The wheel rims for my miniature Burrell traction engine.
I originally wanted to buy some 4 inch diameter steel pipe with a thick 0.5 inch wall, but I just could not find any and so had to resort to round mild steel. I bought 100mm diameter round bar as 2 off 1 inch long billets. The rough machining of these is shown in the youtube video below:
The roughed out blanks are 100mm diameter with a 80mm inside diameter and 25mm thick.
Once roughed out I needed to then move the wheel blanks to the 4-jaw chuck as the next stage was the accurate machining of the rim and it needed to be moved around in the chuck. Hence use of the dial test indicator to align it very accurately, something that could not be achieved with a self-centering 3-jaw chuck.
The pair of rear wheel rims accurately machined to size along with the internal edge for the spokes to be riveted to.
They are now just 97mm in diameter.