Extruder Jam on Replicator..help.

[ian campbell]

Suddenly the extruders on my replicator are jamming. I loaded up a reel of black abs and last night printed for a couple hours with no issue.
Today, I started it up and and I've had to stop 3 times because the plastic stopped flowing. This has happened first to one extruder now the other.
Now I can't load or unload because it does that clicking thing and won't go any further.

I am pretty much using default settings I've always been using. Do the extruders need maintenence? Any tutorials on this?  Thanks.

[Dan Newman]

On 3 May 2012 , at 8:22 PM, ian campbell wrote:

> Suddenly the extruders on my replicator are jamming. I loaded up a reel of
> black abs and last night printed for a couple hours with no issue.
> Today, I started it up and and I've had to stop 3 times because the plastic
> stopped flowing. This has happened first to one extruder now the other.
> Now I can't load or unload because it does that clicking thing and won't go
> any further.

A. Heat up the extruder, then run it in reverse ("unload"), and gently pull
on the filament at the same time. It should come out.

OR

B. Disassemble the extruder with the filament in and clean.

I don't really recommend B

> Do the extruders need maintenence?

They can load up with bits of chewed up ABS around the pinch gear. It is
odd, however, that both extruders would have the same problem around the
same time.

> Any tutorials on this?

http://www.makerbot.com/docs/replicator/maintenance/

Dan

[Martin Galese]

One other thing -- if you can't get the filament unloaded running the unload script, go into the utilities menu and turn off the stepper motors.  Then preheat the nozzle up to something hot, say 230, and try to just pull it out.  If you don't turn off the stepper motors, you will actually be fighting the motor while you pull!

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Martin Galese

[Mark Cohen]

What brand of ABS is it? Perhaps the diameter is too large.
Is your extruder actually heating? If the wires get loose while things
are moving around then the extruder will cool off and cause jams.

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[ian campbell]

Thanks, this helped me get the filament loose. Unfortunately, it seems to me the extruders are
jammed up, I've heated them up several times hoping to dislodged whatever is inside. No luck.
I cleaned out the pinch gear, there was a little plastic dust in there but the problem appears to
be further inside.

I will have to try option B.

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Martin Galese

[TSDF-3D]

I'm working through a similar if not same issue: pasted below are my notes on an open support ticket

In mid print the right side extruder stopped feeding. I aborted the job. There was no teltale clicking from the drive wheel slipping on the filament.

Using Rep G control panel to trouble shoot, I heated up the nozzle and jogged the stepstruder at various speeds. At any speed above 4-5 rpm, it would either feed intermittently or stall altogether unless I assisted by pushing in filament from then top. For comparison, the left extruder will run @10rpm with no problem.

I initially assumed that the Drive wheel set screw might be loose, but disassembly and check confirmed it is tight, and wheel and motor shaft are moving together.
I have done the following in this order:
- cleaned the drive wheel teeth. Some buildup, but not looking too clogged.
- bent slightly one of the brass washers in the plunger stack to add more force to plunger>filament>drive wheel
- removed bent washer, replaced with two new washers- so total of three brass and two thick plastic spacers in plunger stack. This filament was hard to start it was so tight, but problem stayed constant. Intermittent feed above 4-5 rpm. And sometimes no feed at 3.
- switched filament to other stepstruder- works fine, it's not the material or spool resistance or snag in the feed tube, etc.
- with the fan and heat sink off, looking at the wheel as it tries to feed, the stepper appears to be stalling, without the drive wheel slipping on the filament. It advances a portion of a degree and shifts back unless I apply assist force to the filament indeed.

So.... I'm wondering if the stepper is getting full power? Could a driver MOSFET be failing?

Should I try swapping plugs between the two steppers to test this?

NEXT DAY:

Here's an update of additional things Ive tried:

- running filament through at a range of speeds, pushing from the top as needed.

- backing out filament at cooler temps

- swapping motor drives (no change) its not electronics must be mechanical on that extruder.

