The Lesser Spotted Original/Diana 35

[T 20]

Good morning Mick,
After being initially slightly disconcerted drinking my morning coffee and reading of greasy balls I thankfully read on with interest!

I will be most interested to hear of your results with your experiments as I have a lovely 35s example giving low 10s in .22 which shoots great and seems as if its never been apart. But I've always wondered if it could be smoothed somewhat (bearing in mind how long that lube has been in there) and perhaps nudge power into low 11s.

It would be quite illuminating if you can arrive at a good performing 35 with power and accuracy something which Diana claimed it gave but sadly at least on power front it failed to deliver. My own thoughts were to go the route of perhaps a vortex or oem seal when I eventually get inside mine but I can see where you are coming from on the weight of piston and you may well be on to something good there.

Fingers crossed for you. I'll follow with interest.

Dave

Funny you should post this now, Dave.

I've just had an idea which would be more relevant to yourself and to the other Original 35 owners who've contacted me --- I'm just going to up the weight of the leather sealed piston and see what happens.



All the best Mick

[T 20]

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Now for the guide and spring compressor.

Mainspring will be a 28 coil jobby out of a HW95, with 3mm wire.

[HW777]

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Now for the guide and spring compressor.

Mainspring will be a 28 coil jobby out of a HW95, with 3mm wire.

I hope that the spring compressor gets a picture taken Mick, with the balls in mid assembly.

Or even go the whole hog and do a vid showing us how you grease them

Atb

John

[T 20]

I hope that the spring compressor gets a picture taken Mick, with the balls in mid assembly.

Or even go the whole hog and do a vid showing us how you grease them

Atb

John

I just took the barrel off and put the action in my lathe and wound it together with the tail stock.

Unfortunately after reassembly it won't cock --- bugger, but no big deal.

I've just had another quick calculation on Spring height. :-

Factory Spring 33 coils of 3.2mm wire = 105.6mm

New Spring 28 coils of 3mm wire + 16mm weight =100mm

So the spring looks good to go.


What I hadn't noticed before was that the rear of the piston pushes on the cylindrical sear that sets the trigger.
So although I'd cut the spring guide to a length I thought would be OK, I need to cut more off in order for the trigger to set.
I'll chop the guide and double check trigger operation without the spring in before I reassemble it again.






All the best Mick

[jonnyone]

Funny you should post this now, Dave.

I've just had an idea which would be more relevant to yourself and to the other Original 35 owners who've contacted me --- I'm just going to up the weight of the leather sealed piston and see what happens.



All the best Mick

Good idea.
I think that by upping the piston all up weight before you go anywhere else you will see the benefits (or otherwise) in increments. Only slight downside as we all know is the mere act of stripping the gun disturbs the lubes etc. Its near impossible not to disturb lubes on tasks like this.

Instinct tells me if you can improve things with the leather going synthetic will yield more improvements. However those with the leather fetish may (no, definitely, ) disagree
Dave

[I. J.]

'leather fetish' ... 'greased balls' ... I think Ive clicked onto the wrong site (again. I. J - M. P for Oooop North) .

[Shed tuner]

Going from experience in changing HW35s from leather to synthetic I reckon it'd be slammy with a synthetic seal and a 4mm port, Jon.

+10 on the stroke is just a note of the Max available with the cocking lever slots and geometry as standard, in real terms it would be unachievable because any stroke increase over 2mm would need the slot in the piston extending which would reduce that 10mm by a similar amount.

Using a Diana 28mm seal would take it upto about a 73.5mm stroke if needed, but it's a one hour round trip to buy one and I'm happy working at 71mm for now with an O ring.





All the best Mick

Doh, for sure.. was supposed to say leather in second scenario. 3.0 with synth

[T 20]

Good idea.
I think that by upping the piston all up weight before you go anywhere else you will see the benefits (or otherwise) in increments. Only slight downside as we all know is the mere act of stripping the gun disturbs the lubes etc. Its near impossible not to disturb lubes on tasks like this.

Instinct tells me if you can improve things with the leather going synthetic will yield more improvements. However those with the leather fetish may (no, definitely, ) disagree
Dave

Well after chopping an extra 10mm off the guide the gun cocks and fires so I ran it over the chrono. :-

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I'm not happy with it though, and I'm quite happy to admit that I'm way out of my comfort zone using a leather seal.

I soaked the seal in Neatsfoot Oil while I was machining the weight and polishing all the internals, then I dried it off before reassembly.

Though most of the shots over the chrono with Superdomes are in the 585 - 600fps range, every now and then it'll fire at just under 300fps for a couple of shots and then go back up.

When it is running at the higher velocity it's fairly consistent either with or without a bit of smoke which is weird.

Now I know the age old advice with leather seals is to put a couple of tins of pellets through the gun until it settles down but life's too short for that, besides which I'm a tight git --- have you seen the price of pellets lately.



Anyway, I'm going to leave it alone for a day or two now while I think about it, as I still think I'd be happier using a synthetic seal or O ring as I know where I am with them.
Another thing I'm not happy with is the cocking stroke as the gun sounds like a bag of spanners --- I put this down to the awfull Spring guide and piston.


Apart from the above we're all good.

At least I now know why nobody bothered to tune these back in the good old days --- they're a right pain in the arse to work on.





All the best Mick

[TonyL]

Agree with all the above, Mick.

And re your last comments, although I have no first hand experience, people's comments back in the day dissuaded me from trying to get acquainted..

[T 20]

Agree with all the above, Mick.

And re your last comments, although I have no first hand experience, people's comments back in the day dissuaded me from trying to get acquainted..

