Forming circles out of steel angle

[Mendalot]

Hello peeps, I would like to form a 16" circle from 25mm steel angle, with the angle on the internal. Is there a formula to get the right amount and size of cuts required in order to do this?
The same sort of thing Olds has done on his dash scuttle ...... perhaps one for you to answer Dave.
Many thanks

Paul.

[Olds]

Don't know of any formula for this.
Easy enough to work out the difference in circumference between the inner and outer diameters (3.142 x Diameter) and from this you can work out the width of each pie cut once you decide on how many cuts to make. The more cuts the more circular the end result.

[markju]

Just a thought, would it not help to draw it out full size, it's not going to require much. That might be easier to work out number and angle of cuts v

[Manky Monkey]

Being stoopid, that'd be the way I'd do it. 

[poprodder]

same here!!!!!

[the coppersmith]

 Hi Paul, my two penny worth outer ring would be 1277.25mm long, inner ring 1117.60mm long. You have to lose 159.65mm. So thats 80x2mm cuts or 40x4mm cuts, as Olds says more cuts equal smoother finish, lot to weld and dress, and knowing your exacting standards I would adopt plan B. Get a disc or flange lazer cut and weld on upstand. Rolling angle is always a pig. Best of luck.

[Mendalot]

Thanks chaps, no welding and dressing required on this project. The rings will have a 2mm steel base slotted in so will cover the cuts up, they are a pair of pivoting shelves for my roving tool caddy. I got fed up with constantly going back and forth to the tool box, so built a custom tool caddy that has all the common tools on that I use every day, and can go where ever Im working in the work shop. Its an on going project and gets added to when I think of something else useful, like a pair of folding shelves for other bits and bobs required. Will post a pic when done.     

[merv]

I like to see this

[haggis]

Or you could get a shrinker stretcher and make your ring out of a folded angle of steel plate.

https://www.youtube.com/watch?v=GvaFtmAzxNk