I devised a machine to straighten out the aluminium sheet in a controlled fashion.

Here’s the machine:

The frame is made from an Ikea toy; some of the tubing was from a broken standard lamp, and some from a broken towel rack. The black plastic was an amazing bit of luck.

It works like this:

1. With the lever up, feed the curved sheet between the tubing
2. rotate the lever until you have the amount of bend you want
3. pull the sheet through one way
4. turn the sheet round and repeat the process
5. I typically do this several times until it seems to have settled down

The first time I tried it I estimated the new radius at about 50 mm (before it was 30 mm); the second time I estimated the new radius at 70mm.

I’ll report on how I used it in a separate post.