Printing without PTFE-tube.

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stormychel
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Printing without PTFE-tube.

Post by stormychel » Fri Sep 19, 2014 4:26 pm

Can the PTFE-tube be the cause of jams, by being too restrictive?

Have a big print that has failed 5 times now, everytime it started air printing half or 3/4 trough the print...
Now I'm trying it with PLA, and it failed too, air printing the raft.

I noticed the ptfe tube seems to bend the filament in an unhealthy manner... what about taking it out? Any reasons not to?

thanks
@stormychel

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DrewPetitclerc
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Re: Printing without PTFE-tube.

Post by DrewPetitclerc » Fri Sep 19, 2014 5:01 pm

Your problems could be due a multitude of factors, the supply tube from the roll to the extruder is probably not the issue, easy to check, can you pull plastic through with little resistance?
The issue is most likely:
1. buildup of foreign material in nozzle, hair, dust, skin cells, whatever is floating around in the air.
2. plastic diameter tolerance, larger than 1.7mm diameter in a section, an un-modded extruder has no capacity to handle larger or smaller diameters of plastic.
3. heat buildup from the extruder motor traveling to the feed gear, pre-softening the plastic, strip-out/clicking

Last, Natural PLA (clear) likes to jam in the barrel before the nozzle tip, this is due to the swelling effect of the plastic as it heats up and the PLA gets "sticky" in the SST barrel, this has been avoided in the past by home builds because they generally use a PTFE tube as a heater barrel and this allows the plastic to flow easier.

Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

stormychel
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Re: Printing without PTFE-tube.

Post by stormychel » Fri Sep 19, 2014 5:49 pm

So this printer is off-factory incapable of printing PLA without problems? Guess I need to make use of the warranty then, as it was clearly sold for ABS and PLA printing... Because ABS has the same issues, but later on the print, the thing is useless without mods?

I will try to clean the extruder tomorrow, didn't expect to need to do this after 2 weeks of owning the thing... seems like a bad investment.

Thanks for your reply!
@stormychel

stormychel
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Re: Printing without PTFE-tube.

Post by stormychel » Fri Sep 19, 2014 8:45 pm

Update, printed the same model in OEM white ABS - with PFTE-tube- , came out perfect. Measured the black non-oem ABS and PLA, bot measure well around the 1.75 in diameter, more like 1.72 & 1.70. As the teeth of the feeder are clearly visible I guess it still grips, but excess heat is the problem, not diameter. Will buy the Octave temperature mod and test with lowest temperature possible.
@stormychel

pleppik
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Re: Printing without PTFE-tube.

Post by pleppik » Fri Sep 19, 2014 9:04 pm

stormychel wrote:So this printer is off-factory incapable of printing PLA without problems? Guess I need to make use of the warranty then, as it was clearly sold for ABS and PLA printing.
It should work with PLA if you use the Up-brand PLA filament. Other brands, not so much (without modification).

roller
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Re: Printing without PTFE-tube.

Post by roller » Sat Sep 20, 2014 4:32 am

Not that it's the issue here but just to respond to the initial question the PTFE tube can actually be the cause of jams. It can get pinched on the spool end. It happens much more easily if the end of the tube is split or otherwise damaged. I've had it happen once - took me a while to realise this was the issue. It behaved like I had a jam but every time I fed by hand it was fine and the filament would always move fine initially but the pressure at the pinch point would build up over the print and fail after about 10+ layers.

stormychel
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Re: Printing without PTFE-tube.

Post by stormychel » Sat Sep 20, 2014 8:23 am

It's not split or pinched, but I had the feeling it was too restrictive.. maybe because it's a little long... I think a better design for it would be for the filament feeder and extruder head to have a 'tube' where the filament tube sits in for 5mm or so (sorry for the bad English, I hope you understand what I mean), maybe I can model and print these parts to be able to fit the tube in them...

But first, will buy 2 potentiometers of around 30 ohms today, one for a quick patch cable and one to put on a small perfboard with a display to show the target temp on (I'm an Arduino hobbyist so this should be possible with an Attiny85 on it)... This would allow me to lower the temp with 80 degrees celsius (at 30 ohm) if I did my research well on this and other sites. Would bring 260 down to 180 for ABS (I would start at 220 with the filament I have now) and 130 for the PLA setting (the PLA I have is rated 190-200 (RRW Dutch PLA), which I would also test at 190 first to keep the feeder motor as cool as possible). At first I wanted the Octave 8-temp adjuster, but with shipping this would cost me around €100 euros which is a little too much for something that can be solved better with a potentiometer... :|

If this mods work out I'm done modding as I bought this printer for simplicity (have enough soldering to do with the Arduino stuff already :) ), if the gears still strip I will look into a way to cool the feeder motor... I hope I don't have to though as I preferred this printer over a Da Vinci 1.0 for the possibility to use other spools than OEM, research told me that a lot of sites sell compatible spools for this printer, but I guess the sellers are a little optimistic about this... The RRW Dutch PLA is listed as compatible, while it is rated for 190 to 200, and as far as I know the UP extrudes at 210...
@stormychel

roller
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Re: Printing without PTFE-tube.

Post by roller » Thu Sep 25, 2014 7:31 am

Mine didn't appear pinched, instead there was a little split int the bottom of the tube. Under the pressure of printing this collapsed to form a pinch on the filament. Was maddening to troubleshoot. Fix was simply snipping off the damaged part. I have printed rings for the end of the tube to limit future damage. This is not useful to your issue but just FYI on the original question.

If you want a nice temp mod I can do one for you for $30USD plus postage as another user has me making another batch up this weekend. Ugly first versions here:

http://www.pp3dp.com/forum/viewtopic.ph ... tch#p26708

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