Can you build an industrial grade CNC with only DIY resources?
[FloweringElbow] a.k.a [Bongo] on YouTube is definitely trying it out, and we think he’s onto a winner! This epic flatbed CNC construction (video, embedded below) starts with a used structural I-beam, with welded I-beam legs, cast aluminum side plates, and lots of concrete to give a strong and mostly heavy structure.
The ideal machine is as stiff and heavy as possible, to dampen vibrations caused by cutting at high feed rates, or forces from cutting harder materials, so bigger is better. For the frame construction, the steel is strong enough and the mass of the structure gives it extra damping, but some triangulation was needed to counter some extra twisting. He spot-welded the preheated frame in one-inch-long sections to limit the heat transferred into the metal, minimizing subsequent warping. [Bongo] second hand hack Vibration Stress Relief (VSR) constructed from a washing machine motor and an eccentric weight, attached to the frame, with feedback from a cellphone app to find resonant frequencies. There are other videos on the channel dedicated to this topic of these stress relief techniques.
When it came time to add even more mass, a primer coat was made from a mixture of bonding epoxy and sharp gravel, intended for non-slip flooring. The concrete mix used Portland cement, pozzolan Polycarboxylate superplasticizer (silica fume) and 1/2″ fiberglass threads. A second mix added crushed stone for extra mass. One trick was to make a portable vibratory compactor from a plate welded to the end of an old drill bit, mounted in an SDS hammer drill.
Once the frame was turned the right way around (sagging the overloaded hoist in the process), it was necessary to level the top surface to accept the linear rails. This was done using a super flowing, self-leveling epoxy, and checked by running water over it. Once the epoxy surfaces were sufficiently flat and co-planar (and later scraped well), the linear rails were attached, having created epoxy shoulders for them to rest against. End plates to attach the Y-axis lead screws were bolted into the frame with a grain-filled epoxy bond in between.
The gantry design has been ignored for this video (but you can see it here) and once mounted, a quick test showed the machine to be viable. A curious task was to make their own cable chain from ply, on the machine itself, rather than buying something expensive ready-made. Why not? Once the machine was working well enough to mill a flat sheet of steel on a nice reflective surface, it was used to mount a DIY drag knife to cut shapes out of vinyl, so it has the precision. We loved seeing an XBox controller used to manually spin the machine! So much to see in this release and other related videos, we deem this channel worth watching!
We’ve featured many CNC builds, there’s one to suit your needs and budget, but here’s a good starting point for building a machine that’s just good enough to build the tools you need. If you don’t have a structural I-beam source handy, you can do something quite capable with wood, and if you fancy trying 3D printing a knee milling cutter , we also have that.