SpudFiles

"3/4" in sch 120 would be the best fit, I know that harvel makes it but finding it would be another question. If all else fails got to www.onlinemetals.com and get a piece of .75" OD pipe with a wall thickness of 0.035 and that will give you a ID of 0.68"

.75-.035=.68?
Since when, exactly?

Since now.
.075-0.035(2x) = 0.68 (a pipe has two walls.)

http://www.onlinemetals.com/merchant.cf ... its=inches

DeathBlade wrote: (a pipe has two walls.)

Sounds like one of those Confucius-say things. How many walls does a cylinder have again?

Ah ha!
Brain fart.