- changing plunger spacing

- changing filament

- shifting drive wheel fore /aft on stepper shaft, relative to the filament path

- different clamping screw tightnesses.

then i started changing temps. I found that at higher temps i can get filament to feed faster without stalling or losing steps, or slipping: 

220 deg @ 3 rpm

240 deg @ 5 rpm

260 deg @ 7 rpm

after that, at 8 rpm or faster, stalling get progressively worse.

NOTE: the left side 'struder will put out @ 10 rpm @ 220 with no problems. the output diameter is fat though, at .62 mm, whereas the problem 'struder is making threads @ .36 - .42 mm.

So, this leads me to think that perhaps I have a Thermistor calibration problem.

Also, observed the following: the drive wheel teeth do not look very crisp or sharp- appear to be somewhat burnished, and that the threads emerging from the bad side tend to curl and loop rather than drop straight out. this side has gotten about 10 x more use than the other side. perhaps  50 hrs total by now.

Is there a way to calibrate the nozzle thermistor? Tomorrow I will try to measure temps with an IR temp sensor. Should I try replacing the nozzle and drive wheel?

[Dan Newman]

> Here's an update of additional things Ive tried:
> - running filament through at a range of speeds, pushing from the top as
> needed.
> - backing out filament at cooler temps
> - swapping motor drives (no change) its not electronics must be mechanical
> on that extruder.

Do you mean you swapped the stepper motor driver circuits? As I understand
it, the power supplied by the driver circuit is software controlled. (Perhaps
a digital potentiometer?). At any rate, if it is correct that the power
is software controlled, then swapping the stepper driver PCBs may not
be sufficient to rule out an issue with the stepper motor driver. Or, if
the current is manually controlled by an analog pot. and that pot is not
on the PCBs you swapped, then again the swapping didn't completely determine
this to not be a stepper driver issue.

> So, this leads me to think that perhaps I have a Thermistor calibration
> problem.

FWIW, it's a thermistor for the HBP. It's a thermocouple for the extruder.

Dan

[TSDF-3D]

Props to the MB support.

They are shipping a replacement nozzle and drive gear by fed ex. Will report on headway.

T

[Shawn Grant]

I'm dealing with the same issue now... one of my extruders jammed yesterday and I can't seem to get the filament unloaded.  I did as you suggested; tried pulling it out after heating and turning off the stepper motors but it doesn't want to come out.  Any other suggestions?

Other info:
- 2 month old Replicator
- MBI filament
- no abnormal sounds... the jammed extruder makes the same sounds as the functional extruder when trying to push filament forward or reverse.

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[Shawn]

when removing, the motors are going and you are pulling on the filament?
Your pull should be a gentle but very firm pull. I've had once or
twice where the filament wouldn't back out on it's own, and had to pull
fairly hard. It came out and the next filament loaded fine.

In a worst case, you can pull off the fan and heatsink, open up the
plastic cover on the top of the motor, and then remove the motor. Just
be careful not to loose the plunger or the washers. you can then maybe
use pliers to pull on the filament. Keep the nozzle hot though to make
life easier. If THAT fails, I'd just snip the filament and remove the
nozzle to soak it in acetone.

But, I'm still a noob - there may be better options.

Shawn

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[David Stringham]

I think I have the same problem also. The extruder stopped feeding mid-print, and I have done everything short of disassembly trying to remove the filament (PLA in my case).

[RocketSled]

I think most of these are far more likely to be the grub screw holding the drive wheel on to the extruder stepper motor.  Not saying everyone's issue is this issue, but on my Rep, I experienced the "suddenly stopped printing" symptom first on the right extruder, and then a few days later on the left.  In both cases, it was the grub screw.  In the first case, the grub actually fell out when I dissassembled the extruder feed housing.  So I'd been printing successfully for at least a little while without a grub screw engaging the stepper motor shaft at all.  I had maybe done 10 small prints on the right extruder before it failed for the first time.

