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Issue with hobbed insert/extruder drive/hot end/filament blockage

Posted by Sardi 
Issue with hobbed insert/extruder drive/hot end/filament blockage
March 05, 2017 02:54PM
So my problems just keep piling up.

Out of the blue, the filament stoped going through.
First two or three times in a row, hobbed insert came loose (no idea how). After a third try, I finally managed to wind it real good so for now its in place.

But the filament wont go through.

Facts:

I have the filament in the bowden tube + arr 30cm extra out of it
I take the bowden tube out of the extruder, it pushes the filament just fine.
As soon as the brass unit comes back to the extruder - it wont extrude or retract.

I thought the nozzle is clogged, but then the extruder would kick/be stuck in place since it wanted to push the filament out but it cant - instead, the gear and hobbed insert rotate as if there is no problem.

Hot end is heated to 230, checked with my finger (didnt touch it of course).
I cant event push or pull the filament with my hands.
Measured filament on many places, it is within 1.75.
Filament is not broken in the bowden tube - I would have pulled it out than.

Got no idea what to do any more. .. Im about to dismantle the nozzle, its my last try ...
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 06, 2017 12:08AM
So, all of this above was caused by a part of the filament that was thinner than the rest of it.

When that thin part got to the hobbed insert it lost grip and couldnt extrude or retract of course.

Stil dont know why or how hobbed insert got loose, I would tighten it as hard as I could.

Strange things are happening with this printer these days.

Ive been using the same filament for some time now, and till today everything was ok to print 1st layer 210C 2nd 185C. As of today, at 210C it pops, lines are cracked etc. I lower the first layer to 190C, lines are perfect.

Im tellin you, ghost in the machine.
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 06, 2017 04:04AM
If you are getting popping sounds, it is possibly water in the filament. Filament is slightly hygroscopic, so if you do not store it in a sealed container with a dehydrating agent, it will accumulate water.

[edit] - If you are getting small cracking sounds as the filament feeds, it may indicate that the filament has worn its way through the extruder entrance. Look underneath the curved part of the extruder where the filament enters - you may see a crack where the filament has worn through. If so, print another extruder housing before it fails completely. There is a modified design that has a bigger feed channel to take a PTFE liner (3mm OD, 2mm ID). I've recently had to do the same as the filament wore through both the PTFE liner and the printed part.

Dave

Edited 1 time(s). Last edit at 03/06/2017 04:08AM by dmould.
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 07, 2017 02:40AM
Quote
dmould
[edit] - If you are getting small cracking sounds as the filament feeds, it may indicate that the filament has worn its way through the extruder entrance. Look underneath the curved part of the extruder where the filament enters - you may see a crack where the filament has worn through. If so, print another extruder housing before it fails completely. There is a modified design that has a bigger feed channel to take a PTFE liner (3mm OD, 2mm ID). I've recently had to do the same as the filament wore through both the PTFE liner and the printed part.

Dave

This is exactly what happened.
It tore the part of the ptfe tube where it enters the extruder block a couple of times, and I see that the entrance is worn out as that the filament sometimes "sticks" to one place and jammes there.

Quote
dmould
There is a modified design that has a bigger feed channel to take a PTFE liner (3mm OD, 2mm ID). I've recently had to do the same as the filament wore through both the PTFE liner and the printed part.

Dave

I believe this is the one you are talking aboutOrmerod 75mm Diameter Extruder Drive Block - 3.2mm feed


Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 07, 2017 04:02AM
..or Mr.Burns version from many moons ago



[forums.reprap.org]

ex-drive-blockV2.0.zip

Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 07, 2017 05:41AM
I kept hearing some klicks from and arround the extruder, but couldnt really put my ear on it ....

When suddenly this forum arises ...

Exactly my problem


Not my printer, picture taken from the forum page but the problem is the same. Not so much tear though, but Its time for a new extruder block.

EDIT: I drilled the extruders ptfe hole to 3mm wide so that I can insert the tube at least 1cm. Now its not slipping out, and Im ready to print the new extruder block.

