DIY CNC Router Uses Chains The Right Way

There are a million and one ways to build your own CNC router, depending on your tastes, budget, and application, your design choices will differ accordingly. [Steve Tyng] was well aware of this when undertaking his project, and built the machine that made sense for him.

[Steve’s] build has a strong focus on keeping costs down, and that’s reflected in the hardware used. Wanting a large work area of 30″ x 60″, off-the-shelf linear rails in 6 foot lengths were prohibitively expensive. Instead, 1″ angle iron was sourced from the local garden centre, and used in conjunction with steel v-bearings. It’s a lot cheaper, and good enough for the application at hand, so why not? Other smart choices abound, such as using an IKEA cabinet as the base, and a fanless computer to run the show to avoid death by dust.

When it came time to build the axes, there was plenty of roller chain on hand. Chain is usually passed up for options such as timing belts or ballscrews in the CNC community, as it tends to stretch over time and offers poor accuracy. However, [Steve] took stock of the drawbacks of the method, and made efforts to overcome these weak points in the design. The Y and X axes were specially designed to keep the chain supported along its length. This helped avoid the problem of long drooping chains and poor tension.

While it’s not an industrial-strength build with world-beating accuracy, it’s a solid CNC machine that can carve out large workpieces without issue. Over the years, we’ve seen plenty of DIY CNCs, built with everything from PVC pipe to welded steel. Video after the break.

28 thoughts on “DIY CNC Router Uses Chains The Right Way

  1. “While it’s not an industrial-strength build with world-beating accuracy,“
    Did you see the accuracy he’s achieved?
    I’d be satisfied with that. Is it industrial? No, but it’s got some great ideas!
    Thanks for sharing [Steve Tying], I wonder how your accuracy has faired over time.

    1. About 0.1mm, which is what I’m getting with my plywood + GT2 “3d printer belts” CNC as well. Which is very much fine for cutting wooden panels of this size indeed. Wood is quite forgiving, and a bit of sanding is needed anyway or you end up with really sharp edges.

      I’m surprised how good his dust extraction is. That’s my biggest issue at the moment. And finding time to play with it…

  2. I’d just been kicking around designs. Hadn’t thought of chain drive. I’m thinking of building mine on top of the heavy steel military surplus desk from about 1950 that I use as an assembly table in my shop. If I do it right, I should still be able to use it for that, too. Yours looks pretty awesome!

  3. If engine manufacturers have mostly switched from “rubber” timing belts to chains because they tend not to snap, skip or wear as easily why is it different for these CNC machines?
    Chains dont stretch. They wear on the contact surfaces which produces the slack. But so do timing belts at a faster rate.

    1. Because to have precision with chains you need to have closed loop position feedback. If you drive sprocket linearly, you will have small displacement errors repeated at every chain link. It’s cheaper to design with timing belts and they can be faster.

      1. that makes sense. Is it possible to reduce these per-link errors by ensuring high “tooth” engagement? Intuitively I would guess that if you wrap the chain around half of the circumference of the drive sprocket it should help

      2. “Small displacement errors repeated at every chain link”, cogging in laymen’s terms. To reduce that, I went with a larger 12 tooth sprocket on the drive chains instead of the 9 tooth you typically see in a hobby chain equipped router.

  4. Hey look at that, I made it on Hackaday! Thanks for all the good comments Dudes. I built this router to make it easier to build other projects. I never imagined the router would be the center of attention it’s turned out to be. FYI, I’m working on a simpler Mk2 version which I hope to have built in the next few months. I might do a parts kit but definitely a plans set will be available.

  5. The author’s comments are a bit misleading. Take a look at Maslow CNC. A very accurate chain-driven open source CNC platform capable to cut accurately and up to 4*8 feet. This is an innovative use of not needing lead screws.

  6. Great summary of Steve’s work. I saw a complete write up on another site with fixed pictures. Your short video clarified several things. Thank you.

    As for the chain discussion: IMHO timing chains, etc… used some sort of tensioners to alleviate chain sag/droop between the various pulley/sprockets as it goes round and round. This is needed to prevent jumping teeth. Think of a rear bike derailer for example, specailly if you change peddling direction. In short, if a single link moves the whole chain and everything attached moves – keeping mechanically timed.

    How Steve addresses this, again IMHO, issue by not using the chain as an extension from a prime mover to another axle pivot point in a closed loop and travel direction results from the prime mover directional change. Instead the bulk of the chain’s weight is supported along it’s horizontal length (no loop, no sag), and under tension. The X and Y NEMA motors are attached to sprockets that travel along the chain. In short most of the chain is lying there and only the portion near the sprocket is moving. The gantry axis move along the chain path, not the chain moving a separate axis like with timing chains.

    I for one and interested in Mk2 version and instructions.

      1. Awesome! Do you have one that also inverses the color scheme, making the site black on white? We get that complaint super often.

        Indeed, this is the first time I’ve ever heard a complaint about the square brackets. But I’m super glad that you’ve found a workaround. That’s the hacker spirit!

  7. Cool design but why is it so noisy?
    Maybe your motor controllers?
    Chains have typically frowned upon not due to jumping teeth but backlash generally there is a little play in chains and sprockets.

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