Rolls for a wire/rod bender?

For a ring rolling tool these would be the part that is rotated around the outside of the ring with a mandrel on the inside. These are sized for the rod diameter, the mandrel sizedfor the ring diameter. The rings may or may not be jewlery.

On 30 March 2024 at 16:41 Robert Atkinson 2 Said:

These are sized for the rod diameter, the mandrel sized for the ring diameter. The rings may or may not be jewelery.

In the eBay link, the mandrel is plain, suggesting the item to be rolled is flat where it touches on the inside.

Hence, I wonder if there is a better descriptive term than ‘rod diameter’. Let us say I want to roll a ring tomorrow. What should I search for to find the correct shape of material to use? I can find ‘half round bar’ but would a ring use material that is full semi-circle?

Second, what do the numbers in the photo above refer to? Is it simply that 4 is bigger than 3 or do they relate to a measurement system?

I think jewellery rings are of part-circular form, but I would first see if the numbers are of mm.

Measure the diameters of the grooves themselves (not of the entire roller) and see if the sizes and numbers correspond.

Bear in mind they might be slightly shallower than a full semi-circle, but if so should follow a regular, identical or proportional, difference.