PET+ on V4

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benavery
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PET+ on V4

Post by benavery » Tue Feb 10, 2015 8:06 pm

I got my V4 set up the other night, and went to start using some opaque PET+ through it, and had no end of troubles with extruder jambs. I think half the problems were my own, I initially didn't have the extruder mount on tight enough, so it wasn't seated fully, then I must have been overextruding as I discovered second half of the roll was 0.1mm bigger than the first half. But even after those were solved, I still get jamming mid-second layer. I started with the same setup from the v3b, which is 255C (which is already 10C higher than the recommended settings for the transparent PET+). I tried bumping up to 260, but had the same problem.

Any ideas ? I can post settings later - they are mostly identical to the .fff from the madesolid site, with the cooling fan disabled, and temp bumped up by 10C for the opaque filament.

I had some buildup/scraping of material on the nozzle, but even with the extrusion multiplier turned down to prevent that, I still had a jamb.

Should I expect settings from the v3b to work mostly as-is on the V4 ?

Has the extruder piece from the V4 kit been pre-drilled to some suitable size ? I'm finding it is rather difficult to pull buckled/shredded/jammed filament out of it.

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jimc
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Re: PET+ on V4

Post by jimc » Tue Feb 10, 2015 11:18 pm

well the opaque pet+ will extrude at lower temps. 235ish BUT for layer bonding purposes it should be up there where you got it. 255-265. translucent colors are good at 245. as for buckled or squished filament, that is always an issue and wont retract out. requires removat of the filament drive, cutting with an exacto knife near the bearingthen pulling the piece out with some needlenose pliers. as for your jamming. be sure your first layer is not too close to the bed and your blocking the nozzle. also be sure your tension on the filament is not too high. the bearing can squish the filament into an oval so it will get stuck and not slide through the lower hole. pet+ is softer so it will do this easier than pla and abs. other than that i am unsure what else on the v4 could cause this. assuming the filament isnt oversize.

benavery
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Re: PET+ on V4

Post by benavery » Wed Feb 11, 2015 12:32 am

I was thinking here it might be temps as I was getting similar jamming issues with v3b at 245, and 255 fixed it - though maybe I managed to tweak something that reduced nozzle build-up at the same time and the temp increase was never the problem - if you are saying as low as 235 should work too.

The filament is somewhere between 1.82 and 1.87 in diameter - maybe its on the upper end of what the V4 extruder has been bored out to handle. I might do a few ABS prints tonight to just make sure everything is working right before trying pickier filament.

Good tip RE the tension, I actually increased that at some point while debugging thinking maybe the extruder didn't have enough grip, but possible I made it worse.


(I'm a software engineer, so am acutely aware that successful debugging is changing one thing at a time, but am obviously too impatient when it comes to 3d printing, and have tried 800 different things all at the same time, and probably keep making it worse!)

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jimc
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Re: PET+ on V4

Post by jimc » Wed Feb 11, 2015 12:52 am

interesting. 1.87 is really big. if the v4 has the same bore as the v3b then it should clock in at 2mm. the filament path in the plastic drive however is not usually drilled out. a horizontally printed hole is never perfectly round either so the 2mm can be off. i have a 2mm bit here. i always run it through my filament drive to make sure the bore is perfectly straight, smooth, round and to spec. if yours is say 1.95mm for instance and the filament is 1.87 then just a slight amount of tension on it can squish it enough to where its wider than 1.95mm causing a jam. another thing to take into account is that as the filament warms up it will also expand a little. not sure how all that works out on the v4. that would probably be more of an issue once it gets into the hot end rather than the plastic drive path since the 2 arent touching.

i had a spool of taulman bridge that clocked in at 1.90. i could not get that to extrude at all without jamming and that was with my drilled to spec drive unit. i have never had a roll of pet+ that far out of spec. their stuff was always dead nuts on 1.75 or so. i would do a little digging to be sure then contact them about the spool. im sure they will send you another.

benavery
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Re: PET+ on V4

Post by benavery » Wed Feb 11, 2015 1:47 am

Wonder if its been left out in the open and absorbing moisture, I would guess so, but 1.75->1.85 is a pretty significant amount, 11% by volume, so couldn't be moisture. I'll dig around on the roll tonight and check if its that big everywhere, and if its that big when cold. I do have my printer in a cabinet now, which sits at about 29C/84F, but again, 11% increase couldn't be explained by a 10F ambient temp change I wouldn't think (temperature inside the extruder from radiant hotend heat would be way above that)

I'll run a 2mm drill bit thru the extruder and see how that goes too.

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jimc
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Re: PET+ on V4

Post by jimc » Wed Feb 11, 2015 2:03 am

no the pet+ and petg filaments dont absorb moisture like abs, pla, nylon.

benavery
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Re: PET+ on V4

Post by benavery » Wed Feb 11, 2015 8:34 am

Thanks for your help Jim. I think the problem is with filament diameter. I reamed the extruder out a bit with a 2mm drillbit, and it removed a small amount of plastic. Got about 10 layers into a print this time before jamming. In its jammed state the point the filament was feeding in measured 1.90mm. After extracting the filament, particularly the piece below the extruder gear, then trimming off the mangled bits, it was extremely tight to try to push it back in. The slight indentations of the extruder gear teeth alone are enough to push the diameter out to exactly 2mm, and that was with the tension quite loose

I took a quick look at my v3b, and could easily slide the piece of filament though the drive parts in that - so that was made with a much larger hole (Must be ~2.2mm - I can easily slide 2mm filament in, can't fit a 2.35mm drill bit in there)

Anyways, I've let Madesolid know, but for now will try some other filament.

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jimc
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Re: PET+ on V4

Post by jimc » Wed Feb 11, 2015 1:35 pm

Yeah thats too big. As i said their stuff is normally right on the money.

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