Experience with Capricorn PTFE tube



  • Hi,

    I recently changed my PTFE tube, in my "flying Extruder" configuration, approximately 20 cm long, for a PFTE Capricorn tube ..., thinking that it would be an improvement, I have the problem, that from time to time, the tube Capricorn PTFE slides from the Bowden adapter on the extruder ... ruining the print.

    Does anyone have similar experience / problems with this PTFE tube?
    With the PTFE tube (normal) I did not have these problems. Any ideas to solve it?
    What are the reasons why the PTFE tube slips? (It is assumed that it does not have to support almost tension, it is a simple guide for the filament)



  • @peirof said in Experience with Caprocorn PTFE tube:

    Hi,

    I recently changed my PTFE tube, in my "flying Extruder" configuration, approximately 20 cm long, for a PFTE Capricorn tube ..., thinking that it would be an improvement, I have the problem, that from time to time, the tube Capricorn PTFE slides from the Bowden adapter on the extruder ... ruining the print.

    Does anyone have similar experience / problems with this PTFE tube?
    With the PTFE tube (normal) I did not have these problems. Any ideas to solve it?
    What are the reasons why the PTFE tube slips? (It is assumed that it does not have to support almost tension, it is a simple guide for the filament)

    Yes, I had exactly the same problem. I think it's because the Capricorn tubing is made to tighter tolerances than "standard" PTFE. I measured mine and it was 4.03 mm OD, whereas the "standard" PTFE that I use is 4.10mm OD. I think that is enough for the Bowden clip not to grip tight enough. Either that or the surface of the Capricorn tubing is smoother and more slippery.

    My solution was to fit two Bowden clips. I made my own longer design which are a bit easier to get hold of and you can find them here https://www.thingiverse.com/thing:2679119. I fitted one clip, then sort of wedged a second one underneath.

    I had great hopes that with this Capricorn tubing, I would be able to reduce the amount of retraction needed but sadly that wasn't the case. I don't know why, maybe it's because my tubes are only about 150mm long but it does nothing for me. So longer term, I'll simply go back to "standard" PTFE.



  • I found that printing a set of clips with increasing thickness helps. Just select the one that fits with no play. After using for a while, I noticed a bit of play developing, but cured by substituting a clip 0.1mm thicker. I think the capricorn helps - I have a approx 600mm bowden on my delta, and 2.8mm retraction works fine.



  • Ok lets get this out of the way from the start.

    Capricorn appears to be a brand name only. the company DOES NOT appear to manufacture any tubing and they dont specifiy the tolerance of their "Capricorn" tubing.

    It is a marketing ploy and the company uses a commercially available industrial tubing and in all likelyhood it is not even PTFE in construction. Ask Capricorn for a MSDS I dont think they will easily or happily oblige.

    From the piece of capricorn tubing I held it appears to be more of a commercially available product used for Pneumatic applications in heavy automotive and marine enviroment applications.

    I also know that the marketing ploy is making the smart guy who thought it up a stack of cash because I know for a fact that if you purchase a roll of the commercially availabe stuff from Pace or Stauff you will get it at a price per 1m of the stuff cheaper per meter than the price they are charging per 100mm

    But hats off to them they have tapped into a market where the gullible bought the hype hook line and sinker, as you guys are now sadly finding out. Capricorn tubing will die out as they get found out more and more, but by that time they will have sold a shed load of the stuff at their hugely inflated price and will move on to something else.



  • Wow. Kinda bitter, eh? Oh, and thanks for labeling hundreds or possibly a few thousand of your fellow hobbyists as "gullible." It's not like we all are chemists or deal with tubing professionally.

    I'm just a customer, not involved with their company in any other way. However, they do specify the tolerance of both styles for 1.75mm, though for 2.85 filament I only saw the ID spec'd (though I didn't look too hard). And, if it isn't PTFE, they go to a lot of trouble discussing and providing safety considerations for it. If their tubing was involved in a fire, and somehow didn't behave like PTFE, there's room for litigation. That would be a huge risk on their part.

    Is it an existing commercial product that they're putting a spin on? Perhaps. But the vast majority of hardware used in our printers either already existed commercially, or is only a step away. Are they making an obscene profit off it? Perhaps, but if their tubing really is what they claim it to be, they undoubtedly invested a lot of time and money before they ever turned a profit, and deserve to be rewarded. That's called entrepreneurship.



  • @calvinx Capricorn tubing (the genuine stuff) is made by a company called Captubes.com. Web site here https://www.captubes.com/. Technical spec is here https://www.captubes.com/specs.html


  • administrators

    I was able to reduce my retraction distance from 7mm to 6mm after I switched to Capricorn tubing (bought from E3D so it should be genuine) - a small but significant improvement. I didn't have any problems with it coming out of the E3D collets. I use the standard E3D collet clips.



  • @calvinx

    I would agree with most of your points, but that shouldn't reduce the technical validity of the product.

    From a physics standpoint, having the smallest gap between the tubing and the filament will decrease the retraction length and potentially increase the maximum advance pressure (due to a reduction of filament buckling). The lower friction is more obvious, and also has an import role to play in the system.

    Although an ideal gap is around 0, you have to make sure that the filament maximum diameter won't ever be bigger than the minimum tube diameter - thus tube tolerance is an important parameter in the design. If a startup company were to produce their own tubing, I'd expect the tolerances wouldn't be anywhere good enough to prevent jams while maintaining the closer fit. So the most logical step would be to either partner with a larger company, or simply buy it directly from them.

    Also, regarding the friction - the tubes I have do in fact feel more slippery than most PTFE tubing. I'm not sure about the additive they claim to add and how it affects it, but they sure have a superior surface finish on their tubing. The finish alone will substantially reduce the friction with the filament.

    I believe that the 3D printing industry went with the standard 4mm OD tubing solely due to the fact that it was already available in quantity - but that doesn't mean that it was ever optimized for the application. Capricorn is targeting that assumption with their business model - and in my opinion for the high-end commercial printing market, they bring value to the industry.



  • i had similar problem.
    However for me it was the varying diameter of the filament.
    Also it could be a failing pressfit connector. Check this review of different couplers
    http://thrinter.com/bowden-coupler-review/



  • I have Caprocorn too. I fixed it on both ends with some 3d printed brackets and reinforced my tube with some glass fiber tape (TESA MONOFILAMENT) and this way I get retraction under 2mm with 60cm bowden tube (for PLA).



  • @dragonn said in Experience with Caprocorn PTFE tube:

    I have Caprocorn too. I fixed it on both ends with some 3d printed brackets and reinforced my tube with some glass fiber tape (TESA MONOFILAMENT) and this way I get retraction under 2mm with 60cm bowden tube (for PLA).

    The printed brackets do you use.... are downloadable? Thinguiverse maybe? Url?

    Thanks



  • @peirof said in Experience with Capricorn PTFE tube:

    @dragonn said in Experience with Caprocorn PTFE tube:

    I have Caprocorn too. I fixed it on both ends with some 3d printed brackets and reinforced my tube with some glass fiber tape (TESA MONOFILAMENT) and this way I get retraction under 2mm with 60cm bowden tube (for PLA).

    The printed brackets do you use.... are downloadable? Thinguiverse maybe? Url?

    Thanks

    One of them is integrated with my hotend mount:
    0_1541375573730_bf71939f-b84a-458e-a3bf-05791219b1e3-image.png
    The other one on the extuder is that one https://www.thingiverse.com/thing:2868047


 

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