Mini Ptfe quick disconnect coupling

The first problem with the stock solution is its 3 separate tubes. I run my Minis hard and replace the Ptfe every 2-3 months so I want to use Quick disconnect fittings, I Found some 8mm thread/4mm bore fittings but they didn't allow you to pass the tubing all the way through so you could use just one piece. You could drill them out but the main problem with them was the metal fingers would dig into the ptfe tubing so much that you couldn't even get them apart. More than once I did a cold pull on a plugged nozzle only to find little metal fingers that had broken off the fittings.

 Next I tried John Guest water fittings. They work similar but the collet has over molded plastic around the fingers to keep them from digging in too deep and will actually allow you to release the ptfe. They of course don't make a 8mm thread/4mm bore version of the fitting so I bought some of similar size and machined them to the size I wanted and they have worked flawlessly. 

The collets in the John Guest fittings are something that can be bought separately so I thought maybe I could print a body to hold it. I am using the two brass fittings that come with the machine and drilling them out to at least 4mm. Then the collet holder just threads onto that. You could print the threads onto the collet holder so that you don't need the brass piece but the printed male threads just aren't strong enough to last. 

You can purchase the collets all over the place. Aliexpress is littered with listings  which is where I got mine. Just make sure they are for a 4mm tube. 

I'm still testing these but time will tell if they will hold up. I will update if they work or fail.

Here are the ones I bought.