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Author Topic: hammer bounce  (Read 149 times)

Offline Dvlnme

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hammer bounce
« on: November 09, 2018, 08:46:24 AM »
As many co2 and pcp shooters will know hammer bounce plays a significant part in how efficiently these
 types guns use co2 and hpa,preventing or elliminating hammer bounce will very significantly improve
 shot counts in these types of airguns by preventing hammer bounce caused by the valve stem hitting the
 hammer with some force as valve slams shut after the gun is discharged forcing hammer back against
 the spring pressure,often forcing hammer back qiute some distance under spring pressure,obviously the
 spring will force the hammer foward again hitting valve stem and opening valve again to some degree,
 and this will continue until the amout of hammer inertia has reduced until it can no longer be strong enough
 to open valve at all.
 the effects of this being that every time valve opens this small and reducing amount,co2/hpa is vented
 thru valve,so wasting small amounts co2/hpa every time it happens.all this happens in a milli second.
 bassically what this effect is,is an inertia effect caused by recipicating moving parts interacting with each
 other,that continues until there is not enough energy left for it to continue to do so.
 the only way to prevent this happening is to prevent the hammer from recontacting the valve stem after
 the gun has discharged.
 some pcps like daystates use what is called a sling shot hammer.this is a two part hammer,with an outer
 sleeve cantaining a floating piston bassically thats held back from hammer face under spring pressure
 and cant actually touch valve stem when gun is uncocked,but whem hammer slams forward,the outer
 sleeve hits a stop and dosnt hit valve stem,inertia causes the internal piston to continue foward until it
 it hits valve stem and opens valve etc,and immediatly in theory retracts under its own spring pressure
 to the rear of valve stem,this sort of works in that it dose reduce hammer bounce to some degree,but
 relys on every thing being balanced exactly right as far as piston spring pressure goes,quite tricky to get
 right.There is another way of preventing the hammer from contacting valve stem after discharge that
 works evan better,but have never seen used,this is to put an interrupter device in trigger mechanism,
 that works very simialer to the trigger diconnecter used in semi auto fire arms,a disconnecter very simply
 catchs and holds the hammer in full cock mode independant from trigger,even if trigger is still in the
 rearward postion from firing the gun,the hammer is held in full cocked position,trigger rengages the the
 full cock notch when released for next shot,this same method can be applied to an airgun hammer,
 catching hammer when valve slams shut forcing hammer rewards if a secondry notch is cut in hammer
 for disconnecter to catch as hammer moves forward again under its spring pressure,preventing it hitting
 valve stem again,and holding hammer in that postion until hammer is cocked again.
 As some will know i am building a pcp revolver,that has the normal swinging type revolver hammer,this
 is qiute a heavy hammer with strong coil spring,but due to how the mechanics were engineered its very
 easy to cock,requiring very little effort to do so,there fore very sussceptable to hammer bounce,some
 thing i wanted to avoid at all costs,this hammer has a haf cock notch that holds hammer just off the
 valve stem when uncocked,to prevent valve stem from forcing hammer back and giving gun quite
 severe hammer bounce,i needed to catch and hold hammer in half cock notch after valve stem had forced  it back when valve closed,preventing it from contacting valve stem once again etc.
 solution eas to fit a spring loaded fly type disconnecter into the half cock notch,this protrudes out past
 the notch just enough to catch hammer when trigger is still in rearward firing postion,when trigger is
 released to recock gun,the triger sear renages the notch,pushing the disconnecter back into the notch
 and fully engaging the half cock notch once again,keeping hammer off stem etc.
 As hammer is then caught on its first rebound when valve shuts and kept there there now no hammer
 bounce and there fore no wasted hpa,as this pistol only holds 80cc hpa and i want it to be as efficent as
 possible because it uses lot air to get its 30fpe on full power off the reg,any wasted hpa will certainly
 affect the shot count,so preventing that was essentual.
 just bit bs that may interest some,simply coz its another way of looking at ways to prevent hammer
 bounce in co2/pcp airguns,that makes good sense and hasnt been looked at in this way before as far as
 i am aware,that is very worth considering when modifying or building a co2/pcp airgun.
 cheers mike

