The Lesser Spotted Original/Diana 35

[T 20]

Guessing we're now getting into "slammy" territory, Mick, but that's an area where your good self, JB and a few others have more understanding than many of us.

Re the Hobby vs Superdome observations, guessing that will be down to the different pellet release pressures. The Hobby is noted by Jim as being high in this regard, but the 'Dome higher still. Just goes to highlight how interlinked all the differing factors can be.....piston weight and momentum, pellet release pressure, TP size, spring force & rate, preload etc etc.......You'll find that "sweet spot" / balance.

To be honest, Tone.
I wasn't really comfortable with a 300 gram piston flying around in such a lightweight gun as it goes against everything we know on recoil and surge.

276grams I can live with, and with having to fit a bronze piston head and steel piston liner to correct the piston there isn't really any way of shaving much off that figure unless I machine a new head from Aluminum, which I won't be doing now.

Anyway, this morning I totally stripped the action and took the time to drill and polish the transfer port properly at 3mm.
Then I cleaned out the cylinder and transfer port and cleaned the piston, that's when I noticed a little problem, the piston head had a mark all around it's edge where it had hit something at the end of the cylinder --- so I had a look in the cylinder. :-

image.jpg


There was about a 1mm wide ridge sticking up on the outside of the plug that coincided with the witness marks on the piston.
After thinking about making a tool to slide in the cylinder to take the ridge off, I said bugger it and machined the 1mm ridge from the front face of the piston --- job done.
Relubed and reassembled at my original 276 gram build with just 1mm of extra preload using all new seals again I fired a few Superdomes over the chrono. :-

image.jpg

image.jpg




Hobbies are still doing 11.6 so that'll do for me.



As is normally the case on my last buildup of the trigger unit I discovered something that makes reassembly easier.
I've been struggling to get the trigger blade pin back in every time I've built this gun up and even altered a pair of pump pliers to assist in crushing the trigger spring, well this morning I realised what the unused hole was for between the stock bolt hole and the cocking lever slot.

If you stand the action upright on its backend you can push down on the sliding sear with a screwdriver to get the trigger sear hole in the middle of the window in the action. :-

image.jpg



While holding the sliding sear down you can then insert a 3mm (or larger) drill bit into the forward hole to hold the sear in the cocked position.

image.jpg


Then you can fit the trigger without struggling.




So that's it, I'm done and dusted with this one even though I could go further I'm calling it a day on my Original 35 --- what fun it's been.





All the best Mick

[TonyL]

To be honest, Tone.
I wasn't really comfortable with a 300 gram piston flying around in such a lightweight gun as it goes against everything we know on recoil and surge.

276grams I can live with, and with having to fit a bronze piston head and steel piston liner to correct the piston there isn't really any way of shaving much off that figure unless I machine a new head from Aluminum, which I won't be doing now.

Anyway, this morning I totally stripped the action and took the time to drill and polish the transfer port properly at 3mm.
Then I cleaned out the cylinder and transfer port and cleaned the piston, that's when I noticed a little problem, the piston head had a mark all around it's edge where it had hit something at the end of the cylinder --- so I had a look in the cylinder. :-

image.jpg


There was about a 1mm wide ridge sticking up on the outside of the plug that coincided with the witness marks on the piston.
After thinking about making a tool to slide in the cylinder to take the ridge off, I said bugger it and machined the 1mm ridge from the front face of the piston --- job done.
Relubed and reassembled at my original 276 gram build with just 1mm of extra preload using all new seals again I fired a few Superdomes over the chrono. :-

image.jpg

image.jpg




Hobbies are still doing 11.6 so that'll do for me.



As is normally the case on my last buildup of the trigger unit I discovered something that makes reassembly easier.
I've been struggling to get the trigger blade pin back in every time I've built this gun up and even altered a pair of pump pliers to assist in crushing the trigger spring, well this morning I realised what the unused hole was for between the stock bolt hole and the cocking lever slot.

If you stand the action upright on its backend you can push down on the sliding sear with a screwdriver to get the trigger sear hole in the middle of the window in the action. :-

image.jpg



While holding the sliding sear down you can then insert a 3mm (or larger) drill bit into the forward hole to hold the sear in the cocked position.

image.jpg


Then you can fit the trigger without struggling.




So that's it, I'm done and dusted with this one even though I could go further I'm calling it a day on my Original 35 --- what fun it's been.





All the best Mick

Brilliant information again, Mick.

But are you REALLY done with it?

[T 20]

But are you REALLY done with it?

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 of Aluminium.

[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

[jonnyone]

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

[Drew451]

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.

[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

[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