Quote Originally Posted by tonyfoale View Post
What about cutting a strip out of the length of some round tube and then welding in a flat strip to get your D.
Tony,

we have tried that, but the shape isn't a perfect "D" with sharp corners, it's a D shape with rounded corners...in the example we're trying to rebuild, the tube transitions from perfectly round to D shape over a 5" length, and then turns a couple of tight radius turns to step out for the belt rim.

We've been trying to make D shaped tubing by pressing round tube into an offsided ellipse, then a second operation to flatten the offside to create the D... it sorta works, but is nowhere as neat or consistent as the manufacturer managed back in 1909.

We've had plenty of goes at this, and found a number of ways which don't work for various reasons, but finding the way which works consistently is eluding us.
I was starting to look at drawing as an option, but then realised it won't work due to the transition...

Given that bicycle frames were/are using tubes of rounded square, D's, and other shapes, I was hoping someone here had experience in how they are made, or has recreated pieces from round in the past.

Thanks,
Des