Lightest, most flexible Bowden cable

[kenking-King Design]

I'm looking for the lightest, slimmest, and most flexible Bowden type cable I can find, and naturally I also would like extremely low internal friction, and if it costs next to nothing, that would be good too. No harm in hoping, is there ?

I suspect there probably isn't a proprietary system to match, but if anyone out there has come even close to meeting some of those requirements I'll be delighted if you will share how you did it, what materials you used from which suppliers, and so on. The benefit of your experiences will be much appreciated,

Thanks,

Ken

[Bruce Collinson]

Ken,

Would you do some diy research? The thinnest plastic outer I can bring to mind is orange and being remote from the man cave, from memory about 2-3 mm I’d. Not sure it isn’t designed for this reason, although I use it to locate Rx aerials . For the inner, something like 100lb breaking strain nylon coated sea fishing trace wire might be stiff enough, and if not then try 150 lb and so on. It will still be a lot thinner than proprietary Bowden cable.

Of course the thinner wire may create issues at each fixing but I suppose you could bind and glue a short piece of 20g piano wire, a thread extender or, heaven forbid, the sort of servo arm fixing which is the subject of the thread two above this one. I’d simply double it and use a hex or cap head bolt for proper torque and loctite it if I couldn’t get a clevis in.

Probably, a bit of inter web delving could turn up even slimmer tube but I guess the weight is in the wire and you clearly need flexibility too.

Hope you get what’s needed.

BTC

[Denis Watkins]

Ken,

Have often used 1mm Carbon fibre rod, many many times for push pull along a curved path

This rod is so immensely strong that it negates the use of an outer at all thus No outer friction to contend with

Just needs guide holes along its path at intervals

500mm length is £2.65

But is probably the most expensive

And assists low friction and lowest weight for flight

Edited By Denis Watkins on 16/02/2020 07:51:18

[Peter Miller]

Sullivan do some ultra thin bowden cables.

Not sure who stocks rhem these days but a bit of research should find them

[James Green2]

I use bicycle gear cable inner off Ebay.

[Martin Harris - Moderator]

I've bought 2mm OD PTFE tubing and 50lb breaking strain plastic coated stainless steel braided fishing trace recently for closed loop use. No particular recommendation and other suppliers are available...

A tip for crimping - loop the free end round the crimp and back through again so you're crimping 3 strands.  It's much less likely to slip.

 

Edited By Martin Harris on 16/02/2020 11:45:11

[James Green2]

Another option is strimmer cable again off Ebay

[kenking-King Design]

Thanks chaps, I hadn't realised ptfe tubing was available in such small diameters (thanks due to 3D printing apparently), so have sent off for samples, and also looking at fishing trace wire for the inners. I'll check out Sullivan too. Thanks again,

Ken

[kenking-King Design]

Just an update, and for anyone else chasing the same goal.

I found and purchased ptfe tubing on eBay, in 1mm, 1.5mm and 2mm o.d.'s, and have found it to be flexible, slippy and yet solid in compression, so that's ideal for my purpose. I've also bought fishing wire trace in 10, 20 and 40lbs breaking strain. It's multistrand stainless steel with a nylon coating, and fits easily into the ptfe tubing (though I haven't tried 40 lb trace in 1mm tubing, but even that combo might work). I wound two turns round my finger and could move the trace back and forth quite easily. The heavier (!) trace wire can be pushed too, if the unsupported length is not too great, so that reduces the requirements for return springing. All in all I'm delighted with the materials, so thanks to those who steered me in these directions.

I shall have to be careful in making the cable terminal brackets to ensure the ptfe outer tubing can't get into the cable through hole and thus be squeezed inward, but that really goes without saying, doesn't it ?

Thanks again, and hope others find this thread helpful,

Ken