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Old March 8, 2006, 01:55 PM   #1
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34 Tpi

Ok. I searched this forum/site for an aswer to my question. I can't find it - if it exists. So, I am leaving it up for grabs to anyone that can answer this:

1. Walther P22 barrel thread is 5/16" X 34TPI.

2. I want to lathe my own adapter.

3. My lathe (Central Machinery 7" x 10" Mini Precesion Lathe) does not make 34TPI.

4. So I need a Tap that is 5/16" x 34TPI, or a gear for my lathe that will allow me to make the 34TPI.

And the questions:

5. Why can't I find a TAP that is 5/16" x 34TPI?

6. Does anybody know where I can find a Tap that is 5/16" x 34TPI?

7. Does anybody know where I can find or have made a gear that will allow my lathe to make 34TPI?

Can ANYone help me regain my sanity with this problem???
igounfazed! is offline  
Old March 8, 2006, 04:20 PM   #2
Join Date: October 30, 2005
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As you've discovered, that's not a standard tap. There are companies out there that will grind you a custom, but that costs $$$$$$$$$$$$$$$$. I have a friend in the mill supply business who has saved me thousands by finding non-standard cutting tools for projects just like this. I'll drop him an e-mail. He usually can give me a yea or nay in a couple days, and I'll pass it along.
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Old March 8, 2006, 04:55 PM   #3
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The other thing is to see if you actually have a metric thread, or if there is a metric close enough to do the job.

5/16 is 7.9375 mm. Very close to 8.0 mm (0.0025 inches off)
34 TPI is .747 pitch in mm, very close to 0.75.
An M8 x .75 tap will be easier to find and is probably the actual corect size.
It is a standard metric fine thread.
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Old March 8, 2006, 10:22 PM   #4
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Thank You's

Thank you guys so far for the info that you have given.

Willsnipe: You are definitely right about them costing a pretty penny. Just received some quotes for just one peice. Pretty high for just the one piece. Looking forward to knowing what yea's or nea's your buddy comes up with.

Brickeyee: I am going to start looking around for that size also. I have one question though. I found out that it is 34TPI with a thread gauge a friend lent me. Is there a gauge that measures your equivilants (M8 x .75)?
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Old March 9, 2006, 11:26 AM   #5
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Well, my dad was a machinist, and used to work on alot of Aerospace stuff that required some pretty weird taps and dies...I still have 'em... And don't have anything like that, nor do I ever recall us working with anything (any diameter) that was 34 tpi.

i'd bet almost anything its a metric size. (I have a few of thos as well, but all much smaller than that).
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Old March 9, 2006, 01:35 PM   #6
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It's almost surely a metric size !!
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Old March 9, 2006, 03:11 PM   #7
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M8 X .75

A friend of mine says he most likely has the M8. I couldn't bring my part in today, (dumb me forgot), but tomorry I will take it and we will see if that works. I am really hoping that it does. I am still waiting to see what willsnipe comes up with too.

I am trying every avenue possible before spending about $200.00 on one.

I really appreciate that you guys are helping me out with this. Thank you - you guys are great.
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Old March 10, 2006, 10:50 PM   #8
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If you used a typical thread gauge of about 3/8 inch length or so, I will bet money that you have a metric thread.
The dhort run makes errors very easy to overlook.
Given that you are delaig with a Walther, the odds of a metric thread are very high.
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Old March 11, 2006, 01:25 AM   #9
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You guys were on the money!

You guys were right about the M8 X 0.75. brickeyee, my friend Fokai laughed at me when I told him: "Walther is made in germany." He gave me the kind of face like: "You didn't think it would be metric?". And the comment: "That would have helped!" lol. I don't know these things very well though. So I have to thank you guys and him for everything you have done for me.

Now I have to find an M8 x 0.75 tap(s).

I have some more good news also that I just found out. My lathe can make 0.75 threads! I found out the hard way. Harborfreight refuses to tell anyone how to do it. They keep referencing the manual's page 11 (chart on page with standard threads) saying thats all the lathe can do. Page 10 on the other hand says it can make any thread! They still refuse to say how to make the other threads.

So I searched and searched - trying everything on google - and found this website: Varmit Al's. He has everything on that site for the lathe I have. From tools, website links, how-to's, to the most important: A Better Thread Chart. He even has programs for free downloads where you put in the TPI you want; and it calculates which gears for you to use!

With all that. Why do I still need the tap? My friend says that working with such fine a thread, and so little a space; it will be very difficult for me to make them in the piece I want to create. He said the tap is the best way to go with the size I am dealing with.

Well, I just wanted you guys to know what came up with all your help. And to have an answer in the thread for anybody else that might need the information. I see so many threads in forums that have questions, thank you's, but no idea what the answers were.

Thanx again for your help guys.

If anyone can direct me to a tap set M8 X 0.75, I would appreciate that also.

Last edited by igounfazed!; March 11, 2006 at 12:14 PM.
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Old March 11, 2006, 10:29 AM   #10
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Hand - Taps Thread Size: M8x0.75 Thread Type: Metric Fine Chamfer Style: Plug Material: HSS Finish/Coating: Bright

Less than $6 each.
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Old March 11, 2006, 12:09 PM   #11
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brickeyee, dude; you're like totaly awesome!!! Thanks for the link.

I have to thank all you guys that have helped me with this just one more time for all your help. I'll finish this thread with a summary for anyone else that finds themselve in my predicament:

Walther P22 Barrel threading is a Metric size: M8 X 0.75

Anyone one that owns a mini lathe from Central Machinery can go here (Varmit Al's website) for in depth information that Harbor Freight Tools will not give you concerning this lathe. Includes more thread gear set-ups and computer programs that will tell you which gears to use. (NOTE: The programs are very small, with quick download even over a phone line.)

If you need the TAP in M8 X 0.75 go here to MSC Industrial Supply Co. where they cost about $6.00.


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