Z Axis Home Position

[Dalmanos]

Hi,

I recently bought the Prusa i3 X Acrylic version and am figuring out all the problems.
So far I managed to solve them myself, but now I'm stuck.

I do not know why the Z axis sometimes homes at the release of the endstop and the other time on the press of the endstop.
This little strange behavior did already do some damage on the heatbed, fortunately only on the side(3 cm long scratch). Extruder nozzle seems to be fine.

Is there a setting in the Repitier Software 1.6.1 for this or is this a strange firmware behavior?
I do recall that i saw a setting like "Z Offset:" but it was set to 0, so this shouldn't be the problem.

Thank you for your help.

[Mark]

the endstop, if you press it when homing, the motor will stop. Is your endstop wirings correct? and is there a bad contact on the pins?

[Dalmanos]

I will check that as soon as I have time.
Could be really true, as it does most of the time print at the right height.

[Dalmanos]

So I checked for a bad connection but it seems that there is no problem there.

While watching I detected a patten on the Z auto homing:
Every second time it homes approximately 5mm above the switches press point which is the release point of the switch.
So it switches from press point to release point and vice versa.

When the print is started from the Z axis homed on the release point it is working on the right height.
I still need to confirm that, but from the quick test I could do now it seemed like it.

I hopefully can confirm that today, depending on my schedule.
But maybe you already now this pattern and can give me a hint why it does so.

By the way, the deliverd filament seems not to stay on the heatbet. Do I require a tape in order for it to stay on the bed?
Or is this just a result of the poor quality of the filament? It broke yesterday over night. I store it in my bed room.

[Dalmanos]

I proved my theory today. It is true.
Why does it behave like that?

Also I realized that hair spray is a very good adhesive and ideal for 3d printing.

I checked the filament and it seemed that at the part where it broke were around 2cm of bad(hard) filament. Very strange.
Works fine again now.

[Mark]

"Every second time it homes approximately 5mm above the switches press point which is the release point of the switch."
haven't meet it before...did you use the correct firmware?

[Dalmanos]

I used the firmware it came with.
Did not change anything.

[Mark]

I homed Z axis several times, didn't see any different, all stopped in the press point...maybe try my firmware here:

I3_pro_X.zip

(295.69 KiB) Downloaded 653 times

[jeff52]

I have a similar problem with my Prusa I3 Pro Acrylic. If the Z axis is homed when I start a print, it will retract to the release point of the switch, and then begin to print. My fix so far has been to make sure the Z axis is slightly off the home switch before starting a print. Seems like a bug in software; the axis should only home on approach, never on retract.

[RotoGoat]

Did you fix this? I have the same issue with my I3x pro
I tried the firmware supplied earlier in the thread, but didnt fix the issue.
Any ideas?