I would like to introduce you to how to increase the diameter of a seam tube!
Seam pipes are made through the traditional process of forging and rolling, 

so they have excellent resonance and projection, but they can also cause problems if handled incorrectly.



First, in order to increase the diameter, you need to look for the solder wire,

 which is usually one centimeter away from the hole in the head, as shown in the picture. 

(The two lines below are drawn for convenience when you're working on increasing the diameter.)

This is a precaution when increasing the head diameter with a mandrel. 

First of all, we don't use a semi-automatic stretching machine or die. 

It is best to work with a bunisher and sandpaper for seam pipes.

As shown in the second figure, the order of operation is in the order of 1/4 won in one direction, 

1/2 won on the other side, and 1/4 won on the other side.

After increasing the diameter sufficiently with the Mendrill, sand it to trim the surface that has become uneven due to the work.

1.#800 2.#1000 3.#2000 4.#5000 5.#Pollinators (work in this order)



If you've widened the diameter as much as you want,

 it will flatten the underlying section that would have been bumpy by the work.

If it's horizontal, the head diameter is extended.