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All Springer/NP/PCP Air Gun Discussion General > Big Bore AirGun Gate
A little Zeus help
Chickenthief:
Made a crude mockup but really need measurements so i can get it right. I just used POM/delrin as it machines very well and is whicked fast to work with.
What i need is three measurements:
1) barrel diameter just before thread nut
2) length of threads from muzzle to breast.
3) as measured bullet diameter from Mr. HP (or the supplied ones)
The bore is ø19mm~.748" and the 6 ports are each ø12mm~.47"
My experience with powderburners is that when port area gets to roughly 3 X bore it is diminishing returns when more is added.
The ports are tilted backwards 22deg to help channel gasses and maximize recoil reduction.
And area: ø12mm = 113mm2 x 6 = 678mm2. ø19mm = 227mm2, ratio 678/227 = 2.986
So i should be pretty good.
I plan on a narrow nut and some blue loctite for fixing. You just thread on the nut fully and apply a little blue Loctite to the threads and thread on the brake as far as it will go, turn back for correct angle and tighten the nut. Let set and you're good to go. Oh and the final version will be made of aluminiun, not plastic ;-)
If an airgun needs a way different ratio i will lengthen the brake to accomodate 6 full bore ports. Thats why we're here, to learn.
Dimensions: length = @80mm~3.15", Width = @51mm~2", height @30mm~1.18"
lorka42:
As soon as I get mine next week, I'll post the information, poke me if I don't by next Friday. That thing looks sick, I want one!
lorka42:
Boy that was a long week! but it is arriving tomorrow!! will post measurements
BigBird:
--- Quote from: Chickenthief on August 10, 2021, 03:17:58 PM ---Made a crude mockup but really need measurements so i can get it right. I just used POM/delrin as it machines very well and is whicked fast to work with.
What i need is three measurements:
1) barrel diameter just before thread nut
2) length of threads from muzzle to breast.
3) as measured bullet diameter from Mr. HP (or the supplied ones)
The bore is ø19mm~.748" and the 6 ports are each ø12mm~.47"
My experience with powderburners is that when port area gets to roughly 3 X bore it is diminishing returns when more is added.
The ports are tilted backwards 22deg to help channel gasses and maximize recoil reduction.
And area: ø12mm = 113mm2 x 6 = 678mm2. ø19mm = 227mm2, ratio 678/227 = 2.986
So i should be pretty good.
I plan on a narrow nut and some blue loctite for fixing. You just thread on the nut fully and apply a little blue Loctite to the threads and thread on the brake as far as it will go, turn back for correct angle and tighten the nut. Let set and you're good to go. Oh and the final version will be made of aluminiun, not plastic ;-)
If an airgun needs a way different ratio i will lengthen the brake to accomodate 6 full bore ports. Thats why we're here, to learn.
Dimensions: length = @80mm~3.15", Width = @51mm~2", height @30mm~1.18"
--- End quote ---
What ratio do you use for the bore to the exit hole (size) for effective porting but insuring no destabilization?
lorka42:
--- Quote from: BigBird on October 06, 2021, 09:01:26 PM ---
--- Quote from: Chickenthief on August 10, 2021, 03:17:58 PM ---Made a crude mockup but really need measurements so i can get it right. I just used POM/delrin as it machines very well and is whicked fast to work with.
What i need is three measurements:
1) barrel diameter just before thread nut
2) length of threads from muzzle to breast.
3) as measured bullet diameter from Mr. HP (or the supplied ones)
The bore is ø19mm~.748" and the 6 ports are each ø12mm~.47"
My experience with powderburners is that when port area gets to roughly 3 X bore it is diminishing returns when more is added.
The ports are tilted backwards 22deg to help channel gasses and maximize recoil reduction.
And area: ø12mm = 113mm2 x 6 = 678mm2. ø19mm = 227mm2, ratio 678/227 = 2.986
So i should be pretty good.
I plan on a narrow nut and some blue loctite for fixing. You just thread on the nut fully and apply a little blue Loctite to the threads and thread on the brake as far as it will go, turn back for correct angle and tighten the nut. Let set and you're good to go. Oh and the final version will be made of aluminiun, not plastic ;-)
If an airgun needs a way different ratio i will lengthen the brake to accomodate 6 full bore ports. Thats why we're here, to learn.
Dimensions: length = @80mm~3.15", Width = @51mm~2", height @30mm~1.18"
--- End quote ---
What ratio do you use for the bore to the exit hole (size) for effective porting but insuring no destabilization?
--- End quote ---
From what ive been able to gather from the interwebs, it seems that +.020-.030 seems to be best. P.S. getting measurements tomorrow pm for you.
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