Bending aluminium bar

[Vet Tech]

I have a length of 10mm diam aluminium bar that I'd like to bend into a hook shape. Is this feasible using heat from a gas brazing torch or is it a No No?? VT

[R]

Yep.

Old trick we used at school was to wipe ordinary soap along the bar. Heat until the soap *just* starts to smoke and bend as required.

[Vet Tech]

Ok, sounds good but 2 questions arise:-

1. Would that be bar soap or liquid detergent?
2. Should I quench with water when the required shape is achieved?

VT

[R]

DON'T quench as it may crack.

[Rob G]

Umm - I would suggest you google for annealing aluminium to clarify if quenching is correct or not. I use the bar soap technique fairly regularly and once the soap has gone well black, which is the marker I was told to use, I drop the item into cold water - and then it bends easily. Copper similarly is annealed when quenched from red heat, steel not so, Aluminium goes on fire before red heat, hence the soap temperature marker !! One does wonder how these things were discovered.

I haven't used it on something as thick as 10mm - normally sheet or rod around 4mm - so it may well be that my rapid cooling is inadvisable for larger sections.

Rob

[Andy Dingley]

Bend it cold, but use heat to anneal it if it's work hardened.

If it's already stiff (i.e. work hardened) then anneal it first. Otherwise bend it _until_ it feels stiff, then anneal it. Don't anneal it at the end, leave it hard.

To anneal it, wipe it with liquid soap and cook it with a gas torch until the soap blackens. Then air cool or water quench, your call. It won't crack.

[Dave Plowman (News)]

IIRC, the soap turns black on the ally.