PARKER HALE 5C aperture sights ......

[Patrick Chadwick]

It's a 40TPI over a 1/8" diameter......... phew!

Actually, Peter, that is a perfectly ordinary BSW size
For those who can't find Whitworth screws or threading gear, try model engineering suppliers or your local model engineering club: model locomotive engineers use several 40 tpi sizes for small boiler fittings.

The one that really is a curse is the thread on the backsight disk. That looks like it ought to be 1/4" x 40 tpi - a straightforward model engineering thread. Unfortunately, the Parkers (Alfred and -Hale) appear to have used rubber calipers, and the measured diameter is something like 0.222"-0.223" - seriously undersize. So if you need to make a new backsight insert, the simplest solution is to use a taper tap to open out the thread in the existing hole in the crosspiece to a full 1/4" x 40 ME and cut the thread on the new insert to the same dimensions. If you have the appropriate size of Coventry die-head and cutters, then you can tighten up the nominal 1/4" somewhat. However, I realize that not everyone has these items...

Patrick

[RJW NZ]

Here's a useful parker hale tip, found out the hard way ... those lovely iris eyepieces that PH made? If you're mad enough to take one apart for cleaning, which can be done with a watchmakers patience, don't disturb the iris leafs from the base they pivot in. Some were made by laying the leaf in place and the pivot created by pushing/breaking a point through the leaf into its pivot hole so that the tiny flanges of metal that would peel back from the point engage the hole walls. If you remove the leafs from the base these tiny flanges disappear, never to be seen again, and hence no longer exist for second assembly.
Oh well, a few more spares in my kit now ...

[Peter Laidler]

Taking this matter further, I was chuntering on about the vagaries of these sights at Fultons today. The main man there told me that in his earliest days as an apprentice there, it was his job to overhaul these sights and repair them. He soon learned all about odd thread sizes there and also added that he also learned the hard way that there was/is a whitworth thread that goes down to 1/8" - yep, the 40tpi over 1/8" thumbscrew size on the leadscrew........... but not all (thanks for that info Patrick C)!

Anyway, the GOOD news is that they have a half shoebox size box full of these sights in all states of repair if anyone needs spare parts.

If you need to, speak to Rob Taylor there. Address and email on the web somewhere. Let's hope that this will get some of you out of a hole. Mind you, with the variations we and they have learned of, you could end up in a BIGGER hole! Happy hunting!

[RJW NZ]

Thats a great tip, thanks, and those parts might match the parts I've built up.

[Surpmil]

Here's a useful parker hale tip, found out the hard way ... those lovely iris eyepieces that PH made? If you're mad enough to take one apart for cleaning, which can be done with a watchmakers patience, don't disturb the iris leafs from the base they pivot in. Some were made by laying the leaf in place and the pivot created by pushing/breaking a point through the leaf into its pivot hole so that the tiny flanges of metal that would peel back from the point engage the hole walls. If you remove the leafs from the base these tiny flanges disappear, never to be seen again, and hence no longer exist for second assembly.
Oh well, a few more spares in my kit now ...

Another job for the ultrasonic cleaner...no need to disassemble, the fluid will work its way into 1 thou gaps and get the dirt out. Blow off, put in toaster oven while spouse not looking, and dunk in lubricant of choice. Done.

[tbonesmith]

Here's a useful parker hale tip, found out the hard way ... those lovely iris eyepieces that PH made? If you're mad enough to take one apart for cleaning, which can be done with a watchmakers patience, don't disturb the iris leafs from the base they pivot in. Some were made by laying the leaf in place and the pivot created by pushing/breaking a point through the leaf into its pivot hole so that the tiny flanges of metal that would peel back from the point engage the hole walls. If you remove the leafs from the base these tiny flanges disappear, never to be seen again, and hence no longer exist for second assembly.
Oh well, a few more spares in my kit now ...

Just picked up one of these on a sight I bought at the range(on a central), what a beautiful little bit of engineering, with the filter holder too, hey anyone got these parker hale filters?