Extruder gouging filament, run out of ideas

[SchnauzerPup]

I am incredibly frustrated at this point. I have NEVER (n over a month) managed a complete large print (I have done a few small objects).

Every time at some point the hobb wheel gouges into the filament and will not push any more.

I have tried both ABS and PLA from two different high quality vendors at a wide range of temperatures.
I have carefully measured the filament and even artificially adjusted the diameter to lower the feed rate.
I have calibrated feeder steps again and again.
I replaced the hot end tube fan with a bigger one and have it running full speed
The feeder is NOT "hopping" or clicking
My prints look really good, no blobs or excess material
It prints along just fine and then just stops feeding and every single time I find a divot in the filament.

Seriously I am ready to throw this thing out the window.

If anyone can help with additional ideas on how to fix this I would really appreciate any ideas.

RKM

[enggmaug]

Just something to try ,try the script I provided in this thread if you can :
http://forum.seemecnc.com/viewtopic.php ... =10#p26649" onclick="window.open(this.href);return false;

[Batteau62]

You've probably already searched, but if you haven't? I would read this thread. Same subject maybe it'll give some ideas.
http://forum.seemecnc.com/viewtopic.php ... e+filament" onclick="window.open(this.href);return false;

[mhackney]

Do you keep an eye on the hot end temperature when this happens? Is the temp where it should be or is it cooling off leading to a plug?

We could also use some more info: what firmware are you running?

One other thought - remove the nozzle from the hot end then push some raw filament through it cold (no heat) from the extruder out through the hot end. You are looking to feel any snags or anything that restricts pushing the filament easily.

[mhackney]

The very last post in the link Batteau62 posted is my suspicion - constricted PTFE tube. This happens occasionally. The best fix is replacing it with new. Turning it end for end and drilling out the restriction can lengthen the life of the tube.

[Eaglezsoar]

The first thing I would check is the possibility that the hotend or its thermistor is intermittently losing connection and dropping the
temperature. From your description of the problem, it really sounds like the temperature is dropping thus restricting the flow of filament. Carefully check the wiring of the hotend
and the thermistor.

On a related note I believe that everyone with a 3D printer should have a thermocouple meter to verify the temperatures inside the hotend.
You need to verify that the hotend is actually at the temperature the firmware is reporting.
The investment of $30 is well spent so that you know what your actual temperatures are. You would remove the filament from the
hotend and stick the thermocouple into the hotend as far as it will go so that the end is at the nozzle then read the temperature on the meter
to see if it agrees with the firmware temperature. Here is a link to such a thermocouple meter:
http://www.amazon.com/BestDealUSA-Chann ... uple+meter" onclick="window.open(this.href);return false;
http://www.amazon.com/AGPtek-Channel-Di ... uple+meter" onclick="window.open(this.href);return false;

[SchnauzerPup]

Thank you for all the suggestions.
I will try them and report what I find.
RKM

[ccavanaugh]

If correct temperatures are confirmed to be correct, you may need to reduce the acceleration value for the extruder motor.

Is the gouging occurring during rapid / frequent retracts? It takes more force for plastic flow to occur after it has been stopped. This temporary increase in force can cause the drive gear to slip against the filament. It's exaggerated by many retracts over a very short distance of total filament extruded in that the gouge if it has occurred, has not completely cleared the drive gear before another retraction occurs.

By reducing the extruder acceleration, force to extrude does not increase as rapidly and total initial extrusion force is reduced, thus preventing gouging from occurring in the first place.

[SchnauzerPup]

OK.

I manually ran the python script that enggmaug provided (thank you) against an offending G-Code and it cam back with "Clean Code."
I checked the hotend temperature with a Fluke Thermocouple and it was +/- 2 degrees C of what the thermistor reads
I totally disabled retraction just to see if constant retraction restore acceleration were the problem
I checked that my steps per mm in the firmware is 92.65
I carefully dis-assembled the hot end and the ptfe tube is fine and no gaps or clogs.
The filament diameter is accurately set (I rounded up even, which should feed less)

And ran another print, same thing

I am totally convinced that filament is being pushed too fast!

This time I carefully watched the extruder and I could see it "skipping". Every now and then I would manually push the red spring release and the filament would spring back about 2 to 4 mm as if it were compressed in the tube. I would then push the filament by hand to gauge the pressure required and it was not excessive IMO. This release of pressure did not seem to adversely affect the print.

I tried adjusting the feedrate in Repetier but it does not seem to do anything (maybe I don't understand what that slider does).

Any further ideas???

Should I play with the Steps per MM value in the firmware? Should I artificially inflate the filament diameter value? Should I beat the printer soundly with a sledge hammer?

Thanks for the help

RKM

[bubbasnow]

are you ever able to push a large amount through by hand at temp?

[DavidF]

by all means im still a nube, but to me it sounds like just a typical nozzle clogg. Have you tried burning it out? Put the slider to 300% and extrude 100 mm at a time, does it skip?

