[FloweringElbow] Aka [Bongo] It’s definitely getting noticed on YouTube, and we think he’s a winner! This epic flatbed CNC build (video, embedded below) begins with a few second hand structural eye-beams, welded-on eye-beam legs, DIY cast aluminum side plates and lots of concrete to give a strong and, importantly, heavy structure.
The ideal machine is to reduce the vibrations caused by cutting as hard and heavy, high-feed speeds as possible, or to dampen the forces caused by cutting hard components, so large is really good. For frame construction, the steel is quite strong, and the mass of the structure makes it extra damp, but triangulation was required to prevent additional twisting. He sewed the pre-heated frame into inch-long sections to limit the heat transferred to the metal, lowering the next battle sheet. [Bongo] Hacky Vibratory Stress Relief (VSR), built from a washing machine motor and odd weight, has been used, including feedback from a mobile phone app to find the resonance frequency, framed. There are other videos in the channel dedicated to such stress relief strategies.
When it came time to add more mass, a priming coat was made from a mixture of bonding epoxy and sharp grit, which was made on a non-slip floor. The concrete mix uses Portland cement, pozzolan (silica fume) polycarbonate superplasticizer and 1/2 ″ glass fiber thread. A second mixture was added crushed stone for extra mass. A neat technique was to make a handheld vibratory compactor from a plate welded to the end of an old drill bit mounted on an SDS hammer drill.
Once the frame is properly inverted (breaking the overloaded lift in the process) the upper surface needs to be leveled to receive the linear rails. This was done using a super current, self-leveling epoxy and tested by the water flowing over it. Once the epoxy surfaces were sufficiently flattened and coupled (and much later scraped) the linear rails were attached, after making some epoxy shoulders to butt up against them. The last plates were bolted to the frame to attach the lead screws on the Y axis with a grit-loaded epoxy bond in the middle.
The gantry design was omitted for this video (but you can see it here) and a quick test once mounted showed that the machine was working. An intriguing task is to make their own cable-chain from plywood on the machine, instead of buying something peg-of-the-peg expensive. Why not? Once the machine was working well enough to match a flat sheet of steel to a nice reflective surface, it was used to cut some vinyl shapes to mount a DIY drag-knife, so it has accuracy. We’d love to see an XBox controller used to manually jog around the machine! There is so much to see in this build and other related videos, we think it’s worth watching this channel!
We’ve featured CNC builds a lot of the time, there’s a build whatever your needs and budget, but here’s a good starting point for building a machine, good enough to build the tools you need. If you do not have the source of the structural eye-beam in your hand, you can do something quite capable with the help of wood, and if you want to do 3D printing on the knee, we have also covered it.