Need some help re: extruder ability to reliably push filament

Hey guys,

I switched out a Wade's extruder for a modified Greg's Wade reloaded jhead version. I switched this out because it seemed to me that the filament wasn't getting consistently fed, leading to the feeding mechanism chewing into the filament and halting prints. I printed for a while with the new extruder, and all my prints were excellent. I moved to ABS, which I had previously had problems with and dumped, and even the ABS was great. Then, a few days later (today), my extruder started hanging again. Anyway, my question is this:

There is a bearing on the hinged portion that pushes against the filament, to keep ti firmly seated against the hobbed bolt. When the hinged part is fully closed, and the hobbed bolt is pushing out filament, should I not see that bearing slowly turning? I marked it with an indelible marker, and no movement whatsoever. I pulled the hinged portion away slightly from the filament so it was not touching, and still it would not turn. Then, I noticed that the hinged portion on the main body of the extruder was pushing against it when closed, preventing its movement. Any opinions on whether this could be the problem?

Thank you.

Absolutely that bearing should be turning. Perhaps the hinge was not printed with enough clearance for the bearing to turn??

Might be time for some creative filing to loosen it up a bit.

jbernardis Wrote:
-------------------------------------------------------
> Absolutely that bearing should be turning.
> Perhaps the hinge was not printed with enough
> clearance for the bearing to turn??
>
> Might be time for some creative filing to loosen
> it up a bit.


Absolutely! You must be careful when assembling a gregs of this style (hinged) as typically you will have to carefully remove some plastic to provide room to keep the bearing free.

It's easiest to do this before the extruder is assembled. I marked with marker where I saw the rub spots from the bearing and then with a small file (on the hinged portion) and a drill bit (on the fixed bearing holder on extruder body) I carefully wittled away PLA until it had clearance to turn freely.

Edited 1 time(s). Last edit at 01/16/2013 01:51AM by xclusive585.

Sorry, I saw your responses after PM'ing you just now. I've already done some filing, but now that I know I need to do more, I'll disassemble and do so. I made the mistake of using a dremel and sanding, and that seems to have turned it into rock! LOL! Anyway, will let you know what happens, thanks very much!

Filing helped. The printer improved enough to print a new hinged piece perfectly (better than ever). Jamming occurred again on the next (longer) print. I disassembled the extruder (cold and hot end), installed new hinged piece, used a drill press to widen the hole where the filament feeds down to the hot end (just slightly). Reassembled, jamming happened almost right away.

I noticed that the hobbed bolt has slanted teeth (see pic attached), I'm assuming because a tap was used to create the teeth. I have not noticed the filament twisting. The teeth also end right at where the bolt threading starts. Perhaps the filament is drifting towards that part? No evidence of this though. I may order a hyena. Has anybody good experience with this? Or a bearing with a groove (also on site with the hyena). At this point, I'm tempted to buy an entire extruder/hotend assembly. Does anybody have any additional advice, something that I am missing?

Thank you!

Edited 2 time(s). Last edit at 01/18/2013 12:16AM by spacey123.

That is a sad excuse for a hobbed bolt. My bolt actually has a groove about 1.5mm deep. Yours appears to be totally flat. What keeps the filament aligned with the hobbing? I'd bet that your filament is drifting from side to side, and when it disengages from the hobbing it stops moving. Get yourself a better hobbed bolt, or perhaps like you said a grooved bearing, and I'll bet you see an improvement

@xclusive585:
I read your comment the other day, I should have responded immediately. I used your technique of marking the spots that I wanted to file down, and filing enough to remove the marker. After 3 iterations, it was enough. Good idea, thank you!

@jbernardis:
I replaced this hobbed bolt with my old one from my other extruder variety (Wade's original). The grooves are fewer, and very much deeper. My prints are working well now. Crossing my fingers for the bigger prints... Thank you for your patience and expertise!