Definitely check your printhead shafts like gr5 said, and checking the lifting switch function by hand. Also, if you perform the lifting switch test in the Diagnostics menu, does it work? If not, try doing the liftings switch calibration again following this video:
1
12 hours ago, gr5 said:Try changing the nozzle height with power off by pushing the head into the switching mechanism and sliding it forward and backwards. Does it work? Or does something hit something such that it won't go in properly? Also check that your thin rods that go through the print head appear to be perpendicular when looking down on them from overhead.
I'm not sure what you mean by rods that go through the print head. Just not sure what I'm looking for here. Yes when I manually switch it or put it in the bay, it switches just fine. Like I said in the OP, it SOMETIMES go in the bay by itself and does the switching, but more often than not, it acts like it (goes to the far right, though not in the proper forward / back spot to be in the hole) and then does the motion like it knows it needs to change position.
You might be onto to something with the position it's in when power cycled. Today when i went to print something, it worked just fine on the first attempt and every attempt it made yesterday as I printed three things, the last one of which I generated support for, so it would use the 2nd nozzle. It's possible that the switch was in the "wrong" position when powered down / up the last few times and that caused the problem with calibration, though that doesn't make sense either since you always raise it before you start the calibration...
12 hours ago, fbrc8-erin said:Definitely check your printhead shafts like gr5 said, and checking the lifting switch function by hand. Also, if you perform the lifting switch test in the Diagnostics menu, does it work? If not, try doing the liftings switch calibration again following this video:
Yes, this is the process that's failing. 1:13 in the video above is when it goes wrong. I hit continue and it goes home (back left) and then proceeds to NOT go where I just told it it needed to go. It goes back to the far right side, but almost never (until yesterday) goes back to the proper position. Even after that, the calibration doesn't "stick" and it doesn't return to the same place at all when it tries to flick the switch. (Like I said above, yesterday everything worked as intended, but I wanted to at least reply to possibly figured out WHAT happened, to keep it from possibly doing something again.)
What are the rods you both are referring to?
2 hours ago, sajawors said:I'm not sure what you mean by rods that go through the print head.
The head is the part with the nozzles. There are two long steel rods that go through it. They are supposed to be perpendicular but often aren't because one of the 4 belts slips a tooth.
The fix is to loosen the two set screws on the pulleys on one of the 4 long belts and adjust until it seems square by feel and by eye and then retighten.
When these are crooked you can get excess friction (plus your square parts are a little trapezoidal).
Something sounds wrong with your gantry. Try pushing the head around to the 4 corners and feel the friction. You might need to check that the 2 rods are square (my previous post) or maybe add one drop of oil to each of the 6 rods in the gantry (light machine oil such as 3 in 1 oil or sewing machine oil).
Each axis basically has 6 pulleys (although two of them are bonded together) and each of these 12 pulleys has a set screw and if one is a bit loose it would explain your issue. It only has to be a tiny bit loose.
So the issues that I'm thinking about:
1) slipped stepper steps due to excess friction
2) slipping pulleys due to set screws not tight enough
Other possibilities: stepper driver too weak. VERY unlikely unless the room that your printer is in is above 35C.
The metal bars, if off, are off by less than a half a millimeter. I measured from corner to pole on each side, and half a millimeter seems like it might be the difference, but that could also be noise in how I laid the ruler down.
I also did a factory reset and this video was taken AFTER the factory reset. We DID recently update the firmware (4.3.3.20180529) and someone else noticed that they updated it about the same time this started failing. Is there anyway to roll back firmware?
It looks and sounds like the printer was having some issues with the endstop in the corner--it shouldn't grind like that. Since it calculates the home position based on the endstops I think that's where the issue is.
Have you done the Limit Switch test in the Diagnostics menu?
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Just as a comparison, here's what the the calibration looks like and sounds like on a UM3 that's not having issues. fbrc8-erin is certainly right that the homing operation looks and sounds different in your video.
https://1drv.ms/v/s!Aot6t7hrbQ2kkLBIKrWT23oaZcX6_g
Also, the only changes in the 20180529 firmware were adding Tough PLA to the Materials list and a change to how the bootloader works. So that may be a red herring here.
Yeah, I see what it's SUPPOSED to do in the official video posted above.
I don't see a limit switch test in Diagnostics. There's a "Limit Switch" option, but clicking on it just goes to a screen that says:
"Limit Switch Test
X: [ ]
Y: [ ]
Z: [X]
<Return"
And doing the wheel incessantly either direction doesn't give me any choices. Clicking return just returns to the Diag. menu. I even let it sit for a few minutes hoping it would just start whatever test it needed to do. HALP?
I'm not disagreeing with you about the firmware, I'm just trying to suss out a cause since it didn't used to do this and now all of a sudden it almost never DOESN'T do it. =/
Yes, you found the limit switch test. It's not automated like some of the other tests are.
* If you manually move the print head to the left and right, the "X" box should display an "X" whenever the print head is at the left edge of its range.
* If you manually move the print head forward and back, the "Y" box should display an "X" whenever the print head is at the back edge of its range.
* Irrelevant to your problem, but: If you manually move the build plate up and down, the "Z" box should display an "X" whenever the build plate is at the bottom of its range.
* If the "X" for a given axis doesn't reliably turn off and on when it should, then you have a problem with the limit switch for that axis. For the X and Y axis, this can result in homing failures, layer shifts, and failures to properly toggle the lift switch.
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ok, so it failed the Y limit test. I tried to do the XY calibration, but had problems printing out from the 2nd core (if I can't figure this out, I'll make another thread). Once that failed, I manually played with the Y offset and I *think* I have it working. I was able to do the switch test several times and it didn't fail once. I have it printing a job on 2 cores now, so fingers crossed. (Assuming the 2nd core not printing doesn't screw me up.)
Thanks all!
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Try changing the nozzle height with power off by pushing the head into the switching mechanism and sliding it forward and backwards. Does it work? Or does something hit something such that it won't go in properly? Also check that your thin rods that go through the print head appear to be perpendicular when looking down on them from overhead.
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