Hinge Pin Screw Head Indexing

[Old and Reliable]

[quote=Dave Suponski;15848]Francis,The screw shoulders all the way to the hinge pin and the threads are very deep already.The proper way to index the screw without removing the hinge pin would be to remove a few thousands at a time from the back side of the screw head. You will be suprised at how much the screw will move with only a few thousands removed. Go slow...a little at a time...checking constantly....--

I have never removed a hinge pin screw, apparently you have and also refit the screw head to get the proper indexing

[Autumn Daze]

Francis,No I am not aware of any publication for Parker guns the lists screw sizes.Yes I have had a few hinge screws out.They are an extra fine thread a little over .250 in diameter if memory serves....

[Austin W Hogan]

Dave; Are they 1/4 - 24? That is the size of Springfield 1903 trigger gaurd to frame mounting threads. They are designated 1/4 - 24 NS (national special). I was able to buy the taps and dies on special order through Van Hornes Hardware in Fultonville NY to make a T handle set to inlet Springfield Sporters.
I have had a couple of out of register framescrews over the years and wonder how it happens. Perhaps the threaded mate was misaligned after frame recase. This is about the toughest Parker screw to move, and I can think of no reason for it to meander.

Best, Austin

[Autumn Daze]

Austin,If I remember right the TPI is at least 32 or maybe more.

[Old and Reliable]

Wonder if the later 1903-A3 series had that NS thread for the tang bolt?

[Autumn Daze]

If you check your Machinery's Handbook there is a listing for SAE Extra Fine Thread.Not get off topic here but another anomolie was Harley Davidson.In the years that I built them Harley motors had thread sizes that were not SAE,Whitworth or anything else on this planet....

[Double Play]

Originally Posted by Dave Suponski

In the years that I built them Harley motors had thread sizes that were not SAE,Whitworth or anything else on this planet....

See what happens when a pollock gets involved.

[Glenn Fewless]

Gentlemens:

Non standard threads are not at all uncommon in anything made before the second war. It is particularly common in guns made before the first.

Originally it was because there were no standards and all the thread cutting tooling was shop made. When standards were introduced there was still all the old tooling around, and the makers were not going to throw it away just because someone came up with a standard. Plus, if you had been using a thread equivalent to a #10-30 for the last 20 years in all your guns, it would be burdensome to switch to the standard #10-32. Now you have to have two sets of tooling, one to maintain old work and one to make new.

Even when the standards were well established, there was still an advantage to non standard or "proprietary" (often called Bastard) screw threads. You have to go the manufacturer for parts. This practice is about gone now.


As for timing the screw head, it is a fairly simple process. If you have 32 pitch thread (32 threads per inch) one complete revolution will create an axial movement of 1/32", or about .032". Half a turn would equal .016" and a quarter turn .008"

If the slot on you 32 pitch screw head lines up at 8:00 and you want it to line up at 9:00 you need to take one hour's metal off the back.

.032 divided by 12 = .0026" This is what you would have to take off the back of the screw head to bring it into time.


Best to all,

Glenn

[Autumn Daze]

Thanks Glenn...You pretty much nailed it. I was just too lazy to type all that....

As for you Frey...Its spelled POLLOCK

[Austin W Hogan]

Dave Is correct it is a 1/4 x 32; see the photo. If you enlarge the lower side of the screw head, you will see it is chamferred for about 1/32 inch at what appears to be the V of the thread. This particular screw head does not bottom on its flat but on its edge. This is the only hinge pin I have that removes easily so I cannot comment about this being the same in all guns.
An important observation on this gun is that the frame and roll are continuously threaded.

Best, Austin