GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: ackuric on June 07, 2017, 09:14:05 PM
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So I decided to tinker some with the poppet on the marauder. I have 2 valves and it is very easy for me to swap each valve and test them side by side with the same spring/tune.
The poppet was made by hand with a dremel. I don't have pics of the process atm but it is VERY simple. DO NOT LET PEEK intimidate you! I also made a peek insert for my striker on the hammer, figured what the heck might as well get my monies worth, this stuff isn't cheap!
Valve 1: .324" poppet and .195" port, stock is about .34". 13 lb spring with pre-load set to 825 FPS. 51.5 FPE
Valve 2: .25" peak poppet with .195" port. Same exact spring/settings as above. 860 FPS. 55.85 FPE
(this valve got ported to .216" because I was feeling wild, but the same .195" tp was used in both tests)
I don't know why I don't listen to my own advice but I went to town on the throat for Valve 2 and efficiency is pretty bad, around 1.2 FPE/CI @ 860 fps, where I have seen efficiency as high as 1.3 at this power. Maybe its not the throat work though... Not gonna pout about it...
Maybe the efficiency is suffering because the valve is so much easier to open, that hammer bounce is showing its face again...such a mystery! :)
The above info / data is 100% accurate in terms of fps gains...
I just tossed an 11.5 lb spring behind the valve 2 and it is still cranking at 860-870 FPS (56 FPE), where as on valve 1 the most I could get out of this spring was around 47 FPE!!! Wow...
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Hmmm...Mind is boggled
I am hitting 800 FPS / 48 FPE (max) now on my 7.5LB spring that was only good for 30ish FPE Tops with my old valve....
That is a HUGE gain!!! The 7.5 spring is doing what the 11.5 spring did on valve 1, and the 11.5 spring is doing what my 16 lb spring did on valve 1...just nuts!
650/700 fps to 800 fps on the same spring....
This thread isn't about gaining fps per say but gaining fps with less hammer energy required!
I now need a spring in between 7.5 lb and 11.5 lb to tune! Or an even LIGHTER hammer!
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.34" poppet (stock) @ 2k psi has around 189 lbs of force when the valve is closed pressing on it with a light weight valve spring.
.25" poppet (modified) @ 2k psi has around 106 lbs of force when the valve is closed with a light weight spring behind it.
Above #'s @ 2500 psi (avg unregulated) is 234 lbs and 129.62 lbs.
I can't believe I am almost hitting 50 fpe on a 7.5 lb spring and 42 gram hammer...albeit the 800 fps was hit with no gap and would be inefficient for a tune, it's pretty wild when you recall all the complaints in the past about hammer springs being too heavy to make decent power with the SSG....all they needed was to slim down the poppet, and I went to the extreme of .25" just because, which is absolutely unnecessary and I'd say .29-.3" would be plenty of reduction on a poppet in a .25 cal marauder to allow much lighter springs...although YMMV with any other consequences of said modification.
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Pic of poppet/valve(ugly dremel scratch)/custom spring/custom end cap. Custom spring was NOT used in these tests. Just a look at what my hand-made poppet looks like. Custom spring rate you ask? 70 lbs! LOL. Custom end cap was made/used only because I forgot to order one from Crossman and didn't wanna have to swap those out every time I tested one valve to the other. It honestly probably is hurting my performance as it exposes a ton of the valves threads when installed opposed to the stock end cap. May just have to break down and order one on my next call to Crossman...or just remove the threads on valve 2 flush with the end cap ;)
(https://preview.ibb.co/dNHKTF/20170605_193847.jpg) (https://ibb.co/fvttoF)
Pic of the tool one can use to either touch up the valve seat or reduce it, honestly I did neither on this mod but it was a great idea provided by Motorhead/Scott and I tweaked his idea a bit to conform to how I felt safe doing and valve seat work. I used a sand paper glued to a washer of .4" in diameter screwed onto a 1/8" shank put into the valve REVERSE and then hand spun / spun by a drill slowly. This mod would be GREAT for those staying under .1875" ports and really wanting a reduced poppet head for EASY opening of their valve.
