Hello all - I have a Shapeoko XL that I’ve been using for the last ~4 months. I have it sitting on a concrete floor at the moment. I’m currently trying to v-carve some delicate lettering for a decorative box but have been getting fairly poor results (variable depths along the X axis). Unrelated to that project I tried doing some sharpie marker tracing recently and noticed that there were several low spots on my waste board. I decided to re-flatten my wasteboard and noticed some steps that indicated a tramming issue.
All of the board was flat across the Y axis, but there were steps across the X axis at the left and right sides of the ~31" wasteboard. The center is flat across the the X axis. See the images attached where you can see moderate steps on the left side and more severe steps on the right side.
What would cause this?? My only thought is that the center support is sagging or flexing during the flattening process in combination with the entire fixture being out of tram. My thought is that if it is out of tram then on the left side it would have a moderate step up from left to right and then if the cross-support sagged it would counter-act that tram issue and be flat in the middle, then to sag would exaggerate the tram issue on the right side and make it twice as bad.
Or drop the feet, install your machine on a known-flat-and-rigid surface with just a thin layer of whatever soft and thin material you can find to dampen vibrations, resurface it, tram it, profit.
The more that I work with the machines, the less I like the idea of actually machining the baseboard/baseplate (beyond adding a couple of threaded inserts from the bottom to secure a spoilboard) — it’s a lot of risk of a part which is hard to replace. Far better to just spray it with a couple of coats of spar urethane and work with easily replaced parts bolted to the top of it.
Two seems the easiest — put threaded inserts in one (again from the bottom) and make it slightly larger than the machine’s working area and have holes in it which match up with the threaded inserts you put into the base of the machine, then have an actual spoilboard the size of the supported working area which has through holes which match up with the holes in the threaded insert board and put a radius on the back edge which matches the diameter of the endmill you use to tram the spoilboard.
This is actually a SMOG, simple matter of geometry, and doesn’t require sagging for explanation, just a nerdy understanding of cylindrical geometry. See: Smoothing out wasteboard for details.
