The Lesser Spotted Original/Diana 35

[T 20]

Excellent work that. You've put a proper shift in and this tread will be a reference work for others working on any 35s in the future. Though, just reading how many times you've stripped and assembled has fatigued me and I think I'll not be rushing to strip mine in the immediate future

Again, and excellent piece of endeavour there.

Dave

Working on it reminded me of the Eagles Hotel California, Dave.

Hopefully most of this information will be useful to Original/Diana 50 owners as well.



All the best Mick

[T 20]

Excellent stuff. That's a whole new level of power but with nice manners and not a lot of preload. A nice recipe of work and components.
I wonder how it would do with RWS Meisterkugelen. They're usually a good pellet in 35's.

I've actually found a tin of Meisterkugels --- I'll give them a whirl when I get five, Drew.

From memory, the factory Spring was 33coils (32 active) of 3.1 wire, the HW95 Spring I've used is 28 coils (27 active) of 3mm wire with a free length of 230mm.
Inside the piston I have 5.25mm of preload in the form of a Delrin top hat, bronze slip ring and the thickness of the steel piston liner.
On the spring guide I have a stack of six Dowty washers giving a further 12mm of preload, so overall I have 12mm of removable preload on the spring.

If the gun was easier to strip I'd remove the Dowty washers and see what power the gun ran at without them as it could be over sprung, but as it's running well with them in I'm leaving the gun alone for now.




All the best Mick

[TonyL]

I'm now thinking about reducing the piston weight on my ratting Mercury to get it nearer to my Original 35s firing cycle. :

All the best Mick

So, the set-up of one helps that of another which, in turn, reciprocates and....

At least it will be lots quicker to strip and get inside.

[jonnyone]

FFS, Do you think I'm made of cable ties and moly, Tone ?

Having said that, I may sneak up on it in the future with a 28mm Diana seal and a lump ofAluminium m.

After all the work you've put in I feel selfish asking you to do just that in the future

But then I thought for a moment on things and decided I'm selfish so ask Mick to do that in the future
Dave
PS or a vortek seal (I'm not fussy)!!!!

[T 20]

After all the work you've put in I feel selfish asking you to do just that in the future

But then I thought for a moment on things and decided I'm selfish so ask Mick to do that in the future
Dave
PS or a vortek seal (I'm not fussy)!!!!

Unfortunately, I may have to open her up again anyway, Dave.
As she's bedded in a little the velocity with Superdomes has gradually risen to 605fps so I may have to remove a 2mm Dowty Washer from the 12mm of preload.

But by way of some good news I'm really gelling with the gun and it puts a big smile on my face, the fact that the power output is climbing as she beds in is a bonus.
I even removed her recoil pad today and sanded the dry rotted rubber off it and then polished it with Danish oil before refitting it, I may even take her to bed tonight --- just for security reasons mind.

I was thinking today that my resultant tune could easily be reproduced by anyone without a lathe which is a big bonus.
Folks could use a Protek or Vortek synthetic piston seal and adaptor, sleeve the transfer port down to 3mm with a bit of brass tube from B&Q, make a piston sleeve from an empty paint spray can, snot in a Weihrauch HW95 Spring with 16mm of total preload and the job's a good un.
Obviously to complete the job you'd need to get someone to machine a new Spring guide that actually fits the latchrod but I'm sure that could be sorted.
I'm pretty sure that the Diana synthetic seal would give similar results to my O ring piston head and 10mm flat washers could be used to weight the piston.





All the best Mick

[crowbar]

To increase the piston weight I would cut a piece of lead flashing to fit the spare cocking slot and solder it in and onto
the steel piston liner.

I have not done this but it seems (to me) to be the best way to add weight and retain spring room .

[T 20]

To increase the piston weight I would cut a piece of lead flashing to fit the spare cocking slot and solder it in and onto
the steel piston liner.

I have not done this but it seems (to me) to be the best way to add weight and retain spring room .