I noted on mine that while the stepper motor shaft has a Flat, the drive wheel has to be about 1/8" away from the face of the stepper for the grub to be on the Flat.  If I space the wheel closer to the face of the stepper (which I understand is where it's supposed to be), the grub is on the round part of the motor shaft.  Even if I tighten it down hard, and it seems to be gripping, it can still slip.

 

[Eureka]

Noone seems to have given this tip yet, so let me:

I hade really awful problems with feeding problems, i even sent a machine back, got another, and the problem still was bad. Then i learned about the "Minimalistic Mk8 replacement" upgrade made by a thingiverse member "Emmet". I printed it out, replaced the entire plastic parts on the feeder step motor too this upgrade, and all my trouble whent magically away.

I cant praise this upgrade enough. It makes your machine atleast 3 times more reliable, and also able to print at much finer resolution. The key is that it uses a very small ballbearing to reduce the friction in the feeding mechanism. It seems like a small change, but the results are astonishing! I strongly suggest that you chuck the Makerbot Industries solution of filament feeding mechanism and completely dedicate yourself to this great replacement mechanism:

http://www.thingiverse.com/thing:28241

P.S. Just make sure the ballbearing is turning freely. When i printed this, i hade to use a fine scalpell to cut away some plastics that was in the way, and adding friction. Also, if you find some holes to be to small, just drill them out with a 3 mm drill. But use a 2.5 mm drill on the hole for the screw that holds the ballbearing in place. It should be a mechanical threaded bolt, ie, no wood screws, but screws made for use with a nut. That way, the 3mm screw will fit inside the ball bearings inner diameter of 3mm, but still get enough of a grasp on the plastics to stay put.

[RocketSled]

Good point.  Friction can be funny.  Especially when the surfaces have some elasticity.  Parts don't move smoothly past each other with constant drag, they exhibit a stick/slip behavior (the same thing that causes earthquakes along fault lines).  Static stress builds up until it's above some threshold, and the system quickly 'snaps' to a new position, and the process repeats.  The Delrin plunger thing in the MK8 extruder doesn't have a spring behind it, it mostly relies on deforming the filament to fit tightly between it and the drive wheel.  That's exactly what you don't want, if you want the system to move smoothly.

I've been meaning to print out some minimalist parts myself.  I have bearings from my model Helicopters that I intend to use.  I just haven't gotten around to doing it yet.

[David Stringham]

On my Replicator Dual, one of the extruders seems to be unjammed, though I haven't verified if it's temporary or not. The other side extrudes just the barest amount of plastic. I also verified that both motors are actually turning.

[Steve]

Are there any changes required for the two STL files for the Minimalistic Mk8 Replacement at http://www.thingiverse.com/thing:28241 to work on the Replicator 2? 

There was some discussion about having to mirror image parts, 

is this required for the Replicator 2? 

What is involved in removing the existing parts and replacing them with these?

Is it ok to print these parts in PLA on a Rep 2 or do they need to be ABS?

[Andrew Plumb]

Unfortunately these *must* be printed in ABS. No-go with PLA; there's too much heat in that zone for the PLA to maintain integrity.

Worst-case if you don't have direct access to an ABS-capable machine, Ponoko's "Durable Gloss" plastic options are ABS: http://www.ponoko.com/make-and-sell/materials

Andrew.

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[Eureka]

I dont know if anyone else have said this earlier, if so, ignore this answer.

I had a nightmare with clogged nozzles on my first replicator. I actually sent it back for a replacement, and when the replacement acted just the same, i almost gave up. But luckely, i stumbled apon a tip online about replacing the filament feeding assembly with a model made by "Emmet" at thingiverse. Its called "Minimalistic MK8 replacement" and it works like magic. Its like a totally different machine now, and i have not had a single clog ever since. Im completely sold on his solution, which steals much less force from the filament feeding stepper motors, by lowering friction, and also gives the machine more "give" so that variations in the diameter of the filament will not cause the machine to stall. I STRONGLY recommend that you print it out and exchange the original parts with it!

http://www.thingiverse.com/thing:28241

The only thing you need to buy is small ball bearings and suitable springs, which shouldnt cost you more then 10-20 bucks total.

