Heat gun or bowtorch?

I want to get some alloy rearsets hot, so I can bend 'em.

Whats a bowtorch?

Not had much luck with ally tbh, so take this with a pinch of salt: after failing miserably to bend cast ally, next time I'd want to heat it in an oven first because alloy really sucks heat. Then if you have a 2kw heatgun or a decent blowtorch, heat it and rub a bit of soap on it. If the soap goes black, it's reached its ductile range.

Like I say though, I've not had any good results myself...

Screwd

<edit> errm, hang on... http://www.therevcounter.co.uk/mechani...end-alloy.html

Originally Posted by Screwdriver

Not had much luck with ally tbh, so take this with a pinch of salt: after failing miserably to bend cast ally, next time I'd want to heat it in an oven first because alloy really sucks heat. Then if you have a 2kw heatgun or a decent blowtorch, heat it and rub a bit of soap on it. If the soap goes black, it's reached its ductile range.

Like I say though, I've not had any good results myself...

Screwd

<edit> errm, hang on... http://www.therevcounter.co.uk/mechani...end-alloy.html

Blimey. I don't remember that thread at all! Scary!

I think I bent that one back cold in the end!

But this fucker IS bending back, I've seen the price of a new one!

Lamp it with a big hammer. If it breaks, and it probably will, buy a new one.

Life's too short to do blacksmithery.

Buy a new set of rearsets. Just in case. Then use a blowtorch. Then fit the new rearsets.

You don't want to re-work an alloy casting and then send your kid out on the track with it. First off, applying enough heat to rework aluminum alloy will cause manganese depletion, altering the characteristics of the alloy, that can lead to micro-cracking.

Was it originally cast, or was it machined from billet? If it was machined, you need to get up around 350C to bend it with minmal cracking risk, and even then you want slow pressure to bend it, not thumping it with an 'Ammer. If its cast its a lot trickier, because it depends on what mix it is, some (A356 typically being one) are tough as hell and will bend well with a bit of heat. A356 is what most alloy wheels are made from. Others, typically stuff that is intended for highly detailed castings, don't cope at all well, and will crack if you look at them funny. Without knowing what it is, it's educated guess time if its cast. I'd get a spare, try and fix the one you have, and see how it goes under low stress use for a while. Chences are it will get broken long before fatigue becomes an issue anyway.

Originally Posted by Big Pete

Was it originally cast, or was it machined from billet? If it was machined, you need to get up around 350C to bend it with minmal cracking risk, and even then you want slow pressure to bend it, not thumping it with an 'Ammer. If its cast its a lot trickier, because it depends on what mix it is, some (A356 typically being one) are tough as hell and will bend well with a bit of heat. A356 is what most alloy wheels are made from. Others, typically stuff that is intended for highly detailed castings, don't cope at all well, and will crack if you look at them funny. Without knowing what it is, it's educated guess time if its cast. I'd get a spare, try and fix the one you have, and see how it goes under low stress use for a while. Chences are it will get broken long before fatigue becomes an issue anyway.

oH, YOU'VE SEEN HIM RACE?

Holy crap.

I've just about had it with these damned little bikes! I never seem to do anything except fix them and spend money on them! Been a fibreglass and filler and paint day. It'll be an oil-change evening.

Originally Posted by murcan

You don't want to re-work an alloy casting and then send your kid out on the track with it. First off, applying enough heat to rework aluminum alloy will cause manganese depletion, altering the characteristics of the alloy, that can lead to micro-cracking.

It's not cast, it's billet. But I am now worried enough to be off to see GB Moto in Chessington for a new set. £160 for cash. Holy crap.

Originally Posted by Trogladyte

It's not cast, it's billet. But I am now worried enough to be off to see GB Moto in Chessington for a new set. £160 for cash. Holy crap.

Good news, you can straighten a billet part with and application of heat. Get a 350/400 degree temp stick and an arbor press and have a ball.

If its a critical solid aluminium part try giving it a float test.

Chuck it into a canal and if it floats keep it.

Originally Posted by demographic

If its a critical solid aluminium part try giving it a float test.

Chuck it into a canal and if it floats keep it.

Witches sink and ducks float. If it weighs more than a duck it's a witch.