Extruder Drive Problems

OK, this is driving me mad! Whilst printing, the extruder goes through periods of juddering, where it is incapable of extruding. The extruder works perfectly when the filament isn't passing though the hot end, which has lead me to assuming it is a problem with the temperature of the hot end. I have been though all of the troubleshooting listed here: [reprappro.com] and there is no problems.

I have also been though the clearing of the nozzle instructions, again to no avail.

Can any of you guys suggest a solution?

Thanks
John

Edited 1 time(s). Last edit at 05/28/2016 11:59AM by Promethus.

Check the stepper driver, it could be overheating or the stepper current isn't high enough.

Probably should have mentioned that I had already raised the current to 1000mA. I have just tried bumping it up to 1100mA, with no effect. The stepper motor its self is cool to the touch.

As a quick test I have just tried extruding at 5mm/sec, down from the default 40mm/sec, and it has worked perfectly. If I try to raise it to 10mm/sec, the juddering returns. I have printed fine, for months, and with this filament before. I just don't understand why it has started doing this!

If you can extrude into free air at 5mm/sec, that's equivalent to printing at 60mm/sec using a 0.5mm nozzle. So 5mm/sec is probably enough.

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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].

If it is happening while extruding into free air, and you have been printing fine before, it is likely that you have a partially blocked nozzle. You could try heating the nozzle with the extruder driver unpowered (just heat after a power reset without extruding), and then extrude by turning the gear by hand. You should be able to feel whether the obstruction is with the filament or if the extruder mechanism itself is binding. A partially blocked nozzle will make is difficult to extrude by hand, but the gear will feel free and readily spring back with no binding when you remove pressure.

Dave

Hi Everyone

Was this problem solved? I am experiencing something similar.

I have the quick-set nozzle on my Ormerod 1 and it works fine for the first 55 layers and then it just binds up, with juddering of the extruder motor.
This I have found to be because the filament can not be retracted or extruded by the motor or by pushing on the filament by hand.
There is ooze from the nozzle showing that gravity can pull the filament out of the hot part.

I believe there is a problem with the cooling on the quick-set nozzle on my machine and after a certain number of layers then enough filament backs up the quick-set nozzle tube to a point where it cools and then solidifies.

Has anyone else seen anything similar?

Lloyd

@ezwul - That issue is probably caused by the filament melting too far up the feed tube - basically the top part of the hotend is overheating. I've heard of that before with the quick-set nozzle. Ensure you have a good heat-break between the feed-in and the nozzle section, and that the heat sink has a good thermal bond to the top section plus continuous fan cooling.

Dave