Aluminium tube to steel....help!

[timmyfishfinger]

Hi guys, just putting the finishing touches to my tadpole and have found the ideal size aluminium tubing to run the gear cables through. I couldnt weld as i'd just melt the ally so i got some metal glue but it's not having any of it (too cold?- some tight angles putting pressure on the tubes and unsticking them)
Can i solder them on with el cheapo soldering kit or will that again be too soft a join?
Any help appreciated...and i dont want to use cable ties!
cheers and merry christmas to all.

 

[Bsmith]

jubilee clips?

 

[the snooper]

you cant solder aluminium and anything substantial ie bike frame would take a lot of heat so a soldering iron would not provide enough heat if you could.
as above (Bsmith) if the aluminium tube fits over the steel tubing then cut a 2 slots in the aluminium and use a jubilee clip.

 

[rtbcomp]

You can solder aluminium with aluminium solder, but it's expensive and I doubt if it has much physical strength.

 

[Orraman]

.
Not likely to be applicable to a bike frame but any galvanised steel can be easily joined to aluminium by aluminium brazing provided the specific brazing rod and flux is used.

If a steel item has been tinned with solder on it's upper surface a continuous bead of aluminium brazing rod can be deposited onto the solder.
This can be done by positioning the oxy/acetylene flame above the item as if to weld a horizontal but weld, so that the heat from the side of the flame melts the solder.
The pre fluxed rod is melted onto the tinned section and floats on the molten solder creating a bead of aluminium.
The aluminium workpiece is fixed above with a gap suitable for a horizontal aluminium weld.
The joint is made as a combination of a welded joint being made between the previously deposited brazing material and the brazing rod being used while at the same time a brazing joint is being made to the workpiece above.
In all of this it must be borne in mind that a large portion of the solder will be liquid under the point where the joint is being made and must be allowed to solidify before anything is moved. This joint will have a tensile strength of about 5 ton per square inch.

As an example,
The top of a vertical 2 inch steel pipe was tinned with solder, a ring of aluminium deposited, the aluminium fitting of similar size was supported on bent pieces of 3/32" welding rod, tacked and joined as above.

Dave

 

[tigler]

There is a product called Lumiweld , an alloy soldering material. Designed for use with a gas blow torch. Does work , I've used it !!