Another CNC machine?

My Taig CNC mill has served me well for many years, and continues to perform admirably. Perhaps too well, as I always have it fixtured up for one thing or other, and as such I no longer have a CNC machine that I can just hack/play/tinker on.  The foundry class got me thinking about CNC milling foam cores, or perhaps patterns and matchplates out of wood or plastic.  This led me to think that perhaps I should build a CNC router for such work.  I say build rather than buy – gantry type routers are quite simple in construction and building a machine is half the fun anyhow.  There’s many free designs available for CNC routers, so I went looking for one that I liked.  I knew I wanted something based on T-slot extrusion for ease of assembly and straightness (some warping would be almost inevitable if I were to try welding a frame out of square tubing).  After a brief search, I found a promising looking design done by and Fine Line Automation. A 24″ x 36″ working area sounded big and roomy, and I was most impressed by the use of cold rolled steel and skate bearings for linear motion (in a similar fashion to a RepRap) rather than much more expensive linear bearings. The last time I looked at building my own CNC, I realized that the least expensive route would be to buy surplus linear bearings and rails from Ebay in whatever sizes I could manage, and then design the machine around those components. But in this case, I could follow the plans more-or-less as published – a good thing, as once I start redesigning something, I never really stop the design process, and whatever I was working on winds up with a severe case of kitchen sink syndrome.

While Fine Line Automation has kits available, I knew it would be much less expensive for me to simply get the raw materials myself and do the requisite cutting on my own. I did look around for cheaper alternatives to the 80/20 T-slot extrusion that the plans called for (many companies offer ‘aluminum structural framing’), but eventually found that 80/20’s garage sale Ebay store had the best prices, and they actually had all the components that the bill of material called out.

Rough bandsawed extrusion awaiting cleanup on the mill

I chopped the pieces to rough length on the big horizontal bandsaw at work, and then took them home to machine the ends to the final precise lengths.  After tapping the holes in the ends to 5/16″-18 and drilling access holes in strategic locations (all detailed in the prints contained in the set of plans available on Fine Line’s site), the extrusion pieces were complete. A trip to Speedy Metals netted me the cold rolled steel, which I also drilled out on the mill. With stepper motors on the way from Keling, bearings from VXB, ballnuts and ballscrews from McMaster-Carr and couplers from Enco, it seemed like a good time to at least start assembling the base.

Definitely larger than I had envisioned - I'll need to build a special cart for it

Many of the builds that I’ve seen of this design include additional bracing in corners.  The framing itself is quite stout and I don’t intend to do any metal cutting with the machine, but more rigidity never hurts on a machine tool, so I used some aluminum angle on the inside corners.  I ran out of screws, so the base isn’t yet quite fully assembled, but at least I have a sign of progress.

Categories: CNC

7 thoughts on “Another CNC machine?”

  1. So cool! I looked at those plans earlier.

    You know you are always welcome to cut something out on our router if you want! That way you can cast stuff before you finish building your own router.

  2. I’ve thought about asking if I could run stuff on your router, but I don’t have anything yet that I’d like to run! I think my interest in building the router is almost more about just ‘building a router’ than what I can do with it…

  3. Hi,
    Coming full circle, I started out looking at the (then very sparse) RepRap info in early 2009, spent some time on the death march building a McWire, then decided to build a SOLUTION that would address for machining what the RepRap does for RP, namely: modular, flexible, low cost…. yadda yadda – so I started this project:

    Near the end of 2009 and tried to kickstarter the project – this didn’t work with no proof of concept machine to show…

    So, in the late spring to mid fall of 2010, I wasn’t able to work on the project much – but I have started working from home this year and have begun to make good progress most of which is here: — anyhow, if you have time, take a look and give me some feedback – thanx, James

  4. I’ve dealt with overseas suppliers before, and I would be very hesitant about having them make such a one-off project. Also, building it myself means that I can modify it as I go. Yes, part of the build is for my own pleasure. If I wanted something ready-made, I would have bought a kit from FLA – there’s no need to go to China. Plus, the link you posted is for a company that deals with the Australian market (I assume you work for them) – I’m on the other side of the planet.

  5. A little update (4 years later)

    Here’s CubeSpawn today – the website still sux, but I have moved the info to existing sites so it may be irrelevant.. 😉

    (DougsShop and DougsShopPhase2 are the latest)

    3D Models

    Github (this is still a little weak on actual ROS/Machinekit code, but has the mechanical development fairly up to date)

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