(https://preview.ibb.co/jURSha/20170603_110001.jpg) (https://ibb.co/m2202a)
Nothing special here, just a bolt with a bit of peek jb-welded into it, I used a phillips headed bolt so I had less material I had to drill out in order for it to work. I can't say its a huge improvement over a metal striker but it's certainly not worse..
(https://image.ibb.co/dCzmav/20170605_175557.jpg) (https://imgbb.com/)
Valve ported a bit further than I should have! I really shouldn't have but ah well...I'll test it (currently has 40 shots on it) If it holds up I'll inform the community on how I did it for about 10 cents and literally no serious tooling.
(https://preview.ibb.co/b3RGav/20170605_165904.jpg) (https://ibb.co/gLojTF)
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If this mod does hold up, the max porting I calculated out to be around .23"..and could go full through with a tp made out @ .260" which would allow .015 walls which in my experience is plenty for a marauder in .177-.25 cal form. Max allowable margin of error would be down to .005 though on the valve/barrel ports! Probably a stretch so I personally wouldn't go much over .22" to allow slightly larger margins...I really can't disclose the method until I feel safe that IT itself is safe over time, and even then IDK, I am pushing it IMO...but with a .26-.27" poppet honestly this same method would SAFELY work so I may publish a how-to once I test this current poppet that is REALLY pushing it @ .25" with a .225" valve seat..
Yea .225 valve seal / throat
With .216 ports
That means the stem is...bah I am too embarrassed to say! .04 / 1mm in diameter!
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Bye bye stem ... compression loading is IMO going to pretzel it in short order if not the snapping shut of the valve going the other way does not break it first.
JMO ... ;) as you were
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Bye bye stem ... compression loading is IMO going to pretzel it in short order if not the snapping shut of the valve going the other way does not break it first.
JMO ... ;) as you were
I agree Scott, that is why I do NOT recommend doing this as I am just testing and messing around. I found the results quite outstanding. I have taken the rifle apart to inspect and there is zero sign of defect/buckling on the stem so far, only 40 shots or so in though...
As I've stated though, a similar build with a .235" throat, .06" stem, and a .26-27" poppet would be MUCH more ideal and I actually intend on doing one similar in the long run if I stick with a big port of .216". A .06 stem is plenty and I have over 1000 shots on that stem with ZERO ill effects. If I go back to a smaller .19-.2 port I'll stick with a .25" poppet and a .225ish seat with a .06" poppet stem.
One must realize I am only reducing the stem to the factor closely relative to the pressure against it
The above .04 stem survived smacking the valve @ 2k psi with the 70 lb spring I shown pictured quite a few times so far as well...still I DO NOT recommend it as I am being a guinea pig on this and I actually am kinda TRYING to get it to fail to see how safe the .06" poppet is (50% more strength). Nothing like real world data!
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If you did a hybrid type stem using say .040 to.063" tempered spring steel that went into the PEEK poppet head, but also bonded into the more typical 1/8" stem threw the body it likely would survive without fatigue.
* In other words the reduced diameter is precision ground and flexible spring steel where the reduced diameter within throat is at, full diameter threw body to hammer struck end.
Just thinkin out loud
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If you did a hybrid type stem using say .040 to.063" tempered spring steel that went into the PEEK poppet head, but also bonded into the more typical 1/8" stem threw the body it likely would survive without fatigue.
* In other words the reduced diameter is precision ground and flexible spring steel where the reduced diameter within throat is at, full diameter threw body to hammer struck end.
Just thinkin out loud
Great input. I don't think I'll stay so small on the hand ground stem but found the results interesting. My efficiency went back to normal after reducing spring on hammer..
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I only ordered peek+delrin @ .25" and really don't think I can make a poppet that small work with what I am trying to accomplish. It would work GREAT for .22 cal but I think I am going to revisit this with a poppet @ .295" which is a split between stock and .25"...the 40 shots the .04 stem survived was great but I have a feeling it is a huge ticking time bomb as I could flex that part of the stem by hand...the .06" stem I cannot do this to. I like to take risks in life but there comes a point where the line is TOO fine, no pun intended!
I need to find some peek/delrin at 5/16" to attempt a different poppet material! Reduced to .295", a properly turned peek/delrin poppet should seal GREAT on a .24-.265" seat that the marauder provides.
