Bowden extruder and hot-end with Swagelok

I wanted to try a bowden extruder system for my 2nd Reprap. I was reading about the different designs for the bowden cables and hot-ends and read that some people have trouble with the connection of the bowden cable to the extruder and hotend.

At my job i work with high pressurized gasses (for greenhouse gas emmision research), there we always use Swagelok components for all the hook-ups of the gas tanks to our machines. Swagelok has really good quality stuff, but it is also very expensive.

Here my setup:
i mounted a 1/4" union into the extruder, to this i attach the bowden cable (1/4") with on both sides a Swagelok nut and ferrules. The x-carriage is fitted with a 1/4" bulkhead union, to which on one side the bowden cable is attached and on the other side the hot-end (own design with 1/4" stainless steel tube, so the 1/4" swagelok fittings work great). See: [www.reprap.org]

Both the bowden cable and the hot-end can be mounted or replaced with just one solid nut.

See the pictures at:
[www.flickr.com]
[www.flickr.com]
[www.flickr.com]

Maybe this is an idea for the shops?

i hope to get some comments.

Edited 1 time(s). Last edit at 04/03/2012 12:30AM by north90ty.

I have a few bowden cable machines and I just use 1/4-20 nuts threaded onto the tubing. I have never had any issues with it coming apart. But I have seen a few wood based extruder with bowdens break where the cable was attached. Another easier option to your fitting is a PTC (push to connect) fitting which is designed to hold high pressure air lines.

One thing I have found after running a bowden for over a year is the need for a really good hotend. Meaning a really short hot zone and a really cool thermal barrier (at least with PLA). This is the only way I have found to avoid the ooze that bowdens are prone to. My original hotend (no lathe plumbstruder) worked well except it had ooze due to the stainless sleeve around the PTFE. I added a fan to keep it cool and things improved but I was still fighting ooze. I then started building them without the stainless and just a hose clamp at the bottom where the barrel threaded into the ptfe. This allowed the ptfe to radiate a lot more heat and the ooze went down a lot. I mention this is because of your hotend design and the use of the bowden. I don't think it will be a good combination, but I may be totally wrong. Basically a simple rule I have found is that if you can not touch the thermal barrier about 15mm above the heater after being hot for 2 hours it will not work well for a bowden with PLA.

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