Question on Grip Screws
 

I need to make a set of grip screws with a slightly larger head...I see from the Blueprint CD that they are a 3/16" Whitworth thread...but it doesn't say if coarse or fine...[24tpi vs 32 tpi]...

Does anyone know which they are??? I'm tempted to just chase the grip frame holes with a #10 SAE tap and make my screws Yankee... :evilgrin:

Hugh Clark or Tom Heller or Ted Green should be able to answer this question for certain, but I believe that the "Nr. 30" in the description of the screw on the blueprint may actually mean 30 threads per inch...

I would suggest that you wait for one of the lugersmiths to answer before using your #10 SAE tap.

Of course it is your frame, and if you want to change the screw type Rich, :eek: that is entirely up to you.

John is correct...
 

Hi Rich, 10/32 is real close, but will bind up in just a few threads... 30 per inch works perfectly... I'm not for sure, but i believe the Luger used an old English thread size & pitch... No 1 rule of life, "nothing is ever as it seems!" :jumper:... Best to you, til...lat'r...GT

Hi Rich -

I wonder if a person could make a cast of that thread using the bore casting material that is called "Ceros" or something like that? (I know you know what I mean.)

It's available from Brownells and melts at a low temperture so that you can take the interior dimensions of a chamber or barrel. When you do a barrel or chamber, you just plug the barrel or chamber with a rag and melt the stuff and pour it in. Then after it cools you just tap it out with a wooden dowel rod.

I'm wondering if you might be able to use that stuff to make a cast of the grip screw threads? However, instead of tapping it out, you would have to probably make some kind of mold or form so that you would have something to grasp and then unscrew it from the threads, etc.

Just a thought.

Ron

How about using a simple thread gauge to find out.
http://www.google.ca/images?hl=en&q=...w=1280&bih=862

How about using washers? :)

Heck, if they are going to be custom grips, make them out of brass or stainless steel and while you are at it, use allen-socket type heads, or twin steel pin holes like the adjustment screws on an Artillery model sights!

All right, let's not get frivolous here...This is serious business... :mad:

Because there are only 3 threads on a grip screw, and the difference between 30 & 32 tpi won't show up until you get more threads to measure...

The blueprint clearly says Whitworth (pic below)...In 3/16" Whitworth, 24 tpi is coarse, 32 tpi is fine...There doesn't seem to be any 30tpi...as standard, anyway... :rolleyes:

Here's the site I got my info from -

http://mdmetric.com/tech/thddat8.htm

Whitworth doesn't list 30tpi for *any* size screw thread...

custom screws can be made

If you want larger headed grip screws to tighten up a set of loose grips, try the rubber O ring under your present screws. That usually works for me. Otherwise, I have NOS Mauser original grip screws available @$15 each or new repros @$5 or $8/set + $3 S&H. TH

I see your problem, that is funny because i found this on the Inet.

Than this

I believe they have used a bastard thread on purpose. I have found inch diameters matched with metric pitches in some european firearms. They knew exactly what they were doing!

:rtfm:Actually there were two sizes, the early ones were 4.5mmx.8 TPI and the later ones were 3/16x32 TPI Whitworth.I don't remember when the change was made, but 90% of the ones I have encountered were the Whitworth threads. I have taps & dies for both.

From the 8 sample guns I have measured (all 1917 or earlier) , I would descibe this thread as 5mm diameter x 0.9mm pitch. The actual major thread dia. of the screws is 4.70-4.75mm which is a little smaller than the modern ISO M5 x 0.8mm (normally around 4.8-4.9mm).
It's known that prior to the ISO metric standard of 1963, Germany used the French SI sizes in 6mm-12mm only . Outside of these sizes the Germans used their own threads.
My measurements don't equate to any of the British Standard or British Association threads.

You can all postulate what the thread is "close to" but as mentioned above by the OP, The original German military blueprints CLEARLY state that the screw is Whitworth 3/16 English Nr. 30... The use of any CLOSE substitute is still going to bind when you tighten it, and will possibly mess up the frame threads if you force it...

I do not recommend subtituting this screw with something "close".

While on the subject, I need another grip screw for a 1913 Erfurt. This is the other that I am missing!

:bigbye:This company has just about any size die & tap that you would want, some are a little expensive:

www.tapsndies.com

Is this the die we are looking for?

http://www.tapsndies.com/catalog/ite...10/6865208.htm

Alf.

...???...I don't see any reference to these being "Whitworth" anywhere on the site... :confused: