Monday, April 29, 2024


Introducing "Titch"

Here's the first Block Stage prototype which might one day manage actual fabrication. As it has half a chance of working, I've given it a name: "Titch"

It is a reinforced OpenFlexure Block Stage with a larger flexure angle (to increase work area) and a probe platform. The probe holder is now canted at 45 degrees so I don't have to bend probe tips. Various holes have been made to make it possible to screw the thing together, and I've upgraded the NEMA17 motor adaptor plates. The whole thing is screwed down to a board together with two USB microscopes: One for gauging probe height, the other with a more expensive 5MP camera for viewing the XY motion. It can be moved around the bench without knocking everything out of alignment. The USB microscopes are still no match for the proper turret microscope but should resolve well-illuminated scratches down to 15-20μm - good enough for lining stuff up.

Having a basic XYZ configuration it can be driven with either GRBL or standard RepRap firmware like Marlin. As the angle of the delta struts is no longer an issue, the endstops have been temporarily ditched and I'll roughly centre it with a Mk I Calibrated Eyeball.

The stage is much smaller and so instead of microscope slides I am using 22mm x 22mm x 0.13mm microscope slide cover slips (7 cents each here). Attachment is currently with duct tape which is actually working out quite well.

Having less glass in them, the cover slips will let more UV through when it comes to curing resin. The OpenFlexure housing has been modified to have a hole through the stage, and a cavity at the back to stuff a UV light source into. The hole is offset, the theory being that the resin and dunking probe tip will go in the shade when the UV is turned on to cure the resin.

Titch is gloriously uncalibrated but I've given it a test flight with cncjs software and it seems to be moving everything consistently. I don't know the actual resolution but it was reliably drawing parallel lines about 30μm apart using a sturdy hypodermic tip. I'll let you know how it goes, and publish the STL files when I've ironed the kinks out.

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