Originally Posted by 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
Cheers Dave.
The inability for the gun to cock was really a rookie mistake by me in not taking note of how the 3 ball D35 trigger mechanism set itself.
On the T01 trigger the piston latchrod is solely responsible for setting everything, which is why the whole trigger and back block is removable as one unit.
On the D35 the latchrod enters the centre of the trigger unit and passes the point at which the balls can drop onto the reduced section of shaft.
Cocking further allows the tail of the piston to push the sleeve shaped sear which locks the balls in and eventually the trigger sear drops in the hole in the sleeve and the trigger is set.
I only cut enough off the guide for the balls to drop onto the shaft and I didn't take the movement of the sleeve into account, once I'd cut another 10mm off the guide everything worked as it should.
Yes this D35 doesn't owe me much and was only bought for sentimental reasons but as is my habit, I feel I must tinker with it to see what it will do.
Though it's an absolute ball ache to work on I feel I should carry on with it as I know there's an accurate 12 ftlb gun in there somewhere.
Looking at making a spring compressor today I realised it was as much work to strip the gun to use a spring compressor as it is to strip to use the lathe, so for now I'll carry on without a compressor --- this will only become essential for final tweaking so can wait for now.
So the plan of attack for now is to strip the gun again.
Machine a bronze O ring piston head to take a Mercury sized ring --- on paper this will weigh 20.5 grams.
Fit a steel piston liner (plastic won't do) --- this could add another 10grams or more.
Initially sleeve the transfer port to 2.8mm --- this can be opened up if necessary.
Machine a new Spring guide from 316 stainless steel that actually fits the 10mm latchrod --- the original guide has a 12mm ID.
I'll carry on with the 28 coil Spring for now.
Run it over the chrono then either laugh or cry.
All up piston weight will be in the region of 300 grams with a 70-71mm stroke.
I measured up my ratting Mercury this afternoon and that is running a 69mm stroke with a piston weight of nearly 300grams so I should be in about the right pall park for 12 ftlbs with the D35.
If after a chrono session I need to alter piston weight and preload I'll be able to do all that from the backend without disturbing the piston as I'll have the 30gram piston weight with 16mm of preload to play with.
I'll keep you updated.
All the best Mick
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