You could do that but it's probably not the easiest option as there is a couple of simpler options. :-

1) The factory Spring is 33 coils of 3.1mm wire with a fully compressed height of 102.3mm, the HW95 Spring I've used is 28 coils of 3mm wire with a fully compressed height of 84mm.
So using the 28 coil spring gains you 18.3mm of free space within the piston where you could fit nine 20mm OD X 10mm ID X 2mm wide flat washers weighing 36 grams --- they're 4 grams each.

2) another easy weight increase could be made by using thicker steel for the piston liner, I used 0.25mm thick steel but you could get a 0.5mm steel liner in there which from memory would add another 20 grams.




All the best Mick

[crowbar]

I don't do easy I am a bit strange!

I cast top hats from wheel weights , face and drill the big end put them on a little mandrel I made and turn the OD,
Who else does that?

I have to take everything to bit's (break it) and fix it better!

So you see Mick it's a medical condition so I am alright!!??

[jonnyone]

You could do that but it's probably not the easiest option as there is a couple of simpler options. :-

1) The factory Spring is 33 coils of 3.1mm wire with a fully compressed height of 102.3mm, the HW95 Spring I've used is 28 coils of 3mm wire with a fully compressed height of 84mm.
So using the 28 coil spring gains you 18.3mm of free space within the piston where you could fit nine 20mm OD X 10mm ID X 2mm wide flat washers weighing 36 grams --- they're 4 grams each.

2) another easy weight increase could be made by using thicker steel for the piston liner, I used 0.25mm thick steel but you could get a 0.5mm steel liner in there which from memory would add another 20 grams


All the best Mick

Still following with interest

I'm wondering with your option 2 if a bit of twang may be reduced also? A bonus in my books particularly on the hunting front.
Dave

[HW777]

I used 0.25mm thick steel but you could get a 0.5mm steel liner in there which from memory would add another 20 grams.




All the best Mick

Is the 0.25mm from shim or tube stock Mick ?

If from shim and if it's not to convoluted What method are you using to form it

Atb

John

[T 20]

Is the 0.25mm from shim or tube stock Mick ?

If from shim and if it's not to convoluted What method are you using to form it

Atb

John

Hi John.

I cut the 0.25mm sheet steel for the piston liner from the side of an airosol paint tin --- I actually cut it with a pair of scissors.
I formed it by wrapping it round the spring, I also dragged it over the edge of a steel ruler as this induces curvature in the metal.
Once I had the liner in I formed the rear bell mouth by rubbing the metal with the steel shaft of a screwdriver to stretch it out.



All the best Mick

[T 20]

Still following with interest

I'm wondering with your option 2 if a bit of twang may be reduced also? A bonus in my books particularly on the hunting front.
Dave

There's the funny thing with this one, Dave, it doesn't twang.

I had a bit of trouble with a resonance at one point but managed to dial that out by moving the preload from the top hat to the guide.




All the best Mick

[evert]

But, and it's a big but, the gun now cocks as smooth as silk and is near enough recoilless --- yes I know everyone says that but this is a really fast firing cycle with very little movement.

Been thinking about this...
It sounds a bit like my experience with the Webley Vulcan: relatively large diameter heavy piston, not too long stroke, small port giving high compression, and VERY nice recoil while still maintaining power when you use a softer spring.

[T 20]

Been thinking about this...
It sounds a bit like my experience with the Webley Vulcan: relatively large diameter heavy piston, not too long stroke, small port giving high compression, and VERY nice recoil while still maintaining power when you use a softer spring.

Yes, Evert.

I have a nice MK3 Vulcan that has a very nice firing cycle, with a bore and stroke of 27mm X @80mm (?) and a 270gram piston it performs very nicely --- it's just a shame the breech and trigger let the gun down a bit.



All the best Mick

[GS747]

My brother had one of these when we were kids,and he let me have a go of it once in a while.
Just shooting tins out in the garden,and old toys etc
I'm sure he kept it for a long time,and not sure if he still has it.