Offline Pauly5

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Re: hammer bounce
« Reply #1 on: November 09, 2018, 10:49:23 PM »
Yes interesting. Something I had been thinking about recently. My son has bought an Air Chief CO2 pistol, and you can hear that farty  sound as the hammer bounces on the valve with each shot.
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Offline Dvlnme

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Re: hammer bounce
« Reply #2 on: November 10, 2018, 07:25:27 AM »
If you can stop that farting sound,which is exactly what you said it is,you get more shots,thats the sound
 of co2 and money being wasted eh!! I just recently did a radiacl build for fellow forum member on a cpi
 its posted on this thread some where,seems to be just the luck of the draw as to wether these guns have
 bad hammer bounce,as the one i worked on had no obvious sound of it,tho would have had some for sure,
 prob depends some what on the strings the used on different batchs of guns as to how bad if is,these
 pistols seemed be tuned to stay under the english 6fpe limit for UK law,from what i have read on them,
 they seem run in any where from 3.5 to 5.5 fpe range,the one i worked on was at 3.5fpe and possibly
 had slightly stronger valve spring than one you have which would possibly account for its low fpe and less
 hammer bounce due to having more resistance in the valve spring preventing hammer bounce opening
 valve as much etc,i dont yet know enuf bout the cpi to know for sure,but suspect this may have something
 to do with it.
 these are great pistols,very well made,apart from the ugly useless pistol grip they seem be a good gun
 with all the same potentual for modding as the 2240 on a better platform to start with,build quality far
 supperiour to the 2240,which are bassically like most crosman co2 guns just junk today.
 i made an adapter for a suppresser for the one i did recently can make one for you if thats what you were
 looking for Paul.
 cheers mike

Offline Pauly5

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Re: hammer bounce
« Reply #3 on: November 11, 2018, 04:02:25 PM »
Will pm you.
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Offline FLUB

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Re: hammer bounce
« Reply #4 on: November 11, 2018, 11:31:30 PM »
Really looking forward to seeing your finished revolver.........if you can figure out how to load pictures (I suffer the same) 😊

Offline Pauly5

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Re: hammer bounce
« Reply #5 on: November 11, 2018, 11:46:42 PM »
She's a thing of beauty. I got to see it and here's a couple of photos of each cheek.
« Last Edit: November 11, 2018, 11:48:27 PM by Pauly5 »
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Offline Novagun

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Re: hammer bounce
« Reply #6 on: November 12, 2018, 07:41:56 AM »
That is impressive. The skill in making that from raw metal is a test of the fitter turner.
The hours that went into that.

Offline JS

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Re: hammer bounce
« Reply #7 on: November 12, 2018, 02:38:52 PM »
Wow, that thing looks epic! would love to see it in the flesh / in action.
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Offline Pauly5

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Re: hammer bounce
« Reply #8 on: November 12, 2018, 08:00:02 PM »
While I didn't fire it, I can say it's a piece of art for sure. A one off.
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Offline Dvlnme

