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Bowden tube - different grades of PTFE tubing?

Posted: February 10th, 2016, 6:06 pm
by ChrisR
I've recently been playing about with a different material (than the stock bowden tubing supplied by UM) which has a lot less friction. Just get two curves of each tube and push some filament through by hand and you will see what I mean.

As an aside, I've always thought the curve of the filament should naturally follow the curve feed of the bowden tube - path of least resistance etc., pretty fundamental I think. A 90 degrees bend may be ok... as you're asking the filament to twist sideways, but 180, and you're asking for buckling.

I've always found I had fewer problems with the loose more "open" coils = easier on the feeder (as they more closely follow the bowdens curve) - such as those supplied loose from Faberdashery.

The tubing I'm now using in my two UM2s are from Adtech Polymer Engineering ltd., They are (PT1/8X1/4) (3.2x6.35mm)
Very pleased to date. Torture test cylinder is no problem on either of two machines.

Pros: Much less friction than stock UM tubes.
Cons: Physicaly these tubes are stiffer than stock UM tubes. But no problem printing - so far?
Price? More costly.

edit: typos - sorry

Re: Bowen tube - different grades of PTFE tubing?

Posted: February 10th, 2016, 6:08 pm
by ChrisR

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 10th, 2016, 7:04 pm
by LePaul
Do you have to flange the opening to fit the print head or extruder?

I thought you had to do a step to make them work right?

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 10th, 2016, 10:39 pm
by Anders Olsson
The original bowden is made from PFA, not PTFE, which could be part of the explanation to the reduced friction.
I remember discussing this with Ultimaker long time ago, and as I remember it not even people at Ultimaker could recall why they went for PFA :)
It could be because PFA is more transparent than PTFE i suppose, which makes it easier to see the filament moving inside the bowden tube.

I doubt that a slightly stiffer material in the bowden will affect printing quality. There are other design issues in the Ultimaker gantry that have much more impact on the printing quality I would say.

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 11th, 2016, 11:42 am
by ChrisR
LePaul wrote:Do you have to flange the opening to fit the print head or extruder?

I thought you had to do a step to make them work right?
They fit just perfectly. :D But... I did use a large drill to flange the opening just to help when first inserting filament.

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 11th, 2016, 11:48 am
by Titus
I still have trouble with the UM bowden with flange to insert filament while the the bowden is in the UMO feeder. It just gets stuck :(

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 11th, 2016, 11:52 am
by LePaul
Mine used to squeak a lot until I made an adapter pieces.

I also struggle to feed the filament into the feeder when it is time to change rolls. I really have to work hard to guide the filament against the feeder head and into the tube.

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 19th, 2016, 1:58 pm
by drayson
@ LePaul - had the same issue so I first checked if I mounted the bowden the corect way (one end is widened). that worked fine but lately I modified/printed this part to make the entry more straight: http://www.thingiverse.com/thing:1178679

... I might have found this hints app. 2 weeks ago... I recently ordered a few spare parts at igo3d - and there are also 2 bowden tubes in the package... :-(

PS: hope it is ok to link to thingiverse...
PPS: have you ordered samples or placed a "real" order there?

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 19th, 2016, 3:01 pm
by LePaul
Thingiverse, YouMagine....all fine to me

How does that install? Pictures help!

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 19th, 2016, 3:23 pm
by drayson
Sorry, my fault... I had pictures there but not posted them...
Basically remove the grey bowden coupler at the feeder (I got mine out without disassambling...)
Screw this grey bowden coupler into the printed one (the black T-Nut at the picture) and push it in place into the ply.

Holds rock solid and has a tight fit internal diameter :-) ;-)

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 19th, 2016, 3:24 pm
by drayson
Updated thingiverse too...

Re: Bowden tube - different grades of PTFE tubing?

Posted: February 19th, 2016, 3:33 pm
by LePaul
Good to know I am not the only one who goes crazy trying to feed curly filament into that opening!