Wednesday, April 23, 2025

 

Endstops - At last!

The endstop is nigh. I needed a small switch, independent of manufacturer types, with no click and a quick reset. What better choice than a couple of bent bits of wire a la drone. I'm using 28ga 316L stainless ("Vape Wire") here because I bought a bunch for my official (licenced) pyrotechnic endeavours a few years back. So a short length of this gets twisted 8 times into a piece of hookup wire, as you can't solder stainless with 40/60 solder:

 

 This end gets bent round 180 degrees so that the stainless wire points forward, and to stop it coming undone, 10mm of suitable heatshrink gets put over it.

Two of these wires get clamped against grooves in the drive motor pillars with a 2-hole Metriccano strip, and the free ends are folded over the strip's edge so that they cross but don't touch. You need to shove the strip upwards to take out any slack in the screw holes. I'll update the 3D printed parts in the next couple of days as part of the upcoming V0.03 release.

 
 
When the beam arm bends down towards the motor (after about 2.2mm of probe travel), it mashes the two wires together and the endstop switch is closed. The endstop wires go to GND and the endstop connections on the GRBL board for -X, -Y, and +Z. Z homes positive to stop users from driving the probe into the build area when homing.
 
Note that these endstops are not meant to be micron-precise. They're just there to make sure you start off with all the axes vaguely in the middle of the build area and don't unexpectedly run out of axis. Brief testing shows they're good for +/-50μm-ish once they wear in.
 
As a courtesy, the M3 nuts on the back are captive (there are a lot more captive nuts in V0.03) and I have put in vias for the wires to keep them out of the moving parts. I've built one and tested it, the remaining 2 are under construction. This is taking longer than anticipated, because I built the V0.02 μRepRap in a rather ad hoc manner, and undoing bits out of assembly order is proving problematic - hence abundance of captive nuts on V0.03
 
GRBL Config file coming as soon as I've figured out what it should be.

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# posted by vik-olliver @ 3:37 AM 0 comments

Tuesday, May 01, 2007

 

Opto-endstop cutie pie'd

After ARNIE, Adrian and I have been cooking up better ways to fit the optoswitch for the axis endstops. We've designed this 50mm long assembly for Darwin so that it comes with its own PCB and clamp (as standard).



Assembly instructions have been wikified here.

Flags for the axis have been fitted and, although there's a couple of mods to do, Darwin is on its way to being wired

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# posted by eD @ 11:56 AM 5 comments

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