Thread Wires

[redlee]

I have used Pee Dee for years with no issues .
On a 20" 16 TPI seat ring thread you need 3 hands or help.

[redlee]

[redlee]

We used these also, great for freeing up a hand and compared to 3 wire.

[nickel-city-fab]

The little triangle bit fits in the thread and you measure over that? How are they held onto the thread, same as thread wires?

[redlee]

The little triangle bit fits in the thread and you measure over that? How are they held onto the thread, same as thread wires?

Yes has 3 different flats for different leads, just put mike on flat and and other end of mike just sits on the thread crests. You have take Nominal OD measurement and use that in calculation..
It measures Pitch Dia.

[nickel-city-fab]

Yes has 3 different flats for different leads, just put mike on flat and and other end of mike just sits on the thread crests. You have take Nominal OD measurement and use that in calculation..

Cool, thanks. Never seen that before. I used thread wires *once* in school, and then I went and bought thread mics.
But I know of at least one shop in my area, that cuts threads a few feet in diameter... you could use pipes instead of wires to measure that one I bet.

[J Tiers]

Never seen a "single triangle" version. Seems as if that might not be very accurate at all. Taking an OD measurement first is all cute and nice, I guess, but you don't necessarily get a good reading even so. That would depend on the thread AND any crest defects being symmetrical.

I have a set of two triangles, which do a good job on clean threads. I have thread wires, they work also. I have a number of thread gauges, but they are also inaccurate unless you use a full-form cutter, since any burrs throw them off.

I have thread mics for some diameter/pitch combos, and they are not very accurate, they are to thou only, and you need to set them to size by means of a standard first, for best accuracy. The thread gauges are go-nogo, and are not "on-size", they are limit gauges.

Wires usually don't care about normal burrs, triangles can be thrown way off by them, while gauges are wildly wrong if there are burrs, and so are thread mics.

[MattiJ]

Measuring threads over wires is annoying at best, I do a good deal of it, if another method is available such as a thread micrometer use it.

If one is truly concerned about PD accuracy simply buy high accuracy matched wires for each job, these are available from such sources as MSC for less then $100.00 per set of three wires.

Mitutoyo has holder for the wires that clips to the micrometer anvil.

tool gloat time: I have full set like one shown below
https://www.actionis.com/mitutoyo-31...1-um-tolerance