Stops extruding randomly, hours between

Been printing for maybe 50hrs so far. I first started with some PLA samples which went really REALLY well, but have since moved to ABS (which has proved a major pain). Extruded with ABS for maybe 30min before printing anything...

- "Natrual" color ABS from the eBay seller in the Czech Republic
- Sampling filament revieals consistant diameter of 2.6mm - 2.8mm
- Extrusion temp 230deg
- J-End .4mm nozzle
- 0.25mm layer height
- Printbot with Wades setup and hobbed bolt from Ultimachine
- TIGHTLY sprung counter bearing on filament
- Plastic ooses from tip upon heating

Randomly it'll just stop extruding and I'll have to give the filament a manual push to get it started again. I find that if my first layer height is too thin, it'll kinda clog and I need to manually push it through again. Otherwise, it'll print for hours. Really getting frustrated by multi-hour prints being ruined midway through by a jam.

I just realized I'm using a 1mm retraction when the nozzle moves farther than 3mm without extruding. Could this be the cause of the problem? the filament getting mangled by the hobbed bolt once, then the second time around it doesn't grip?

Any help/advise greatly appreciated.

Edited 2 time(s). Last edit at 03/12/2013 02:40PM by eatkabab.

Can't see retraction being an issue.
I think many extruder problems are caused by the hobbed bolt. I have read topics where people have changed the hobbed bolt 2 or 3 times and still have a problem so they, not surprisingly, look for the problem elsewhere. I had the same issues -good for PLA but erratic on ABS. So I decided to design my own hobbed bolt and have had no problems since. What kind have you got?

waitaki Wrote:
-------------------------------------------------------
> Can't see retraction being an issue.
> I think many extruder problems are caused by the
> hobbed bolt. I have read topics where people have
> changed the hobbed bolt 2 or 3 times and still
> have a problem so they, not surprisingly, look for
> the problem elsewhere. I had the same issues -good
> for PLA but erratic on ABS. So I decided to design
> my own hobbed bolt and have had no problems since.
> What kind have you got?


So I actually bought my hobbed bolt from Ultimachine. I feel that it's a really really well designed hobbing likely done with a lathe. It's directional and really tears into the plastic. I bought it upon recommendation from a local print shop. Like I said, excellent on PLA, annoying on ABS (at least this only spool I have).

Edited 2 time(s). Last edit at 03/14/2013 12:28AM by eatkabab.

Maybe try stronger springs on extruder idler?

I would try some different filament suppliers or samples. I received one spool of filament from a supplier that would not extrude. It would start out ok but then just quit. The filament was brittle\crumbly and dull vs the shiny surface my other spools have. Also on my last attempt at using this material the filament actually measured 2.4-2.5mm vs the 3mm. This large reduction in size and brittle\crumbly surface caused it to stop feeding.
Swapped filament and zero problems.

I had a problem with the hob loading up with plastic filament. This causes a slippage and the filament stops feeding.
The hot end works great, 40 watts with a custom brass nozzle. The brass maintains the heat at a constant 235.
I tried air pressure to clean out the hob, but this process is real pain.
So I tried some heat sink paste, which I applied sparingly to the filament.
Works great!!!! THE HOB STAYS CLEAN, NO PLASTIC BUILD UP.
Just one small step for mankind and one giant leap for problem free extruders.