Problems feeding flexible filament

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jimc
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Re: Problems feeding flexible filament

Post by jimc » Mon Apr 28, 2014 5:22 am

toby, you should really run a drill bit down the filament drive. it is a 3d printed part and horizontal holes never come out perfectly round. you need a 3/32nd drill bit

Toby
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Joined: Wed Apr 09, 2014 9:44 pm

Re: Problems feeding flexible filament

Post by Toby » Mon Apr 28, 2014 5:53 am

jimc wrote:toby, you should really run a drill bit down the filament drive. it is a 3d printed part and horizontal holes never come out perfectly round. you need a 3/32nd drill bit
Thanks, I'll give that a try tomorrow.
jsc wrote: 2. feed the filament off the gear into the hot end, then mount it. A friend with an M2 has done this successfully.
That's what I've been trying to do. And I actually just got lucky- by fiddling around with the hot end while it was in the filament guide, I got the filament to enter into it. For whatever reason on my filament drive the alignment is not perfect. I can feel the resistance at the point of entry even when hand feeding PLA.

After getting it to go into the hot end I just had to loop a bit of dental floss around it from the opening where the cylinder was, pull the filament out of the way, and remount it on the gear. Then put everything back together, turn on the M2, etc., and it extruded successfully. Woot!

Unfortunately I was only doing this testing on a piece of filament that was about 10 inches long. I was able to print two layers of the perimeter of a 3" square before I had to kill it. But hey, it went down smoothly, stuck to the bed, and now I've got myself a rubber band I didn't have before:)

I think tomorrow I'll try again with the whole roll attached and see about printing something interesting with this stuff.

markb
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Joined: Tue Apr 15, 2014 11:06 pm

Re: Problems feeding flexible filament

Post by markb » Mon Apr 28, 2014 4:06 pm

I had the same issue and rsilvers' filament drive (http://www.thingiverse.com/thing:267137) works much better on mine. I printed up a spare of his drive in ABS just in case.

jbarnhardt
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Joined: Wed Apr 09, 2014 10:56 pm
Location: Seattle, WA

Re: Problems feeding flexible filament

Post by jbarnhardt » Mon Apr 28, 2014 7:22 pm

FYI I have a slight filament feed alignment problem most times I load the machine - the filament (PLA, ABS and PET+ so far - all similar symptom) will go in until just past when it is engaged by the gear, and then hits an obstruction (I presume it's missing the bottom side hole, just past the gear-bearing interface) and the extruder stepper starts skipping. A combination of loosening the filament feed tensioner and (most importantly in my experience) rotating the filament such that the natural curve direction (the way it's curved due to coming off a roll of filament) is toward the right hand (bearing) side of the filament feed mechanism has allowed me to get past this every time so far. I have printed off an rsilvers filament feed housing to hopefully improve this but haven't installed it yet. FYI.

-John

MarkG
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Joined: Thu Apr 10, 2014 6:29 pm

Re: Problems feeding flexible filament

Post by MarkG » Mon Apr 28, 2014 7:51 pm

I can relate further problem, not just with the hole, but also with the seating of the hot end in the filament drive. I had been having lots of clogging problems with one of my drives for months, and I finally got frustrated with the drive and with a pair of plyers, tightened the peek hot end against the drive. "Pop" ... I thought I had broken something, but it turned out that the hot end had never really seated the right depth into the drive. No more problems with that hot end for a while. Percussive Maintenance.

Mark

jsc
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Re: Problems feeding flexible filament

Post by jsc » Mon Apr 28, 2014 7:53 pm

The stock hot end has a very (very!) tight fit. rsilvers' drive has modified that tolerance to be "snap fit". I find it a better fit; some people report that they think it is too loose for them and shim it tighter.

Toby
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Joined: Wed Apr 09, 2014 9:44 pm

Re: Problems feeding flexible filament

Post by Toby » Mon Apr 28, 2014 8:22 pm

I like the snap fit idea better. I've just ordered some ABS from pushplastic and will print rsilvers filament drive when it arrives.

I'm getting better at feeding this flex polyester filament by hand, but still haven't tried a real print. It helps to pare down the tip to as sharp a point as possible, cutting in from both sides so the tip is more centered.

meanwhile I wrote the vendor of the flex polyester (pastic2print.com) and they're responsive. I got two rolls from them, the black seems to have some issues with diameter not being consistent (from 1.77 to 1.91), but the white seems to be spot on at 1.75-1.77. And it's the white that I've been able to feed by hand sporadically.

Maybe they will have some additional ideas. Once I got it feeding I was happy with how it extruded. Very clean and straight and laid down beautifully on the bed.

Toby
Posts: 330
Joined: Wed Apr 09, 2014 9:44 pm

Re: Problems feeding flexible filament

Post by Toby » Thu May 01, 2014 4:19 am

I finally got this stuff to print. Here's what I did make it work:

Pare the filament tip to a sharp point on several sides, so the tip is in the center.

Load the filament by taking the filament drive off the gear and hand threading it through the drive and into the hot end.

Mount the filament reel a few feet above the M2 directly over the filament drive.

Switch to a .5 mm nozzle and set the extrusion multiplier in S3D to .9

Send the command M203 E1 before doing any extruding. It slows the feed rate down to 1mm/sec. Also put the same command in the S3D start script.

Print at .25 mm layer height with retraction turned off and print speed set to 900 mm/min. No outline underspeed or first layer underspeed. The idea is to keep the filament flowing at as constant a rate and pressure as possible.

The manufacturer also recommends modifying the filament drive so that the hole from the gear to the hot end is large enough to accommodate a piece of PTFE tube with an inner diameter of 1.9mm

It printed slow as molasses but just getting it to work was good enough for me. And the stuff is bendy:
polyflex.JPG
polyflex.JPG (36.3 KiB) Viewed 5938 times

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