I had an odd thing happen on my Shapeoko 3 XXL while resurfacing my MDF waste Board. I drew a rectangle the size of the board (about 32" square) and did a pocket toolpath which cut from the inside out. I used an Amana 45525 resurfacing bit only removing .03" which it did in one pass. All went well, or so I thought. I then decided to engrave a series of lines 1" apart in both X and Y directions using a 60 Deg vee bit 0.03" deep. That also went fine, except that the lines look fine around the outside of the square but get more and more faint as they get toward the center. The only thing I can think of is that the Amana bit was very slowly moving upward in the collet as it was cutting the pocket. Any other thoughts? Thanks! Larry
More likely the machine has settled in and sagged.
Put it on a sheet of foam, then try again.
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Do you think it sagged after I did the resurfacing? And are you suggesting that I support the center of the underside of the waste board?
Yes, and yes. SO3s at the XXL size benefit markedly from supporting the rather large span of their bed.
One way to make sure you get a flat surface is to put pencil lines in an S pattern in both the X and Y directions. I only take 0.010" per pass. If the first pass all the lines disappear great. If not I rezero in the spots where the pencil lines still exist and run the jog again. That way I only remove the least amount possible.
My SO3 XXL is sitting on a 3/4" rigid foam with the leveling feet removed. The center of my XXL had sagged as many do because there is no support in the center. I also built a torsion box for it to sit on on top of my table. The torsion box and foam leveled up my spoilboard.
To keep your spoilboard in reasonably good shape try using bottom of material for through cuts. You always have to measure material thickness but it is doubly important when using the bottom of material. The first cut will cut deeper than expected if the material is not measured properly. Give it a try to keep your spoilboard from being cut up. The spoilboard is meant to be cut up but when I used top of material I either cut through or got an onion skin. Since I went to the bottom of material for through cuts it has barely scratched my spoilboard I replaced on October 2022. There are a few scars but that was an operator error and not the machine’s fault.
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Will do that!
Thank you all for the quick replies!
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