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PC4 M8x1.25 Bowden Pneumatic Connectors  

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ignacmc
(@ignacmc)
Eminent Member
PC4 M8x1.25 Bowden Pneumatic Connectors

I have managed to find on Aliexpress some PC4-M8 Pneumatic Connectors (M6 and M10 are much more common). They are Pass Through type allowing the 4mm PTFE tube to enter without restrictions. Could I get rid of the three separate PTFE tubes (hotend, bowden and extruder) and use only one piece of equivalent length? Everything could be much easier, I have not had good experiences with the brass olives in the bowden part. One failed and slipped away with use and its replacement was not well installed by me and I am now waiting for new olives to arrive. I would prefer to use the good old quick release connector 😉

Posted : 15/10/2020 10:42 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors
Posted by: @ignacmc

I have managed to find on Aliexpress some PC4-M8 Pneumatic Connectors (M6 and M10 are much more common). They are Pass Through type allowing the 4mm PTFE tube to enter without restrictions. Could I get rid of the three separate PTFE tubes (hotend, bowden and extruder) and use only one piece of equivalent length? Everything could be much easier, I have not had good experiences with the brass olives in the bowden part. One failed and slipped away with use and its replacement was not well installed by me and I am now waiting for new olives to arrive. I would prefer to use the good old quick release connector 😉

I have already implemented this idea:

https://www.aliexpress.com/item/32967678995.html?spm=a2g0s.9042311.0.0.63fb4c4dIhAxxY

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 15/10/2020 7:53 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

Indeed. And if you have some M6 at hand, you an get quick fix by printing this adapter while waiting for M8 to arrive. There may be M10 somewhere as well.

This post was modified 11 months ago by Crawlerin
Posted : 15/10/2020 8:42 pm
amdragon
(@amdragon)
New Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

Is there any way to verify the tube has been pushed in all the way on each end? I want to try this out, but I'm worried about not pushing it back quite far enough and getting a clog.

Posted : 01/11/2020 5:01 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@jakeprogrammer

My simple way:: I always measure the depth of the bore with a caliper gauge and make a mark on the PTFE tube with a waterproof pen to help me orientate myself. This allows me to quickly detect changes in position.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 01/11/2020 12:05 pm
Alex Hung
(@alex-hung)
Trusted Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

Forgive my ignorance, does getting the PC4-M8 connectors allow me to replace the Bowden PTFE tube with something like Capricorn XS one?

Posted : 02/11/2020 12:47 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@alexhung

Of course you can use Capricorn PTFE's when using a PC4-M8:

(E3D V6 hotend, extruder with PC4-M8 and capricorn PTFE) - well working and no jumping out PTFE.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 02/11/2020 6:44 pm
Alex Hung liked
ignacmc
(@ignacmc)
Eminent Member
Topic starter answered:
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

I would say even more...Capricorn XS has an inner diameter of 1.9mm instead of the standard 2.0mm. In order to not crush the tube during brass olives installation, you have to introduce a small shaft or drill bit of 1.9mm diameter which do exist, but are not easy to find. I think that the Pneumatic Connector is the best choice when using Capricorn XS tube...by the way, which tube length are you using? Are you doing it in only one continuous piece?

Posted : 03/11/2020 8:35 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@ignacmc

With the original Prusa connections I constantly had the Capricorn PTFE tube pop out, even when I replaced the crimp connectors (brass olives). With the PC4-M8 it runs absolutely trouble-free now.
The Capricorn is an extended continuous tube, about 5cm longer than the original.

 
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/11/2020 2:26 pm
ignacmc
(@ignacmc)
Eminent Member
Topic starter answered:
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

Good to know. Then i don’t understand why Prusa used brass olives instead of pneumatic connectors. i thought the only advantage of the olives was a stronger grip to the PTFE tube. Everything else are disadvantages!

Posted : 03/11/2020 2:32 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@ignacmc

As I said, I had these problems with the Capricorn tubes. Possibly the Prusa PTFE's are more stable. But I read that others had such problems with the original Prusa PTFE's. I also think that the PTFE tube might be squeezed by too much pressure and the inner diameter might be reduced, which could lead to blockages through the filament tip.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/11/2020 3:33 pm
ignacmc
(@ignacmc)
Eminent Member
Topic starter answered:
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

I have the original Prusa PTFE and had the olive sliding out of the tube. Yes I personally like the Pneumatic Quick Couplings much more...It's only that I was afraid they could be weaker than the olives

 

Posted : 03/11/2020 5:07 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@ignacmc

That's what I thought at first, since this is a Bowden system and a higher pressure is built up in this area. But even when printing carbonaceous material the PC4 connections held.
The PC4 are not expensive and it was worth a try so far.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/11/2020 5:30 pm
vintagepc
(@vintagepc)
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

I much prefer the olives as I've found over time with the MMU using PC4s it will cut through the PTFE over time. I suspect you will see the same with the Mini because there is constant rotational force. 

I switched my MMU to some drilled-out compression fittings and don't regret it. 

 

Posted : 03/11/2020 5:44 pm
ignacmc
(@ignacmc)
Eminent Member
Topic starter answered:
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

Yes, I got your point....But for my personal taste I prefer to have to change the entire bowden tube (around 300mm) from time to time, than to install those damned brass olives. I have had several bowden printers in the past and it is true that the Pneumatic Fitting cuts a bit into the PTFE walls, but it had never failed to me, neither I had to change the tube for that reason. I was just wandering why Prusa took a different choice than the rest of Bowden type printer manufacturers....

Posted : 03/11/2020 7:08 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

With the MK3 the brass olives work quite well, because the extruder works on tension and therefore no pressure is built up. With the Mini I had no chance, therefore the PC4-M8 pneumatic couplings. Several attempts with new olives with different tightening torques were unsuccessful.
I am less worried about the cuts, because the Mini extruder has less rotational movements than the MK3.
As I said, it has been running flawlessly for months in contrast to the original.

 
 
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/11/2020 7:56 pm
ignacmc
(@ignacmc)
Eminent Member
Topic starter answered:
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

Yes, the MK3 is not Bowden but Direct, right? So the ptfe tube is almost not subject to any stress

Posted : 03/11/2020 8:27 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@ignacmc

If you would like to test this - I got the PC4-M8x1.25 here:

PC4-M8x1.25

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/11/2020 8:35 pm
Alex Hung
(@alex-hung)
Trusted Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors
Posted by: @karl-herbert

@ignacmc

If you would like to test this - I got the PC4-M8x1.25 here:

PC4-M8x1.25

$28 shipping! 🤣

Posted : 03/11/2020 8:38 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: PC4 M8x1.25 Bowden Pneumatic Connectors

@alexhung

 😣

shipping costs to Austria US $6.12 🙂 

PC4-M8x1.25  worldwide free shipping

 

 

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 03/11/2020 8:51 pm
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