flexible filament help

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walshlg
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flexible filament help

Postby walshlg » Wed Aug 31, 2016 11:20 pm

new to flex filaments, Polymaker PolyFlex loaded, finally got the 2x2x1 cm cube printed but it keeps jamming. It unloads with a kinked up bunch usually. Latest, I thought retraction was jamming it, but its jamming on the raft 2nd layer! I'm printing at 230, speed 30, shells bottom and top at 20,had increased retraction to 2mm, set it back to 1, left retraction speed alone.

here is the latest failure, not sure where to go from here.
Attachments
20160831_184736.jpg

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Vicky@Raise3D
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Re: flexible filament help

Postby Vicky@Raise3D » Thu Sep 01, 2016 10:34 am

What filament did you print with this hotend before? Is that some high temperature filament?
Heat the nozzle to 240C and dredge it with steel wire to check whether there is something inside.

Then load polyflex with 220C for a little while. Check whether the loaded filament is thin or normal or normal at first but then become very thin.
If extruded very hard, try a little higher.

Check whether the hotend has leakage.

Check whether the cooling fans are working.

Or the nozzle is not in a very good condition. Replace a new nozzle may help.

Did you print with extruder front cover?

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walshlg
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Re: flexible filament help

Postby walshlg » Thu Sep 01, 2016 2:52 pm

was using the nice raise3d PLA in that nozzle before
the flex loads fine, extrudes a nice solid stream for 2 meters before I stopped. BTW it pushed out the pla easily.
I started printing at 230, also did 225, I'll try 220 and lower too - only issue was it was really quite runny, looked overheated to me and also overextruded a bit so setting flow to 98%
no hotend leak, cooling fans working, I do not have bottom fan covers on - should I?
this is a 1 month old nozzle and when it works, the flow is excellent.

The problem seems to be a jam up high (my conclusion since the unloaded filament is all twisted up) but this must be caused by something jamming down below.

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Billucas
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Re: flexible filament help

Postby Billucas » Thu Sep 01, 2016 4:32 pm

''The problem seems to be a jam up high (my conclusion since the unloaded filament is all twisted up) but this must be caused by something jamming down below. ''

From John :
For flexible filament, please print it in left extruder.
Do you have the acrylic extruder cover installed? If not, please install.
Let the filament free, not in the guide tube.
There are 4 screws holding the motor and loose those you can adjust the gap. ( I solved my problem with this recommendation! )
Also do not forget the clean the gear.

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walshlg
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Re: flexible filament help

Postby walshlg » Thu Sep 01, 2016 4:38 pm

OK using guide tube, will remove, need to clean gear - certainly have neglected that.

Adjust gap -> which way tighter or looser? It certainly pulls hard when I hang on to it!

I'm printing at 200um layer thickness, is that too low?

what temperature do you like?

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Billucas
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Re: flexible filament help

Postby Billucas » Thu Sep 01, 2016 5:46 pm

For the Gap, it is better closer, to touch the small pulley. I realign the step motor to have a better alignment, straight.
I only tried TPU for now. I like between 235-260c on my TPU to get different hardness. The bed is at 80c.
For layer thickness, 0.15mm is ok for me.
Attachments
extruder head.jpg
Picture 7.jpg
Last edited by Billucas on Fri Sep 02, 2016 12:28 pm, edited 1 time in total.

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Vicky@Raise3D
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Re: flexible filament help

Postby Vicky@Raise3D » Fri Sep 02, 2016 5:43 am

You can insert a cardboard paper as a shim at the left side of the motor to ensure the feeding gear is close enough to the bearing.
Extruder Shim.jpg

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walshlg
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Re: flexible filament help

Postby walshlg » Fri Sep 02, 2016 2:05 pm

More thoughts:
I failed to mention that after this jam it is very difficult to unload the filament without heating up the block to 250. THis has me thinking that it is an isolation tube clog - hence my worry about retraction and my doubts on extruder driver failure. Another finding is that there is no ground down area on the filament, rather the stepper is failing! I put a mark on the gnurled drive wheel and you can see it bounce up and down, not continuing to turn. Me trying to help pushing the filament in is not productive. I took the filament out of the guide tube - yes there was a lot of friction - the filament has a lot of stiction, and I ran that over a single high support. Filament was hand loosened and it still clogged.

Along this line, I tried decreasing the temperature to 220. It extruded fine and still jammed after about 30 min. So next I'll try going over rated temperature range (rated from 220-235 C) and also increase and decrease the extrusion rate.

Any suggestions are welcome

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Re: flexible filament help

Postby Jetguy » Fri Sep 02, 2016 2:17 pm

I've printed some flexible filament and yes, I found that 4mm OD -2mm ID guide tubes depending on the exact material (not all PTFE tubes are the same) can drag filament and cause extra force making it fail. I also found that some spools of genuine Ninjaflex are stuck such that you have to unwrap several meters of filament and roll back up.

I long ago moved from the stock feeder, it's not worth the time to troubleshoot when you get into this situation. Between the mass of it, the fixed distance idler, and just limited adjustments and limited grip on flexible filaments even after workarounds, the Bondtech was an easy decision.

