Mini Kossel will not stop grinding filament

I try and try to fine tune the tension (pressure) on my extruder, but it ALWAYS starts grinding the filament sometime during first layer (filling)

I have a nice and smooth filament path, and I can safely print into open air at 700mm/s, which seems at least as fast as any stage during printing.

It seems as soon as I've adjusted the pressure on the filament to the point where it doesn't slip, it starts grinding instead. Incredibly annoying!!
Does anyone have the same problem, or does anyone know a solution to it?

I have another issue at the moment, and I thought I might mention it in case they're related:
- One specific layer goes wrong EVERY print. By wrong I mean the filament starts grinding like on first layer

Thanks,
Eddy

This is my extruder; bought the kit from think3dprint3d



Edited 1 time(s). Last edit at 03/27/2015 01:20PM by Eddy.

If the problem happens during infill but not when printing perimeters, then it sounds to me that either you have the nozzle too close to the bed when you start printing, or you are over-extruding. [Or just possibly trying to print infill too fast.]

I suggest you check the following:

1. Have you set the printer such that G1 X0 Y0 Z0 really does send the nozzle to Z=0 and not slightly lower, so that it just grips a sheet of paper between the nozzle around the bed, but you can still move the paper around? This must be done when the bed and the nozzle are at operating temperature, not cold. If you are using bed compensation, check it after running G29.

2. Have you calibrated the extruder steps/mm as described in the T3P3 instructions?

3. Have you entered the correct filament diameter in the slicing program?

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thank you dc42.

It's all checked and rechecked.. I forgot to mention that when I occasionally get one one nice first layer, the next few layers aren't much better...

But you have a point; why does it ALWAYS fail while filling? it's either during solid fills or infill, as far as I've seen.

I just had a print going superb, which was very thin walled so it almost didn't have any infill. It printed fine for two hours, then failed at ONE layer, kept going strong, and then failed when it started filling on top..

It could just be that the filament you are using needs a lower extrusion factor. Depending on your printer firmware, you may be able to adjust the extrusion factor while the machine is printing (M221 command). Or you can adjust it in slic3r.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Good idea. I did manage to get one trouble free layer once when I set first layer down to 40%speed instead of 50%. I really want to be able to go down on temperature too, cause it's oozing like mad when doing anything else than perimeters.

Btw if the extruder grinds filament when it can't be pushed through the hot end, instead of skipping steps, then it is probably a good idea to reduce the stepper motor current. On my T3P3 Mini Kossel I have all the motor currents set to 800mA, and the extruder motor skips if I have the extrusion factor set too high.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Another hot tip, thank you!

Come to think of it, I have had this issue with the last 3 types of filament I've tried, and they're all from different suppliers.
Also, when printing previously successful prints with previously trouble free filaments, I'm still having these issues. I'm kinda leaning towards something mechanical, and that's what I'm hoping too.
Maybe there's something wrong with my hot-end? I can squeeze filament through it by hand, but I have no idea if the force required to do so is more or less than I should expect.
I have the plastic hot-end that t3p3 swapped out a few months ago or so; was it prone to fail in any way? And for those of you who has the same hot-end: is it meant to have a piece of bowden tube inside it?

Have you tried reducing the extrusion factor yet? Try 0.9 and if that solves the problem, increase it just enough to get good solid infill on the top layer.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I will now, have been away for a few days. thanks

Found my culprit while trying to extrude some plastic by manually turning the big extruder gear (only tried feeding through the remainder of the path before).
The photo is taken after manually extruding a few cm's of plastic, letting the hot-end cool, and then pull the hot end STRAIGHT down after unscrewing it. Clearly there's something there causing a kink and a bend, furthermore a much bigger resistance in the flow of filament.

I tried the best I could to drill the path clear with a 1.5mm drill bit, but with limited success. So I guess a new hot-end is on order really soon.

Eddy

Edited 1 time(s). Last edit at 04/02/2015 06:27PM by Eddy.

You need a 2mm. Bit. Drill again.

---

My Personal Blog. Build blog.
[engineerd3d.ddns.net]

Modicum V1 sold on e-bay user jaguarking11

Drilled again with 2mm bit. Didn't help. Should I keep drilling till I actually start drilling on the brass?

Thanks!