAD, but it has some stability issues.

    PyCAM is only for 2D, if I am correct.

    For the machine controller, I can recommend EMC2. I installed the live-CD, and it worked perfectly out of the box.

  8. ironring says:

    I have a G0704 in my shop, and I was considering CNCing it, but I was having second thoughts after reading about someone with a BF20 (same machine, different branding) that they CNCed, and it basically wore out their ways. Apparently, the cast iron in it couldn’t stand up to all of the traversing they were doing. I’m not sure if it was just a lubrication issue, though (as in, maybe they just weren’t lubricating their mill properly)…

  9. joel says:

    @ironring- I haven’t heard of the wearing issue (sounds feasible though) but I spent good money on decent way oil (Mobil Vactra #2, supposedly sticks well to vertical surfaces) and I oil the bejeezus out of my machine. I would imagine keeping the machine within reasonable operating parameters wouldn’t hurt either… not running balls out with your rapids, keeping the gibs adjusted properly, etc.

  10. anyone says:

    seriously? no pictures of the mill with the hand milled cnc parts installed? TERRIBLE

  11. quezz38 says:

    I’ve got a converted g0619 in my shop back home. Unfortunately i recently moved away from my shop to work… in a bigger shop! I should’ve built a nice control pendant/console like this one. I just put mine in a bbq like a chump.

  12. Mike says:

    Superb job. Great workmanship. Looking forward to more pics, especially the CNC stepper motor conversion and add ons (I take it you can manually override in case you want to do things by hand). Am also very interested in how this does with metals such as aluminum or steel.


  13. xnaron says:

    I’ve got some pictures of the milled parts for the conversion of this same mill on my build thread here

  14. Ulrich says:

    Just figured out, PyCAM imports 3D mesh models, too, using STL files.

    So the error was in front of the computer, as always, i suppose ;-)

    Using FreeCAD, PyCAM and EMC2 with Ubuntu. Really works quite well now.

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