Uneven table causing chatter?

So on a Pro XL there’s 3 rails front to back at the very bottom, upon which the aluminum slats rest.

I have a suspicion my middle rail is not making good contact with my table. Likely my table is not perfectly flat. I think the center of my spoilbord is subject to some vibration as a result. Basially if I pound the center of the spoilboard with my first, I will get a form of resonance.

Has anyone dealt with this? I have the 46" husky adjustable height worktable.

some folks put that “hard insulation foam” stuff underneath, it’s both firm but absorbs vibrations… and it’s usually flat


I put some Harbor Freight anti-fatigue mats under two of my machines — mostly trying to dampen resonant vibrations, but it also seems to help w/ flatness.

Okay both of those sound like good ideas. The PRO is quite heavy, so ideally it will push on the front/rear beams more as needed and all 3 will share an equal load.

I guess another thought/option would be to drill the 3 crossbeams to the work table? Then re-level the spoilboard?

It would only make sense to secure to a work table which one knew to not only be flatter and squarer than the machine, but one which one was confident would remain so in the future.

Moreover, this would be an unsupported modification of the machine — please don’t — if you wish to secure, use the PEM nuts for the leveling feet, going into threaded connections which allow adjusting for level.

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+1 to @WillAdams 's use of rubber mats. I have one used to isolate a washing machine under my Shapeoko 3 XL. I’ve also removed the levelling feet so the whole bed is supported by the mat. I used to be able to make the MDF spoilboard bend with moderate pressure even though there were cross straps below, now it is rock solid. The mat takes up any unevenness under the frame.

It does make things a a bit of a PIA to move around now though as nothing can slide on my bench.

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What are PEM nuts? Just to be clear the SO Pro I got did not come with any feet/hardware. The 3 aluminum cross bars lie flat on the workbench.

I put rigid 3/4 inch foam under my 3xxl. That is on top of a torsion box. I think it supports the center better and keeps my machine dampened from noise and movement. I removed the leveling feet so the frame rests on the foam.

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You can also shim any spots where there is a gap to your bench.

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PEM nuts are special nuts which are inserted to our plates where threads are necessary — I’d assumed that the Pro and 4 had them for leveling legs, but apparently not — just use a sheet of foam or shims.

The SOPro/SO4 have some countersunk holes that are unpopulated that are apparently there for bolting down. But I don’t recall anything threaded for legs. When we get the SOPro at work, I’ll refresh my memory.

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Yes I did notice on the extremities there’s some deep counterbored holes. Have not noticed a set in the center though which is perhaps where those would be most useful in my case.

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