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1930s Diana Model 27

SteveMedlock
(@stevemedlock)
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Hi all,

I'm just stripping this down at the moment and I'm assuming that the trigger block is screwed onto the piston tube but I cant move it at all. could anyone please confirm that this is the case and I'm not missing anything?

Steve.

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Topic starter Posted : 16th February 2021 16:58
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Garvin
(@garvin)
Curator in Chief Admin
Posted by: @stevemedlock

Hi all,

I'm just stripping this down at the moment and I'm assuming that the trigger block is screwed onto the piston tube but I cant move it at all. could anyone please confirm that this is the case and I'm not missing anything?

Steve.

You're right, Steve. But they do get jammed on tight and need a lot of treatment to release them..

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Posted : 16th February 2021 22:36
SteveMedlock
(@stevemedlock)
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@garvin Thanks very much. I've just managed to free it but that was very very tight. I was worried about damaging the tube with the amount of force needed. I did apply lots of heat but stupidly, I was heating the trigger block rather than the end of the tube!

Are the internals the same as the later Model 27 with the full stock or is that a completely different rifle?

 

Steve.

 

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Topic starter Posted : 17th February 2021 13:44
Garvin
(@garvin)
Curator in Chief Admin

@stevemedlock

To be honest, Steve, I've been inside a later one but not an earlier buttstock prewar model. I assume it's similar apart from the trigger block and and bog standard prewar break barrel like this:

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Posted : 17th February 2021 14:56
SteveMedlock
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OK thanks Garvin. The spring and piston washer are actually good enough to re-use if necessary. I've also found a couple of other springs which have the same dimensions so I may be able to try those as well.

 

Steve.

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Topic starter Posted : 17th February 2021 16:48
Garvin
(@garvin)
Curator in Chief Admin
Posted by: @stevemedlock

OK thanks Garvin. The spring and piston washer are actually good enough to re-use if necessary. I've also found a couple of other springs which have the same dimensions so I may be able to try those as well.

 

Steve.

If you have time, could you take a few pics of the rifle disassembled please? 🙂 

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Posted : 18th February 2021 16:01
SteveMedlock
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Topic starter Posted : 28th February 2021 15:25
Garvin
(@garvin)
Curator in Chief Admin

That's excellent, many thanks. 🙂 

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Posted : 28th February 2021 15:38
SteveMedlock
(@stevemedlock)
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Bad news! I re-assembled the rifle today and having cocked it, I was just about to put a pellet in the breech when the spring let go and the rifle jumped out of my hands onto the floor. At first I thought the sear had slipped but in fact, the piston rod had broken at the point where it joins the front of the piston. Never seen that happen to an air rife before!

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Topic starter Posted : 1st March 2021 17:01
marflow
(@marflow)
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i have seen the crimp once loose before

so the shaft snapped off ???

i was looking for a parts diagram of a similar rifle and saw the model 23 appear that the rod was pinned into the piston 

23 Diana/Original - Airgun spares | Chambers Gunmakers - Airgun, Shotgun & Rifle spares. Parts for Air Arms, BSA, Crosman, Diana, Gamo, Relum, Webley, Weihrauch and many, many more

i guess you could take a weld the shaft to a steel washer 10mm thick and then you would have to figure out how to hold that in place in the piston 

drill the piston and weld the washer from the out side or pin it and would the spring need to be shorten, maybe 

just ideas a new used piston could be a hard find and knowing if this was the only rifle or if more rifles used that piston could help and or if the design was used after the war 

good luck 

mike in the states

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Posted : 2nd March 2021 20:16
SteveMedlock
(@stevemedlock)
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Hi Mike,

Although the post-war models had a different trigger system and piston rod, this one does appear to have been pinned much the same. The rod snapped right across where the pin hole is!  I think I'm going to drill out the remaining part of the rod first and see how much metal there is at the end of the piston. I can make a new rod and presumably that could be welded instead of crimped. I might have to think about this a bit before I rush in!  

Steve.  

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Topic starter Posted : 2nd March 2021 21:05
marflow
(@marflow)
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does the screw holding the seal touch the rod end, it is going be tricky repair maybe 

if you can remake the rod i guess just pinning it would work again

it will be an interesting repair when done, beyond me pay grade

 

mike

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Posted : 3rd March 2021 20:31
SteveMedlock
(@stevemedlock)
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Well I had a think about this and decided that the best course of action would be to make a new rod. I've ordered some 10mm tool steel rod and will mill a new sear and then thread and tap M10 into the steel block which fits inside the piston. Instead of the lateral pin, I may tap and use a grub screw. I'll need to centre drill and tap the rod for a washer screw but I'll probably use a BA screw smaller than the original. 

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Topic starter Posted : 3rd March 2021 20:59
marflow
(@marflow)
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i'm i wrong to think that been broken for awhile, i see no shiny metal 

so there thinking was to pin it and that would make manufacturing faster because the rod would be in the right position, down 

and that will be your challenge also but it sound like you have the right tools and know how to do this job 

also you might thing of use some of these at the spring ends, i use 2 good faces together

https://www.ebay.com/itm/10-50X-M2-M40-Stainless-Steel-Ultra-Thin-Flat-Washer-Ultrathin-Shim-Plain-Gasket/164573184907?var=464134224073

please show us the repair, it will help other with the same problem down the road 

take care 

mike in the states

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Posted : 4th March 2021 20:09
SteveMedlock
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Yes, I think it had probably at least fractured some time in the past. For the repair, I used some 10mm 01 tool steel round bar to make a new piston rod. I cut an M10 thread on one end and milled the sear notch at the other. The hardest part maybe, was tapping an M10 thread into the steel block that fits inside the piston. I also tapped the end of the rod to take a piston washer screw. After re-assembly, I also partially drilled and tapped the old pin hole, inserted a screw and then cut and filed it flush with the outside of the piston. Quite a lot of work and I hadn't done screw cutting in a lathe before!

[img] [/img]

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Topic starter Posted : 11th March 2021 11:30
marflow
(@marflow)
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well the gun is in the right hands, there are few of us with the right tools and knowledge to do such work

and you are going to have success fixing something that would have stayed broken 

great work 

mike

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Posted : 11th March 2021 20:00