Desktop size steel welded router 3 axis

[Neale]

Tom - are you using proximity switches by any chance? I had very similar problems with my own machine - homing was very problematic. I had configured it to home Z then X+Y together. Z homed OK, but I had random limit switch trips while X and Y were moving. Turned out to be because the proximity switches I was using had no hysteresis. What should happen is that switch-on and switch-off points should be slightly separate. Mach3 homes the axis until it trips the switch, axis comes to a halt but slightly overshoots, then backs off slowly until the switch trips off. Machine is now at home position and the switch goes from home switch mode to limit switch mode in Mach3. However, because on/off points are so close, any vibration after that point can cause the switch to trip on again, which is where the limit switch error occurs and everything stops. In my case, the only problem switch was on Z, and might have been something like resonance in the mounting plate for the switch. Perfectly strong enough for its function where there is no physical contact but it's just a flat bit of steel plate edge-welded to the gantry tube, and we are only talking maybe 10um to trip the switch so not much movement needed.

Fix for CSMIO users (courtesy of Dean, whose knowledge of these devices is invaluable!) is to set the home offset position in Mach3 to 0.5mm or so from the actual switch trip position. Axis homes in the usual way, then the CSMIO moves the axis by the small offset and sets zero at that point, enough to bring the axis trigger clear of the switch. After I made that tiny change in the homing and limits table for Z, I have not had a single false trip while homing, and the CSMIO is very happy to do simultaneous XY axis homing. It also means that you can safely move Z to 0 for rapid XY moves without any false triggering as the Z trigger is now far enough from the switch.

Of course, that might not be your problem but in my case, after playing about with switch changing, even buying a second batch of switches (which were just as bad), worrying whether it was noise or interference or something really difficult to track down, the workaround was trivially easy.

And our control boxes aren't a million miles apart either:


I have made some slight changes since I took the pictures - driver feeds to axes are via a row of XLR connectors on the LH side of the cab. I found that I was fitting and removing the cab fairly often when setting up the machine and the hard-wired connections were a pain in the neck. Literally, given their position...