G’day folks, this could be done using a propane torch but you’d need a fair bit of luck on your side, probably not going to be successful as a first go. The main reason is that these propane torches just don’t have the oomph.
I’d suggest either taking it to a job shop and carrying some cash in your pocket, looking at your local tip shop for a wrecked mower of the same type with an intact handle or looking at gumtree etc for a similar thing, this is much more likely to be successful.
I’ve joined lots of metal together and had heaps of failures along the way so, if you do want to try, here are my suggestions.
Firstly this won’t be welding, if you get things exactly right it will be brazing. Welding is when the base material is melted and joined to another component by fusing it at the margin. A hand held propane torch won’t get things hot enough to melt steel.
To braze effectively you’re going to need a few vital things to be spot on. If any of these are not right it’ll just create a mess and can cause serious injuries. You’ll be dealing with molten metal, poisonous gasses and intense heat.
For brazing to work well everything in and immediately surrounding the join needs to be back to bare metal and smoothed out. Rust, paint, dents etc cause failures. Cleaning the inside of a tube can be problematic, I’ve done it with emery paper on a dowel in the past.
After surface prep it needs to be completely dust free and wiped down with a solvent to give you the best chance of success.
A brazed joint works through capillary action drawing the molten filler material into the very small space between the parts to be joined. The two parts must be close fitting but they also need to be able to be moved over one another without galling. The very small space is what allows the joint to form. Too tight and it won’t allow the filler to be drawn in, too loose and the joint won’t form with any strength.
The filler material forms an extremely thin alloy on the surface layer with the base material, filling the very slight void in the process.
You’ll need flux suitable for the base metal and filler selected. The flux does several jobs that there’s no time for me to explain right now.
So, with everything scrupulously clean, close fitting and the flux applied you then heat the entire area of the joint to a uniform orange heat. This is aided by putting fire bricks around it to retain the heat. An orange heat is what happens after the red heat phase. You’d then apply your filler rod and, if all the prep work is right, it will be drawn into the join by capillary action.
Brazing will not result in a strong joint if you try more than once to heat it and apply the brazing filler. The filler will just be evacuated from the joint and leave voids. So it’s a one shot chance, if you don’t get it spot on the first attempt you will need to strip back the joint, clean everything and try again.
Best of luck!
Ironbark
