On Thursday, January 30, 2020 at 12:16:47 PM UTC-5, Klay Anderson wrote:
So--I've a tap and die set for plastic pipe (think sprinkler system). Any ideas for the best lube for threading same? Dry alone snaps the pipe. I think petroleum products will attack the plastic. Silicone?

I had to thread some 1" Schedule 80 dry. No problems, other that I couldn't find anyone with a handle fot that large die when I needed it, so they were cut by hand. Don't force it. I did a quarter turn, backed the die off to clear the treads and took another pass until I had what I needed. I was making mounts for some GPS antennas for frequency and time standards. I had to pole mount them to clear a metal roof.