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Unread 03-13-2003, 11:08 AM   #18
BillA
CoolingWorks Tech Guy
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Join Date: Dec 2000
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Teflon tape is convenient, dope is better - takes less force to seal
why the 'less force' is important has to do with the 'brittle failure' mechanism

one has to assume that micro-cracks will result from the threading operation in acrylic or polycarbonate
so we are concerned not with crack initiation, but rather propagation
the cracks will lengthen at MUCH lower (crack tip) energy levels than that required for initiation
hence radial (or hoop tensile) stresses should be kept to the lowest possible levels
- note that simple thermal cycling is often quite sufficient for crack propagation w/o ANY applied load at all
(a poor/unsuitable material is always going to be a poor material)

Ben is a special case (36,881 posts and counting)
BTW, thread gauging itself is almost an art form (I have designed SPC thread inspection systems)

EDIT: gone_fishin' had a link to a polycarbonate barb source
pretty slick - but why thread ?
drill a hole and bond-in a tube
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