garageFab.cc

After milling tests, I tried drilling out small hole pattern in the cutting mat (which would make a vacuum table surface for the paper prototyper). Initially I used tiny 0.01" drill bit and drilled a short sequence of holes, only to realize that there would have to be 50x50 grid of 0.01" holes spaced at 0.01", i.e. 2500 holes per square inch. Even without doing the math it was clear that it was going to take forever to drill out 8.5"x11" rectangle on the mini-router, so I switched to 1/32" drill bit, with more realistic 16x16=256 holes per square inch. This would take forever/10 in theory. In reality, one square inch took 10 minutes to drill at 12 IPM which wasn't that bad. Still, at 6 sq.in/hr it was going to take about 20 hours to drill the letter paper size area + 1/2" outside margin. I spent more than an hour just watching Dremel peck the cutting mat and then decided to stop because a faster (e.g. belt driven) router design should be able to do this faster.

I did not want to leave the mini-router unattended because the earlier endurance test of the router resulted in stalling Y-axis. In addition, I had also snapped one 1/32" bit on a toolhead crash in earlier drilling tests, which I think was caused by a bug in GCode interpreter - it seems that max feedrate after initialization is not updated when switching to inches. At least it exceeds the maximum value from config file until explicitly set via F code.

A separate problem that I'll need to look into is the hairy stuff left in holes after drilling.