Drilling and Tapping a PVC Blind Flange

[MattL]

I would like to drill and tap a PVC blind flange for a project. I have no trouble using the taps to get NPT threads. The problem is, the drill bits I've used don't produce a smooth enough hole (I get chipping, vibration, etc. when using a drill press)

Moreover, the holes typically use very odd sizes (to the 64ths), making finding a n answer difficult.

Has anyone ever tried to drill and tap holes in plastic on the 3/4", 1" size?

Matt

 

[mcgyvr]

What type of bits are you using?

A regular twist drill really isn't the best for plastic like that and certainly not in that size..
Spur/Dowel bits can work better in plastic...
Other tricks like smaller pilot holes/countersinking,etc... in addition to firm/solid work holding can be used.

Bi-metal hole saws can be used too but use caution to avoid overheating/melting the piece.. Shallow "pecking" and even water cooling can help there..

Beyond that a CNC router/zero or single flute bit does a great job too boring the hole..

You can likely get by though with a drill press and a regular twist drill but you must clamp the work piece, lock down the table and go very slow.. (try the pilot hole/countersink too)