I have a HDM arriving in a few days. I built a 48x43" torsion-box table for it to live on, but messed up and physically moved it too soon (apparently wood glue can still shift slightly even after 5+ hours of drying) and its sagged so 2 of the corners are ~2mm lower than the center when checked with a straight-edge.
Can the HDM be shimmed so it’s sitting level and won’t conform to my sketchy uneven tabletop ?
How many contact points does it have with the bench ? If the whole thing is on 4 rubber feet then this is all easy-peasy. But from some photos it looks like rails that run left/right under the bed all sit flat on the table - is shimming under the ends okay to where they’ll be mostly raised above the bench, or is it better to have everything firmly against a flat surface to avoid flex.
The obvious fix is: ‘make the bench flat’, and I have a few ideas on how to fix it. But not sure if I should be doing that before even thinking about cutting anything, or a few shims will get me by for a while.
I added 4 leveling feet in the holes that were used to fasten the machine to the palette. (under the leftmost & rightmost table slats). They tapped out to 1/4-20 perfectly. I ground ~150° tip on some 1/4-20 screws. Although I am not lifting the machine, rather just applying enough pressure to stabilize it and account for a tiny bit of ‘un-flatness’ on my table. (I machined the table flat on a bigger CNC so it’s within 0.005" over the footprint of my machine).
With the solid aluminum rails and crossmembers this thing is extremely rigid for a CNC router.
I would still try to get the table as flat as possible, but assume that if you’re shooting for near perfect there will be some adjusting / shimming.
I have leveled worktables with countertop epoxy. Make a form around the edges, apply a release agent to the form, mix and pour the epoxy in a thin layer, just enough to level the surface.
Question for your question. Does the table need to be level?
I can see that we want it to be close, not create any tweaking to the machine. Once the machine is sitting on the surface we zero with devices other than a level. (squares…)
As long as my cutter is true to my spoil board, does it matter?
No, not at all. It should be pretty “flat” (planar) though. My table sits in my garage, which is graded toward the door. It’s probably a good inch lower at that end. The whole table is however, flat within < 0.005"
If you are going to be pouring epoxy fills while the job is still on the machine, then you would want it pretty level. Otherwise, the machine should sit flat, and be square & parallel to itself.
Pouring an epoxy surface on the table is going to render it flat & level, so you’d want it close to level while pouring.