Den fredagen den 4:e maj 2012 kl. 05:22:26 UTC+2 skrev ian campbell:

[Guidozelf]

I've just made the Minimalistic Mk8 replacement from emmet (http://www.thingiverse.com/thing:28241) which allows for a spring loaded ball bearing to feed the filament.
Printed in PLA and Sems to hold, also om long prints......

I feel the spring load is essential here: look at the comments on Thingiverse ;-)
My Replicator 2 has never (not even when just unpacked) printed so beautiful and smooth as after this upgrade. It's beyond me why Makerbot hasn't done this as standard, but perhaps things aren't so bad with ABS as with PLA (my only experience is with PLA ,as I only have a Rep 2).
In order for this mod to fit, you need to modify the black plastic cover that's holding the filament tube: you need to cut out a small piece.
I used a Dremel for this, at low speed, after disassembling the 6 Hex screws and disconnecting a few wires. Easy, fast and simple proces.
I'm now printing at 0.1mm with RepG40 and MBI firmware 6.2 without any problems, no clicking, no missing plastic and smooth as a baby (is that the expression?) ;-)
I've made a few pictures, may be that helps you with the build / mod. Highly recommended!
Pictures are available on: https://groups.google.com/forum/#!topic/makerbot/hpIebvPqRiY

Couleur Br this helpt you om uur was for Rep 2 modification.

[PropellerScience]

The extruder replacement should be the first thing a person makes with
their Replicator IMO. No more load/unload filament routines, and no
more plunger issues. Also, Now I can see the filament drive wheel
moving, and that's pretty cool!

[Steve]

The extruder replacement sounds like it has improved the machines for a number of people. In looking through this topic, and a couple of others, I have seen suggestions that the Thingiverse STL file for the extruder replacement needs to be reversed or modified, and other indications that it does not need to be. Some people report they have printed the part in PLA, and others said it must be ABS. 

I am just getting started in 3D printing with a Rep2, and am wondering what the best thing for me to do is. For those who have made the extruder replacement for a Rep2: Did you just print the files as is from Thingiverse, or did you need to alter them? Did you print in PLA from the Rep2, and if so did it work? What other issues did you encounter when making this modification to the Rep2? Is it possible to put the original parts back in after the modification process? 

 .

[Guidozelf]

Steve,
I've not modified the files from Emmet, just printed ExtruderR from the .stl provided.
Since I have Rep2, a non reversible mod (cut out) had to be made. I saw no obvious way to alter the design such that a cut out could be avoided, but may be there is....
You can always put the original plunger design back in. ( although I'm sure you don't want to do that ;-))
I've printed mine in PLA, if this doesn't hold, I'll ask help for a print in ABS, which I can't do myself.
So far I've ran several print jobs, some pretty big, without any probs.
The whole process only took an hour, apart from printing the part itself with the plunger still in place: it took me 3 attempts because PLA would get stuck.....I used 100% fill, no extra shells.
I re-used the existing 2 imbus bolds that previously held the original plunger solution.
Found the bearing and a spring at the local hardware store, easy and cheap.
Hope this answers your questions!

[randyzimmer]

The Mk8 replacement pinch drives are much better than that dumb plunger.
Another thing I've found is that after a while, the nozzle just gets crusty inside.
I went to the local machinist's supply and bought a tiny drill and pin vise.
If the output looks funny, I run the drill up the nozzle (after pulling the filament out) and pull out some errant plastic.

[Steve]

 .

Guidozelf 

Thanks for the info. My Rep2 is still being born in the BotCave, but I am getting close. Trying to learn everything I can

so I am ready to roll when it arrives. It is hard to tell without looking at one exactly how the replacement parts go and which part to modify.

I may just have to sort that out when the machine arrives. Is your Rep2 as good as advertised? Anything you wish you knew

when you first started printing?

randyzimmer 

What size bit did you buy for the nozzle? Are you on a Rep2 or a Rep1?

 .