Filament slipping

Hello everyone.
I am using Aitrippers v3 bowden extruder with MK7 gear from reprapworld.com. However, my filament keeps slipping on the gear/bearing. Gear spins normally, bearing seems to be struggling, but also turns a little. I am running 1.7mm ColorFabb PLA with e3d v6 bowden hotend at 200 degrees. Hotend is not jammed. I have tried adjusting bearing pressure against the gear, but there seems no good point : when it's too loose, filament slips, when it is too tight, it wont turn also

Edited 1 time(s). Last edit at 01/26/2015 07:36AM by Capinho.

Do you have a picture of the extruder mounted ?

---

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

15 mins and I will upload some, cause I am reprinting the axle right now and will mount another bearing i found lying around. Maybe it was poor bearing

Ok, i mounted a new bearing and apparently it was not the bearing. I also noticed, that this slipping occurs only when the filamend reaches the hotend, until then - it runs smoothly. I have also removed 3rd jumper from my Ramps board, so now i have 1/8th microstepping only. Whats the issue? Jammed hotend? Not enought motor power? Too small nozzle (0.25mm)?

Here is a link to few photos and a video.
[onedrive.live.com]

First, your bearing does not roll. Maybe it don't touch the filament or maybe it's blocked by something inside the extruder. Seccond, the filament seems to me twisted. It should be folowing a straight line from input tt output. Is your hobbed gear clean and well alligned ? Is your filament in good shape ? Normaly, if it stays blocked while the gear runs, the gear grind the filament and it cannot be driven anymore. a grinded filament :

Mark the gear position on the filament, pull the filament and check out any grinding. It should be grinded or there's something wrong.

Second, unmount your bowden tube and make your trys with the filament free to move. It's not the time to connect it to the hotend until all is checked on the extruder side.

Edited 1 time(s). Last edit at 01/26/2015 10:05AM by Zavashier.

---

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

I am so frustrated right now. I have tried changing plastics and everything, it seems to be problem with the hotend, because it works perfectly until the filament reaches the hotend.

Could my stepper motor be too weak? I am using stepper of holding torque 4000 g*cm

Edited 1 time(s). Last edit at 01/26/2015 01:10PM by Capinho.

How are you sure the hotend is not blocked? Can you push filament through the tube by hand to see it squirt out the nozzle?
What it the inside diameter of your PTFE tubing?
Are you sure the filement is making it all the way to the nozzle tip? If there is a lip between the teflon guide and the hot end, the filament might be snagged there. My Wade's extruder can snag just before the hotend unless I ensure to "start it" throught hotend sleeve by hand.
How tight is the feed gear against the filement? Do you see the feed bearing turn as the filament advances? My initial extruder feed problems were due to "not tight enough". I recall some instructions saying "its so tight it hurts my fingers and I still can't pull it out" is the correct tightness. Unless it is so tight that the filament does not feed down the teflon tube (i.e the filament is getting mashed and destroyed, that would be too tight. But in my case tight means really darn tight.

Hang in there, once you get past this, you will be golden.

from the video he posted, the bearing does not seem to be moving when the hobble gear is advancing the filament (Zavashier above mentioned this). It could be a combination of the gear not applying pressure to the filament side AND a blockage of some sort at the bowden tube end.

Quote
prof braino
How are you sure the hotend is not blocked? Can you push filament through the tube by hand to see it squirt out the nozzle? .

I agree with prof braino, Check the hotend pushing the filament by hand. (245°C for ABS, 200°C for PLA) It should be as easy as inserting a knife into some butter. If it's not, take the hotend apart and check if it's in good shape and nothing obstruate the nozzle. With low quality nozzle/filament, sometimes some dust or metal chips lay into the nozzle.

Edited 2 time(s). Last edit at 01/26/2015 05:23PM by Zavashier.

---

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

Motor power does not seem to be an issue. The bearing looks like its oversized for the job. One more thing that bearing has exposed balls, you should look for one that has at least dust sheilds as the filament dust will eventualy get in the bearing and clog it if not so already. With a direct drive the motor has a tough enough time to push anything at reasonable speed, if the bearing is working against it it will reduce quality.

It honestly sounds like the hot end is clogged. If its a metal hot end soak it overnight in acetone and clean it out.

---

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

Modicum V1 sold on e-bay user jaguarking11

I have changed the bearing, changed the gear, made temperature higher (230 degrees). Results are a bit better, but still pretty much the same issue.

here is a video
[onedrive.live.com]

Quote
Capinho
I have changed the bearing, changed the gear, made temperature higher (230 degrees). Results are a bit better, but still pretty much the same issue.

here is a video
[onedrive.live.com]

I see, what kind of speed are you feeding the filament through? It is possible your over-saturating your hot end. What kind of orafice does your hot end have .4mm .5mm .3mm .2mm? It also does sound like your motor is skipping. One more thing, how long is your bowden tube?

---

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

Modicum V1 sold on e-bay user jaguarking11

My feedrate for extruder is set to 50 mm/s in Marlin software. My nozzle is 0.4mm atm, at first I had 0.25 mm. My bowden tube is about 50 cm long. Skipping might be appearing when i thightened bearing all the way possible

Tighten up your bearing tension and slow your extrusion speed way down. You should only be extruding no more than about 5mm/s, the hotend cannot melt filament at 50mm/s

Okay, I have just checked in my Marlin software, the parameter is Maximum feedrate. How to change the feedrate of the repetier buttons, so I can adjust the actual feedrate, not the maximum?
New question, do I have to define microstepping somewhere or is it enough just to have jumper pins installed? Thanks

If you are using 1/8 stepping for the extruder then change this line in configuration_adv.h

// Microstep setting (Only functional when stepper driver microstep pins are connected to MCU.
#define MICROSTEP_MODES {16,16,16,8,16} // [1,2,4,8,16]

and then half your extruder steps per mm in the configuaration.h

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,1280,490} // default steps per unit for Ultimaker

for example mine is 490 then I would change to 245.


Once you get the extruder from slipping then you need to actually measure how much filament is being fed out of the bowden tube and adjust the steps per mm more accurately. Also I read you are trying to extrude PLA through a .25 nozzle which creates tremendous back pressure for your extruder. I recommend switching to a .4 nozzle until you get your printer working then try switching back to .25 when things are working better. PLA causes a lot of friction in the hotend as it is and a .25 nozzle makes it that much harder.