Quick connect/disconnect magnetic Bowden coupler

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-------------------------------------------------------------------------------------------------------------There are connector versions to cater for both PC4-M6 and ECAS04 couplers. I have printed and tested both types and both work exactly as planned.   I personally stayed with the ECAS04 version as the coupler itself takes up less vertical height than the PC4 type and means a less rigid length in the PTFE tube.

This design uses either six, nine or twelve  5x2mm magnets depending on your choices. I have a stack of 5x2mm magnets so they are obviously my preferred option for things I design myself that require small magnets.  5x2mm are pretty much the cheapest to buy in a bulk pack and always useful to have on hand.

Each half of the coupler requires either a PC4-M6 pneumatic coupler, or an ECSA04 depending on which you choose to print. The PC4 version is threaded to accept the coupler being easily screwed in place. Don't go all Rambo on it when screwing it in, it is a small 3d printed thread when all is said and done and gets more than tight enough with gentle pressure.

Both the ECSA and PC4 variants come in two versions. They are named ‘single mag’ and 'double mag' respectively. I would highly suggest using the double magnet option.  The single magnet version works fine but only in an area of the tube that does not experience any major bends in the PTFE tube with associated sheer forces involved. The mating faces of all four are identical so there is nothing stopping you using a PC4-M6 at one end and an ECSA04 at the other if you need to do that for any reason.

For maximum magnetic grip, print 2 double mag versions. Each half then has the 5x2 magnets double stacked resulting in you needing 12 magnets in total. If you use one double mag and one single it's 9 magnets, while both parts printed in the single mag version would need 6.

Make sure you get magnet polarity in the right direction for attachment before committing to adding any glue to hold the magnets in place. I printed mine in PLA and used superglue to affix the magnets in their slots. 

The hole through the print is sized to allow the PTFE Bowden tube to be pushed through so it sits flush with the mating surface of the print meaning there is almost no gap in the tube where the tubes meet when the couplers are attached.