Nebula working great, part marking question

Thanks, David. HDPE machines easily, no burning, no melting, no plastic buildup on the cutter, although it always generates a massive amount of fine shavings. On this first panel I did not use the dust collector as I wanted to see the cutter at all times. I will on the second panel.

I used Onsrud 65-020 and 65-021 3/16" upcut bits 1/4" shank, at 19000 spindle speed and 70ipm feedrate.
Each part takes about 23 minutes, with the interior ring with the 7 holes nearly half of that, holes are slow, and mostly 3 or 4 passes for 0.75" part thickness.

Lettering on plastic parts: I never worked with V-bits and/or engraving before. I used 60deg V-bits, maybe I should use 30deg bits. But the shape of this bit just does seem right to me to produce fine single/solid line markings. I tested various depths using these V-bits. I'll try the 1/16 and 3/32" straight end mill next, if that does not work I'll take another look at V-bits. I use VCarve Pro (and also Draftsight for geometry construction work).

I did a variety of tests engraving 'uturnhandles' on HDPE thermoplastic using 11, 30 and 60 deg V-bits using Solid Line and True font options, and Text and Vcarve toolpaths. Text height varied from 0.25 to 0.40inch. 100s of combinations possible, way too many to try! So far 60 deg V-bits, true font, Vcarve toolpath looks best for approx. 0.35" letter height but still feels a little bit rough on top. I'll try a small burner on various marks and see if it improves. I stay away from sanding as I found that sanding HDPE always leaves marks and scratches. I also have damaged handles with an extra groove at the edge and see if the burner makes those acceptable too, i.e. good enough for use, maybe not good enough for sales.

For roundover edges I use a separate benchtop router and use 5/16 roundover bits for the peripheries on 0.75 thick parts. As the spoilboard (two) and the HDPE sheet all vary slightly in flatness/thcikness over the sheet, I cannot do the roundover edges on the CNC machine. If I do, the edges do not come out uniformly nice.

I'll keep you posted if the 60deg V-bit + burner touchup will do a good enough job. The larger the lettering the better it looks so simple conclusion is that using a CNC Nebula may not be very good for small letter engraving. However I have no experience with professional engraving so there may be other ways/bits/speeds that work better.

Examples on scratch HDPE