Has anyone tried bending a windscreen frame from aluminum channel? I have tried doing so with a tool similar to the type in the book, but the sides keep buldging outwards. Tried heating it with a propane torch, it was an improvement but still not prettty.

Anyone had luck with this?

I've wondered about that myself, and the answer I received was to anneal the channel first.

Edit: Oops, I see you tried this already. How about bigger plates on the sides of the tool to constrain the material?

Also, you can make sure that you've accomplished full annealing by coating your piece with soap and heating until the soap blackens.

HTH,

Pete

[Edited on 3/5/04 by pbura]

[Edited on 3/5/04 by pbura]

To anneal aluminium or copper heat then quench in water.

You should allow aluminium to cool in air once heated, don't quench. You will create a very brittle grain structure by quenching leading to 'fissures' on the surface of the material when bent.

Cheers

you dont need to quench the alu.

I tried annealing channel and it didnt work. There is too much material to go round the bend at the top of the screen and it just kinks badly.


Dunno how it was acheived in 'the book'.

I ended up using steel channel.

At the corner, cut it into segments approx 20mm long at the channel sides. Dont cut the bottom of the U - I did this with a 3mm cutting disk. The resulting floppy assembly can be guided round a wooden former to make up the shape. Then weld up the slots you cut, and grind the outside (and inside if you penetrated too far) flat. If it doesnt look A1, you can get a can of black or chrome paint and spray to suit.

This method worked for me - alu was a total no go


atb

steve

I agree the channel material is too significant a section not to buckle under such a tight radius. One thing that I did neglect is to make large enough side plates to keep the material from side buckling. I will try this first, then resort to the notching & welding suggestion if it does not work out

Thanks guys

I made a windscreen frame yesterday in an hour. No buckling or cracking, using aluminium section, worked around a wooden template as per the book, and using a roller with shortish sides on.

Not sure why mine worked so easy and yours is causing such problems perhaps its the actual channel material thats different or perhaps the radius' i'm bending it around, but mine are still fairly tight.

I'll post a pic tomorrow perhaps of the frame.

Kind regards,

Darren

the channel I used was summat like 14mm sides, and it buckled like a ba$%ard even after softening the channel. I used a dinner plate as a template when drawing the curves on my wooden former, so not a really tight radius.....

Perhaps shorter sides would have been better on the channel, but the next size down at approx 10mm looked way too flimsy to stand up to wind pressure at speed.


atb


steve