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:

The diameter and thread pitch are correct, but you should contact the company via email or phone to inquire about whitworth threads before ordering...

:rolleyes:It really doesn't matter as the only difference is that the Whitworth has a 55 degree thread and the standard has a 60 degree thread. The spacing is the same. As thin as the Luger grip is, with only 3 or 4 threads, the thread angle isn't going to matter. Also, after extensive searching on the internet, that was the only place I found that size available, without ordering from England.

You will have to telephone them to ask questions.


From the internet:

"The Whitworth tap is a designation assigned to taps that use the British unit of measurement for its pitch and size. Named after Sir Joseph Whitworth of Stockport, England, the Whitworth type of threading was not initially meant for fasteners such as screws or bolts. It was first used as the measurement of the threading within a rifle barrel that adds spin to a fired bullet. Due to its ideal helix angle, it allowed bullets to be fired further and more accurately. This helix angle can now be seen it the threading of screws and bolts that follow the standard measurements of British taps. Unlike their American counterparts who use a standard 0.013 mm pitch distance it their threading, Whitworth taps generally use a 0.0005 inch pitch distance in their threading. Although these taps are no longer as common as the metric tap since the US standard has been adopted internationally, Whitworth taps are still available in all types of taps. From thread cutting dies and cutting taps to forming taps and custom dies, the Whitworth tap is still very much in use."

"There are three main divisions of British measurements used in threading screws, bolts and nuts. The first is the British Association or BA series of taps. This is the rough equivalent to the Society of Automotive Engineers or SAE standard taps that use the metric system. These are numbered 1 to 14 in sizing. The second is the British Standard Fine taps or the BSF. This is the counterpart of the SAE Unified National Fine taps. These are available in sizes ranging from 3/16 of an inch to 1 inch, with pitches ranging from 32 for the 3/16th inch tap to 10 for the 1 inch tap. The third is the British Standard Whitworth tap or BSW. These are equated with the SAE Unified National Coarse taps of the metric system taps. These are larger taps that range from 1/8 of an inch to 2 ½ inches in size, with the pitch ranging from 40 for the 1/8 inch tap and 4 for the 2 ½ inch tap. These tap sizes are available at Newman Tools Inc of Canada or their US office located in Hartford, CT, USA.

Another Whitworth tap that offers the quality and effectiveness of a large tool making company is the Whitworth tap from Axminster Tool Center. These tap and die tools from Axminster are made from high quality materials and offer long lasting function. They are available in three forms. There are tapered Whitworth taps to start threading off. Another form is the intermediate Whitworth tap that is used to follow up a tapping job. The third form is the bottoming Whitworth tap that cuts threads from the bottom of a hole that has been previously drilled. These are available in various sizes at approximately $3 to $4 a piece."

Thank You, Hugh! :thumbup:

Just for S&G, I tried a Luger grip screw in my crimping pliars...(electricians pliars)...It went in nice & easy; not too tight, not too loose...It's the #10-32 hole... :rolleyes:

A #10-32 HHCS goes in nice & easy, too...But won't go in a Luger grip frame... :)

...Doesn't prove anything...Just thought I'd throw this in here... :D

I drilled & tapped three holes in a piece of scrap steel today...Using the following taps & drills

Tap/Drill

3/16" x 30/#23

3/16" x 32/#22

#10 x 32/#21

(The two 3/16" taps obtained from www.tapsndies.com; the #10 is from Ace Hardware)

Pics below...Both the 3/16" x 30 & the 3/16" x 32 tapped holes accepted a Luger grip screw...(off an S/42 Luger)...The #10 x 32 tapped hole would only allow 2 threads of the screw before binding...The two 3/16" tapped holes allowed all 3 threads of the grip screw...

I ended up tapping my grip frame with the 3/16" x 32 tap...The Luger grip screw fits just fine... :thumbup:

Here is my experience regarding this issue. I took a gun to a shop that produces taps and sells numerous taps from other producers. They must have dozens and hundreds of different sizes and shapes, types and thread counts. They concluded it is 32 TPI, Whitworth, as I told him I understood it to be.
He used a "starter" tap and gently placed it into the threads in the gun; worked it into what he could feel as the starting point and, just with his fingers, made a quarter of a turn 3 or 4 times and gradually got it taking hold. When it got too tight for finger turning, after visually checking it numerous times, as he worked, he put a "T" wrench on it and worked it through. He only visually checked the screw and put it into the hole and once again gently turned it into place. It worked slick as anything. That was on a 1915 Arty. We repeated it on a 1900 AE with the same results. I bought the "starter" tap for $15 and brought it home to become a new addition to my tool box. Nothing was done to the screw. Apparently from the shape and bluntness of the screw, it is most often that the threads in the hole get damaged - not the threads on the screw.

"I ended up tapping my grip frame with the 3/16" x 32 tap...The Luger grip screw fits just fine... "

Hi Postino, is the 3/16"x32 BSF or Whitworth.
Alf.

The way I recall the Whitworth tap I just bought and chased grip screw threads with was listed both ways. BSF=British standard fine, which is the fine version of BSW=British standard Whitworth(coarse thread). So whit.3/16-32 would be the same as 3/16 BSF.
Here's a thought, did the original post seek larger diameter HEADS for the grip screws? I've noticed that this is the case for Erma La-22's; but since I am away from the guns in question, cannot say right now. The Erma grip screws have a significantly larger head diameter, so if thread size and pitch somehow match, they could work where this would be needed--or turned down a tad if the dia. is excessive.
David Parker

Thanks, the problem is I can't find 3/16"x32 Whitworth(BSW), only 3/16" x 32 BSF .
Alf

In two guns for me, 32 Tpi at 3/16 - Whitworthworked just fine and cleared up my problems. One was a 1915 Arty the other was a 1900 AE.

Albert, the BSW is coarse Whitworth thread, the BSF is fine Whitworth thread...

Yes. Here is a copy of the Numrich Luger P-08 parts listing, just for S&G...I only noticed this today (Numrich has a habit of listing 'Not Illustrated' parts wherever they please...) :rolleyes:

466070 Grip Screw (.258 OAL, .393 Head Diameter, Thread Pitch M5 x .8; 2 Req'd) $3.55

1430020 Grip Screw (.193 OAL, .344 Head Diameter, M5 x .8) $3.45

1430010 Grip Screw (.214 OAL, .373 Head Diameter, M5 x .8, Beveled) $3.45

I ordered two of the .393 dia screws...I'm doubtful of their thread pitch, but I hope they can read a caliper correctly...