Epoxy for leveling table or rails

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#1

This is more of an idea discussion as I was thinking about this while designing an air bearing surface at work.

If you had your table top for the lowrider, would it be beneficial to put a small perimeter on it and do a light pour of epoxy to make it perfectly level. You would need just enough to fill the lowest spots on the table.

For attaching the spoil board you would just need to drill holes through the epoxy and the table top and run screws into the bottom of the spoil board from underneath

Alternatively if you had rails on the side of the table out of C channel, you could cap the ends and then pour epoxy inside. You would still have issues with aligning the rails vertically from one side of the table to the other (you could compensate with z axis adjustment) but your roller surface would be perfectly level and smooth.

Am I out of my mind?

Again, I don’t know if I really need to do this but it’s such a cheap way of making a level and smooth surface that it’s gotta be useful for us.

#2

Having it level (to the earth) is not really that helpful. Having it parallel to the motion of the bit in XY is. In fact, if the gantry flexed and it was 5mm lower in the middle (of. 1200mm wide work area), then you’d want the spoil board to also sink 5mm in the middle. Any plywood you out down will match a curve of 5mm over 1200mm.

So it is better to flatten the spoil board with the router instead of letting the flow of epoxy and gravity determine the surface of the spoil board. Plus, I would guess there are other problems like total cost and the surface tension on a thin layer.

I had the idea of making a frame and using the router to flatten the frame first and then put down the spoil board instead of milling the whole spoil board. But I’m not sure how practical that is either.

And, it needs to be said, surfacing or flattening the spoil board usually isn’t necessary. Milling through a few extra mms while cutting out parts doesn’t add much time.

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#3

Good point with the sagging gantry across the x axis.

Flattening the frame is a decent idea but I feel like the seasonal changes of the wood would throw it out of wack pretty quick. I guess the same could be said for an epoxy top pour.

I agree that surfacing for flattening the spoil board is not necessary. I’m running 1" floating MDF top and it’s good enough. It would really come into play with carving or half lap joints.

More of a thought exercise than anything else.