RepRap: Blog

With the same resolution as before (50μm) I scanned the smallest details I could find on the NZ 10c coin: the letters 'IRB' found just above the year numbers and so small most people don't know they are there. I misplaced the probe a bit and only got the first part of the 'I' but the results are clear enough. It's reaching the limits of the robust probe tip:

This is what the original looks like, shown on the stage with my horribly clunky probe below it. The letters approximately protrude 40μm and are 0.7mm high, or for those used to colonial measurements, just less than half the width of a piece of printer filament:

With the previous scan of the 'A', the xy slope adjustment was (0.2,-0.06) and for the 'IRB' scan, (-0.018,0.033) so it is fairly clear that the slope changes drastically depending on where on the stage the probe is. Unfortunately I did a demo to my brother-in-law just before making the scan and lost my zero, so I don't know what point the probe started from.

During the demo scanning process, the coiled copper grounding probe lost its spring and would not maintain contact, so I affixed a little PET plastic arm with a nut to ensure downward pressure. I kept nudging the coin around while putting the ground probe on, and I'm afraid some duct tape was deployed for stabilization...

Here's the little perisher. I know a weak point when I see it so I purchased 3 spares. Now 2 spares.

Fitting the new one requires a 3D printed tool and a lot of brute force. They get hung up inside 2 out of 3 times, requiring fishing around with tweezers before trying again. Still, better case than fixing the Y limit switch.

UPDATE: I thought the Y-axis limit switch (actually a couple of sprung, crossed wires) had failed. This is, of course, right in the guts of the thing and I'd have to unscrew every single component of the base and remove all the 'O' rings that are under tension to get at it.

The update, once I'd taken the Y motor off, is that the switch is fine but the 'O' ring in the Block Stage has failed. These are starting to be a royal pain, and when I design my own stage they will be the first thing to go! But, once I unbolt the stage, I should be able to replace a broken 'O' ring without having to dismantle it. Of course, an attachment point could have broken off, in which case I'll have to print a whole new stage and do all that tedious disassembly/assembly.

Also, the probe with the jumper pin sticking out the side won't fit in the nice storage pot I made for it. Damn. Bigger storage pot needed. Fortunately, this is a very tough probe that I use for test-fitting things so it can rattle around until I'm done.