Extruder idle lever tension - stops extruding

Hi. How tight do you run your idler lever tension? I find that I have to run it really tight, otherwise I get a lot of slippage and extrusion stops. This doesn't seem right though? I dismantled and cleaned the hobbed gear yesterday, and I'm experimenting with prints. At the moment I can't even print the stock robot file without it stopping part way through, and I keep tightening the lever. If it makes any difference, I'm printing with Rigid Ink PLA at 195' (first layer 210').

Thanks.

Edited 1 time(s). Last edit at 11/07/2016 01:29PM by pixelseventy2.

I had a print fail part way through last night, and since then I can't get a single print to complete without stopping extruding. I've dismantled the hot end, the nozzle and PTFE are clean. On the robot it stops each time just when it starts the body. Tried printing the whole thing at 210 if that made a difference, but it didn't. I'm concerned about putting too much load on the stepper motor, but at the same time I'm getting too much slippage or extrusion stopping. Is there another reason the extrusion could be stopping?

In fact, on the last attempt it sounded like and looked like the extruder motor was slipping a bit, before it stopped extruding completely.

Edited 1 time(s). Last edit at 11/07/2016 01:49PM by pixelseventy2.

Any ideas? I do have a spare nozzle so I can try that, and I saw some reference to increasing the current on the extruder motor, so I can try that. I've checked the diameter of the filament, and that's still within tolerance (~1.73mm), and I've printed probably 2/3 of a 1kg roll with only occasional failed prints due to extrusion failures; it's just now started failing on every single print. I've never been able to leave the printer alone, as I've never trusted it enough not to stop, which doesn't seem right; my Dad has an Ormerod 2 and he doesn't have the same issues. I print slower than the default reprap config.

@pixelseventy2

What type of extruder drive are you running?
Fisher 1's extruder driver provides 3:1 gear ratio that has more torque than Beta's one.

I replaced the stock extruder motor with 5:1 geared one because weak torque of the motor caused jamming two or three times in the past.

Motor current and acceleration in config.g controls the motor torque also.
Try Increase E### for extruder motor upto E1000 or or maxium current, decrease acceleration to E1500.

M906 X800 Y800 Z800 E800                ; Set motor currents (mA)
; 10/19 13:45 reduced extruder motor's acceleration (4000)
M201 X4000 Y4000 Z4000 E3000            ; Accelerations (mm/s^2)

Also use slow speed of retraction about 20 mm/s in the slicer program.

If it would fail to push through filament in printing, you need a stronger motor or extruder driver that has higher gear ratio.

@janpenguin. Thanks. I'm running the stock Fisher-1. My extruder current is already at 1000, as it came; I was going to try upping that to 1200. Acceleration is 4000, I'll try dropping that.

M906 X800 Y800 Z800 E1000            ; Set motor currents (mA)
M201 X4000 Y4000 Z4000 E4000         ; Accelerations (mm/s^2)

What motor did you replace it with? Or can you point me in the direction of an alternative extruder to print?

Do you have the idler tension lever tight to provide sufficient grip on the filament?

Also, how easy should it be to push the filament through by hand? I was getting quite a bit of back pressure when trying to push the filament through, is that normal? I've replaced the nozzle, and tried to make sure the filament pushed smoothly down the bowden tube to the end, but I've not tried with heat yet; only put it back together last night.

Thanks.

I did have a problem with this originally which was caused by the hex bolt going through the large gear.

The cutout for the hex head on the gear was preventing the hex bolt head going fully into the 'socket' and when
there was a bit of resistance in the filament the gear was spinning around on the bolt head...I fixed this by
dismantling the extruder and using a normal nut (not nylock in other words) on the bolt to pull the hex head
fully into the gear - it is now slightly recessed rather than sticking out, and after cleaning the bits of filament
off the hobbed gear things started working properly.

The tensioner is fiddly but mine is just using the spring to press the filament onto the gear, and there is not much
pressure - I can lift the bearing wheel away from the gear with my fingers against the pressure of the spring?

If it helps I could try and take a photo?

One other issue I had was the filament extrusion getting stuck in the hot end - caused by me not shoving the bowden
cable sleeve fully in, it ended up going in perhaps half an inch in the end? Think there must be a step inside the heatsink
for the pneumatic fitting and the filament was hitting that perhaps? With the bowden sleeve fully against
the step the filament was held in the centre and could feed into the heater block

Anyway, when I extrude now, the filament comes out of the nozzle and it didn't before!

You do have to do a bit of fettling, I have broken two sets of the print head arms already...

Regards

Chris Parsons

@cparsons. Thanks, I'll check that, too. I think it's OK, but I'll double check. I'm having to have high tension otherwise I can hear it grinding on the filament. When I rebuilt with the new nozzle I did spend some time making sure the bowden tube was screwed fully in, running a bit of filament through by hand checking for resistance. There was a bit of a change when getting to the nozzle, but it didn't feel like there was a step or anything. I'm not using the pneumatic fitting, as I've got the stock Fisher 1; I was thinking of that upgrade once I get it working again. It was running mostly OK for the better part of a year, but it's just stopped playing altogether now.

