Joe's 1000x600x200 steel and aluminium router started

[Kitwn]

Epoxy sounds a bit too complicated for something so simple and you'd have to confirm the frame was adjusted to make the plane of the rails orthogonal to local gravity or it becomes pointless.
I'd go with the shim and skim. That cannot fail to put the plane of the base parallel in all directions to the plane which the spindle moves which is what you really want and will minimise the thickness of material you need to skim off the final, sacrificial surface.

[JAZZCNC]

I would use epoxy metal paste. Use levelling grub screws in the bed and adjust until planer, then remove and skim all the surfaces with a lite coating of epoxy putty then put plate back on and tweak it out any error from lifting etc.
Tape the bed where it meets the epoxy and when dry you will be able to remove bed.

[JAZZCNC]

I'd go with the shim and skim. That cannot fail to put the plane of the base parallel in all directions to the plane which the spindle moves which is what you really want and will minimise the thickness of material you need to skim off the final, sacrificial surface.

It's not possible to skim the whole surface using the machine because plate is the full size of the base so cannot skim the portion under the gantry.!! Only way this could work is if the plate was the actual cutting size.

[Kitwn]

It's not possible to skim the whole surface using the machine because plate is the full size of the base so cannot skim the portion under the gantry.!! Only way this could work is if the plate was the actual cutting size.

Obvious when you point it out!

I like the grub screws and epoxy putty idea, but might it be better to use ordinary bolts instead? It would mean a slightly thicker layer of putty but it would allow you to adjust each bolt with an open spanner while the gauge is on it's head rather than have to measure, move the gantry away to adjust, move it back to measure, move it away to adjust again etc.

[JAZZCNC]

I like the grub screws and epoxy putty idea, but might it be better to use ordinary bolts instead? It would mean a slightly thicker layer of putty but it would allow you to adjust each bolt with an open spanner while the gauge is on it's head rather than have to measure, move the gantry away to adjust, move it back to measure, move it away to adjust again etc.

No point really and you want to be measuring off the bed not the bolt head. A M3 or M4 socket cap grub screw is easily adjusted thru the hole and is small enough not affect the bed too much.

There are several ways to do the same thing and it depends on how your planning on using the bed regards fixtures etc. The main point was Epoxy putty works good for this application, it could easily be car body filler(Bondo to you upside downers) if your on a budget...Lol