Why can one not use their thread gauges to cut thread?

The formula used in the three wire method is E = M-3W +.88803/n while the one used in the single wire method is E =2M2-M1 -3W +.86603/n.

If you can make a measurement within +/- .0001 of the true measurement and you assume a worst case erroro stacking the three wire method would give a maximum error of +/- .0004" while the single wire method would give a maximum error of +/- .0006". For most practical purposes they are equivalent. I have a set of PeeDee wires and FWIW, i miked them and found that they can vary from the nominal size by +/- .0001.

Weighing the slight decrease in potential accuracy against trying to balance three wires while making an accurate mike measurement, I believe that I will use the single wire method going forward.

I bought my set of wires from Enco just before they left the scene and they were quite reasonable. However, if a person didn't want to spring for a set of thread wires, I would suggest getting a set of 010" - .060" pin gages. They run about the same price as the thread wires but they have other uses in the machine shop
 
To my knowledge the gauges you link to will not cut threads. They are for inspection of threads already cut. They are go and no go gauges. There is no taper in those threads hence they will only follow what is already there.

"Billy G"
 
Bill Gruby said:
To my knowledge the gauges you link to will not cut threads. They are for inspection of threads already cut. They are go and no go gauges. There is no taper in those threads hence they will only follow what is already there.

"Billy G"
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I suspect he meant "for measurement during the process of thread cutting" ;-)
 
the sole purpose of a thread gage is to verifiy threads per inch 'gear box or change gear setting' guess I'm a gettin
to old amazingly all the young ones have to be concered with wires thread mics math>>>>dumpster by by!
The best wires are your ears and eyes. All these threading posts I read = (oh I gotta be perfect first
time so I need math wires & mic) People you are over killing your brainm unless your are a cnc'er. which I am not.
thousands of threads under my belt and I feel hear and see the perfect form THEN try the nut. Spring cuts ya best
friend. So the nut a little tight? try valve grinding coumpound 'under power back an forth'
 
I can't imagine my 76 year old fingers holding those wires while I simultaneously manipulating a measuring device with my other hand all while bending over my lathe. I just use nuts to check fit. After all. I don't do work for NASA.
 
gonzo said:
I can't imagine my 76 year old fingers holding those wires while I simultaneously manipulating a measuring device with my other hand all while bending over my lathe. I just use nuts to check fit. After all. I don't do work for NASA.
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Very few tasks are more annoying then measuring small threads over wires, Large threads are much easier until one reaches leads that are wider then a common micrometer anvil where a gauge block is required.
 
Plasticine, Blu Tack, etc. there are many options which avoid "fumbling wires" ;-)
 
I absolutely HATE using 3 wires but I use them because I don't have a thread mike and I believe the 3 wire method is the only accurate alternative to a mike. I know some guys use the one wire method but as it uses the thread crests on one side it will only be accurate if the flats on your new thread are exactly the same as the thread you'r trying to replicate. The one wire method removes 50% of the error that would be introduced by the no wire method. (Just measuring the OD)
 
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