Decent dies should be steel, good dies shold be hardened. Material costs
and heat treating a 20 pound die are substantial.

You can do them on a manual lathe and cut off the part you don't need.
To get the perfectly round cross section you need requires the special
swivel tool holder. You can to it on a CNC lathe and skip the special
tool holder.

You can do them on a manual mill and a roatary table: use the table
vertically with a long roughing mill, vertically with a ball mill, or
horizontally with a suitable half round cutter. CNC mill can be done
horzontally or vertically with a 4th axis.

If I were running low to medium volume production I'd run them
horizontally in a CNC mill using a 1/2 round cutter with a cutting edge
radius much smaller than the desired cut, then off to heat treat.

I've seen the the one off's in larger sizes (3" and 4" tube diameters
done on a 20" tool room lathe. 1" tube in 4" radius goes fine in a
vertical mill with a rotary table.

Larry Jaques wrote:
I'm curious (Gunner, please don't make the cat pun here
how the dies are made for the tubing benders like these:

http://www.vansantent.com/model_4_bender.htm#Mod4Dies
http://www.medfordtools.com/mb3.html Good price.

Are the dies usually milled, cut on a lathe, or what?
What makes them worth $200-500 a set?

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