what is involved in rebuilding k-h disc brake calipers?????????????
Annealed copper 3/16 is only rated at around 1600 -- 1900 psi working pressure. There is a REASON that NO manufacturer uses copper tube in brake systems
So far as using air to pop pistons out, this is easy if you put some thought in
1 Try to use grease which reduces accidents
2 if you do use oil, or air, "rig" the pistons by assembling the caliper around a thing plate so that they have a stop, and pad and wrap the thing with rags so the piston cannot "get away" or do damage to itself or other things / people.
Especially single piston brakes, SERIOUSLY consider buying rebuilts. They are guaranteed, something your work is not. That is, you buy kits, and they leak. "Now what?" You buy rebuilts and THEY leak, you take 'em back