How to strip the insulation off electrical wire

Among electricians, the tradition seems to be that the newest apprentice
gets to take wire scraps home, and then to the copper recycler.
If the new guy isn't interested, then the next in-line has the opportunity.
When working commercial, there's lots of wire. Some like you see at Home Depot,
and some heavier. MUCH HEAVIER. About the diameter of your various fingers.
When you take it all to the recycler, it varies, but you get $2/pound with
the insulation, or $3/pound without. (Referred to as bright copper.)
Now it's very handy if you can bring all that wire over to dad's house,
and have him do all the stripping work. You want to do this on hot days,
and leave the wire in the sun to warm up, because then it's more pliable.
And you have to have to have something to cut the insulation, to get it off.

The first thing to note is that there is green wire and black wire.
The black wire is a little heavier, like 1/2" as opposed to 7/16".
When the wire gets that thick, you don't use #16, #14, #12, etc.
I forget whether you use diameter, or weight.
There's also a short piece of stripped wire, and some stripped black wire.
That's 3 different sizes, that require 3 different size holes in the blocks.

When planning, the first thing you want to do is make a jig to pull the wire
through to cut the insulation. I've made, perhaps a half dozen such jigs.
The pic shows a couple of them. To make one, the process is:

• Take two pieces of 2x3 that are about the same size.
• Put the blocks together, and drill one hole in each end, through both blocks,
  that will hold a piece of dowel so that the blocks will always line up, stay together, and not move.
• Put a piece of dowel into the holes on one block that also goes in the holes on the opposite block,
  so the pieces can always be put together, and the alignment will always be true.
• Drill holes that are the diameter of the wire to be stripped, centered on the crack between the 2 blocks.
• Get a utility knife blade, and place it on one of the blocks, so that the end sticks out
  into the hole you're going to pull the wire through.
• Drill a couple holes, and put screws in that will hold the blade in the correct position.
  The head of the screw is on the outside, and just the end is between the blocks.
• Put the blocks, with the blade, together, and put 'em in a vise.
• Draw the wire through the hole, cutting the insulation.

I've actually made several of them, because the wire is a different size each time.
Here's a couple of 'em. The tip of the blades don't last all that long, but I have 100 of them.
I probably have 4-5 jigs, but at the moment, I could only find 2.