Adding Screws To A DIY CNC Machine

When it comes to CNC machines, your SureFine has screws on its axes, and the Bodgeport does too. A shopbot has an amazing rack gear system, but when you start to dig into the small CNC routers available for under $2,000, you’ll only find belts moving a router back and forth. This isn’t to say belts won’t work — you can create a fine CNC machine with bits of rubber. However, belts stretch, they wear out, and if you want more precision screws and racks are the way to go.

The WorkBee CNC machine is the first desktop CNC router we’ve seen that uses screws instead of belts. It’s a project on OpenBuilds, and a reasonably well-configured machine is now available from ooznest for about £1,700 ($2,200 USD), or just a bit more than other CNC routers that consist of a Dewalt router and some aluminum extrusion.

The WorkBee CNC is based on the OX CNC machine, another cartesian router machine built around the OpenBuilds aluminum extrusion. The OX, while a fine machine for DIY tinkerers, uses belts. The WorkBee trades them out for screws, and should gain better accuracy, much lower maintenance, and deeper cuts. Screws are slower, yes, but do you really need that much acceleration when routing a thick piece of wood?

24 thoughts on “Adding Screws To A DIY CNC Machine

  1. First aside from all the 3020/3040/6040 type Chinese aluminum extrusion machines, which have had screws for the many years they’ve been available, and even come in trapezoidal or ball screw variants. I’d swear I’d even seen projects with them go by on HaD.

    They may typically come with garbage electronics, but the frames are surprisingly good, and considering you can currently order a complete 3040 kit for $6-700, they’re hard to argue with. I replaced my old Shapeoko with one (that I kitted out with electronics of my own choosing) and have been quite pleased with it.

  2. pocketnc’s machine shield (no longer produced, it seems?) also used screws.

    since there might be a bunch of people who know about the 6040 showing up in the comments to tell benchoff about them; anybody know where to get replacement extrusions for the bed/table of it? looks like they’re 20x120mm, and have a profile kind of (but not exactly) like this:

  3. If a belt stretches then then internal cords are broken and that is pretty significant. That should not happen. Belts are actually a good low to zero backlash solution and at the speeds that a cnc machine runs at they should last a very long time. You do need to pick the right profile for the application though.

    It looks like they are using high pitch lead screws which usually have plastic nuts. If they dont keep the dust out of those they will wear pretty fast too.

    1. Plusone!

      Belts have embedded wire rope, typically made of steel. That’ll stretch, but those kinds of forces on a system like that suggest that you have *much different problems.*

      If your CNC is build of Aluminum extrusion, it simply *is not rigid enough* to justify the sort of forces which would stretch or break a toothed belt.

      Like, you’re trying to mill steel, with aggressive depth-of-cut on an al-extrusion gantry router? Really? Your problem isn’t belts, it’s OPERATOR ERROR.

    2. +1 The small belts at least have something like Aramid in them. The timing belt in my car goes for ages at high temperature and accelerations. I can see some vibrations maybe from the length of belt between pulleys. On the other hand, good screws and ball slides have gotten very affordable.

      1. Generally it is a myth that belts stretch. People think the v-belts like in cars stretch when what is actually happening is the flanks of the belt wear which causes the belt to sit lower in the V-groove and the belt becomes loose.

        Yeah, there are several sellers that sell decent ball screws for pretty cheap. Considering how much they are charging for this router I am surprised they dont use that. Even some of the cheap tabletop cnc routers from china come with ball screws.

  4. Wow….such a lack of knowledge about these machines. it is actually VERY VERY VERY rare to see a CNC with a load bearing tool (mill, router etc.) that does not use screws. This article is so ass backwards…….

  5. I’ve got the ox, but china sourced. As it turns out, the speeds are very ueeful if you’ve got a high speed spindle thar runs between 8000 to 24000rpm. It can’t go much slower than that or it will loose power rather quickly. This does mean that to reach a sufgicient chipsize you need some speed or it rubs the material rather than bite into it.
    It’s also not very difficult to upgrade it to screws if it’s primarily used for milling aluminium. I’d recommend higher voltage voltage dtivers, they can reach higher speeds.
    Even without lead screws I can mill aluminium without much problems. Backlash isn’t that bad, with 3d printed belt tensioners. I’ve meadured about 0.1 to 0.2mm backlash, depending on the hardness of the stock.

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