GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: 3crows on August 17, 2022, 03:00:57 AM
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I do not understand I guess. I thought I did but apparently not. Keeping all other adjustments the same, how does running the striker in or out (of the hammer) change stroke and power and air consumption?
I am seeing on various threads and forums and videos that running the striker out (towards the valve poppet stem) decreases stroke and decreases power and uses less air etc. And conversely that running the striker fully into the hammer (away from the valve poppet stem) increases stroke and increases power and uses more air (longer dwell etc).
I would think the limiting factor is the face of the valve when the poppet valve stem is shoved flush at hammer impact to the valve face?
Is it that because running the striker fully in gives the hammer more time to accelerate before impacting the poppet valve stem and thus can push it further inward, more open and for a longer time?
Does the valve not fully open upon hammer impact regardless? Well, if there is a buffering O-ring or some mechanical limiter, sure, but otherwise the limit is the face of the valve body is it not?
Thanks,
James
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Running the striker into the hammer (shortening the stroke) takes away momentum from the hammer, thus not opening the valve as much. Think of it same as using a carpenters hammer. Hold the hammer 1" from the nail and hit it. Now hold the hammer a foot from the nail and hit it. Or drop a baseball from 2" off the ground and then drop it from waist high.
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Running the striker into the hammer (shortening the stroke) takes away momentum from the hammer, thus not opening the valve as much. Think of it same as using a carpenters hammer. Hold the hammer 1" from the nail and hit it. Now hold the hammer a foot from the nail and hit it. Or drop a baseball from 2" off the ground and then drop it from waist high.
Thanks. I think the hammer stroke is made longer by running the striker into the hammer and made shorter by running it out, or I am just misreading you?
James
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Do some research on "dwell time".
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James, you are correct. Threading the striker into the hammer allows the hammer to travel further before hitting the valve stem, thus it will deliver more momentum.
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James, you are correct. Threading the striker into the hammer allows the hammer to travel further before hitting the valve stem, thus it will deliver more momentum.
Thanks. That all makes sense now. I would think intuitively it would be that way so it is.
And I will try to understand next what really controls dwell and how I can adjust that parameter.
J
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I don't know what gun you are tuning but adjusting the part of the hammer that will hit the valve out is also used to fine tune a Bstaley tune. The Bstaley is O-rings around the valve stem so the hammer doesn't bounce into another valve opening. The first thing I determined was how many O-rings to use. Too many and the valve doesn't open. Too few and you are not accomplishing anything, hammer operation is not affected. There is a finite range of adjustment. So on my Prod I put in 4 and then extended the striker of the hammer to let out a little more air. Small changes make significant velocity change. Optimum seems to be in the range of 1.25 to 1.4 turns.
Other than adjusting my B-staley, I haven't messed with this adjustment. I did turn it a few times but it didn't seem to do much. Perhaps I was not observant enough.
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I don't know what gun you are tuning ------- So on my Prod I put in 4 and then extended the striker of the hammer to let out a little more air. Small changes make significant velocity change. Optimum seems to be in the range of 1.25 to 1.4 turns.
Extending the striker reduces stroke and therefore reduces air volume, correct? I am working with a Marauder rifle with the TH valve, JSAR Super Hammer and TH hammer spring. The Super Hammer has the OE striker installed and is set just barely below hammer surface so as to achieve longer stroke.
So you are putting an O-ring on the valve poppet stem? rather than on the ID of the air tube behind the valve?
Thank you,
James
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The "bstaley tune" is not so much a tune as it is a completely different way of tuning a PCP. It involves putting a stack of o-rings that fit tight to the air tube up against the face of the valve, typically 3 for a Marauder rifle and 4 for the pistol. This results in the hammer hitting the o-rings on the way to the valve, absorbing some of the energy.
This actually reverses the function of the adjustable striker - at least for for the first hunk of adjustment. If the striker is flush to the hammer, the gun barely fires, if it fires at all (this depends on how much spring is used). We then extend the striker out closer to the valve to increase the valve opening / air usage / pellet speed - to the point that the key element of tuning the gun becomes the amount of striker adjustment used.
The function that you described of the striker adjustment is the correct way it works in a conventional set up - the bstaley set up basically reverses that.
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A diagram of a bstaley O-ring stack may help:
(https://i.imgur.com/kFMFEeo.gif)
This diagram does not depict an adjustable striker threaded into the nose of the hammer, but you can picture the effect of threading it in too far to increase stroke / momentum / dwell...pretty soon the hammer's forward travel is arrested by the O-rings before the striker even touches the valve stem. So when tuning a bstaley arrangement, the goal is to adjust the striker so the valve opens enough but not too much.
Without the O-rings, the striker's projection has a more direct effect.
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Ahhhh, okay, that makes sense, sorta ;).
Thanks, let me mull that over some.
James
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Thanks guys for explaining the Bstaley better than I did.
I would also add that I think it was very worthwhile for my Prod. My ES was significantly reduced and I gained about half a dozen shots on my 18 fpe tune.
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Yes, thank you everyone.
James