XXL Base Rigidity

I am awaiting delivery of my XXL, but I have read several posts about the need to put insulation foam or a rubber mat under the XXL table to prevent flexing. So far I haven’t been able to find a lot of details, such as:

  1. Why does this happen? Is it a design problem?
  2. Is there a less kludgy method for doing this i.e., adding stiffening rails underneath?
  3. Some talk about removing the legs. Why?
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  1. It’s a long span — when manufactured the cross straps are made so that the bend in them is positive/up — for some this isn’t quite enough to overcome the sag. For other folks, it’s a matter of workholding (you can actually bend the frame if you put a clamp on things from the top of the stock to the underside of the table)
  2. Some folks have added additional leveling legs in various ways, a few folks have done stiffening rails, a metal bed or T-track setup can usually be set up to integrate such adjustments or be made sufficiently rigid to overcome this
  3. Reduces the height from which the sag can occur — w/o the legs the machine is down on the cross straps and the unsupported spans are much shorter.

Most folks don’t need to do anything beyond just assembling.

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My XXL is from 2017 and the center dipped significantly. I put a block of 3/4 inch plywood under the center support and solved the problem. The 3/4 inch rigid foam and removal of the leveling feet would be a good way to go from the beginning. You want to make sure your table is level. A torsion box is one of the best designs to ensure your table is flat. The added benefit is there is no hidden space for objects to mysteriously disappear to. I have had many pencils roll under the Shapeoko frame. No telling how many creepy monster bugs live under there.

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None of these, hopefully…
:spider: :bug:

or,… you can use the supplied base supports and board to help square the machine during assembly, then remove the board, supports and feet, secure the machine to your table and build a spoilboard on the top of your work table.
Worked out pretty good for me.

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I bought adjustable 3D printed feet on Etsy for my xxl. They slip onto the frame at 8 points (if memory serves)). Once I got them dialed in, the frame was much stiffer.

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