Luger Grip Screw Thread Size
 

I have a few frames that could use a clean out of the grip screw threads...Does anyone know the correct size tap/s to buy..??? GPC lists their replacement grip screws as M5 x 0.8 pitch ....???
TIA :thumbup:

It's an obsolete Whitworth thread, good luck finding a tap!
Norm

Some info here:

http://www.practicalmachinist.com/vb...screws-221376/

Just a note of interest to readers of this thread...

the User named as "biometrics" in the thread that is linked above by mrerick was ME! :thumbsup:

Check with Hugh Clark, I think he has info about the screw size and also possibly a tap. Jim

I bought the proper tap about four years ago, at around the time this was discussed back then. It wasn't too hard to find. I'm sure they're still available somewhere, but as Rich suggests, I can't remember the source of mine. Same fate for the info of which Whitworth size and thread it is, as well. John S's blueprints reveal it, I'm sure.

I believe the following will "work"....

http://www.tapsndies.com/tap/tap-3-16-30.html

Oooohhh! I need some?
 

Hi Joe, if you're going to order some, get me a set as well? Or, if only one, get the taper tap? I guess depends on cost... but, I'm in if you want to do the ordering?....GT....:thumbup:

I know this fellow!
 

Hi to all, ...:eek:....I know it seems kind of rude to randomly request a member buy something for you... and that is not what I want to convey, I have some history with Joe.. so I think, maybe, it's ok?... :thumbup:... we shall see! ... best to all, til...lat'r...GT...:jumper::jumper:

That's the ticket! ...if they export to the US.

It also appears that the threads are larger diameter than the shank, which is handy for getting the best shot at restoring the threads while minimizing the material removed. I recommend running completely through the good thread and chasing the buggered one from the inside out.

GT,
I'll see if the "British" seller will ship here.
If so I'll get at least 3 or 4 taps.

If the answer is yes, I'll start a new thread and see if others want one also.

But in the mean time, the difference in 55 and 60 degree threads will not be significant for the 3 threads of that diameter in the frame.
So if you have/buy a current std 30TPI , it should be just fine.

My link is to tap/die in correct 3/16" diameter 30 TPI Withworth 55deg thread form.
What more do you need?

http://www.tracytools.com/taps-and-d...roduct_id=1057

The Whitworth tap for Luger grip screws is not obsolete. There seems to be enough help provided to make a purchase, if not I will see if I can find my data for the right tap. But a little tip to help: If one side of frame hole is O.K. start the tap from that side and go through the mag well into the damaged side (after applying a drop of oil, of course) and re-thread the side needing straightened out. Slow and easy is a key.
Jack

Since they are in the UK, do you know if they ship to the US and the shipping charge?:bowdown:

That is what I "need" to know; and thanks much for the link.

I got mine (Whitworth items) right here in West Virginia. They might still be in business.
Jack

The Whitworth tap, etc. can be purchased at: Sabatelli Precision Grinding, 312 Sabatelli Drive, Mt. Clare, WV 26408. Phone: 304 622-8915.
I don't recall the exact size of the threads or other specs of the opening in Luger grip screw holes.
Jack

Ok, I'm confused. I thought Whitworth was a British thing. Why would the Germans use it? Obviously, there's some factoid I'm missing...

The first screw machines they bought were from the UK, at least that is what I read.
Whitworth predates "standardized" metric pitches, IIRC.

The luger screws and threads are a hybrid, metric diameters and TPI. Whitworth is a 55 degree angle thread, the current standard is 60 degrees, so depending on the use/tolerance/number of threads, a 30 TPI Whitworth will "fit"(close enough) a 30 TPI modern thread.

Changing the gearing from TPI to metric is a bear and old "english system" lathes just won't do it.

Why would it matter to you? Do you want to know the
history of industry in
Europe from the 1700s?
That would be a lot to learn. Many people that come up against this during current times have the same bewilderment.
Let it go.
Also read the thread above and get a portion of it.
Jack

At the time, the Brits were ahead of Germany in product standardization. The Whitworth thread was a documented industrial standard and Ludwig Loewe adopted that standard not only for grip screws but for barrel threads as well. Loewe also looked to the USA for standards for mass production as was initiated early on by Eli Whitney. Loewe wanted to produce quality and interchangeability so he wasn't reluctant to stand on the shoulders of those who had already been there, done that.
Ron

As described in my thread on this subject some time back, both a 3/16"-30 and a 3/16"-32 tap would thread holes that the three threads of a Luger grip screw would comfortably fit in. :rolleyes:

http://forum.lugerforum.com/attachme...0&d=1302648889

http://forum.lugerforum.com/attachme...1&d=1302648889

The #10-32 would not go all the way in.

IMO having the correct size Whitworth tap is nice but not essential for only three threads. :)

From the Luger blueprints in TBLAP -

http://forum.lugerforum.com/attachme...0&d=1299622711

Yes, as a matter of fact!

Such things interest me.

I used this method for a buggered-up/cross threaded Luger grip screw hole. The tap thread was short enough to 'free-bore' once it cleared the 'good' threaded hole. I also used an old worn/dull 3/16"-30 tap as I wanted to push the metal back in place rather than cut it. Used oil, came out fine. :thumbup:

I made a pair of grip screws. They are 0.010" small than the 5mm screw, but 0.8mm pitch. I used a 60 deg screw cutting tool.
Not Whitworth as they are too course.
I'll about to make some more with over size heads so as to stop the grip movement. Standard ones are 0.420" diameter

I have made grips screw by screw cutting the lathe. At the time, I found them to be 0.010" under 5mm and 0.8mm pitch. Just checked my taping chart and they are 3/16 x 32 tpi or 3/16 BSF.
Yes, I know, what are the very clever Germans using a Englander thread. That I don't know??
Maybe a Reasonable Knownable Person can answer??

The best metal fabrication and manufacturing machines made at the time it was initially designed and produced were made in England... does that answer your question Mark? :)

IF YOU READ the Practical Machinist thread noted above, it explains why Germany would use a British thread on their screws. It is a GREAT read!