T

tdarling

#1
Hello to all,
I have a question pertaining to thread wire measurement, and I have tried to Google it but I"m not having any success.
I have BSPP thread plug gauges and I need to measure them. I was told that you can use Metric thread wires to measure the BSPP threads, but there is a formula to convert the 3 wire metric threads which I could then use them for the BSPP threads. Could someone please help me on this or direct me to whom may know this?

Thanks!
 

fabricator

Starting to get Involved
#2
BSPT & BSPP are NOT metric threads. British thread forms have a 55 degree flank angle and use sizes similar to our own pipe threads - 1/8, 1/4, 3/8, 1/2, etc. General practice is to use measuring wires of "best size," i.e., a wire that contacts at the pitch line. From the Machinery Handbook: Best wire size=0.5 pitch/cosA, where A = 1/2 included angle of thread in axial plane.
 

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