UM2+ Z-axis leveling issue

[arodgers 1]

Honestly not sure right now whether this is a hardware or software issue. I have an old UM2+ that is used by my high school students. This one has gone through the wars -- preCovid students thought it needed oil and oiled it so much that it fried the motherboard, among other things. So we have a new motherboard, with an old printer, at this point.

The printer is screaming when trying to home. X and Y axes move fine; Z axis finds the lower bound without an issue but moves up and up and crashes into the nozzle while whining/shrieking. I haven't tested the length of time that it'll keep doing this (it seems bad for the printer!) but pushing down on the print bed or turning the printer off stops the noise and stops the printer from trying to continue to push up.

On searching for Z-axis problems, it appears that the z-end-stop is at the base of the printer and actually functioning fine, and that there may be a software issue that the printer isn't sure of its upper bound.
 

Printer was restored to factory default to try to fix this issue; does not seem to have helped. Students were supposed to flash updated firmware; I'm not sure whether they successfully did or not. Printer says that the current version is DEV (which implies to me that they were unsuccessful).

 

I'd love some help to decide what to try next!

[Dustin 54]

Sounds like someone might have flashed UM2+ Extended firmware on a UM2+
 

[arodgers 1]

Flashing firmware fixed it! Yay!

 

New issue (of course) - I started printing a Benchy, and found that the printer was working fine in the X and Z direction now, but the Y seems to be having trouble. Does this look like a belt-tightening issue?

[gr5 2,024]

loose belts?  No.  Loose pulleys?  Maybe.

 

First if this is an old printer try oiling the rods.  Just one drop on each of the 6 (not 2, not 4, 6) rods in the gantry.    Push the head around to see if resistance is much higher in one axis versus the other.  They should be the same.

 

Your issue is missed steps or slipping pulley.  The first is usually caused by unusually high friction.  The second is when a pulley came loose.  So check that next.

 

It's almost always the pulley on the stepper.  So if you have the long hex driver that came with the printer (black and green handle) then you can do it without removing the stepper covers.  Push the head around until you see the setscrew deep in there between the 2 sides of the short belt.  Tighten the hell out of that set screw?  It only takes two screws to remove that metal cover that hides the stepper motors.  That's your backup plan.

 

Tighten the other 5 set screws for the slipping (Y) axis as well but it's usually the one on the stepper and you have to tighten it so much the hex tool twists a bit.  Scary tight.

[Dustin 54]

Looks like you should probably just go thru the whole suite of recommended maintenance on this machine to make sure everything is working correctly..

Guides can be found here: https://support.makerbot.com/s/article/1667410778200
There is also guides with pictures that cover the steps recommended by gr5 🙂

[gr5 2,024]

I don't see anything about how to tighten the set screws (aka grub screws) in that list.  Probably because it's usually not an issue but...   this symptom where you are losing Y position is most often caused by the grub screws thing (but check friction first).

[Dustin 54]

11 hours ago, gr5 said:

I don't see anything about how to tighten the set screws (aka grub screws) in that list.  Probably because it's usually not an issue but...   this symptom where you are losing Y position is most often caused by the grub screws thing (but check friction first).

Check for play on the Ultimaker 2+ axles covers this: https://support.makerbot.com/s/article/1667411289738

[gr5 2,024]

Oh yeah.  Sort of.  But it's usually the pulley on the motor that needs it's set screw tightened because that one experiences the most torque (close second is the other pulley on the short belt).