Edited 2 time(s). Last edit at 03/07/2017 06:27AM by Sardi.
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 07, 2017 10:04AM
So I printed the block, but the holes are too narrow.

- Screw holes are for a 2mm screw instead of a 3mm.
- I can not put my ptfe tube 40mm in (as is stated in the description of the model) but only 10mm max.
- The part where I should insert the bowden tube brass is also to narrow
- Also no chance of inserting the bowden tube tongue

I printed this with 0.3mm layer, 20% infill .. is there some other setting I missed?

I know there is an XY Size compensation, but shouldnt the part be almost the same as is the original? The screw holes at least ....

EDIT: the 9mm bearing cant fit, all the holes are simply too narrow

Edited 4 time(s). Last edit at 03/07/2017 11:18AM by Sardi.
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 07, 2017 12:57PM
Quote
Sardi
- Screw holes are for a 2mm screw instead of a 3mm.



Quote
Sardi
EDIT: the 9mm bearing cant fit, all the holes are simply too narrow



The model looks perfect to me, must be your printer or slicer setting...btw, printing outer perimeters first could help

Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 12:28AM
Quote
ormerod168
btw, printing outer perimeters first could help
Erik

Now that I remember it, he did print the inner circles first.

Did some tweaking, extruder steps back to 420, extrusion multiplier to 0.97, and XY compensation to -0.01 - just to give me a little more space to work on (and to be sure that the holes will be ok) + external perimiters first. Gone printing.

Edited 1 time(s). Last edit at 03/08/2017 01:25AM by Sardi.
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 04:05AM
Quote
Sardi
extrusion multiplier to 0.97, and...

My ditto setting is 0.90 and spot on for both printers

Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 04:19AM
The print came out perfectly. Ptfe tube went in 40mm as it should, bearings fit nicely... I am a happy guy now..

So as long as you are here, let me ask you just this, is this a good slic3r and cura start gcode?

;Sliced at: {day} {date} {time}
;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
G21        ;metric values
G90        ;absolute positioning
M83 ; use relative distances for extrusion
M203 X6000 Y6000 Z500 E3000 ; will allow 100mm/s sliced gcodes to work...
if they have time/distance to get up to speed
M116; Wait for all temperatures

Ive been changing things in the start code and Im afraid if Ive forgotten to put something back ...
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 06:33AM
Quote
Sardi
The print came out perfectly. Ptfe tube went in 40mm as it should, bearings fit nicely... I am a happy guy now..

..as Mr.Burns would say ...Excellent!

Quote
Sardi
So as long as you are here, let me ask you just this, is this a good slic3r and cura start gcode?

I have nothing in my start gcode, but then I use Simplify3D only, and things like wait for temp. is preset inside the program .... and I home the printer manually before starting a print

I would ad a line with "T0" to select tool, cant hurt

Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 07:10AM
Yes, for some reason I have always needed to use an extrusion multiplier of 0.83 (83% or 5/6ths) despite the fact that my filament diameter is accurate and my extruder correctly calibrated. I've never worked out why that is.

Dave
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 07:13AM
Let me pick your brain a bit more than, is S3D worth it?

Ive been using Cura and Slic3r since day 1 of printing, jumping from one to another depending what model I have to print.

Cura does better with thin walls, Slicer doesnt etc.

So since S3D is not a freebie, is it worth the money?
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 07:57AM
Quote
Sardi
Let me pick your brain a bit more than, is S3D worth it?

For me it was then, time was more important to me than money - dunno about now, Slic3r has grown faster, more stable and very important for me, got a very nice preview of the print

I still have Slic3r installed and use that for cutting models, something S3D cannot do

You can run multiple processes in in S3D, besides that I don't think there is much difference now
..and don't expect to get better prints

Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 08, 2017 01:49PM
I use S3D and I can recommend it - as long as you have only one type of 3D printer. I find it appalling at switching between my Ormerod and my Delta. Whereas slic3r is a breeze.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 09, 2017 05:23AM
I've gone back to Slic3r. There were too many STLs that S3D could not handle but worked fine in Slic3r. The published STL for the Ormerod Z end cap, as just one example ... S3D puts 2 or 3 single layer bridges across the large opening at different heights. Repairing with NetFab made no difference. Slic3r worked perfectly. This is not the only case by a long way - while it always printed my own OpenScad designs OK, a lot of STLs downloaded from the web printed with strange artefacts using S3D that were not seen with Cura or Slic3r. Sometimes repairing the STL would correct it, more often not. The S3D tech support were as useless as a chocolate teapot - they just say that the STL is faulty so it's not their problem, and its up to me to find a solution, not them and refuse any further discussion. Not the response I expect to get considering it is pretty expensive software.

