Hey folks,

since a short time i have an annoying problem - the filament gets stuck and the extruder doesn't move it forward and just rotates "empty". After i pushed the filament a little, it works again.

It does not occur during retractions, but during straight prints - mostly during filling. Different filament rolls - same result.

Any idea what could cause that or how to fix it?

Edited 1 time(s). Last edit at 08/05/2014 04:10PM by djar.

I had that happen a lot in the beginning, since I had forgot to install the idler bearing (that the hobbed insert pushes the filament against to get grip). Assuming you assembled it correctly, other reasons for the extruder drive slipping include too fast extrusion speeds, too low hotend temperature, or a blockage somewhere. If you turn the extruder gear manually (turn hotend heat on, but turn motors off when doing that), does it feel very stiff?

Once you have had the filament slip, you may need to take the extruder drive apart to clean the hobbed insert. If it has gathered plastic shavings in the grooves, it will have less grip and will be more likely to slip again.

Edited 1 time(s). Last edit at 08/05/2014 06:00PM by jstck.

I had the same thing happen recently with a new roll of filament. When I measured the filament I found its diameter was only 1.64mm. The diameter increased to 1.70mm further into the roll and that was feeding correctly. However, I have now switched to the spring - loaded extruder drive modification described in another thread.

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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].

I had the same thing a week ago. The filament had started to cut through the feed body where it bends to approach the hobbed nut. I got the machine printing again initialy by cutting the bend off the bottom of the feeder. Then the next print I did I printed the modified feeder with the longer bend on it. The last few days before it finaly jammed I had noticed a fall off in print quality. It was slight, and at the time I put it down to the filament picking up dampness from the humidity here. After cutting the bend off, the print quality was perfect again.

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete

Quote
djar
Any idea what could cause that or how to fix it?

Hi djar,
in this way I work with all filaments (PLA only)
1 the spring - loaded extruder drive (wonderful)
2 PLA Filament Oiler

I put 2 drops of pure olive oil and the problems have disappeared...
Prints are perfect... the smell is good.


Dario

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Ormerod 187
Firmware Electronics: Duet 0.6
Firmware Version:1.18.1 (2017-04-07)
Web Interface Version:1.15a
Slic3r 1.2.9a and Simplify3D 4.0.0
[www.dropbox.com]

I forgot to mention that when I had a problem with the extruder feeding under-size filament, the filament was also wearing through the wall of the extruder drive. I solved the problem temporarily by pushing a piece of PTFE tubing into the extruder inlet and feeding the filament through that. This seemed to reduce the friction enough that the extruder could cope with the under-size filament. The spring-loaded extruder I am now using is the version that has a PTFE liner running all the way along the inlet curve.

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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].

It's also worth mentioning that the hobbed part may require the occasional cleaning, because plastic dust can clog the teeth so that it stops gripping the filament well enough. When that happens it starts slipping, quickly wearing a groove in the filament and causing the failure to feed originally described.

Dave
(#106)

In my case, the hobbed part was completely clean, so that wasn't the explanation. I think the problem was the combination of under-diameter filament and extra friction due to the filament wearing a groove in the extruder body. I think RRP ought to redesign the extruder drive filament inlet to take a PTFE tube liner all the way round the 90 degree bend. With this change, it probably isn't necessary to spring-load extruder drive, although that is still a nice-to-have.

I am of course assuming that the filament wouldn't wear through the PTFE anything like as fast as it wears through the extruder body. Even if there is some wear, replacing the PTFE tube would be much easier than printing and building a new extruder drive.

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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
In my case, the hobbed part was completely clean, so that wasn't the explanation. I think the problem was the combination of under-diameter filament and extra friction due to the filament wearing a groove in the extruder body. I think RRP ought to redesign the extruder drive filament inlet to take a PTFE tube liner all the way round the 90 degree bend. With this change, it probably isn't necessary to spring-load extruder drive, although that is still a nice-to-have.

I am of course assuming that the filament wouldn't wear through the PTFE anything like as fast as it wears through the extruder body. Even if there is some wear, replacing the PTFE tube would be much easier than printing and building a new extruder drive.

There was a design of an extruder posted a while ago with an increased diameter feed hole that takes a PTFE liner all around the bend, and that's what I switched to after I experienced the problem of the filament cutting a groove. I guess it has fed about 4kg of filament so far. The PTFE can be pulled out easily and I occasionally check it for wear, with none seen so far. I bought 1m of tubing for use with the modified extruder, so I will be able to cut plenty of replacements should it show any signs of wear in future.

Dave
(#106)

After the same dicussion in earlier threads, I think you are all discussing this extruder RepRap Pro Ormerod Spring-loaded extruder which I have upgraded to and works really well with the RepRap Pro Ormerod iamburnys Extruder Gears - Parametric - Double Helix - Herringbone.
If you print the correct parts then the PTFE tube can be pushed almost all the way up to the hobbed part. Also, check if you need the parts with support already incorporated on the hinge ends to make slicing and printing much easier.

The only down side is that the filament needs to be helped round the hobbed part to line up with the opersite hole, and so changing filament has to be done with the hinge open, but, then you get to clean the hobbed part at the same time, plus points counter the minus points.

Lloyd

Quote
dc42
I think RRP ought to redesign the extruder drive filament inlet to take a PTFE tube liner all the way round the 90 degree bend.

It's on the 'to do' list! Just rather busy, at the moment... There's always a list of parts to tweak, it's just what can be done without causing other problems (ie documentation), and what gets rolled out as part of a larger update.

Ian
RepRapPro tech support

Quote
droftarts

Quote
dc42
I think RRP ought to redesign the extruder drive filament inlet to take a PTFE tube liner all the way round the 90 degree bend.

It's on the 'to do' list! Just rather busy, at the moment... There's always a list of parts to tweak, it's just what can be done without causing other problems (ie documentation), and what gets rolled out as part of a larger update.

Ian
RepRapPro tech support

As said, an STL was posted for such an extruder a while ago - I printed it and it is working well. I cannot recall who posted it.

Dave
(#106)

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dmould
As said, an STL was posted for such an extruder a while ago - I printed it and it is working well. I cannot recall who posted it.

Dave
(#106)

Mr.Burns

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Mr.Burns
..I've modified the filament guide, so now its possible to put in the pfte-tube about 40mm. It will now guide the filament as far as possible. I extruded the block in the area of the gone housing a little bit,too.

Furthermore, i put a flap under the gap, where the retaining tongue has to secure the bowden cable. Now its possible to fix the tongue with a M3 screw and a Hex nut or in a simple way with a cable tie. I also dthe high of the gap for the retaining tongue a little, so the tongue will fit in exactly...

[forums.reprap.org]

Erik

Thanks for all your helpful answers. I will upgrade to the spring loaded extruder very soon!

I think i have a project for the evening