Bowden Extrusion Issues and Calibration

So I've been working on my Rostock since July and it hasn't yet worked 100%, I have been dealing with the bowden extrusion system since August and its sort of driving me crazy.

Here is what I have been doing:

- original configuration: greg/wades extruder (hearingbone gears) with a bowden clamp using zipties. This didn't end up working as the bowden tube kept popping out during prints.
- 2nd configurations: greg/wades extruder (hearingbone gears) with bowden clamps using both zipties and M4 nuts. This fixed all the problems with the tube popping out of place. The problem with this set up was that the plastic extruded was not enough and the layers were thing and crunchy, not attaching well to eachother at all. I then conducted research and found out my NEMA17 stepper for the extruder did not have enough torque for consistent extruder

Fast forward to now, new configuration:
- Greg/wades extruder (hearingbone gears) with bowden clamps using zipties and M4 nuts, now with a 76 OZ-in NEMA17 stepper. I am still getting the same problems as before. It seems that the two M4 nuts on the extruder end and the hotend end together create enough friction to cause the filament to jam for a short period which leads to the hobbed bolt grinding the filament, when the filament is grinded like this it pushed backward until the hobbebolt locks on to it again.

76 OZ-in should be enough to crank through (especially at 215C for PLA) I am having trouble figuring out what to do.

Here is my setup:
- Printrboard Rev B Marlin 1.0
- Makergear hotend with 0.35mm nozzle
- 2mm ID / 4mm OD PTFE tube for the bowden tube.
- The tube is mounted using clamps that hold M4 nut threaded around the tube with zipties for insurance. The bowden tube on the extruder side has the nut threaded a ways down such that the bowden tube is right up to the hobbed bolt, on the hotend side the clamp mounts the tube such that it is right on top of the hole. Could the fact that my bowden tube is threaded so far down on the extruder side be causing the problems?
- Extruding 1.75mm PLA from Ultimachine

How confident are you of the hot end temperature? For that matter - what hot end are you using?

Do you have the same issues with something like a spiral vase that has no retraction?

How fast are you trying to print? How fast are you trying to extrude? What happens if you cut the print speed in half?

Your filament may be deformed with the hobbed bolt to such extend that it wil buckle inside the bowden tube that will cause to much friction or it may cause the filament to deform to a more flat profile that is more than 2 mm causing it to stick to the sides of the tube. If this is the case try this hobbed bolt( [www.tridimake.com] )

I have a similar setup 3mm bowden tube, using M6 nuts. I have found that the nuts reduses the inner diameter of the tube. I fixed this by drilling the tube by hand using a 3mm drillbit....

I just realized my steps/mm for my extruder were way off. I think that might be what the problem is. I'm going to give it a shot and let you know how it goes.

It was a combination of poorly assembled extruders and the wrong steps/mm for the extruder, I am now using a SeeMeCNC EZStruder with 92 steps per mm for the extruder, now I just gotta work out some bed level issues.