GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Show us your Custom Airgun Parts (TRICKS-N-TIPS) => Topic started by: DarkmatterX1 on August 23, 2016, 11:06:04 PM
-
So, I've got a bug in an uncomfortable place - if ya take my meaning - regarding my Disco. I like the gun in it's current form, but I'm a bit obsessive, and would like to "beef it up" some. I already have some parts (valve, o-rings, new barrel, challenger hammer, which I know I have to machine down to space for the breech screw) and will be placing an order with Crosman tomorrow for some others. My question regards Frankensteining OEM parts from other guns into my project. In my opinion this has the benefit of using parts which are engineered for the applications, and prevents me from having to scour the corners of interwebnetz for fasteners, and other doodads. Anyway, I guess I'll post up a quick list of parts and ideas, and will be open to and happily receive any and all info or advice the members are willing to offer.
Disco Stuff
Valve: I intend to hog out the inlet to 6.75mm (.266"), which will leave a wall thickness of 2.625mm (.103" - factory is .112"). This results in an increase of about 16% in volume. The exhaust port I want to go to about 4.5mm (.177") or 4.6mm (.182"). This is an equivalent increase in volume in the exhaust port to maintain gas velocity between the valve and the breech. My thinking being that more air at the same velocity will yield higher velocities with the same projectiles, while hopefully preventing supersonic travel.
Barrel: drilling out the port slightly (haven't done any math on that part yet.)
Hammer: Swapping to a challenger hammer after milling the top for clearance. Welding an insert in place of the striker recessed 2mm to gain throw distance over the original disco hammer. Adding 4 grams of weight to the hammer inside of the spring opening which will serve two functions . This will serve to naturally increase momentum and energy in the moving hammer, as well as adding some built-in preload to the spring on the hammer side.
These are in addition to my current use of challenger power adjuster and 1.8" .042" wire spring.
Now, I have a Disco tube coming as well. I've seen Lloyd's video regrading the shear force danger of the OEM valve screws with reference to overfilling the rifle past 2000 psi. Now, I want to have a fill capacity of about 2500 - 2700 PSI. Here come the questions about other OEM parts and Frankensteining.
The Crosman 1720 Target Pistol is a 3000 PSI fill vessel. It uses 8-32 x 3/16" screws to hold the valve in place. These screws should in theory fit the Disco valve. They also prevent the necessary cutting of other 8-32x1/4" screws, or drilling and tapping the valve for 10-32 screws. It's no t that I can't do that, it's just that they present a simpler solution to the problem. Is anyone aware of any reason why they wouldn't fit, or shouldn't be used?
Gauges, gauge blocks, threads, and mix and matching. I'd like to have a gauge installed on the rifle that accurately represents the current fill pressure. Would the gauge and block from the 1720 pistol work? Or will I have to shop for other off-the-shelf solutions? Any advice with respect to this aspect would be unbelievably helpful.
I think that's the brunt of it for now. I'm sure I'll either come up with something else, or a commenter or commenters will think of something I haven't. I hope my idea turns out well, and I want to extend thanks in advance to anyone who chimes in with any advice, ideas, information or helpful commentary.
Thanks for being a great community.
-
The more I think about it, and considering the direction I think I'd like this thread to go, could a mod please move this to shop talk?