Hi all,
I have been into airguns on and off 30+ years and have a few Dianas.
I am inquiring to see if anyone has blueprints or dimensions for Guides and Tophats for the 34, 48, and 350.
I have a mill and a lathe and plenty of materials and I am going to purchase seals and springs to play around a little, I'll start with the 34 first.
Also does anyone know the total compressed dimension of the guide/spring/tophat allowable in the cocked position?
PJ
measure the the existing springs coil wire diameter. lets say its .128 multiply that by the number of coils. lets say its 30 coils. that means the compressed (coilbound) length is 3.84". add the thickness of the existing guide base and you have an approximate working length for the compressed spring and guide. in choosing a new spring you wouild want its compressed length+guide base+ top hat flange thickness to be in that ballpark. as long as the total compressed length of that assembly is not longer than the stock springs compressed length you should be ok for a starting point in choosing your replacement. then you can experiment with spacing. at some point you would not be able to add any more spacing and the gun would fail to cock. if you start with a spring that is too long you will have to cut it. that can certainly be done but spacing is probably the better avenue.
just for you informaition i have an HW 50s. i put a macarri grt spring that was made for a diana 52 in it. that spring fit the guide and piston closer than the stock spring and it also has larger coil wire. i cut that spring down to 8". the original spring was more like 11". the rifle has as much power but it has a smoother firing cycle and cocks easier. it also no longer "twangs".if i wanted more power i could have cut that spring less, or i can space it quite a lot if i want to. i don't want more power from it since i shoot it indoors.
in fact i may take another inch out of the spring.
Each material in the guide will have different parameters
December 18 2008, 7:28 PM
If you want to make the guide out of naval bronze, you can use a 0.002" interference fit between spring ID and guide's OD
If you want to use Plastic materials, you can go as high as 0.006" interference fit.
Larger diameter wire springs will "fatten" more than thinner ones at compression. These numbers are what I use for JM's springs when I make a metallic guide.
Other pointer: Top hats are only used if you want to use heavy for caliber pellets. Do try them as no two guns are exactly alike, but keep in mind general principles.