Soldering Brass Tubing

[Atak_Kat]

I know this is a long-shot, but with all the DIY guys around, I thought I'd check if anyone has a suggestion.

I'm making a small project (for simracing) that involves soldering pieces of brass tubing.
I've figured out the soldering, and it's working OK, with good strength, at least for my purpose.
(If you're interested, I'm building a new/better TrackIR headphone mount (with LEDs), with included rechargeable battery so is will be wireless)

My intent is to create the frame/structure from brass tubing, that will allow small wiring to be passed through the tubing (to connect to the LEDs at the ends). And the issue I'm facing is that each solder joint ends up filling the internal cavity of the tubing, and blocking any wire passage after the connection is soldered.

My guess is to pack/fill the internals of the tubing with some sort of material that will keep the ID free during the soldering, and then allow for removing it after the soldering is done. But I'm struggling to think what this material might be. It has to be flexible, since my design has multiple curves and 90 deg joints that the wires will have to pass around.

I thought about sand or salt to fill the tubing, but my guess is that the solder will just wick into that and create a block/blob that won't freely come out. I also thought about some heavy guitar/music string, but also this I guess would get soldered internally as well.

Interested in any ideas or suggestions anyone may have.

Thanks

 

[hotak]

If you can keep it from flowing out, i'd try wax

 

[GagarynGaribaldi]

Get some high temp silicone tubing with an OD slightly smaller than the ID of your brass tube. Don't use wax. Not only will it melt and flow away from where you want it (obvious!) but it will also pollute the joint making it impossible to solder, no matter what flux you use. Silicone melting point is higher than your soldering iron tip, that's why soldering irons have silicone covered cables.

 

[Atak_Kat]

Get some high temp silicone tubing with an OD slightly smaller than the ID of your brass tube. Don't use wax. Not only will it melt and flow away from where you want it (obvious!) but it will also pollute the joint making it impossible to solder, no matter what flux you use. Silicone melting point is higher than your soldering iron tip, that's why soldering irons have silicone covered cables.

Thanks so much. I experimented just inserting some pipe cleaners into the tube. It actually worked not bad. But will definitely get some high temp tubing. Great suggestion and thanks a lot.

 

[Emery]

Solder won't stick to steel cable wire, like that used for hanging pictures if the brass tubes are small diameter. Shouldn't stick to coat hanger wire, either, though make sure you scuff off the shellac/varnish.