[Eaglezsoar]

He says that small objects print fine, the larger objects stops feeding and the hobb wheel gouges into the filament.
You would think that a clogged nozzle would not print small objects correctly either.
I agree with everyone else who mentioned feeding by hand to see what happens. I especially like Michael's idea of removing the
nozzle and let everything cool down then push the filament through by hand to see if you can feel any restriction in the filament.
If no restrictions are felt then I am back to thinking the electronics either the Rambo itself or the wiring to the hotend or thermistor
stop working, enough so that the hotend cools down stopping the flow of filament. It only takes a loose connection that opens while
printing to cause that sort of problem. If there are connectors on the thermistor or hotend they should be inspected closely for a loose
wire or anything that could cause them to intermittently loose contact. If there are no restrictions it is the only thing left that makes
any sense.

[mhackney]

Two things: 1) when the PTFE tube has softened and constricted, it can be difficult to see. Push filament through it, it should go with virtually no resistance.

2) If you don't have any constrictions in the filament path - which my test would eliminate as a suspect - then I suspect your extruder stepper current is too low. What values do you have set in Configuration.h? Perhaps post your configuration file here too so we can scrutinize it.

[SchnauzerPup]

Perhaps I may have found the problem.

The tollerance of the hole in the aluminum block at the output side of the hobb wheel is so tight that it can become jammed.

My previous technique for clearing jams was a little ham handed and I never noticed the problem but on the last run it jammed so badly that when I tried to pull the filament out it actually broke off inside the aluminum block and I really took a close look. It was jammed in there so tight I had to use a drill bit to clear it out.

I think that either (a) when the extruder skips (as described previously) small flakes of filament are falling down and packing the hole, or (b) perhaps the deformation of the filament form the skipping jams the hole.

I am going to rotate the extruder 90 degrees, reposition the spool, and open the hole slightly (I have some very small files used for cleaning welding tips that should do the job) and see if that helps.

[Eaglezsoar]

I hope that's it. Let us know the result so we can keep that in mind for future troubleshooting.

[SchnauzerPup]

I increased the size of the hole at the output side of the extruder by a little under 0.1mm and that has (so far, knock wood) totally fixed the problem.

Before I did that I experimented and mounted the block in a vise and tried to pull my entire spool of filament through it and wind it onto another spool. It got totally stuck in a couple places, and took more force than I think the extruder can exert in a number more.

I tried this same experiment with two spools of PLA from different vendors and a spool of ABS. In every singe case I found at least one spot where it was too tight.

I never realized the filament had so much variability.

I am seriously considering building a test rig (something like the old time hand film winders) so I can test (and maybe shave down or apply heat to fix?) spools of filament before using them.

RKM

[Eaglezsoar]

Thanks for letting us know what the issue was and how you fixed it. If memory serves me correctly
you are the first to report that you had to enlarge the hole in the bottom of the EZstruder.

[wildideas1]

ok i am having issue also but i have tried to take picture thru the bowden tube but wont show clear enough what is happening is that when the machine retracts the filament it slightly cuts away a small bit and when it returns to start feeding again it takes a bit more out of filament Hence the gouge which then cause the filament to skip and more than often the filament wont keep feeding and print gets messed up. i am currently printing while typing this and have sat and watched it happen and can see it very clearly how it is happening as described above my question is how/what setting do i change in Kissler and Slcr to slow retract down so it doesn't cut a gouge in filament in both directions and keep print running. i even rounded over supports for filament roll above printer and spool inside also to make as smooth a pull as possiable

Ian

[bubbasnow]

ok i am having issue also but i have tried to take picture thru the bowden tube but wont show clear enough what is happening is that when the machine retracts the filament it slightly cuts away a small bit and when it returns to start feeding again it takes a bit more out of filament Hence the gouge which then cause the filament to skip and more than often the filament wont keep feeding and print gets messed up. i am currently printing while typing this and have sat and watched it happen and can see it very clearly how it is happening as described above my question is how/what setting do i change in Kissler and Slcr to slow retract down so it doesn't cut a gouge in filament in both directions and keep print running. i even rounded over supports for filament roll above printer and spool inside also to make as smooth a pull as possiable

Ian

[wildideas1]

filament gouge issue

well that only took a hour before it messed up again here is pic

[wildideas1]

what spped are you using i was at 55 and man that was fast moving cutting action i am now going to try 20 and 2mm suck instead of 10 or ??? setting does one recomend.

Ian

[wildideas1]

http://www.youtube.com/watch?v=dTZaTvau3Ic" onclick="window.open(this.href);return false;
here is video of the ezstruder skipping every once in a while ???? what cause this. only thing i changed was nozzle from .5 to .7

[wildideas1]

running temp ABS at 215 still doing it now at 217 still doing it and the teeth on ez is clogging up not sure if adding to insult, retract is 1mm and acell speed is 25 down from 55
any ideas ??? never had this with .5 nozzel switche so i can make prototypes faster. so far not made a single one.

[wildideas1]

once again fail

once again the failures are killing me ever since the NOV challenge i have not had 1 print complete only changed nozzle to .7 from .5 upgraded firmware host as eaglesoar pointed out today is now .95 host not rambo and just verified that rambo is .80 so i guess i will update that next. but that shouldn't cause issues im having with the ez strudder skipping and eating the filament then not extruding due to the gouge in filament. to day i slowed down the accelerate of prime/suck from 55 to 25 and that helped but still is happening and ez teeth are clogging up fast. THIS NEVER HAPPENED till nozzle change i am determined to figure it out then i will be able to go back and forth on nozzle size.

[pyrophreek]

Do you have any cooling on your Ramb0 controller board? I saw something like this when mine was overheating.