I can't see what benefit there would be to the slit being diagonal or
tapered and it'd be a tricky cut to make. The important thing is that the
pipe be able to contract a bit after the laminate has cured.

A couple of other possibilities:
Coat the pipe with a thin (maybe .020") coating of paraffin wax and melt the
paraffin out after the laminate's cured.
If using a core of styrofoam (with packing tape finish), the core can be
mechanically destroyed after the cure.

"Brian Whatcott" wrote in message
...
On Thu, 10 Jan 2008 10:59:46 -0500, "Conlin"
wrote:

You've had many good suggestions for dealing with the shrinkage of the
glass-epoxy laminate. Here's one more.

With a tablesaw, cut one lengthwise slit in the pipe and cover the slit
with
... tape.

Make that a long straight diagonal (shallow taper) cut, and success is
pretty certain, I'd think....

Brian Whatcott Altus OK