hobbed bolt destroys filament

just finished building my mendelmax 1.5+ by following this guide [docs.google.com] first times i printed everything was okay ,but now every time i print my hobbed bolt destroys my abs wire.if i make it to loose my hobbed bolt dont picks up the wire and if its to tight it destroys the wire .i have been tinkering for hours now but after every print i end up with wire clogged up in the hotend and wire destroyed by the hobbed bolt.i cant find a good solution for this sometimes it prints sometimes not.after every print i need to clean out both the hotend because wire is stuck and around the hobbed bolt because it destroyed the wire.


this is my config
i use this extruder [www.thingiverse.com]
and from gadgets3d i use my hotend version 1.2
here is my config maybe the mistake is in my config ?

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Configuration.h.txt

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Edited 1 time(s). Last edit at 03/18/2014 06:12PM by NewPerfection.

Any reason why your using nuts and washers in places of springs on the extruder idler? The springs give it a little wiggle room.
Also did you nyloc or double nut your hobbed bolt (can't tell in the picture)? If not the bolt and gear won't move freely, it shouldn't cause this issue, but will put extra stress on the extruder stepper.
You can see the double nut and springs on here.
With your bolt you'd probably have to use a nyloc though as I don't think you can fit another nut.

Edited 1 time(s). Last edit at 03/17/2014 11:43AM by JoeDaStudd.

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adjusted the extruder and addes springs,also put my temperature higher and my feedrate lower still the same problem ,also every each print between my hotend and extruder its clogged up

So… having had a pretty similar setup on one iteration of a first build, i've run into a few different things…

what kind of hotend are you using?

issues i've seen can be

- crappy hotend (rough bore, improper alignment)
- clogged hotend (you should be able to push filament through it at temperature without much resistance, and the resulting diameter should be slightly larger than the bore of the hotend). I've had cases with PTFE bits from tubing / hotend parts clogging the nozzle multiple times until removing / completely cleaning the PTFE parts.
- hotend not tightened well enough; internal gaps (especially around melt zone) allowing plastic to expand and form a plug
- hotend not at right temperature
- ABS left in hotend when switching to PLA
- bad hobbed bolt
- printing speed too high for temperature
- bad choice of springs (finding the right spring tension can take a bit to get used to)
- nuts on hobbed bolt not properly locked, slowly tightening and compressing extruder
- hobbed area of bolt not aligning properly with hole in extruder
- gap between top of hotend and top of hole in extruder, causing filament to buckle inside gap (if there is a gap, you will want to find something to fill it with
- extruder made for 3mm filament, using 1.75mm filament, so the hole is too large (I reamed mine out to 2mm from the top & put a length to PTFE tubing in -- long enough to also solve the previous issue. If you do this, don't ream all the way to the top -- you want some material left at the top to keep the tubing from being sucked backwards into the hobbed bolt on retractions)
- crappy filament (though after taking care of the other issues & going to an E3D hotend, even the old filament that caused headaches prints fine now) -- note some cheap filament has a lot of variations in diameter and tightening things enough to grip in the narrow areas may cause it to jam at other points. Proper spring tension can help a lot with this though.