.295" poppet with .24" throat and a .09" stem would have good enough flow for a .21" exit port which SHOULD theoretically perform well at lower psi.
Not enough time in the day to do all the things I need to do! I am sure all can relate, lol.
On another note, peek may be VERY easy to machine/work with but getting a seal to hold over the long term is another story! I certainly made a mistake when doing some valve work I didn't clean the seat and when I installed the poppet back in, I created a few imperfections on the seat with brass remnants being squeezed between the poppet and the brass seat, and of course guess which material gave first? :D
Lack of attention to detail on my part!
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Another thought on this subject matter.
I reduced the poppet from .324" to .25" which is 22.8%
The above changed required me to go from a 16 lb spring to a 11.5 lb spring which is... 28.1%
I attribute the extra ~6% to the material being changed from whatever stock is to peek, and the seat reduced from .25~ to .235~
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Took valve # 2 apart, inspected, and the poppet actually wasn't what was leaking...was the GLUE! I couldn't even get that thing to seal with a stock poppet...the above dmg I mentioned in the prior post that the seat sustained was not sufficient enough across the entire seat area to cause a leak, at least imo.
I moved the seat forward .04" with a brass washer, it held up actually great, ZERO sign of failure, but due to me going with such large ports, a good portion of the original seat (where the exit port is) was destroyed which didn't allow full coverage/contact with the new seat to the old + glue. I actually believe the damage occurred when I dremeled around that area to smooth from the new seat to the exit port
I'll likely revisit the .25" poppet attempt with a fresh valve and much smaller ports as I don't think the two mix well without doing things like Scott suggested above to guarantee no poppet stem fatigue over time.
It'll be next week likely as I'll order another valve tmrw...but I'll attempt this again. Valve #2 will now become, oh idk...a paper weight! I actually may try to glue another washer/plug down but with how the old seat got broken I have little faith in obtaining a seal.
I did fire one off at 1400 psi for giggles with the leaky valve and made 46 FPE / 902 FPS with a JSB 25.4. That's some good power down low ayy! :)
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I would suggest using a Cothran valve if you can get one. I did all the tricks with PEEK poppets, yes they work but the numbers will always be severely restricted by the fact that the seat is so close to the exhaust on the stock valves that you are limited in what can be done with the stock valve. In the long run, it's just simply not worth the time to tweak one and stay within the limitations. I probably went through 4 stock valves modding them and porting, even moved the seat forward in one using stainless tubing set in JB weld. It worked, but nowhere nearly as good as the Cothran.
By the time I quit wasting efforts on the stock valve, I had spent over $100 on them, and had enough time invested in my efforts to buy ten Cothran valves if I paid myself $5/hr.
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I would suggest using a Cothran valve if you can get one. I did all the tricks with PEEK poppets, yes they work but the numbers will always be severely restricted by the fact that the seat is so close to the exhaust on the stock valves that you are limited in what can be done with the stock valve. In the long run, it's just simply not worth the time to tweak one and stay within the limitations. I probably went through 4 stock valves modding them and porting, even moved the seat forward in one using stainless tubing set in JB weld. It worked, but nowhere nearly as good as the Cothran.
By the time I quit wasting efforts on the stock valve, I had spent over $100 on them, and had enough time invested in my efforts to buy ten Cothran valves if I paid myself $5/hr.
I have 22$ in the valve and 20$ in the poppet materials and about 2-3 hrs labor into the both, which even at 10$ an hour is only about 70 bucks where the Cothran is around 180$...and sadly hobbies are just that, hobbies not a source of income so I can't pay myself to play. So it's just a 22$ loss wrecking the above valve, and another 22$ for another attempt!
Even if I spend 150$ at the end of the day to achieve what I personally want (50 fpe with a 7.5-11 lb spring?) then I'll still end up saving money and having that sense of pride that I did it.
I don't disagree that the Cothran valve is a great valve but its MUCH better suited for very high power rifles...I am more-so learning and enjoying myself while doing some tinkering and attempting to do by hand what the pro's do with major tooling. No disrespect to them and not taking any credit away as what they do is quite amazing!
