[GME]

That's one beefy setup. Keep going....

Thanks, David. Beefy is what I'm going for. Although this will mainly be a wood router, I plan to cut aluminum as well. In fact, I plan to use it mill to caps for the extrusion ends, hard stops, etc. Much faster than manual milling with all the setups, tool changes, etc I can also cut fancier shapes with the CNC as compared to my mill.

I've given thought to using 3/4" HPDE for the spoilboard top (re: your build thread), but I'm on the fence.

On profile/through cuts, I zero to the spoilboard, then move Z axis up the nominal thickness to the piece I'm cutting and hit zero again. My cam thinks I'm zero'd to the top of the piece and the thickness I set is nominal (vs. actual). So, for 3/4" plywood, which is less than 3/4", I tell cad/cam the thickness is 3/4" and Z=0 is the top of a 3/4" thick plece. As long as the offset for my touch plate is accurate, and it is, my bit will always stop at the top of the spoilboard, but never cut into it. With my other machine, except for when my Z screw coupler slipped once, it worked 100% of the time. Long way around to reach one conclusion: The cost isn't as much of an impediment as it might otherwise be, because my spoilboard will probably have a useful life of several years. (For two-sided carving, I'll use a sacrificial piece of MDF for drilling locating dowel holes).

What keeps me on the fence? HDPE is slippery as heck. Maybe not as slick as UHMW plastic, but still slick. That makes clamping an issue. Up until now, I've used T-track ala Orange Aluminum (https://www.orangealuminum.com/t-tra...cessories.html) and cut maple blocks of varying lengths for clamping. MDF provides frictional resistance; nothing moves. I question how to get enough resistance with HDPE. I can see parts slipping around and ruining the job.

What technique(s) do you use for clamping to HDPE? Reaching under a 4 x 4 machine (actual frame dimensions 74" x 60") to tighten bolts won't work for me.

Gary