Grinding when starting a print

[toddwallace 0]

I thought I posted this, but could not find it.. so posting again. We have an Ultimaker 2 which was working fine. Recently, it started grinding when starting a print. The print head comes to the front (and center) and starts grinding like it has lost its homing. The end stops are in the back, so I don't see how it knows when to stop. I have homed the head and tried different settings, but can't get it right. Not quite sure what triggered this to start, but nothing has really changed on the printer. The grinding is the stepper motor trying to push the head past the front of the Ultimaker. I did see a past post where a user said it was the mother board. Hoping that is not my problem. Any thoughts?

[gr5 2,224]

Did you install new firmware? Please update your profile to indicate you own a UM2.

If you accidentally put the UMO firmware on the UM2 that would explain the problem.

Try fighting the head during homing. If it seems weaker in one axis than the other then probably one of the 4 wires going to the stepper is broken. The most common place for a while to break is under the metal covers in the back corners which come off with only one (or two in some models) screws.

There is a DIR (direction) pin/signal that runs from the arduino chip to the stepper controller chip. So either the arduino could be bad, the PCB trace, or the stepper driver. The trace is very unlikely. The stepper driver is more likely.

You can reverse the two wires in either pair to the stepper but don't do that because I suspect it's the DIR pin and the head will keep moving always only in one direction and reversing the wiring will just make it always go the other way.

[tinkergnome 927]

And this only happens, if you start a print? "Home head" from the menu works normal?

What about the gcode file? "front and center" sounds like it is not prepared with Cura / UltiGCode? Are you printing from the sd-card? Perhaps you've just changed anything at the start-gcode (accidentally)?

And yes...: which firmware version?

[toddwallace 0]

Firmware was updated a while back, but think the grinding started a lot after I did the upgrade. Update was done through Cura connected through USB to the Ultimaker. Grinding happens when I change filament or start of a print. It does it when the print head is moved to front and center. I have honed the axes many times. Once print starts, everything works find and no grinding.

I do have a recent update and have to admit, I didn't look for the grinding, but it didn't happen on the first print that is still running. I replaced the heater cartridge and hot end pack. Somewhere along the way, the heater cartridge got broken (wire). After assembly, I loaded a print job and it didn't grind and print looked great. Filament loaded fine as well. I'll run it through the tests after this print job finishes.

[gr5 2,224]

Wait - I think we are talking about different kinds of "grinding". I think a video would have helped. Everyone replying to you is talking about where the head hits one side of the printer and makes a loud enough noise that everyone in the house comes running and says is "everything okay?". Loud enough that the first time it happens you just assume the printer is destroyed beyond repair (but it's fine).

Instead I think you are talking about the feeder grinding maybe?

Please clarify.

[fbrc8-erin 296]

Have you taken the feeder apart for any reason recently? Pinching one of the endstop wires between the feeder motor and back panel can happen pretty easily with the UM2 feeder design, especially if the feeder is removed without taking the cable cover off.

[toddwallace 0]

no.. the grinding is the belt trying to drive the head past front and center. not the feeder.

[gr5 2,224]

Well if it grinds when it is homing (which should be left rear corner but maybe it's moving the wrong way) then it's one set of possible problems. If it homes the wrong direction it's another set of possible problems. And if it doesn't grind until *after* it homes then it's a 3rd set of possible problems (this third set means either you have the wrong firmware or you need to do a factory reset which takes about 10 seconds to do - just choose it on the menu). In the 3rd case you could also have the wrong firmware - for example um2 firmware for a um2go would cause this.

Maybe post a 10 second video taken from a phone camera (with sound) would help a lot!

[Torgeir 259]

Hi Folks,

I've looked at this in a few days. Could this be a too large Y setting (normally should be 223) in Cura defining the size of the bed? Assuming a to large defined bed, so when the printer go to the fwd start point it will try to go this extra step and hit the hard stop a number of times?

This may explain why it can continue printing and print an object Ok. ?

Just a thought..

Thanks.

Torgeir.

[gr5 2,224]

Yes. My thoughts also but @toddwallace takes days to answer simple questions. He'll get there eventually. I'd try factory reset and if that doesn't do it then reload firmware. steps/mm could be off (if so parts will be stretched out in Y) - could be wrong firmware. Lots of possibilities - most of them easy to diagnose and fix.