The latest Slic3r seems to be pretty stable with only a couple of bugs that don't affect me or are easily worked around. The only place it falls short compared with S3D is in generating supports, which S3D is really excellent at doing.

Dave
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 09, 2017 07:01AM
Quote
dmould
considering it is pretty expensive software.

Exactly the reason Im asking winking smiley

Thanks guys, Ill stick to Slic3r and Cura. In my experience, if an stl does not turn out good with one, it (almost always) will with the other one. The biggest difference I noticed are thin walls, while Cura has no problems with them, Slic3r tends not to do them very well.
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 09, 2017 07:40AM
Quote
dmould
..The published STL for the Ormerod Z end cap..
Dave

Do you mean z-upper-mount - and published where?

Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 10, 2017 03:56AM
Quote
ormerod168
Quote
dmould
..The published STL for the Ormerod Z end cap..
Dave

Do you mean z-upper-mount - and published where?

Erik

Yes, the Z upper mount, published in the official RepRap "Ormerod-master/stl/individual parts" directory of the online repository that I picked up ages ago when I first got my Ormerod. I've attached it here. S3D places about 3 solid membranes at various heights inside the rectangular hollow box section (which it does not show on its 3D view, they appear after slicing).

Dave
Attachments:
open | download - z-upper-mount.stl (98.3 KB)
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 10, 2017 04:13AM
Quote
Sardi
Quote
dmould
considering it is pretty expensive software.

Exactly the reason Im asking winking smiley

Thanks guys, Ill stick to Slic3r and Cura. In my experience, if an stl does not turn out good with one, it (almost always) will with the other one. The biggest difference I noticed are thin walls, while Cura has no problems with them, Slic3r tends not to do them very well.

There is a known bug with Slic3r and thin walls - it will over-extrude in some situations if you enable "detect thin walls" The trick when you have thin walls (4X extrusion thickness or smaller) is to ensure that the wall is very slightly wider than an exact multiple of the extrusion width. In most cases you would set an appropriate manual extrusion width in Slic3r rather than leaving it automatic, though if it is your own design you could change the wall thickness of your model instead. If your wall is 1.5mm wide, for example, set the extrusion width to 0.49mm

Dave
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 10, 2017 11:37AM
Quote
dmould
Yes, the Z upper mount, published in the official RepRap "Ormerod-master/stl/individual parts" directory of the online repository that I picked up ages ago when I first got my Ormerod. I've attached it here. S3D places about 3 solid membranes at various heights inside the rectangular hollow box section (which it does not show on its 3D view, they appear after slicing).

Dave

Very strange, I don't see this and print just fine for me

Your posted file (left hand side) vs the one from the Ormerod 1 (383 and 384).zip:





Erik
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
March 14, 2017 07:17AM
Quote
ormerod168
Very strange, I don't see this and print just fine for me
Erik

In that case I'm even more critical of their lack of support. It was a while back when I was printing some parts for another forum member, so maybe S3D has been updated, or maybe it was to do with my settings (layer height would have been 0.25mm), but apparently the STL is not to blame. At the price, I expect support issues to be investigated, not fobbed off by pointing fingers at something else.

Dave
Re: Issue with hobbed insert/extruder drive/hot end/filament blockage
May 05, 2017 12:10PM
I have seen odd things happen in S3D with a couple of STL's and the cure seemed to be moving the part a fraction of a mm in the Z axis, it's as if the layer thickness slicing was hitting a certain point in the STL and getting confused.

Jon
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