To be fair to the Original/Diana 35 it's a weird mismatch of over designing on some parts and a couldn't care less design attitude on others.

Cutting two cocking slots 180 degrees out on the piston is a bit mind boggling and begs the question, Why ?

Having a transfer port traveling upwards at 45degrees from the centre of the cylinder --- pointless, and is still done by Diana today.

Having a trigger group on a Sporting Airgun that needs a dedicated spring compressor to disassemble --- wtf.
The simplicity of stripping a HW35, Feinwerkbau sport and Mercury shows the shear stupidity of the M and G design.

For comparison, it takes me about ten minutes to swap out springs on a HW35, it takes me at least an hour to swap the spring on an Original35 and it's not a pleasurable experience.



I'm now trying to decide whether to build a dedicated Spring compressor and carry on going down the synthetic sealed route, or whether to chuck it in the back of the gun cabinet and walk away whistling a happy tune.


My adding piston weight experiment saw some improvements but as said, I'm not overly happy in using a bit of dead cow for a piston seal.
There is a story that the HW80 was born because M and G refused to fit a synthetic seal to the Diana 45 for the American market, so Bob Beeman approached Weihrauch to make him the R1/HW80.

I was double checking my piston weight idea last night and managed to find this again :-

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So I'm happy with the weight I added but not happy with many other parts of the gun which will take a fair bit of machining to put right --- I'll have to have another think on what to do with this one as working on it really isn't enjoyable at all.




All the best Mick

[VALE BOY]

Hi Mick, in order to burn 🔥 off the excess oil from the neatsfoot soaked piston seal, you could save money on pellets by firing them into an old cushion or pillow or thick foam sponge* which should absorb them without deforming them… combine that with a bit of target practice at 30 yards or so and it won’t seem such a waste of time!
Guid luck with your project.
A’ the best Mick, Graeme 😎

* Money saving methods collated by the Aberdeen-Yorkshire coalition of Tight Arses ( The Deep Pockets- Short Arms Society) 🥴

[TonyL]

Hi Mick, in order to burn 🔥 off the excess oil from the neatsfoot soaked piston seal, you could save money on pellets by firing them into an old cushion or pillow or thick foam sponge* which should absorb them without deforming them… combine that with a bit of target practice at 30 yards or so and it won’t seem such a waste of time!
Guid luck with your project.
A’ the best Mick, Graeme 😎

* Money saving methods collated by the Aberdeen-Yorkshire coalition of Tight Arses ( The Deep Pockets- Short Arms Society) 🥴

That money saving tip might prove even more useful when we have to use the more expensive, harder, lead-free stuff, Graeme.

[TonyL]

To be fair to the Original/Diana 35 it's a weird mismatch of over designing on some parts and a couldn't care less design attitude on others.

Cutting two cocking slots 180 degrees out on the piston is a bit mind boggling and begs the question, Why ?

Having a transfer port traveling upwards at 45degrees from the centre of the cylinder --- pointless, and is still done by Diana today.

Having a trigger group on a Sporting Airgun that needs a dedicated spring compressor to disassemble --- wtf.
The simplicity of stripping a HW35, Feinwerkbau sport and Mercury shows the shear stupidity of the M and G design.

For comparison, it takes me about ten minutes to swap out springs on a HW35, it takes me at least an hour to swap the spring on an Original35 and it's not a pleasurable experience.

I'm now trying to decide whether to build a dedicated Spring compressor and carry on going down the synthetic sealed route, or whether to chuck it in the back of the gun cabinet and walk away whistling a happy tune.

So I'm happy with the weight I added but not happy with many other parts of the gun which will take a fair bit of machining to put right --- I'll have to have another think on what to do with this one as working on it really isn't enjoyable at all.

All the best Mick

Any ideas that may have been remaining with me re, maybe, one day trying one of these seems to have somewhat evaporated away.. If it's winding you up, Mick, what help for the rest of us?

[jonnyone]

Hiya Mick.
I have huge sympathies with your predicament and you've hit the nail on the head as to why so few D35s get anything other than a basic service to keep them going. It's an absolute balls ache stripping the gun down. I've not been inside a 35 but having done so to a 50 that trigger takes a bit of fiddling to get right so finding all your efforts have resulted ina gun that wont clock is the ultimate sinking feeling. As you know the later modular triggers are a lot easier to work with.

Being butally honest though your pain and suffering will help others through this article by taking away some unknowns and giving some good information on achieving given results so you are doing a good deed.

I think you are right about the ditching the leather seal. To me with airguns I ether buy a gun to keep it 110% original so it's a factory example of what was produced (I've always GOT that concept), but at other times if I have an example of a gun a little less than pristine then this is fair game for some serious tinkering and improvements. It seems to me your gun falls into this category. Leather is a durable material and has stood the test. But to move forward and get the best potential from a gun you need to move to modern materials and gain the benefit of better consistent results. After all we have ditched mineral oil in our cars this long time for oils with friction reducers built in that reduce wear and add longevity lower emissions etc. To improve a gun leather needs to be parked up. I've had many debates with a fellow member here about his leather fetish and refusal to accept modern materials in older guns

So thank you for your pain and suffering in the name of giving the rest of us some knowledge to undertake similar mods to our own guns. Though each gun is an individual unit, your results would give a strong indication as to general outcomes. For me the M&G guide has to be ditched in any improvement to remove twang. Is there merit in gliding the piston whilst at it? In for a penny philosophy comes to mind......

Hope you keep going and well done with the results thus far.

Dave

[TonyL]

A very well thought out and reasoned post there, Dave.