Sunday, December 01, 2024
Various Variations On A Stage
I've been quite busy in the background. I've been through about 5 iterations of the stage, finding out there to reinforce, lengthening arms, changing mount points, testing various drive nuts, changing flexure profiles etc. I've eliminated the vertical flexure in the arm as the drive nut translating left/right has an unexpectedly large impact on stage movement. I've also had to shorten the flexures to 2.5mm reduce twisting. Here's a part of the prototyping debris:
I was getting some curious flex at one point, which counteracted the movement of to top of the stage, making the movement appear uneven. This is because I was supporting too close to the motor, which it turns out needs to free-float. This has lead to a change in mounting. I've increased the mechanical advantage to 3:1, and the range of accurate motion should still be in the +/-2mm area with inaccurate motion possible +/-4mm without breaking anything.
As you can see on the yellow stage at the front, I've the beginnings of a new probe arm coming together which is much lower profile, allowing the USB microscope to get much closer and thus provide better resolution.
The M3 Nylok nuts appear to wear out after a few assembly/disassembly cycles, so I'm back to locknuts on the drive screw. The drive nuts are back to ordinary M3 nuts again rather than sections of brass pillar, which had just too much slack in them. The modules are slowly getting easier to assemble/disassemble, and there are a few spare mount points that can be trimmed off now I know where things are headed.
With the new arm/pivot lengths and new mount points the drive stages don't match the XY table quite so well, so more tinkering required there. The blue Z stage drive won't fit the new probe holder, so that has to change. I'm planning on using the same stage driver for all axes to keep things simple. From the development viewpoint anyway.
The black is a much more optically sound colour, but it is much more difficult to determine what is going on. Unfortunately, I have a lot of black PLA, and the bright colours are being nicked by the family for Xmas decorations, so black it is.
Season's Greetings all.
