...you get to mess around (warning: or up!) the old-fashioned way, with various pointed and edgy implements. Think you have a reasonably steady hand? If so, then I'd suggest taking the blade out of a metal saw and use it to make a couple incisions inwards from the end of the inner pipe, perhaps half an inch, or a little less(*), apart and stretching inwards for about half an inch or a little more(*).

That ought to give you a "tongue" of material that you can separate from the outer pipe by carefully bending it inwards; insert the point of a screwdriver or knife or something and twist or push (carefully, so you don't bend the *outer* pipe, with the threads, in stead!). Then you can try to pull on the inner pipe by gripping this tongue with a pair of pliers. If the tongue breaks off, you get to start over and make two of them, opposite each other, and hope you A) have, and B) can fit *two* pairs of pliers into the outer pipe. (You can, of course, also decide to go for twin tongues right from the outset.) If that still doesn't work, i.e, both tongues break off...

Well, there are several different views you could take then. One is, of course, to declare yourself SOL as a plumber, and call in a professional. A second is, make "tongues" like this *all the way around* the inner pipe (except for the two or three missing ones that you've broken off earlier), and then either see if you can pull on *all* of them at the same time(+), or just say "sod it!", break them all off, and leave the rest in there.

The last option, which IMO is rather risky and difficult -- which is why I left it as the last option (But OTOH, not all *that* more difficult than the preceding; cf "(+)", below) -- only works if you have a *very* steady hand, AND the piece of inner pipe stuck in there is fairly short. It is: Using that trusty metal-saw blade again, saw a slit in the inner pipe, all the way to the end. This only works if the inner pipe is three or four inches long, tops, I'd say. But if it *is* that short, and if you trust yourself to split it like this without sawing into the *outer* pipe at the same time, then you can curl the inner one up into a "tighter roll" than the inner diameter of the outer pipe. Insert the point of your knife(#) into the slit from the outer end, wiggle-twist-and-push it inwards until you've got a gap big enough to grab the material with the pliers and roll it tighter by twisting the pliers from your wrist. If this works, then you should get a curled-up sheet of copper in there that you can just pluck out.

HTH!

---

(*): Damn, what a clumsy way to write "about one cm" and "about 1.5 cm", respectively -- your units SUCK!

(+): Which has the following problems: Do you own about five pairs of suitable pliers? If so, how the *fuck* do you get them all to fit in there at the same time? And, if by some miracle you manage to do that, then do you have about five hands to pull on them all at the same time with?

(#): Do you guys have the concept of a "working-knife"?

Seems to be a bit more limited than your "utility knife", in that it's a rather specific model; they all look pretty much the same; namely, like "generic knife". This is -- or at least was, at least in Sweden -- a standard item in most every toolbox or workshop tool supply: It's used for a couple of years or a year or a couple of months, however long it takes for it to acquire too many dents and nicks, and lose its edge and possibly its tip; then you just get a new one.

In Swedish, they're actually called Mora knives, for the town where manufacture started about 100 - 150 years ago; AFAIK at least one of the biggest manufacturers is still based there. I suppose the technique of folding a sheet (or ribbon, rather) of fairly high-carbon steel between two lengths of softer, tougher and less brittle, iron was first adapterd for cheap masss production there. Anyway, that is -- or used to be -- the distinguishing mark of a Mora knife; though judging from what I saw in a shop a little while ago, they've widened their selection a bit, lately.

Check this [link|http://www.the-ekd.co.uk/800/sweden.htm#mora|Swedish knife page - Mora] place; scroll down a little bit and you'll see a picture of five knives stuck in a board or something. The middle (dark-red- or maroon-handled; painted wood) one is how they looked when I was a kid; the next one (red plastic handle) is how they've looked for about the last twenty years; the last (blue and black) one is how they look now -- the new colour seems to be intended as a signal that this model has a one-piece, un-laminated blade (in both high-carbon and stainless steel varieties, IIRC), while the traditional red colour is still used for the traditional laminated blade.


[Edit] Here are the two remaining manufacturers of genuine Mora knives: [link|http://www.frosts.se/|http://www.frosts.se/] and [link|http://www.kjeriksson.se/|http://www.kjeriksson.se/].