IR Trigger height suddenly changed a lot

[JKaechler]

Here we are printing with a recalibrated z offset of Z4.956
This is the same part, after i resliced it and double checked all my settings. Hopefully it works. Its a 9 hour print.

[dc42]

Have any of the IR components at the bottom edge of the sensor board become contaminated with filament?

[JKaechler]

@dc42

i never thought of that. what is a safe way to clean them? I dont think there is actually plastic stuck on there, but there was contact between the sensor and some heated up molten plastic. I could see how some kind of contamination would cause a difference in refraction on either emitter or receiver and make it trigger at wrong height

[dc42]

You can clean them using a cotton bud moistened in isopropyl alcohol.

[Billsrf]

@dc42 I have encountered a problem much like this. My machine has been flaw less for the last 1000 hrs of print time. I went to start another print this morning and the IR sensor triggers at 20mm above where it is supposed to be. I tried the recalibrate and i get nothing but error messages. I am stumped, I did not do any updates or change any settings. 0_1553533768486_config 3-25-19.g

[Phaedrux]

@billsrf Have you tried cleaning the sensor as DC42 suggests above?

[Billsrf]

@phaedrux yes, i even change the sensor and getting the same results. No matter where it is at, it moves 10 mm down towards the build surface and stops.

[JKaechler]

For what its worth, I also cleaned the sensor and got essentially no change. After further testing I have also found that the sensor is making increasingly large errors as well. Basically i have to watch the first bit of the first layer and baby step it a bit to get it right each time.

[Billsrf]

@dc42 , @jkaechler yes exactly! now when i run HOME.ALL, it moves to the center, dives 10mm , the sensor triggers at 200 mm from the build surface. This is crazy. it has been perfect for 1000= hours now i cant figure it out. reloaded firmware and config.g same thing again.2_1553547133616_homeall.g 1_1553547133616_config 3-25-19.g 0_1553547133615_homez.g

[dc42]

Is your IR sensor the older sort with through-hole phototransistor and IR diodes, or the new sort with surface mount ones? If it's the older sort, then you have probably had a collision and one of those components has been bent into a different position. If it's the newer sort, then perhaps it has developed a fault.