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Re: hammer bounce
« Reply #9 on: November 13, 2018, 01:49:29 PM »
aw shucs Paul,you sweet tongue rogue,bet you say those sweet things to all the girls eh!! you making poor
 thing blush mate,havnt done much on it tho lately,got another project on the boil,with two other local
 guys,designing a new 177/22 cal pcp regulated match target pistol we intend to build soon.
 fact is its very near impossible to buy a decent pcp target pistol any more,except the rediculously over
 priced european ones none us can afford any way,due to the BS legally dodgy import ban NZ police have
 instigated making it impossible to do so.
 we are in final stages of completing what exactly the requirments need be for a compeditive pcp match
 pistol and now have the bassic design for a regulated hpa system and breech,sights,trigger etc now
 designed on paper to form the bassis for a standard universal platform,that can be configured in several
 ways using standard componants that will fit all guns.
 as three us have well equiped home machineshops,its been decided we will set each workshop up to
 make a certain set of componants for the guns on small production line bassis on tooling specific to each
 set componants being made in each workshop that produce these parts to precise specs etc so are all
 interchangable on all guns,this will require we make tooling for each componant,to suit each workshops 
 machinery as we all have slightly different machinery,while this does spread the production out over the
 three workshops.it makes good practical sense.
 this guna be bit of a mission,but will work out well in the end,initially we only intend to build few guns for
 our own use,wether we get into building guns for sale is yet undecided,as there are some legal issuses
 we need explore further before that decision is made,bassically means all three us will need dealers
 licences if we start making guns for sale,NZ police not exactly easy to deal with when comes to dealers
 licences these days,so would expect some resistance to them granting any of us the required licence.
 early days yet,and this will be a long term process for sure,just setting up the workshop tooling will take
 some time on its own,the other bridges we will cross if it goes that far i guess.but whatever way it goes
 a few us will end up with the target pistols we want,will up date on another thread as we go along,may
 turn out the only guns built will be our own,such is the way world seems to work these days.
 cheers mike

Offline Novagun

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Re: hammer bounce
« Reply #10 on: November 13, 2018, 05:54:12 PM »
Nice idea. A cottage industry. I dare say that it will all work well using three workshops as long as the measuring tools, whatever they be are calibrated to the same standard.

Don't want a pcp pistol but maybe the worlds best springer made in the heart of Taranaki.

Offline Dvlnme

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Re: hammer bounce
« Reply #11 on: November 13, 2018, 07:02:41 PM »
once all the tooling /jigs etc are made,no need for measureing most things intil final assembly.That will all be done in one place,its easy to calibrate all measureing tools to same same standard any way with certified
 gauges we all have,its not actually that critical that everything is perfect,we all old school trained engineers
 and well used to old school production methods,it how things were done for hundreds of years before CNC
 many younger machinists wouldnt know how to produce anything without CNC tooling and machinery,but
 we all do coz was how we were trained,same as none us could even use CNC machinery coz we never have
 to each their own eh!!its not as if we are ever going to build huge numbers of guns,even if we ever get the
 paperwork to go commercial,prob only ever make 40/50 guns in total at max,there isnt a market for that
 many in NZ
.This was never bout making money,just bunch of guys wanting better target air pistols than they can get
 any other way,but build them for themselves,its the KIWI DIY thing eh!! there absolutly no reason why
 excellent target airguns cant be produced on small scale in this country for local use,its pretty much got
 to the stage thats going to be the only way we can get this type airgun in NZ now anyway as NZ Police
 pretty much wont issuse import permits now for most types air pistols,even toy soft airguns on the
 banned list.
 cheers mike

Offline xyon

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Re: hammer bounce
« Reply #12 on: November 13, 2018, 09:27:23 PM »
Hi Mike,
That was an interesting read about preventing hammer bounce by catching the hammer. Pics of the pistol look amazing too.
 
Cheers
Bruce

Offline Dvlnme

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Re: hammer bounce
« Reply #13 on: November 16, 2018, 10:04:06 AM »
There are some interesting possiblitys in using hammer bounce to an advantage in designing semi auto
 compact pcp pistols,using hammer bounce rather than trying to stop it,using the energy from inertia,
 magnifing it by mechanical means to generate more energy,recock hammers and cycle a semi auto action
 Food for thought eh!!
 cheers mike

Offline Pauly5

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Re: hammer bounce
« Reply #14 on: November 16, 2018, 08:04:35 PM »
Food for thought for sure. So you're cooking up a nice semi auto made in nz pistol? I will be your first customer. ;)
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