Heating aluminium to bend it?

red97, Nov 30, 1:21pm
Hi all, I have an aluminium propellor that has seen better days and i am contemplating hitting it with the gas today and try and straighten it out, does heating aluminium like this make it more workable like mild steel or does something bad happen!
daryl14, Nov 30, 1:33pm
You can heat it, It goes soft in the middle while the outside oxidised layer stays hard, You don't see a colour change or anything to indicate it's heating. Then if you give it too much, it suddenly collapses without warning. Take it real slow and you should be right.

I haven't done it for a long time so others may have more info.
martin11, Nov 30, 1:33pm
Very gental heat will take the temper out of alloy but you made need to heat treat it again if you want to use it . is it a boat or airplane prop !
red97, Nov 30, 1:34pm
it a blade off my hughes 500 e model
red97, Nov 30, 1:35pm
nah i wish its a boat prop 90 hp
liggy2, Nov 30, 2:16pm
It will melt before you bend it.
red97, Nov 30, 2:21pm
i have been able to bend it cold and was wondering if heating would make it more pliable, so i would have to go as far as to say you are full of shit
liggy2, Nov 30, 2:22pm
F**k you too!
red97, Nov 30, 2:29pm
calm down, i was only stating a fact, you made a ridiculous statement under the guise of giving advice, why would you feel the need to comment on something you clearly know nothing about! ive had a lot of great advice off this message board in the past but unfortunately its people like you throwing in your two cents that confuse things for people like myself withvery little knowledge about this kind of thing.
budgel, Nov 30, 2:34pm
I agree with the first reply. Heat it just to the point where your spit will sizzle and dance on it and no more.

I have memories of trying to heat up a motorcycle brake lever and suddenly having a gob of molten aluminium drop to the floor.
the-lada-dude, Nov 30, 2:50pm
like working with metal, you must know what the base metal is alloyed with.there's heaps of different iron/steel based alloys that are just poles apart, but look identical. some like mild steel are very forgiving to mechanical/ heat inputs, but they trade off other qualities to achieve this. same with aluminium as a base metal, these are alloyed with different elements and will give totally different properties. many aluminium alloys are tempered to a certain hardness and heating them will ruin the temper. and bending aluminium beyond certain radii buggers them to. google for infomation,how bad is the bend !if it is badly bent its probably cracked already.personally i'd take it to a marine prop shop and let them decide, even though you mat take the bend out the pitch on the blade could be all to f.kif your going to have a go ya self, heat the blade to about 200 c and air cool. the other nasty is if it is flawed it well may throw the blade and kill some poor bastard.
we used to soot the aluminium being welded ( acetylene ) then when heating the part, once the soot started to disappear with heat you new you had about 50 deg to go b4 the jolly thing melted
and chopper blades are'nt aluminium.
mrfxit, Nov 30, 5:14pm
Aluminum is a very odd metal in that most variations are normallyhappy to bend in 1 direction but DON'T normally bend easily back.

It has a "one way memory" = bend it once, then leave it alone.

Mag wheel repairers KNOW how to get around this issue
red97, Nov 30, 5:16pm
thanks for that, it is a three bladed prop and one of the blades is out by about 10mm but the bend only starts about 50mm from the tip, all i really have to go on to judge the pitch is by eye while spinning slowly when it is mounted on motor and match itup with the other two blades, sounds like it should be ok to heat it gently, thanks all for the help

p.s not that it matters but all new r22 and r44s come with aluminium blades due to delamination issues with the stainless skinned ones
kenw1, Nov 30, 5:33pm
I was once taught to smear soap onto aluminium and when its heated the soap will just start to turn brown, then it is at the right temperature to have a go with.This was many many years ago, but it worked for me then, dont know about modern soap.
sr2, Nov 30, 5:39pm
I still use soap as a temperatute indicator when straightening bent dirt bike levers.
the-lada-dude, Nov 30, 6:21pm
OH ok !is that the main or torque rotor !we don't actually have delamination problems here in nz, cause they crash em b4 that happens
desmodave, Nov 30, 6:32pm
You had better be quick or you will miss the tide
jenny188, Nov 30, 8:20pm
Another trap heating props come across is that quiet often they are rubber bushed and the rubber (which cannot be seen) then fails under full load. Props are a science of their own.(put wet rag around the hub) Some makers go away from stainless for several reasons. Ali bends whereas Stainless snaps off and props push so need grip. Stainless give more slip , so less grip.