Extruder fail

Last night I left a large object printing on my Ormerod but this morning when I checked on it I saw that there was only half of the object that had been printed.

What has happened is that the knurled bolt had stripped a chunk out of the filament and has not been able to extrude anything else as it no longer had any grip on the filament.

Does anyone have a fix for this issue?

I do have the spring loaded extruder already

It will not have damaged the hobbed bolt, just clean the plastic dust off it with a toothbrush or similar. The bigger issue is why the filament stopped feeding in order to cause that. It could just have been a build-up of plastic dust clogging the hobbed bolt until it lost its grip, it could be that you are printing a bit too fast, maybe your cooling fan failed (causing the filament to melt too high up and jam) or it may be a blocked nozzle. In my experience if the nozzle was not blocked before the failure, it probably is now because you have had plastic cooking in the nozzle for hours, and every time that has happened to me the nozzle became blocked soon afterwards (though maybe that only happens with ABS). Clearing a blocked nozzle is a bit hit-and-miss (there are instructions for a couple of methods in the Wiki). I ended up buying a new nozzle. If you use the method of burning out the blockage in a gas flame, remember to take out the PTFE liner first, otherwise that will burn as well.

Dave

Edited 2 time(s). Last edit at 07/20/2016 07:20AM by dmould.

Quote
dmould
It will not have damaged the hobbed bolt, just clean the plastic dust off it with a toothbrush or similar. The bigger issue is why the filament stopped feeding in order to cause that. It could just have been a build-up of plastic dust clogging the hobbed bolt until it lost its grip, it could be that you are printing a bit too fast, maybe your cooling fan failed (causing the filament to melt too high up and jam) or it may be a blocked nozzle. In my experience if the nozzle was not blocked before the failure, it probably is now because you have had plastic cooking in the nozzle for hours, and every time that has happened to me the nozzle became blocked soon afterwards (though maybe that only happens with ABS). Clearing a blocked nozzle is a bit hit-and-miss (there are instructions for a couple of methods in the Wiki). I ended up buying a new nozzle. If you use the method of burning out the blockage in a gas flame, remember to take out the PTFE liner first, otherwise that will burn as well.

Dave

I dont expect the hobbled bolt to be damaged, and i have had to clean out the dust off in the past.

Perhaps i am printing too fast, I print with PLA (I fail at ABS every time i try, it just wont bloody stick!!)
What is the max speed that you print?

Part of the solution is to use the correct extruder motor current. If the nozzle gets obstructed temporarily, you want the current to be low enough that the extruder motor skips steps instead of grinding a notch into the filament.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Part of the solution is to use the correct extruder motor current. If the nozzle gets obstructed temporarily, you want the current to be low enough that the extruder motor skips steps instead of grinding a notch into the filament.

Thanks, Its worth a try. I had another failure today 2 hours into a print (this is after cleaning out the hobled insert.

What is the correct motor current for the extruder stepper?

1000mA works well for me, printing PLA at 195C first layer and 185 or 190C subsequent layers.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
1000mA works well for me, printing PLA at 195C first layer and 185 or 190C subsequent layers.

I dropped the extruder current down to 1000 from 1200 but same issue again.

Perhaps something to do with the ambient temp in the UK over the last few days?

I guess it could be that the higher ambient temperature softens the filament so that the hobbed insert doesn't grip it as well. I have been on holiday so I haven't printed for several days.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].