RepRap: Blog

The new X & Y stages are moving smoothly enough in 10μm steps. Remember this isn't corrected for arc movement on the flexures, but what it does it is pretty repeatable. I've tested it at ranges of +/-4mm against a 0.1mm grid, and in the photos below against a 0.01mm per fine division grid. Sorry about image quality, but my homebrew test system involves sticking bits of painter's tape on the screen viewing the USB microscope. Painter's tape does not screenshot well. Here's my view at (0,0) and offset by 0.2mm & 0.3mm on both axes simultaneously:

So from this I'm getting 15-ish microns from where I'd expect to be, but like I say this is repeatable rather than linearly accurate. Not getting any indications of backlash above a micron either (a guestimate based on sub-pixel flicker, which is bloody obvious on low refresh rate cheap USB miscroscopes). So if I can map out a grid and apply corrections, and they turn out to be consistent with long term use, then near enough to micron accuracy looks achievable.

This is good. It gives some validation to the performance of the XY table and the long flexure rods used to drive it. With motion ranges of a few mm the X axis position doesn't seem to be affected visibly by the Y axis within margin of error of my microscope. Here's a picture of the current setup:

The connections between the drive stage and the flexure rods are a bit rough. The new driver stages are a different size, in a different location, at a different level, and I haven't had the chance to fix it all up properly. It was thrown together from what was at hand and needs all-round improvement - though didn't wobble at all during testing.

Next up, I'll get working on a Z axis. When I know where that needs to be I'll improve the bracing and fixture locations all round. Then we need a probe and end stops, and we'll be in the same position as we were when the OpenFlexure stage died.

Except this time I can put it all on github under the GPL. This needs to be done in time for Everything Open 2025 on the 25th January, because guess who is doing the first presentation of the conference in Room A after the keynote: https://2025.everythingopen.au/schedule/

# posted by vik-olliver @ 5:20 AM