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diamond bit success; fixing Makerbot

December 27, 2011

Holiday shenanigans have kept me from doing much lately, but I had a few successes.

First of all, I fixed the Z-axis problem I was having with my second Makerbot (“Baby Blue”) – it just needed a new belt.

Long ago when I was first building one, the standard belt was not available, so I subbed in a heat-resistant model. It turned out to be substantially thicker and less flexible than the original neoprene one, which has caused no end of problems.

So, I finally bought a proper replacement, and that solved the problem.

I’m continuing to print parts for a low-rider XY axis assembly, and after that I’ll print a Z-rider. More urgently, I have identified upgrade parts for Baby Blue’s extruder- I’ll be using Ruttmeister’s stepper adapter for the MK5 extruder. That way I can keep the MK5 drive system and hot end, which has been working quite well for me, while upgrading to a stepper driver. I have a spare stepper motor and driver board, so once I get these parts printed I should be good to go.

On the Mantis front, I bought a single-point 90 degree diamond bit from Dremel. The first one was defective and failed instantly- the diamond just popped out. Dremel replaced it for free, and the new one arrived Friday.

It works great! Spinning the bit at high RPMs makes it engrave just as well as a vibratory engraver, apparently. A Z height of -0.005 gave very fine lines on glass; I think I can probably back that off to -0.003 or 2.

When attempting to engrave acrylic with carbide bits, a higher feed rate did result in less melting, as did more aggressively toothed bits. This is to be expected. I still haven’t found a proper feed rate to fix the problem entirely. It may be that a pot. wired into the spindle motor could decrease the spindle speed enough to help as well.

The problem of course is that this isn’t a true spindle so it won’t maintain its torque at lower speeds. Does not hurt to try, though; I really don’t know how much torque is needed to engrave acrylic.

Pirate Box- no movement lately.

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