I certainly am not lacking performance, I have achieved both my desired power and shot counts and am just trying to make the valve easier to open. My next attempt should fair well as I will be very conservative on the ports (.18"-.19")
This was a proof of concept to me, and to only pay 22$ out of pocket to prove to myself something works is worth it to me!
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So I have given up on going as small as .25" on a poppet (maybe) for now, may revisit it someday..
I currently have a .295" stock poppet in my Valve #1 that I am testing and ordered some delrin @ 5/16 (.3125) that I'll likely reduce down a bit to test out, but I don't feel I can reduce peek down to where I want it to and keep it true/round without a lathe and I cannot find any 5/16 peek rod! I'll look again someday or maybe Scott has an idea where to get some?
The .25" poppet will have to be left to those with .177's and .22's.
I can't speak for what fps gains I have currently achieved going from .324" to .295" but they are certainly there.
7.5lb spring @ 1/4" pre-load with .324" poppet with 42 gr hammer prior to tear down was doing 500 fps on 25.4's = 14 fpe (was doing 45 fpe on this with a .25 poppet! max preload)
7.5 lb spring same pre-load with .295" poppet with a 35 gr hammer yielded 515~ fps with 25.4's = 15 fpe. Considering the huge drop in hammer weight, nearly 20%...I'd say the little modification / tweak was worth it to be able to sling a lighter hammer around and make more power without requiring more spring energy!
the 11.5lb spring makes 52 FPE now no problem as well with the .295" poppet and 35 gr hammer, where before it topped out around 48-49 fpe. I had to use a 13 lb spring to hit over 50 fpe on the .324" poppet and 42 gr hammer.
Can't say going to delrin will make a huge difference but I'll report back if/when I make one. I can see trying for a .275-.285" delrin poppet with the stock seat, leaving around .025" on sealing the surface, but considering I'd be doing it by hand I'd want bigger margins of error so I'd stick around .295" as I am now.
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My last 36" piece of 5/16" O.D. natural PEEK came out of Interstate plastics here in Sacramento
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I wonder how a coned shaped plug poppet would do instead of the traditional flat stopper style configuration when making one with a larger OD.
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My last 36" piece of 5/16" O.D. natural PEEK came out of Interstate plastics here in Sacramento
Thanks Scott!
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I wonder how a coned shaped plug poppet would do instead of the traditional flat stopper style configuration when making one with a larger OD.
You mean Tapered like this? / \
I believe most of the experts suggest/recommend a concave seat as that will allow less surface area to to create the seal? At least that is my interpretation of that.
My .25 peek poppet DID have a VERY concave seat/sealing surface and it sealed wonderfully. Just a shame I took the port so far on that valve and trashed it!
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More like this /\, but ok. Just thinking out loud.
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Pointed cone shape on the pressure/spring side or on the throat side? I'm curious would a pointed cone shape on the pressure side make a difference on the force needed to knock the valve open? As pressure is supposed to apply an even force perpendicular to the surfaces it affects, does the poppet head shape affect the force needed to open it against the pressure?
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Oh man I can't help but tinker...
Tossed in the .25 poppet again on the glued # 2 valve...not sure if it holds air but
Same settings as .3" poppet, same spring/ect...
I went from 500 fps to 700 fps on jsb 25.4. That is 14 FPE to almost 28 FPE....I am just in aww how little spring cracks this valve...I will defniitely be trying the .25" poppet again with alterations :)
That is with the lighter 31 gr hammer (35 gr with striker + cocking lug)
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Pointed cone shape on the pressure/spring side or on the throat side? I'm curious would a pointed cone shape on the pressure side make a difference on the force needed to knock the valve open? As pressure is supposed to apply an even force perpendicular to the surfaces it affects, does the poppet head shape affect the force needed to open it against the pressure?
Both sides is really what I was thinking. ♢
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Pointed cone shape on the pressure/spring side or on the throat side? I'm curious would a pointed cone shape on the pressure side make a difference on the force needed to knock the valve open? As pressure is supposed to apply an even force perpendicular to the surfaces it affects, does the poppet head shape affect the force needed to open it against the pressure?
