Giant CNC Machine Measures A Full Cubic Meter

There are plenty of designs for table-top 3D printers, engravers, and general CNC machines out there. However, if you wanna build big things and build them fast, sometimes you need a machine that can handle bigger jobs. This gigantic 1x1x1 m 5-axis CNC machine from [Brian Brocken] absolutely fits the bill.

The build relies on 3D-printed components and aluminium tubing to make it accessible for anyone to put together. [Brian] notes that 25×25 mm tubing with a 2 mm wall thickness does an okay job, but those aiming to minimize deflection would do well to upgrade to 5 mm thickness instead. Stepper motors are NEMA 23 size, though the Y-axis uses a pair of NEMA 17s. This is necessary to deal with the immense size of the machine. Control is thanks to an Arduino Mega fitted with a RAMPS board, running the Marlin firmware.

The plan is to use the machine to test out a variety of CNC machining techniques. It could make for a great maxi-sized 3D printer, and should be able to handle some basic 5-axis milling of very soft materials like foams. This might seem silly on the face of it, but it can be of great use for mold making tasks.

We’ve seen giant CNC routers built before, too, and they can readily be put to great use. Video after the break.

32 thoughts on “Giant CNC Machine Measures A Full Cubic Meter

  1. Carve foam. Glue pieces together. Lay up glass fiber and epoxy. Sand smooth. Spray on gel coat resin. Sand smooth. Apply mold release. There’s your new boat hull mold.

  2. I see a lot of 3D printers underbuilt using 20 or 25 mm t-slot. The stuff is spaghetti. Same-size tubing is more rigid and cheaper, but for some reason everyone uses t-slot.

    If you really want to maximize rigidity, larger cross section tubing is better than thicker walled tubing.

    1. I think the fancy expensive extrusion gets lots of love because its expensive, so much be better!
      On upside – It is considerably more convenient for tuning and tweaking the geometry – its easy to make a shape with it, and then correct that shape – with normal tubing you have to put the holes in the right damn place, or make them all oversized/slots to allow for that fiddle factor which is a lot of work, particularly if you don’t already have a decent drill press (mobile or static) or a big enough milling machine…

      1. Personally prefer thick-walled perforated 2″ square mild steel tubing for ease of use, but we must acknowledge not everyone has a local supply source. In general, the shipping cost for small lengths of Aluminum extrusion under 1m in length is more reasonable for some situations.
        Although some insist they have slotted Al extrusions that are straight and square… I must assume this notion is an urban-legend, as I have yet to encounter a product that didn’t have a serious twist/bend/taper in it right from the factory. It has to do with low torsional strength of slotted Al extrusions, and the final pulling operation done to work-harden thin walled Al construction…
        The other benefit of thick-walled square tubes, is a larger height/length piece can hold dimensions fairly well… especially if the last operation is facing (holes/welds already done). There often is just not enough “extra” material on slotted Al extrusions to bring it into reasonable tolerance… even if a milling machine is large enough to handle facing the part.

        1. Never heard of perforated square steel as a product before…
          The local suppliers I’ve used just have solid box and other various profiles. Interesting looking product though – doesn’t have all the versatility of the AL extrusion shape, but its a great middle ground between that and basic tubes, which is what I’ve always gone for.

          All the Al extrusions I’ve ever had interactions with have been pretty straight and square, rather floppy and twisty of course, its the nature of the beast, but unloaded or joined together square by the rest of the frame adequately square, at least for some tasks – things like the kit 3d printer much of it came from.

      2. Uh, you must not be familiar with the 3D printing community. For 99.9% of the 3D printer design community, low cost is the no. 1 factor in any decision about parts to use. Function and performance are distant second and third factors. For the kit buyer/builder cost is no. 1, and someone else having produced a complete BOM so they don’t have to make any effort is no. 2.

        t-slot is good if you have to hang stuff on it that is going to get moved around from time to time. Prototypes and one-offs should be t-slot. Kits and commercial products would be cheaper and probably better performance if they were made from tubing.

        1. There is a difference between low cost material and low cost kit – to use proper tubes in a kit- implying precision drilled hole patterns is bloody expensive in labour, set up costs etc – just hacking some 20-20 extrusion to about the right length for the t-slot bolts into the various parts is cheaper by miles in making a kit.

          But the raw extrusion vs the raw tube, which mechanically is vastly better in the same footprint, is hugely weighted cost wise in favour of the basic tubes. There is a reason all my extrusion experience is from kits – as a kit of parts it can be cheap, but as a part purchased separately it really isn’t.

          So folks using it to build their own its all about the convenience, not the cheapness. Or simply that they are so comfortable with it – as their first kit printer etc was built from it, that they don’t even look at the better material and profile options.

    2. If you include positional feedback, rigidity is not that important. As long as you accurately know the position of the head and compensate for deflection, you’re fine. That’s probably a better route to go than assuming your structure is stiff enough.

      1. Sounds like you are assuming very low speeds and slow events, giving time for dynamic compensation calculations and motor and drive system response times.
        Rigidity makes a huge difference when cutting edges are hitting the work at high frequency or when it ‘grabs’ the work, as most who have used a router by hand can attest.

          1. Alright guy, I wanna see it in practice. I dare you to mill steel on a flexible frame like this using positional feedback to compensate, because I just don’t believe you.

      2. How is the position of the head going to be accurately known? If the machine is out of tram, or has curvature in the axes, or flexes as the head moves, using simple motor feedback or linear encoders isn’t going to help.