Jetguy
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Re: flexible filament help

Postby Jetguy » Fri Sep 02, 2016 2:20 pm

What I'm saying is, if you optimize everything including filament feed from the spool, then the stock extruder can work. I've seen it.
But you have to remove all limitations, drag, pay special attention, adjust the feeder for maximum pressure (the shim mod).
And then it's still potentially on the edge, and failure is not 100% preventable.

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walshlg
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Re: flexible filament help

Postby walshlg » Fri Sep 02, 2016 2:34 pm

thanks, was coming to that conclusion

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Billucas
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Re: flexible filament help

Postby Billucas » Fri Sep 02, 2016 5:55 pm

I am curious; Finally, did you tried this solution ''There are 4 screws holding the motor and loose those you can adjust the gap'' ?
It solved all my problems. Now I can let print the machine alone, and I am happy guy know!

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walshlg
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Re: flexible filament help

Postby walshlg » Fri Sep 02, 2016 7:41 pm

I will try that. I don't think that is the problem because after a jam there is a mass of filament all twisted up in the top - hence, I don't need to push more filament in, I need it to come out

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walshlg
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Re: flexible filament help

Postby walshlg » Mon Sep 05, 2016 8:52 pm

OK Latest Findings:
I have been having a tough time believing that my problems are related to feeding because it pulls so hard that I am physically unable to stall the stepper, yet when the filament jams it doesn't eat up the filament, rather it makes the stepper skip.

Instead, I have had to increase the temperature so high to prevent jamming that the filament becomes liquid and oozes and drips out of the nozzle faster than it feeds, making dropouts - as if it is too hot and liquid.

SO what helped -> I replaced the stainless steel nozzle with the original brass and covered the bottom of the cooling fan. This maintains the temperature of the nozzle more efficiently. Sure enough, its printing much better, still some dropout at 225 but not too bad. Pictures when the print comes out, assuming it comes out.

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walshlg
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Re: flexible filament help

Postby walshlg » Tue Sep 06, 2016 10:32 pm

20160906_182228.jpg
SUCCESS!

lessons:
1) print with brass nozzles only for flexible filament
2) If you have to heat it up out of its print range, then it is too hot, it will drip like water and cause dropouts
3) The filament may jam after a print when left to cool overnight. If this happens, heat up to 240, unload, trim and load again. Cool to print temperature (225 for me) and ensure that it loads properly at that temperature.
4) Imagemaker supports worked very well, even with flexible filament, I used sparse connection.
Attachments
20160906_174620.jpg

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Billucas
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Re: flexible filament help

Postby Billucas » Tue Sep 06, 2016 11:20 pm

Good! Happy to see that is working for you. Thank you for sharing.

NewbPilot
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Re: flexible filament help

Postby NewbPilot » Thu Sep 08, 2016 4:47 pm

walshlg wrote:OK Latest Findings:
I have been having a tough time believing that my problems are related to feeding because it pulls so hard that I am physically unable to stall the stepper, yet when the filament jams it doesn't eat up the filament, rather it makes the stepper skip.

Instead, I have had to increase the temperature so high to prevent jamming that the filament becomes liquid and oozes and drips out of the nozzle faster than it feeds, making dropouts - as if it is too hot and liquid.

SO what helped -> I replaced the stainless steel nozzle with the original brass and covered the bottom of the cooling fan. This maintains the temperature of the nozzle more efficiently. Sure enough, its printing much better, still some dropout at 225 but not too bad. Pictures when the print comes out, assuming it comes out.


Interesting because I've been printing my Sainsmart TPU at 235 and it's been pretty good. I wanted to go cooler, but each time i did, it gave me problems. I'm also concerned because I just bought the SS nozzle to swap out my stock brass nozzle and since i want to print a lot of TPU, it may be $15 wasted.

snowcraft
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Re: flexible filament help

Postby snowcraft » Sun Sep 18, 2016 2:17 am

walshlg wrote:
20160906_182228.jpg
SUCCESS!

lessons:
1) print with brass nozzles only for flexible filament
2) If you have to heat it up out of its print range, then it is too hot, it will drip like water and cause dropouts
3) The filament may jam after a print when left to cool overnight. If this happens, heat up to 240, unload, trim and load again. Cool to print temperature (225 for me) and ensure that it loads properly at that temperature.
4) Imagemaker supports worked very well, even with flexible filament, I used sparse connection.



Do you use imagemaker to generate the support? Can you share more infomation about the software? or you just meant the ideamaker?

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walshlg
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Re: flexible filament help

Postby walshlg » Mon Sep 19, 2016 4:58 pm

SUPPORT: Image maker works well BUT NEVER use support less than about 1 cm thick or you will NEVER get it off. Also set the support gap up to something like 200um. (default is 100um iirc). So if something needs a thin support, raise the entire model up by 1 cm and let it support everywhere!!

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walshlg
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Re: flexible filament help

Postby walshlg » Fri Sep 23, 2016 4:33 pm

NEW PROBLEM: not sticking to build plate

on larger objects they keep popping off the build plate after about an hour or 2 of printing. Last print at 50C with hair spray. Some parts stuck well others not, I don't know why. ANyone else notice this??

THis is with polyflex, now the ninja is here - likely to be even worse. But first - reprint the mangled fan ducts!


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