Thanks

According to this page, my stepper motors, JK42HS34-1334AC, are only good for 22 Ncm, half the recommendation on that page. Do you think it's worth upgrading to 1703HS168A with twice the torque?

@pixelseventy2

Set the current of extruder motor between 1000 (90% of maximum) to 1200, at 1000 mm/^2 acceleration.

M906 X800 Y800 Z800 E1080            ; Set motor currents (mA)
M201 X4000 Y4000 Z4000 E1000      ; Accelerations (mm/s^2)

Set the retraction speed in Slic3r to 10 mm/s.
If Fisher prints parts without failure, then you increase the retraction speed by few mm/s till printing quality degrades.

If it fails, you need new extruder that gives more torque, i.e. Greg's Wade's geared extruder (http://www.thingiverse.com/thing:961630)
or a bigger stepper motor that you linked. You probably need to print a mount plate for the extruder.

Wade's geared extruder requires a decent hobbed bolt. I got rid of mine after two or three days of testing due to filament slip.


[e3d-online.com]




I'm running a B'Struder extruder (http://www.thingiverse.com/thing:711401).


Ideal spring spec is for B'Struder:
Length: 30.00 mm
Wire thickness: 1.30 mm
Diameter: 10.00 mm


Fisher mount for B'struder
[www.thingiverse.com]

Edited 1 time(s). Last edit at 11/09/2016 10:50PM by janpenguin.

Thanks. I've ordered a new motor, and will try again with increased current and reduced acceleration. Fingers crossed!

OK, so, the story so far...

New motor, 1703HS168A, running at 1200mA. Extrusion acceleration at 1000 mm/s2. Retraction speed in slic3r 10 mm/s, length 3.4mm. New nozzle. Tensioner looser than I've had it before though. Spent the time trying to make sure the bowden tube to nozzle join was a good as I could get it.

Managed to get to 80% on this print, which is better than before, but still 20% off where I need to be.

Things to try. Increasing the current more (the motor is rating for 1.68A, and I gather the duet 2A). Tightening the tensioner a bit more. Try a filament cleaner/lubricator like this: [www.thingiverse.com]

Hi
My extruder is the internal type that came with the kit, when assembling I wanted to do everything by the book to start but thought the inlet path to the hobbed gear was just too tight a bend and kept catching when trying to insert filament. I modified the extruder block to take the inlet tube straight inline with the outlet and brought it out the top with a bend the other way as in this sketch.
.
with the heat on I can now extrude manually with just one finger turning the knob, I really can't see that the motor should need to be that powerful if the path is mechanically free. My tension lever is the original with just a slight pressure on the filament as in the instructions just enough to not slip when holding in fingers.

Keep an eye on the temperature you're extruding at, if this is too low or drops then you'll get this effect. I found my Fisher needs to print hotter than the filament suggests or I get these issues.

Quote
pixelseventy2
OK, so, the story so far...

New motor, 1703HS168A, running at 1200mA. Extrusion acceleration at 1000 mm/s2. Retraction speed in slic3r 10 mm/s, length 3.4mm. New nozzle. Tensioner looser than I've had it before though. Spent the time trying to make sure the bowden tube to nozzle join was a good as I could get it.

Managed to get to 80% on this print, which is better than before, but still 20% off where I need to be.

Things to try. Increasing the current more (the motor is rating for 1.68A, and I gather the duet 2A). Tightening the tensioner a bit more. Try a filament cleaner/lubricator like this: [www.thingiverse.com]

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DC42 Kossel 330mm x 2meters
My Thingiverse Creations

@Steve. I thought the same thing, but didn't think about changing the route completely. I might take a look at this. When it stops extruding it just grinds the filament.

@DADIY. What temperature are you printing PLA at? I know it's filament dependent, but wondered how much higher you go. I do my first layer at 210, then drop to 195. Next time it jams I'll have to remember to check the temperature at that time.

Quote
pixelseventy2
When it stops extruding it just grinds the filament.

Hi,
hope you visit the forum from time to time

I've got the exact same problem you describe: grinding the filament, stops extruding "at random", mostly with larger prints and so on.
Did you find a solution?
I changed nearly everything, From extruder motor to one more powerful, the nozzle (multiple times), the bowden tube, fan, everything. I even tried a completely different extruder, same problem. Tried different brands of filament, color, temperature, pressure of the idler, everything. Every time just one thing, then back to testing, methodicaly.

But I found a workaround: Not at all pratical, but if i smooth the filament with sandpaper, it works. Reproducable prints that would fail are going smooth that way, but 'sandpapering' for nearly 2 hours to print for 4 hours doesn't seem practical... I'm out of ideas. Did you find a solution?

Greetings,
Zuujin

Zuujin I have read about people making the filament pass in a lightly oil-impregnated sponge before getting in the bowden tube.

If you haven't already, maybe you could try that ? Kitchen (olive ?) oil could be an affordable testing product, and would not damage the filament or produce toxic fumes when heated.

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

Hi. Touch wood, mines been ok since replacing the nozzle and motor, and increasing the motor current. I also added one of these to lubricate the filament, like DuexVis suggested : [www.thingiverse.com]

I'm also making sure the filament isn't jamming on the spool. I need to make a proper filament feed at some point, rather than unravelling it manually.