        In my (painfully extensive) experience in this area, getting good “3rd-party” positional data (which would need to be 6DOF) generally required an external laser tracker and mounted measurement elements, totalling easily $100K US *before* any of the hours to setup and align that system were added.

        1. It’s not hard to build in-house. You can make sub-micron laser measurements with inexpensive parts. The part that’s not fun is the calibration and reference surfaces, but after the initial setup, it will work flawlessly. You don’t need to do 6DOF if you understand the mechanisms for out of plane travel are weight and the reactionary forces from cutting. Bring in a model of your machine into Ansys, and run a parametric sweep of possible loading schemes, and map out what that does to the cutting head. Then you can create a lookup table in your machine firmware. If at Position((X,Y,Z) deflection is measured as (dX,dY,dZ), then your cutting head is actually at (A,B,C) and twisted by (alpha,omega). If you do this multiple times a step, you’ll never stray too far away from your desired cutting path (as long as it is reasonable considering the abilities of the machine). You’re not going to cut through inconel at a feed rate of 1″/s, but you’ll know how far you still have to go for completing a cut and which way to nudge the machine to stay on track.

    3. This.

      And when your Z is a meter, lateral opposing forces to get significant deflection are probably measured in grams. Even with a dremel as a spindle, I bet just moving the Z axis causes deflection, regardless of how rigid the frame is.

      I have no idea what application for this would be good for.

      1. Its like many larger format CNC – good for foams or 3d printing – stuff with no meaningful tool loads.
        Seen something like this used to form foam ribs and formers for lots of projects – when light on large human scales is what really matters foam, perhaps with a single thin layer of fibreglass to protect it some is exactly what you want!

        This is probably accurate and stiff enough for that application across its whole working envelope, going to have to work slowly or use some smarts to dampen the ringing but it doesn’t look unusable to me. At least for this sort of work – can it be better, definitely! There is always more factors than just functionality when building though, so I wouldn’t call it bad, just no of any use to me, or you right now it sounds like.

    4. i understand wanting something more rigid but i think maybe you’re underselling the advantages of t-slot?

      anyhoo i love my delta printer, the carriages ride in the grooves in the t-slot. don’t know how to compare the rigidity but i haven’t had any troubles with it. its end effector positioning has nice repeatability within my ability to discern. i suppose it kind of over-uses t-slot…it has about 9 meters of material but only 3 meters of it actually uses the groove for anything other than end-attachments

      one of the reasons i wanted a delta printer is that the non-orthogonal axes of a lot of other designs struck me as a flex-amplifier. so many printers have this crazy z-axis that seems designed specifically to translate every material weakness into sagging on one side. and a lot have different x/y axes that could do the same.

      so maybe delta is just a sweet spot for extrusion, where the whole length of the slot is useful and the lack of rigidity isn’t a big problem.

      i have never really thought about how to make carriages that ride on something different so maybe it’s a gratuitous requirement.

      1. Unistrut is not THAT stiff, not for building a machine – it’s probably worse than similarly sized Rexroth extrusion.

        There’s a reason industrial CNC machines use huge solid castings weighing tonnes.

  3. I can’t imagine this being rigid enough for much of anything. In fact, I’ll bet the author currently cannot draw that QR code on the “full bed” without a “leveling” adjustment. I’d love it for the author’s sake if I was wrong! My experience with making large printers says to use giant aluminum tube, or even bigger extrusion. That or a lot of very very very very very very difficult to get right torsion boxes…..I tried…and I made the torsion box inside parts with a Haas VF-2, used a renishaw probe to find the parts, and then cut them precisely. I had measured each extrusion width using mitutoyo quantumikes, and the pieces fit together snugly, as they should. I even made spacers, and used a machinist square to line things up. I assembled it on my mill table for a flat reference surface….and still induced a twist (easily notable on the mill table). Bolting to a steel plate would probably have fixed everything….and I may one day do something like that, but its already ludicrously heavy for a printer :) (must weight in at around 50lbs, mostly aluminum! That’s beefy!)

    Anyhow, I do wish the author well. For any aspiring large machine builders out there, buy a piece of your preferred material cut to your max length. If you can visibly deflect it with your hands, (you’re probably only putting 50-150 lbs into it depending on how strong you are) it probably won’t support its own weight. If it passes the human test, that doesn’t mean it will be good, it just means it wont be ludicrously undersized like my first attempts were! (Mine was so bad the Y carriage bowed down being the worst at the middle obviously!) With an x axis misaligned, and its very difficult to get perfect, it would appear as though my bed was warped from one corner to its opposite, which is not possible to correct with cartesian machines. Once I realized it was a bowing in the Y axis, I set about building a better support system for it (torsion “box” (minus the top and bottom plate, so not really a torsion box at all) and linear guides supported by aluminum, rather than linear rods supported by air).

  4. I admire the effort, but trying to make this work with thin wall aluminum extrusions is just asking for a bad time. You can get away with it for small machines, but the square-cube law is a fickle mistress, and will ruin your build in short order. Not even considering resonances, this is gonna be a bad time just in terms of static deflection for any cutting load – even foam.

    Vibration and deflection analysis is something missing from a lot of makers’ skillsets, and its cases like these where it can limit you.

  5. While this does indeed look as rigid as a wet paper bag, I was wondering how you might actually make it a bit better; if you braced the corners with 45 degree legs down to the floor (ideally, bolt the whole thing to a solid floor) you would take a lot of wobble out of it. That plus some more judicious triangulation and corners made of something other than thin 3D printed plastic and it might just work.

    I’ll be very interested to see the follow-up article when he starts printing or machining things with this.

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