Extruder HELP!!!!

I have a EckerTech RepRap printer that I just built. After some problems getting the printer working, I had everything running fine yesterday and printed for a total of 11 hours, four different prints, but on the last print, the extruder started giving me trouble.

Early in the print, it stopped extruding. The hobbed bolt had chewed out the side of the filament. I cleaned the nozzle, cleaned the hobbed bolt, and started again but it only printed 6" to 12" before it plugged up again. I cleaned everything and tried again many times. I have tried higher hot end temp (up to 290C), lower temp (230), lower feedrate, lower flow rate, each time cleaning in between, and it does the same thing every time. The printed trace starts to get narrower and then the filament strips in the extruder drive.

The nozzle is 0.45mm but I don't have a .45mm drill bit and can't get one until Monday. I use the cleaning wire that came with the kit (0.43mm) but it isn't long enough to pass all the way through the nozzle. The extruded filament (when it IS extruding) is 0.63mm (0.025")

I can't, for the life of me, figure out why it quit working and started plugging! It is SO consistent in printing 6" to 12" and then chewing up the filament!

HELP!!!!

This problem could be a number of things really. Bad thermistor reading the wrong temperature, low quality filament, loose idler etc. it's frustrating for sure but you'll really have to get into it and start testing all possibilities in this case. Good luck.

I had something very similar last week and after taking everything apart and back again, in the end I think the issue was with thermistor that was not making a good contact. I couldn't find anything wrong in the head itself. It would start printing, then after a couple of inches it would slowly stop. It is temperature related.

I didn't see any temperature drop on the Repetier screen but I did find the thermister pulled out of the head the last time I cleaned it so I poked it back in place with some thermal compound and recalibrated the head.

I got many contradictory opinions on what temperature to run at for ABS, everything from 220C to 260C.

There are definitely some modifications coming for the RepRap when I am done with the current batch of prints!

1. The extruder is going to get a friction drive so it doesn't strip filament! Just a spring-loaded friction plate with indicators painted on so I can see if it is slipping or feeding. That will save having to take the extruder apart to clean it after a jam and will keep ABS 'debris' out of the head.

2. I am going to modify the hot end to make the nozzle removable (and clean-able) without having to remove the entire hot end.

It is all clean and ready to test again but I am not going to do that tonight - don't want to spoil my good mood LOL!