Stuttering filament feeder

Hello!
Me and my father just got into 3D printing, and we bought and put together the Ormerod. We've had many issues that we've been able to work out, but one that we can not. The extruder feeder starts stuttering, so no filament is fed through. This seems to happen at random with about one minute intervals, and we can't figure out why. It seems that it happens when it tries to push through the filament quicker than it can. When it starts stuttering it doesn't stop on its own, however if we help push it a little it starts working again. Why might this be? We've almost managed to get our first print out, and everything looks fine except we need to sit and watch it constantly to help it when it starts stuttering.

Does the stuttering still occur if you raise the nozzle well above the bed, heat up the hot end, and try to extrude filament?

If yes: you have a blockage, probably in the nozzle, and you need to clean it out.

If no: the head is too close to the bed when the stuttering occurs, so that the bed is physically blocking the nozzle. This is probably the most common reason. If you are using the original IR sensor, only run z-homing or bed compensation when there is no direct sunlight or incandescent artificial light on the bed. Preferably, add the bed-levelling screws as described in the instructions, so that you need little or no automatic bed compensation. Even better, replace or reinforce the MDF bed. Before starting a print, heat the bed to the required temperature. Then put the head at X=100 Y=100, lower the nozzle until it just grips a sheet of standard 80 gsm photocopier paper, then send the command G92 Z0 to define that as the Z=0 position. Then command the nozzle up a few mm, then print.

Edited 4 time(s). Last edit at 05/12/2014 04:08PM by dc42.

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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].

Hi m3832

I had this problem soon after starting assembling my printer. The cause turned out to be the filament tube tight where it connects to the brass end fittings, I took the tube off and run a drill up the end to give a little more clearance. After that I had no more problems with the extruder stuttering.

Edited 1 time(s). Last edit at 05/12/2014 04:41PM by 3djim.

A couple of other reasons I have come across.

I am sure the roll of filament I was using had "skinny" bits which tended to slip on the hobbed insert as it was attempting to push it thru. This evenutally cleared but it was very frustrating.

The filament wasnt loose enough on the roll/drum and so the hobbed insert struggled to feed as it had to pull the filament from the drum.

whatever the cause the hobbed insert tends to get a bit clogged up and might need cleaning and also you might need to reverse out the filament and cut off "roughed" up bit of filament and start with a fresh bit.

Do what DC42 suggests first but then you might want to consider reducing the extruder multiplier in Slic3r. Have you calibrated the Extrusion as per the commissioning instructions?

Tim

I discovered the other day after having a nozzle blockage, that it was being aggrovated by me cutting the end off the filament to square, and it having a corner.
I now taper the end of any filament with either a pencil sharpener, or file to get rid of the edge.
As the filament goes into the nozzle, a sharp edge will catch on the PTFE tube inside the nozzle, and either start to compress it, and it springs past with a crack, or break a bit of the PTFE tubing off, and drags it into the nozzle and blocks it.

When I first started printing I also had cable ties on the PTFE tubing, which was gripping the filament... (Just one of those things you don't think about when starting out).

I would guess that, as DC says above, either your nozzle is to low, and your blocking it off with the table. Or your filament has chipped the PTFE tube and that's blocked it.
To clear a nozzle, just turn the heater on to 200', then turn it off and wait till the temp drops to about 140/150' and then retract the filament. It might take a few goes, but eventualy it will drag out the blockage stuck to the end of the filament... PTFE being clear is difficult to see, so just remove the end off the filament, and feed it back into a hot hotend. Make sure you get rid of the square edge on the end of the filament thou....

kim..

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