Extruder still jamming...

Hi all. I have a Wade's extruder with a PEEK hot end. I am having the same recurring problem. The extruder keeps jamming. The hobbed bolt that I bought online I noticed had really small teeth so I made by own hobbed bolt by dremeling and filing some new teeth. I noticed that this worked like a charm for a while. A couple of prints after installing the new bolt, the extruder jammed up again. I took apart the extruder and cleaned the plastic out of the bolt teeth and tried to clear out the hot end using a small metal rod. The extruder then worked for a little while then jammed up again. I thought the issue could be temperature related so I cranked up the extruder temp to 250. Still I got jams.

I am quite fed-up with the performance of my extruder. Can someone recommend a place where I can just buy a new assembled extruder with a hot end?

Thanks

I know Makergear makes reputable extruders, but it might be worth it to do some more triage before throwing the baby out with the bathwater. This latest time it's jammed, were there any filament shavings stuck between the teeth? The problem is that once the filament becomes stripped, the teeth become clogged which makes it more likely to strip filament in the future. You should narrow the problem down to which part of the extruder is to blame. Is your nozzle too small for the speed you're running the motor? Or maybe the nozzle is too close to the build platform which retards the flow. Neither of these problems would be solved by buying another extruder, so it'll be worth it to understand what's gone wrong before making a purchase decision.

I do notice that there is some material in the teeth, but its not much. I have a picture of my extruder here: http://img535.imageshack.us/img535/791/img20110829202742.jpg There is a small amount of white plastic in the teeth.

I have read that increasing the tension on the idler block will help with this issue, but if I increase the tension too much, my motors stall and increasing the motor current makes the motor controller (pololu board on RAMPS 3.0) get too hot.

are you incorporating the threads of the bolt in your new teeth?

I use a piece of all thread with teeth dremeled into it with a fine cutting wheel.
Ten plus hours of printing this weekend with out a jamb.

I got the idea from the wiki page of the wades extruder.
hope this helps
-E

I wonder if your teeth aren't sharp enough. They look a bit dull. To remove the bolt from the equation, try feeding some filament by hand. Remove the idler, heat up the hot end, lift the extruder far from the build platform, and try to push some filament slowly into the hole and down through the nozzle. You should be able to do it without much pressure. If that doesn't work, you may have a clogged nozzle or a blockage in the tube. Also, make sure it's not too hot. If you're printing with PLA, I've found that it likes between 185 and 200ºC. Abs needs it hotter; more like 220 or 230 may be required. If this works, I'd wager it's your feed mechanism, and probably the teeth on your bolt.

I've learned that it's best to set the stepper motor torque such that it misses steps before the hobbed bolt starts to slip to prevent the extruder from jamming.

Have you tried pushing the filament in by hand to get a feel for how much force is required? The PEEK insulator might have too much friction. Usually, there's a PTFE lining inside the PEEK insulator to reduce friction. Does your hot end have that lining?

I think you should either make another hobbed bolt of buy one. The one shown in the photo doesn't look very good. I think you need to file the bolt down further before hobbing with a tap.

Edited 1 time(s). Last edit at 08/29/2011 09:06PM by brnrd.

I've tried pushing the filament through the extruder by hand. It takes a lot of force to get the plastic through the whole assembly (.5mm nozzle). I am using a PEEK barrel without the PTFE lining. The teeth are not particularly sharp. I am not convinced it is one problem or the other. I've tried buying various hobbed bolts in the past but I've had problems with jamming also. Is there a particular barrel that others have used for ABS? Makergear sells hot end "Superpacks" with a hybrid (PTFE and PEEK) barrel. Is this worth getting?

A lot of people here seems to be happy with the makergear hot end. I got an Adrian style push-fit hot end with PTFE lined PEEK insulator from cdnreprap.

Anyone take a look at the filament being used for the extruder? Is it possible that the filament is not round?

That's a good point James. Since the bolt was not hobbed deep enough, it's possible that it's flattenning the filament as it goes through it. I've seen this before with Adrian's geared extruder. This would make it harder to push the filament through the PEEK insulator.

Ok thanks guys. I'll try switching out the hot end with one of the makergear hybrids. 420e had an interesting suggestion that I think i'll follow as well.

@hazuki please let me know who you are so that i can match your ID to your order. And, be sure to use the MakerGear IRC channel for questions.

Rick
rick@makergear...

I got my hot end from makergear and an really happy.
Im redoing my hobbed bolt.
Ill put it up here later today.
My walls on my prints are uneven and i think my bolt is slightly bent.
We will see.Cheers
-E

One thing I noticed wasn't mentioned at all here was the diameter of the hollowed out heater barrel. Has anyone noticed this to be an issue? Mine seemed to be too tight to get the filament into it cold so I hollowed it out a little bit. I'm going to try cranking up the temp and hand-feeding the filament tomorrow, but has anyone found any issues related to the bore diameter?

-Kevin

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[ kevinhajek.blogspot.com ]

one common thing is the filament heating up while pressure is pushing down on it and it swells.

try putting a fan on it like this:

[reprap.org]