Constant extruder issues

I have been having some horrible luck with extruders this year, it's been months since my last print as my last two nozzles oozed all over. I decided to get the QM-BD MBE extruder and it does not ooze one bit buuuut...

My setup:
QM-BD MBE extruder
42ozin NEMA17
1.75mm PLA
MK8 Drive gear
1/16 microstepping (105steps/mm)
Bulldog clip idler
10mm/min print speeds for everything

I tried to use this as I can not find a single useful size of spring in my area but I think it does not provide enough tension as I have my pololu at max current and have the hot end at 230deg and it constantly skips and strips the filiment. I then cracked the bearing mount as it is only a few layers thick and now I am stuck with a rigged together extruder that can barely print.

I was thinking of trying out BDring's modifications but could I replace the spring with a set screw? What supposedly makes these good is the idler allows slight variations in the filament so "less jamming"

What do you guys recommend I do to get a working a reliable extruder so the last year doesn't turn into a huge waste of time and money??!!

Well, in the beginning, when I had no suitable springs, I just nipped the screws up against the filament until it extruded. It really didn't take much pressure to achieve the desired result. I never had a problem with it but eventually found some decent springs.

What sort of pressure and torque settings are good for the MK7 extruder gears??

Should I have as much pressure with my idler and the pololu at maximum current or is their a sweet spot to avoid grinding the filiment up?

Right now printing at 10mm/s I can get 6-8 layers down before the drive gear is coated with dust, I figured it was skipping every so often but even with the temp at 230deg for PLA it still looses grip. I have a spring clamp in reverse putting so much pressure on it now it is warping the idler and it still skips. And 10mm/s is SLOW...

Clever designs from Makibot/Solidoodle used a thick piece of acrylic to provide the tension (Acrylic bends like a canteliver/spring over small distances). IT would provide ~5-15 lb of force I guess?

Please observe SD2, the top right of this picture
[armanicreations.com]
I hope this gives your some inspiration

Edited 1 time(s). Last edit at 03/22/2013 09:26PM by Simba.

In that cantilevered configuration you would get 2x the force from the screw applied to the filiment.

Here is my setup

Those little clamps are VERY strong (cant put them on your finger as it hurts) so I am using the back to provide my spring action.

Simba Wrote:
-------------------------------------------------------
> Clever designs from Makibot/Solidoodle used a
> thick piece of acrylic to provide the tension
> (Acrylic bends like a canteliver/spring over small
> distances). IT would provide ~5-15 lb of force I
> guess?
>
> Please observe SD2, the top right of this picture
> [armanicreations.com]
> /12/2012-12-10-23.36.22.jpg
> I hope this gives your some inspiration


No, there's an actual spring on that tensioner arm.

greenman100 Wrote:
-------------------------------------------------------
> Simba Wrote:
> --------------------------------------------------
> -----
> > Clever designs from Makibot/Solidoodle used a
> > thick piece of acrylic to provide the tension
> > (Acrylic bends like a canteliver/spring over
> small
> > distances). IT would provide ~5-15 lb of force
> I
> > guess?
> >
> > Please observe SD2, the top right of this
> picture
> >
> [armanicreations.com]
>
> > /12/2012-12-10-23.36.22.jpg
> > I hope this gives your some inspiration
>
>
> No, there's an actual spring on that tensioner
> arm.

<<I sit corrected