The Lesser Spotted Original/Diana 35

[T 20]

So tomorrow I'll be machining up another piston weight/Top hat from 316 stainless and a bronze bearing for it to sit on, these two should weigh about 28 grams.

My mistake, they add 29 grams, so from my calculations I now have an all up piston weight of 305 grams --- which is about the same as a Mercury/Airsporter piston.

I've just got to machine 2mm off the front of the spring guide now, reassemble it and chrono it.

[T 20]

Over the chrono with a 305 gram piston :-

Hobbies = 645fps = 11.09ftlbs

Superdomes = 585fps = 11.02ftlb


And I think that's as far as I can go with this Spring.


Edit :-

I forgot to post a picture of where to put the cable tie round your shaft :-

image.jpg




All the best Mick

[Shed tuner]

now just leave the poor old girl alone and just shoot her

[T 20]

now just leave the poor old girl alone and just shoot her

Nah, where's the fun in that, Jon ?

Next up is piston weight back down in the 270s with factory 33 coil Spring --- I've got some cable ties left so I may as well use them.

This will give an indication of what power can be achieved with a Protek synthetic seal conversion kit and a factory Spring for the folks without a lathe.




All the best Mick

[TonyL]

Any normal fettler would be declaring this as "job done" and be happy to just shoot and enjoy now.

But I think Mick has really got into playing with his tie wraps, lubed up shaft and greasy balls!

Your further experimentation will help others for sure, Mick. Well done for utter dedication.

[T 20]

Next up is piston weight back down in the 270s with factory 33 coil Spring.

This will give an indication of what power can be achieved with a Protek synthetic seal conversion kit and a factory Spring for the folks without a lathe.

With the "Original/Diana" factory 33 coil Spring with 276 gram piston, chrono results were :-

Hobbies = 580fps

Superdomes = 500fps


So I stripped the gun again and weighted the piston back up to 305 grams and put the 28 coil Spring back in but added 4mm of extra preload to see if it would lift the power a tad, results :-

Hobbies = 610fps

Superdomes = 590fps



So the tune I've now chosen to go with is the 270gram piston with 28 coil HW95 Spring with 16mm total preload that gave 11.6ftlbs with Hobbies.

11.6ftlbs will do me for a bit of paper punching in the garden and dealing with the occasional rat.



All the best Mick

[TonyL]

How does it feel to shoot in this current tune, Mick?

If you're happy with the cycle and the resulting accuracy, is this "job done" now?

[T 20]

How does it feel to shoot in this current tune, Mick?

If you're happy with the cycle and the resulting accuracy, is this "job done" now?

I'm not happy with the firing cycle with the 305 gram piston, Tone.

The best firing cycle was with the 276 gram piston with Hobbies giving 11.6ftlbs which is why I'm going to strip the gun back down and reset to that tune.
With the 276 gram piston the firing cycle was not quite right with Superdomes for some reason, but firing Hobbies was really nice, it's hard to describe but with Hobbies everything seemed to work in a no nonsense fashion --- I pulled the trigger, the piston shot forward and the pellet came out with very little movement of the gun.




All the best Mick