I always question that myself and assume the only benefit would be against the drag maybe as it opens? Since the air rushing by is going well over 1,000 FPS I would imagine drag laws apply to the poppet head, but then again you would potentially reduce the closing force so idk how that poppet head would behave without extensive testing personally!
I do know that my .25" poppet both have less pressure against it while fully seated, AND it has less drag on it when opening. Mine is shaped like stock as you can see in the pictures but much smaller.
Testing for leaks on Valve #2 again now but really not holding my breath anymore than I don't think it's gonna hold air. But I do have valve # 3 on order to attempt this again with smaller portings!
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Pointed cone shape on the pressure/spring side or on the throat side? I'm curious would a pointed cone shape on the pressure side make a difference on the force needed to knock the valve open? As pressure is supposed to apply an even force perpendicular to the surfaces it affects, does the poppet head shape affect the force needed to open it against the pressure?
Both sides is really what I was thinking. ♢
IMO if we could get a perfect seal with metals like a car valve, that would be most ideal for flow (ie: flat and kinda the shape you describe except inverse on the exhaust side to allow the air curtain/bubble more room/flow) but that is just IMO.
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(https://preview.ibb.co/dStdqv/20170610_121230.jpg) (https://ibb.co/fzTBAv)
Here is what I would imagine would be pretty stellar...
.225" poppet head made from hardened steel
.42" OD and .205" ID peek (nylon pictured) washer to seal against
With .180" porting and .06" valve stem reduction, that thing would crack open with 3-5 lbs of spring energy, and should be VERY snappy...hmmm! Tempting to try but peek washers need to be bought in bulk, need to find a local source! I would love to try this...
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And if you could also use say 30° or 45° (depending on lift/valve head size relation) valve seat angles like in cylinder heads, that would also flow some air. A poppet valve with 0° valve seat angle like most air gun valves use are simply a disastor for air flow.
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24 hrs on the .25" peek poppet, 100 + shots even with the .04" stem, ZERO signs of failure so far and all is holding air :)
Gonna keep this puppy in for awhile and stress test it...
This a glued / moved forward seat with a .25" peek poppet on .216" porting.
Poppet holds air down as low as 1k psi which is the lowest so far I've tested it :)
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This poppet is still holding up! New updates are as follows...
I decided this poppet was REALLY easy to crack open, so I tossed a 21 (25 grams with striker + cocking lug) gram hammer behind it instead of my old 31 gram hammer. (35gr loaded)
7.5 lb spring = 20-30 FPE
10.5lb spring = 30-45 FPE
13 lb spring = 45-55 (max I've tested) FPE
Gun seems quite a bit quieter, certainly ZERO negatives from doing the above, have yet to run any long strings to test efficiency but that isn't what I am after...
25 cal with a .25" peek poppet and a 25 gr hammer, 25 cc plenum extension...just having fun with the play on the number 25 and so far its working out!
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I can see how the .25 poppet head would make for less hammer energy requirements, but you only have a 0.025 overlap on the seat. Not sure about the longevity of the seal/poppet with that small of an overlap. You maybe digging the poppet out of the throat soon, lol. At least you get a gold star from me for your efforts if it does happen to fail.
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I can see how the .25 poppet head would make for less hammer energy requirements, but you only have a 0.025 overlap on the seat. Not sure about the longevity of the seal/poppet with that small of an overlap. You maybe digging the poppet out of the throat soon, lol. At least you get a gold star from me for your efforts if it does happen to fail.
a .01 sealing margin is recommended for peek poppets. Actually...but to pull that off by hand imo deserves a gold star considering it holds a seal :)
I've inspected the poppet and there is zero sign of defect or failure.
There is a max of 100 lbs being pressed against the poppet when the valve is closed :)
My sealing margin is at most is .0125" which I left the extra .0025 because of me doing it by hand. :D
I have my ports restricted a bit as well to around .211" currently with a reduced tp as that throat only flows sufficiently for it, I would have to push the throat out to .23" to flow well for my max porting of .215/.216" which I don't feel entirely safe doing!
