Hinge Pin Screw Head Indexing

[Larry Harwood]

Gentlemen,

Assuming that the proper tools are used, what is the proper procedure for indexing the hinge pin screw? I have one on my GH 20 that when tight has a slot position of approximately 8 instead of 9 o'clock. No big deal functionally, just one of those things that bug me and it seems like something I should be able to correct myself, with a little guidance.

[Bruce Day]

Maybe ask the person from whom you bought the gun? Not many know as much about Parkers as he does.

[Steve Huffman]

Hmmm !

[Harry Collins]

Steve,

I have the same problem with a DH 10 gauge except my hinge pin was about 10 o'clock rather than 9. I think Austin had one that he was able to tighten with a screw driver made to fit the whole slot chucked into a drill press. Don't do this until it is confirmed by others. The hing pin is pressed into the frame and I would think it would have to be pressed out and reinserted to get the screw to index. Don't tell the rest of the guy's here but, I took the hing pin screw out of my DH and shimmed it with enough brass sheeting to make it index.

Harry

[Richard Flanders]

I think Harry has the right idea. Thin copper sheeting would work well I would think and would act like a crush washer in other applications and allow some latitude for indexing and would hold the screw head in place well. I've always thought the same thing could be done to floor plate screws out of time. I think that thin copper sheeting or even aluminum foil 'washers' could be made with a leather punch and added under screw heads as needed to get them indexed.

[Dean Romig]

The possibility however, of relatively fast ocurring corrosion would concern me if using aluminum or copper in contact with a dissimilar metal (steel).

[Larry Harwood]

Thanks to all for their input. I believe the shimming idea is a sound solution especially in situations where the screw is indexed somewhere between the 9 and 12 o'clock positions. However, I think steel shim stock, cut into washers, would be the best material to use since it can be aquired in various thicknesses and, being a similar metal, would not likely promote corrosion.

As I wrote in my original post, in my situation the screw is just short (approximately 30 degrees) of being correctly indexed. Adding enough shimming material under the screw head to bring it to the 9 o'clock position would, if my math is correct and assuming the screw has approximately 32 TPI, require about .026 of shim material. That just seems to me to be too much shimming.

Another option ... If approximately .005" of material was removed from the underside of the screw head the same results would likely be achieved. I fully realize that removing any metal on a gun had better be well thought out in advance, but this solution seems so simple and innocuous.

I'm looking forward to your thoughts.

[Robert Rambler]

Larry, Check your PM.

[Francis Morin]

[quote=Dean Romig;15825]The possibility however, of relatively fast ocurring corrosion would concern me if using aluminum or copper in contact with a dissimilar metal (steel).

Interesting! Aluminum foil or sheet copper should have no problem with contact with any of the carbon range steels used by Parker Bros.

[Dave Suponski]

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....:)

[Francis Morin]

[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

[Dave Suponski]

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

[Dave Suponski]

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

[Francis Morin]

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

[Dave Suponski]

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....:rolleyes:

[Larry Frey]

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

See what happens when a pollock gets involved.:duck:

[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

[Dave Suponski]

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

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

[Francis Morin]

[quote=Larry Frey;15894]See what happens when a pollock gets involved.:duck:[/

:rotf::rolleyes:

[Austin W Hogan]

The screw nut and bolt business was a major division of the Parker companies. They made custom threaded fasteners for many other manufacturers.
Most of the screws inside Parker locks and frames are 40 tpi; what we now call a micrometer thread.
Returning to the initial question; it may be possible to distort a Parker frame by adjusting the head of the screw, as the threads are continuous through three mating parts.

Best, Austin