Reducing mechanical sound of hammer strike in PCP

[shorty]

I have a few PCP's now and the report on all of them is extremely low ( mostly 20fpe up to 80fpe  / .177's to .25 cals ).

The mechanical noise of the striker hitting the stem is much louder than the report. I have heard of using a plastic striker and at one time using leather. I will ignore the leather and focus on a plastic material.

I read lot of people using PEEK. What I have found is that the PEEK does hold up but the noise level is similar (slightly less /high pitch) impact sound.

Since I think about airguns all the time ( even at work ), something caught me eye. Rubber isolators. So I got home and started doing some research.

I found out that PEEK has a durometer of 126D. This is very hard ( good stuff ) and rubber isolators are around 50/70A duro (car tires around 70).

Then,
I went to the garage and opened the junk drawer. I found a skateboard wheel. Whacked it with a hammer, little compression, very little noise, little to no visible marring.
Found out it is made of polyurethane with a Durometer around 80A/90A.

Then went on Mc mastercarr and found this:
https://www.mcmaster.com/8695k171

So what do you think. Has anyone used anything like this to reduce the strike noise to almost nothing ?

[Hobbyman2007]

Nothing ventured nothing gained as they say ( still not sure who “they “ are) . I think if you have the rubber rod counter sunk into the face of the hammer it should hold up for a while . Skateboard wheels do take an extreme beating without deforming , I would start somewhere around 90 D and work my way up from there .

[shorty]

Had some time to cut up the skateboard wheel and mount it in the gauntlet hammer.

Initial thoughts, holy mackeral this is stupid quiet and it can't be firing at 25fpe. Didn't have time to run it through the chrony at the time but, just got back from the B ball game and fired some through the Chrony.

It is stupid quiet. I mean, nearly no hammer smack noise. It would have been the quietest gun on earth if the power was the same. No kidding.

Completely disappointed.....

The gun was at 25 FPE before and without any changes besides the hammer, 10FPE. What a let down.Could only get it up to around 14FPE before everything binds up.

Gonna have to pull it and try something else.

I am trying to use something other than PEEK just to be different. Any one got any ideas to try out? I was thinking maybe some brass.

[shorty]

You know,
Some peoples failures can be somebodies holy grail. I'd be really curious how this would work with a balanced valve.

There's somethings I don't understand why I lost so much power at the same hammer spring setting.

Was it or:
Absorbing the collision energy (counter sinking the stem into the plastic)
A higher elastic collision (rebound) higher efficiency
Combination of both
Would increasing the hammer weight bring the power back at the same noise level

When the hammer spring was at coil bind, the shot signature was still crisp. Sounding very efficient. Weird

[rsterne]

Compressing the rubber insert requires energy.... That comes from the hammer strike, slowing the hammer before the valve cracks.... Less hammer energy is left over to produce lift and dwell in the poppet....

Bob

[jackssmirkingrevenge]

Interesting experiment. 

Would a bigger surface area on the valve stem help, to prevent it digging into the soft surface of the hammer?

Another alternative could be to surround the hammer area with sound absorbent material, though that could get a little bulky.  Something like the PSDR-3 prototype fully suppressed .45 ACP Smith & Wesson Model 625 revolver that encased the drum with a "clamshell" design, though that was more to seal off the propellant gas.

I'd be really curious how this would work with a balanced valve.

You need much less hammer energy in that case so it would follow that the noise would be greatly reduced.

[shorty]

For me, it was a good little experiment. Got me thinking again.

I can really see how the peek poppet can trump the stock QB style poppet with soft seat.

It just amazes me that this little bit of absorbing can change the power so dramatically.

[Motorhead]

Why try and be different when so many of us have already been down the same path & tried MANY materials .... PEEK IT and be done.

JMO tho

[shorty]

Before I pull the hammer and change the hammer face "rubber", I am going to try and shoot down and below the reg set point of 1250/1300 psi.

Maybe I can get some kind of numbers to crunch to see what it will take to using a material like this.

Really,
I am just looking for a minimum of 800fps in 14.3 and the quietest on EARTH.

So close right now.

[Mole2017]

Like Bob was saying, the urethane is essentially too flexible, especially if the insert has a larger diameter than the valve stem. However, you might try increasing the hammer spring tension to compensate.

[skorec]

I am not sure but the same energy of hammer strike should product  the same energy of noise .  Only frequency of noise may be different and valve assembly may reduce some frequencies more effective.

Are you sure that the noise is not producing mainly via valve cracking itself ?  Did you test the noise without any air pressure by using very strong poppet spring instead of air pressure ?