It probably took me around 10 attempts to get a hole drilled perfectly (by eye) centered into a .25" piece of material...talk about tedious! I was determined though to make my own poppet by hand and the end result of saying "hey I did it" feels very good, I am far from as accomplished as many of the guys that have been around for years building/tuning pcp's and have many of them to thank for the knowledge I have obtained reading around on forums or pming questions :)
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To put in perspective I took a stock poppet down to .29" on the .265" stock throat and the poppet showed signs of failure (bulged out some on the outer diameter)..Peek is tough and the throat itself won't fail
The above showed signs of failure just after 10 shots at medium power, the current peek poppet has been from 12-58 fpe for 500 shots, removed and examined, and holds true shape/form
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Interesting seems like you can get some big gains with light hammer and spring by reducing poppet head size looking forward to hearing about more testing and also if different shape would change how hard the valve opens will be following the post
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Interesting seems like you can get some big gains with light hammer and spring by reducing poppet head size looking forward to hearing about more testing and also if different shape would change how hard the valve opens will be following the post
On a stock unmodified Marauder valve with stock poppet I wouldn't reduce it further than .32" personally. When going to delrin / peek on the same stock valve you might get away with .28" safely, all being said if you don't alter the valves seat.
I modified my valve by adding a washer that was .418" OD x .275" ID x .04" thick on to the existing valve seat with a thin layer of adhesive (I chose a plumbing adhesive that can withstand 3500 psi and doesn't dry completely hard, although its compression is minimal as its layer between the old seat + new seat is less than .01" therefore cannot compress further than that and likely doesn't compress/decompress more than .001". I used that as an adhesive to avoid a dry/hard one that would crack upon impact of valve seating over time. Hopefully it holds up...The old seat supports the washer and was drilled out to .23". This is in a rifle that operates at a max of 2000 psi and I would likely not trust it if it were unregulated and seeing pressure as high as 3k which would increase the force against the poppet by 50%, most prone to failure would by my .04" valve stem, or the adhesive I used.
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I agree with it possibly failing at higher pressure in a unregulated gun . By seeing your tests there is definitely room for improvement over the stock valve set up
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The .25 PEEK Poppet with a .04" stem is still holding up, getting smacked around by a 42 or 25 gram hammer making 12-60 FPE. Ton's of shots on this stem...I hope this thing holds up forever!
.25" poppet on a .226" valve seat allowing .012" sealing margins with both valve seat modification and poppet done by hand! I wouldn't challenge anyone else to try attempting this as I took a lot of care to, and I'm likely the only guy running around with a .25" poppet on a .25 caliber marauder, although I would certainly recommend attempting this in .177 or .22!
I attempted to open up the seat to .23" on the original valve I did this modification to and could NOT for the life of my obtain a seal (accidentally went further than .23"), so I began with a new washer/seat on my original valve...I have made a custom .226" valve seat work twice amazingly in two separate valves, feels very rewarding to accomplish!
The .226" seat with a .04" valve stem limits my ideal porting to around .212" so this new valve is ported only to .212" currently, although my barrel port is .212" x .238" and can take a .225" port I find too much enjoyment out of the .25" PEEK poppet to currently attempt bigger ports with another valve.
I have 0 pellet loading issues with polymags, jsb 25.4, and jsb 34 mk ll's with my .212" wide barrel port.
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You would think there would be an ideal throat size poppet size where you could reach ideal power with little effort . I wonder if it would scale down farther as far as smaller throat equals smaller poppet and would be easier to open but create same amount of power until the throat is to small to flow the air . It is cool that the spring doesn't have to be 14 lbs to make alot of power and that's what I'm trying to say is do you think it could get any lighter or more efficient. Idk
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You would think there would be an ideal throat size poppet size where you could reach ideal power with little effort . I wonder if it would scale down farther as far as smaller throat equals smaller poppet and would be easier to open but create same amount of power until the throat is to small to flow the air . It is cool that the spring doesn't have to be 14 lbs to make alot of power and that's what I'm trying to say is do you think it could get any lighter or more efficient. Idk
Pretty much was my goal and intention on this modification, resulting in MUCH lower cocking efforts even when coupled with light weight hammers, the material I am using doesn't compress much (PEEK) and the throat/seat area is smaller than stock and the force applied against .25" surface area is only 100 lbs @ 1925 psi...when compared to a stock throat that is .26" seat area with a material that compresses a lot more than PEEK and with a .34" surface area even at only 1925 psi that poppet has 180 lbs of force against it...at stock unregulated that .34" poppet has an average (@ 2500 psi) of 230 lbs against it. I am well under half that which requires half the hammer spring even with a much lighter 42 gr hammer.
