# SF Millenium Thread Pitch



## Boltgun (Mar 25, 2006)

Does any one have the Thread pitch info for the SF Millenium lights (M3,M4,M951,Etc)?

TIA

Boltgun


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## gadget_lover (Mar 25, 2006)

I know the surefire E series is 20 tpi. I don't know about the millenium series.

You can actually use a ruler to check. If there are 5 threads (peak to peak) in a quarter inch, it's 20 tpi.

Daniel


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## CLHC (Mar 25, 2006)

Hello One As-Te-Risk (sounds like—)! :huh: 

Well on the tail end of my SureFire M3 there's seven (7) threads. On the bezel end it's five (5).

—Enjoy!


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## gadget_lover (Mar 25, 2006)

CHC, I think he wants the pitch. Is that 7 threads total, or 7 per inch or 7 per 1/4 inch?

Daniel


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## CLHC (Mar 26, 2006)

Ooopps! :thinking:

That's the total thread count. Been out of the "mechanical" thing for more than 20 years. . .One of those "use it or loose it" matters. :huh:


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## Vee3 (Mar 26, 2006)

Just a note -

"Pitch" and "Threads per inch (TPI)" are not the same thing (Although they are often incorrectly used interchangably).

Pitch is the distance from one point on a thread to a corresponding point on an adjacent thread.

Threads per inch is just that - how many threads there are in 1".


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## gadget_lover (Mar 26, 2006)

If they were cut using unified national threads, wouldn't the appropriate measure be TPI? One could measure the DP, but that won't do much good without the TPI to go with it, right?

It's late, I could be totally wrong.

Daniel


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## Rothrandir (Mar 26, 2006)

threads per inch and threadpitch are two different things, but they both tell you the same story. which number you want to use depends on what you're doing.

on the minilathes, you select your gear ratio based on the threads per inch number, using a chart that tells you what gears are used for what tpi.

when programming cnc, you specify the threadpitch, essentially that acts as the feedrate. for example, a 16tpi thread would have a pitch of .0625 (1/16). that is essentially the feedrate, .0625 inches per revolution.


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## Boltgun (Mar 26, 2006)

Thanks for the replies guys....I am looking for both pitch and TPI if needed to cut them. 

Regards
Boltgun


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## wquiles (Mar 29, 2006)

Somebody has to know this info ...

Will


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## wquiles (Apr 5, 2006)

*Re: SF Millenium Thread Pitch -> no-one knows?*

 

Will


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## CLHC (Apr 6, 2006)

*Re: SF Millenium Thread Pitch -> no-one knows?*


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## Rothrandir (Apr 7, 2006)

*Re: SF Millenium Thread Pitch -> no-one knows?*

i can't believe noone has reponded yet, the answers are certainly out there!

i have extended this offer in the past, but strangly no-one has taken me up on it:
send me your m2, and i will measure it and send you back the dimensions (but no light).

seriously though, if it need be, i can indeed measure your light (and even send it back i suppose), but i know that there are at least several people on this board who either know it off the top of their heads, or have ways to measure it.
heck, i used to know it, but it's among a long list of things i've forgotten


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## will (Apr 7, 2006)

In another life I had been a machinist - TPI is threads per inch, ( diameter does not matter ) PITCH is the angle the actual thread forms in relation to horizontal line of the object . I believe most threads are 60 degrees, which is the same as a triangular file. There can be differences in pitch from this standard for special applications. The cutting tool in a lathe (for threading )is pretty much a 'standard' thread cutter. 

I don't know what the TPI or PITCH is of the light you are looking at. What you can try is a poor man's thread guage - go to a store that has a large selection of nuts and bolts ( home depot - lowes - ace or someplace ) and find the bolt that lies in the threads of the flashlight. Notice I said lies in the thread - you should be able to hold the two objects together, the threads should line up. this works for most standard threads.

most sae threads are 56, 40, 32, 24, 20, 16, and so on I may have missed a 
few.. but you should have the idea.

good luck


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