In article , DSK
wrote:

wrote:
What to make the spacer of? Are there commercial products available or
are we talking about cutting a chunk of rubber to fit? Are we talking a
bronze dougnut?


Well, this is what I've been doing the last couple years...
haven't seen any down side, nor read anything about it yes
or no: cutting board

Go to K-Mart (or whatever cut-rate retailer is closest) and
buy a large inexpensive plastic cutting board. The plain
cheap ones are about $3 for 2' square. It's tough and won't
rot, it's relatively easy to work, it even takes a thread
fairly well (although I have not used it for strength).

It's not too bad but it's not wonderful either. We pulled the cover off
a sea chest last dry dock and found the big12KHz transducer had
vibrated most of the threads out of the tapped holes in a 50mm thick
block of HDPE. Holes were tapped 3/4" BSW IIRC.

It'd been 4 years between inspections and a hell of a lot of use
between times. Not too bad. We helicoiled it back.

My advice is to use as coarse a thread as possible if you're going to
tap this stuff. Preferably, thru-bolt it to a backing ring of some
kind.

PDW

DSK wrote:

The basics of the right way:

Always start with clean thread.

Always double check that you're using the right tape for the
service.

Start one thread back from the end of the nipple. The
initial thread contact must be metal to metal.

Wrap the tape the same direction as the threads, so that as
you screw in the fitting, the tape wraps tighter.

Never more than three wraps.

Never put teflon tape on any non-tapered fitting, and never
use teflon tape as a substitute for the right size & pitch
of thread.

What is recommended for a bronze-on-bronze straight thread fitting?
Anyone have pipe dope brand suggestions? Is there anything specifically
wrong with teflon tape on a straight fitting, and what is it? I've seen
here and there that teflon on NPS is fine, and one of the reps at a
west marine shop just told me that that would be fine..

I have also read that teflon tape is a lot cleaner than dope/goo..
which I can believe.

But of course I must turn to the experts on this group

Thanks,

-CB