$150 CNC mill is a tad slow but very solid


Like just about everyone else out there, [Adam] thinks that CNC machines are pretty cool – so cool that he decided to build one of his own from scratch.

The CNC machine was constructed mostly out of MDF and scrap wood, with drawer slides used for smooth gantry movement. An off-brand rotary tool was used to do the actual cutting, and [Adam] picked up a few Sparkfun stepper motors to drive the machine.

The assembly was completed without too much trouble, but [Adam] says that programming the mill was a long and frustrating process. Cutting was rough and not very accurate at first, but little by little he got things working pretty well. As you can see in the video below, while the cuts look great, improvement came at the expense of speed. He says that the machine could use a redesign to speed it up, which he’ll get around to if some free time comes his way.

It’s not the absolute cheapest CNC build we’ve seen, it’s pretty darn close. With a few tweaks, it could definitely be a solid budget-friendly contender.

19 thoughts on “$150 CNC mill is a tad slow but very solid

    1. The Joes 4×4 Hybrid is a solid machine that uses MDF parts. Over 100 have been built. They can be found on youtube. The rails are v bearing mounted on extruded aluminum channel. Maybe MDF is is upgrade from partice board / foamboard? Have you seen that they are making CNC machine on youtube out of?

    2. “sol·id/ˈsälid/
      A substance or object that is solid rather than liquid or fluid.
      Firm and stable in shape; not liquid or fluid: “frozen solid”.
      firm – hard – strong – sound – steady – substantial”

      Since it’s not liquid, and the materials must be considered “firm” or “hard” and maybe even “strong”, then in my opinion this is a solid machine. :)

  1. The z-axis alignment problems can be avoided by match-drilling (pin top and bottom plates together and drill both ends of matching holes together with drill press). There are details here, as used on mantis 9.1 cnc (successor to the older $100 “cheapest cnc” mentioned in link above, but $85, less parts, easier to align):

    Video of mantis 9 cutting pcb at 30 in/min here:

  2. That ‘previous 100 dollar cnc mill’ was a bit of an untruth. David said he spent only 100 dollar on that design, but what he did not say that he built it from the remains of his previous 8 designs. Essential stuff like stepper motors and drivers was missing from his bom (which was conveniently published way after the publicity around his design died down).
    This design at least has a BOM plus costs breakdown, which is much more believable. Unfortunately, it has some fatal design flaws in it that make it under-perform. Just to mention a few: the slop you get with drawer-slides, the asymmetrically driven gantry that does not meet under the table, and the very low torque Z-motor where you need quite some torque.
    For milling pcbs, you probably need an other Zstage design that uses a feeler to keep the depth of the cut constant.
    I’ve (helped) built 25 Mantis-30 routers…

    1. I know I am replying to a very old post of yours, but could you help me understand what you meant by “uses a feeler to keep the depth of the cut constant”? Even using auto-leveling software to adjust my gcode, I still have lots of issues getting the cut depth right. Any details you can supply would be greatly appreciated. Thanks, Todd.

    1. yes, anything you can do with a dremel you can do with a mantis. Iwould not be too sure about this one though, you probaly would need to go very slow to avoid deflection and slop. But it sure can, just that the results might not totally be as expected.

  3. Great work!

    I built a very similar machine a couple years ago, right down to the MDF, drawer slides and pipe clamps. A couple of suggestions from my experience –

    My design also uses heavy-duty drawer sliders. JelleAtProtospace is right about the drawer slides, my experience is that they tend to have significant wiggle room in one of the two axes they aren’t meant to move along. If you laid a drawer slide on its back, with its intended pull direction toward you, it would be rock-solid in the left-right direction but have significant play in the up-down direction. To constrain out any play, place a 3rd slide (or 2) at right angles to the first. The Z-axis of my machine has 2 slides “upright” (as if there were actually a drawer between them) bolstered by two on their backs. This way the ‘weak’ axis of the vertical slides (left-right) is bolstered by the horizontal ones and vice versa.

    On the threaded rod – probably the quickest and cheapest improvement you can make to this machine, speed and otherwise, is to ditch the V-grooved threaded rod (the thread shape is actually designed to bind so as to keep a nut & bolt tightly together) and use an ACME-threaded nut and bolt. This is a completely vertical (not V-shaped) thread designed for transferring motion. I used 1/4″ rod with 10 threads/inch from ENCO (use-enco.com); I remember it being maybe a few US dollars per meter, and the matching ACME threaded nuts maybe a buck and change each. I used JB Weld to affix the nut to the metal structure of each axis. Oil or grease the rod to ensure smooth motion and prevent rust, especially with these cheap (e.g. oil rolled steel) threaded rods. If the machine is well aligned, you can use 2 nuts per rod to eliminate backlash (play caused by the difference in thread width between the bolt and nut) – when affixing the nuts, place something in between to physically force them apart so that each nut is riding on the inside edges of its respective thread.

  4. I would save the $60 and make it out of particle board. MDF is only marginally stiffer but significantly more expensive, about 4x more than particle board and with MOE of 2600MPa vs 3300Mpa. Not worth it, especially because the play isn’t coming from the chassis anyway.

  5. You can even see it flopping around in the video. You won’t need very much more money to get some much better linear components than the drawer slides. Maybe then you can cut something useful, like wood.

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