18 pounder primers

[Jamestheredcoat]

Hi all. I have the shell casing from an 18 pounder an I wish to remove the primer from the underside. dose anyone know how to remove the primer? are there pre-existing wrenches or keys which could fit into the primers two indentations to unscrew it or will I have to create a custom key?

[Chasemuseum]

There are pre-existing keys but you are unlikely to ever find one. You will need to make your own. After 100 years and being fired, they will not unscrew easily.

[Spaceman]

They are extremely hard to remove. I found the same key from one of my angle grinders was exactly the right size but it simply wouldn't budge the primer I wanted to extract from an 18-pdr shell case, even after applying a lot of heat from a gas torch. The problem was that the primer looked as though it was held in by a tough cement although it was probably a combination of corrosion and deposits that had built up over at least 100 years.

The other problem is that the primer case is not that strong and is relatively easily damaged if you apply too much force. I'm a fairly experienced metal worker and, in the end, I managed to remove the primer (from a battered old case to put into one in good condition) but it was a real challenge and eventually required the use of a suitably sized parallel punch. 

[Gunner Bailey]

1 hour ago, Spaceman said:

They are extremely hard to remove. I found the same key from one of my angle grinders was exactly the right size but it simply wouldn't budge the primer I wanted to extract from an 18-pdr shell case, even after applying a lot of heat from a gas torch. The problem was that the primer looked as though it was held in by a tough cement although it was probably a combination of corrosion and deposits that had built up over at least 100 years.

The other problem is that the primer case is not that strong and is relatively easily damaged if you apply too much force. I'm a fairly experienced metal worker and, in the end, I managed to remove the primer (from a battered old case to put into one in good condition) but it was a real challenge and eventually required the use of a suitably sized parallel punch. 

Depends upon the angle grinder key. I have an original primer removal tool and its about 14" long, so a lot of torque. I'm not sure primers were used with Pettman cement but some fuzes were and in fact still are, despite Pettman Cement being about 130 years old.

 

Edited 19 March by Gunner Bailey

[Gunner Bailey]

Here's photo of the tool.

 

[Spaceman]

As well as using a suitably sized tool, the other problem you have to solve is how to hold the shell case firmly enough while you try to unscrew the primer- you can't hold the case in one hand while trying to unscrew the primer with the other, especially using a two-handed tool. I managed to hold my shell case firmly enough while I removed the primer but, unfortunately, I can't remember how I did it! Ideally, it needs to be put into a clamp around its base where it is strongest but this would not be simple to fabricate. However, I may have another go with a spare 18-pdr shell case I have to see if I can repeat what I did before!

[Chasemuseum]

Holding the case is a fairly traditional metal working problem. If I were to try it again I would use a piece of timber about 2 inches thick, use a hole saw to cut a suitable hole to take the case. Then saw the timber into two pieces. Wrap the case in plastic rope, Put the timber around it and bolt the two pieces together to be good and tight, and apply the compressive load to stop the case from turning in the jig. Then put the lot in a wood-working vice to hold it in position.

Gunner Baileys' tool gives a good idea of the minimum size tool required. In practice, to move a primer after 100-years. I would consider leaving the shell case in a tin and put an inch of penetrating fluid in the tin and inside the case and leave it for a couple of months in the hope that the fluid may make its way though the screw thread.  The I would consider using a tool atleast twice the size of GBs. 

[Spaceman]

I might have another go with my spare 18-pdr case - I like a challenge. I vaguely remember that I may have used a suitable piston ring clamp or maybe a ratchet strap to grip the base of the case which was then clamped in a vice. This time, I may make up a double handled tool as depicted by Gunner Bailey. I will certainly try a bit of PlusGas over night to try to free up the thread but I think unscrewing the primer without damaging it is still going to be a massive challenge!

[Gunner Bailey]

You have to remember that these tools were for factory use with new clean parts. They were never designed to overcome 100 years of corrosion. So yes, you may have to make a bigger version.

[Dave66]

Years ago you used to be able to get an oil filter removal tool…that may hold the case steady and not mark it…https://www.amazon.co.uk/Draper-Redline-68813-Filter-Wrench/dp/B011R8ON60?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A2US33UZVDCQLO

Dave.

[Spaceman]

When I got back this afternoon, I knocked up an unlocking tool from 1" flat steel bar 36" long in the middle of which I threaded two suitably sized bolts spaced 1.25" apart.  I then used a strap wrench and vice to hold the shell cases very firmly. I just happened to have 3 x spare 18-pdr cases sitting on the floor of my workshop, one of which I had already removed the primer from. Using my new tool, I managed to unscrew both of the other primers without difficulty although they definitely needed the much longer tool to be used. One was easier than the other because the holes in the primer for the tool were in much better condition. An interesting exercise

Edited 20 March by Spaceman

[Gunner Bailey]

Well done!