Spoilboard not flat after flattening?

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey BPSWoodworks,

@Aiph5u

a gantry-type CNC machine can be twisted. This is usually the case after setting it up. In this case all your workpieces, including the flattened wasteboard will be twisted. Therefore such a machine needs to be adjusted for coplanarity. The QCW frame offers the Any Surface Leveling Feet. But you can also use heigt-adjusted feet or casters. In this case if you move the table around, it is necessary to repeat the check and adjustment of coplanarity each time you moved it. The fishing line test is useful for checking coplanarity.

A machine that is not adjusted for coplanarity, i.e. is twisted, can let the wasteboard remain curved concavely after flattening it.

Surfacing the wasteboard will not help against lack of coplanarity (twisted machine base), the machine will only reproduce the twist on the surface of every workpiece you mill with it.

@Aiph5u

Furthermore, on a machine with no accurately adjusted coplanarity and rectangularity, the Y movement can block, or have “hiccups” or loose its position reference coordinates.

I would consider a machine ready to use only if you first checked and ensured that it is

1. rectangular (“squared”) (bar gauge) and 2. coplanar (“not twisted”) (fishing line method)

Only then I would proceed with