Cross Straps Bow Upward

I can’t get a perfectly flat waste board as these cross straps are bowing up. Did I miss something in what could possibly be the worst directions I’ve ever followed in my life?

If not, what should I do?

That’s nice - mine sags a ton on an xxl. Getting a perfectly flat waste board will mean milling the board flat. I’d guess the slight crown I see May flatten with the board on it or would prevent some future sagging after milling.

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There’s no cross strap on my SO3 but when I installed the wasteboard it was nice and flat. Some months later I discover it has sagged in the middle. I somewhat fixed it by attaching a wooden “leg” to the bottom middle of the wasteboard that was just the right height.
It could be that having the wasteboard attached will help to flatten that bow.

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I can tell you the waste board did not help. I have been running it for a couple days hoping it would and I cannot keep it straight. I can’t run something across or else the gantry/router will hit it. I’m going to call tomorrow. If they can’t give me any answers, I’ll figure something out.

What I have found is that if your table is square and flat, bracing the bottom of the shapoko to the table top as a continuation of that works. There is a reason the big boys in the machining world are substantial and heavy,and its full name is Mr. Minimizing Deflection…
Your spoilboards and underlying supports don’t sag at first because they have not experienced the downward forces of machining and gravity across their span, as they do, the sagging sets in. Add to that the flowing nature of MDF when exposed to temperature/fhumidity/ change. The aluminum rails-and the steel end pieces are the lasting rigidity in the Shapoko, When you build a table/ base to hold your machine it needs serious flatness and rigidity built in, four adjustable feet across a long span don’t add up to that. Adding a support under the middle is a big help-coupling a rigid “enclosed x” between the entire base and the feet would be a way to take care of this. In my own setup, I am working on a hollow (Wraping a foam pattern) carbon fiber “enclosed X” to set as a replacement (or a supplement) to the shallow 10G steel channels-deeper channels would be more rigid. The floor of the machine has to be rigid and flat for machining to be precise-larger machines have more flex than smaller machines…pretty sure that deflection is part of why the Nomad is the size it is…

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I think YoMan has the correct approach: Make your bench/table/whatever as flat and sturdy as possible, then shim between the Shapoko and that.

If something is bent UP, I’d tend to bend it down by about the same amount, and then shim it back to flat.


Agree here… shim your machine to your level work surface, or lose the leveling feet and let it rest directly on the work surface. I’ve done the latter and I had an immediate improvement in the flatness of the machine bed.