Quote Originally Posted by Boyan Silyavski View Post
2. My experience shows that proximity limit switches/ Chinese at least/ have an error of approximately 0.4mm or i could call that hysteresis / imagine a backslash/ even if you home repeatedly again and again. Always first time off 0.4mm. Then right correctly. I tested aluminum, brass and steel. First i thought / on yellow machine/ that my error was a design error, cause not sensing perpendicular to them. Now on this machine sensors are NC, perpendicular steel/ best material for sensing/ as far as i remember when reading documentation
What i am saying is that even if you home in mach3, if you are machining steel or aluminum,not wood you would be way off 0.1-0.4, so let's not brag about continuing the job correctly, cause i have been there, done that with aluminum and its not ok. In short, if power stops in a middle of metal job you are f%%d up and can not depend on home switches but instead of that have to use Zero Z axis DTI setter or touch probe.So its absolutely useless speaking how PC will recover from power failure.
Simple solution there, buy better switches for homing.
A machine is only as good as it's weakest link, and if you need accurate homing, then you shouldn't cut corners on homing switches/sensors.
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IIRC on my old lathe, the slot sensor was about £30, and it had no measurable hysteresis. It would home to within 0.01mm every time, regardless of temperature. I know you had to make sure it was kept clean and a bit swarf hadn't landed in the slot, but it guaranteed accurate homing every time.
I would expect better than 0.1mm from a good quality mechanical switch, and I see no advantage using proximity sensors, given how variable they can be.