I think PEEK is the cats meow when it comes to poppet material. Coupled with smaller seats + poppet head surface area it's a win-win-win.
You could make the seat area smaller but then you'd restrict power, which would make it easier to open...but marginally so compared to the length I've gone over stock.
-.34" poppet reduced to .25"
-Material changed to PEEK from stock
-Seat reduced to .23-.25" over stocks .25"-.265".
If you wanted only say 40 fpe MAX then you could go smaller...
I only need 10 lb of spring to hit 58 fpe and 7.5 lb of spring to hit 50 fpe currently, with a slightly heavier hammer I could reduce the spring effort much more, say with the stock 78 gr hammer I likely could use my 6 lb spring to hit 58 fpe lol.
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So I thought the throat diameter was around .200 on stock valve so the seat is .050 to .065 larger and your seat area is .030 to .050 . I'm just trying to picture it couldn't you go smaller at least in theory or am I missing something thanks for helping picture it
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So I thought the throat diameter was around .200 on stock valve so the seat is .050 to .065 larger and your seat area is .030 to .050 . I'm just trying to picture it couldn't you go smaller at least in theory or am I missing something thanks for helping picture it
Stock throat is .2" but the seat is around .26"....My throat is .226" on a .25" poppet which allows for a max of .024" seat area / 2 which is .012" per side of poppet.
You could reduce the seat area down to .22" with a .22" poppet but that would limit porting to around .1875" on a .2" throat...and as I said its not that much of a difference considering the reductions I have already done are much greater over stock...I wanted to take advantage of my seat being moved forward with greater ports which I can run .212" on this valve with the .226" throat + .04" valve stem....as the throat still flows 10% greater than a .212" port. I took a .25" Peek poppet as far as I personally could by hand, I am certainly not going to try to reduce my port size back down under .2" as that takes half the intent of this project away.
This modification not only allowed a .25" PEEK poppet but it allows porting as big as .225", but to run .225" ports I would need a throat of .24" and a valve stem of .05" and I don't have the right size material to pull off a PEEK poppet that is .275" in diameter to attempt it. On a stock valve going beyond .19" on the valve exit port is risky without getting creative.
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I follow you now sorry took me a bit to wrap my head around it .
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Don't think I ever posted a good picture...She's still kicking and plan on running this till it blows! That stem is every bit of .04" and still holds straight and true. That Chinese grade steel for HSS blanks is pretty stout ;)
(https://image.ibb.co/cxvLua/20170611_095021.jpg) (https://imgbb.com/)
(https://image.ibb.co/m3hfSv/20170611_094959.jpg) (https://imgbb.com/)
And here is the mod done to the valve, .04" thick by .418" washer glued on top of original seat.... with a .2255" ID
(https://image.ibb.co/bPEoEa/20170608_082612.jpg) (https://imgbb.com/)
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Lol still holding strong . I wouldn't have guessed it
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How many shots does it have now
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On that poppet? Approaching 1000 but many are at a lower powered setting (18-20 fpe), I'd say at 50+ fpe it's put out at least 200 shots though (with pellets). I have on multiple occasions rapidly fired it at 50 fpe (40-50+ shots) as fast as I could (dry-fire empty)
This same valve mod can be done by anyone with enough patience / will to DIY to make any throat / poppet size one desires with different materials.
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I'm running a .095 on my unregulated .25 mrod didn't touch the seat or stem head . My disco I turned the stem head down to .400 and stem to .71 but that is regulated to 1800 . I'm not using peek though so I don't think I should push it any farther.
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Good work Matt
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Good work Matt
Thanks. Never thought I'd be making over 50 fpe on just 7.5 lbs of spring and a Light weight hammer. Cocking is so reasonable now and easy. The 7.5 lb hammer spring is only 1.75" in length as well :)
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I'm running a .095 on my unregulated .25 mrod didn't touch the seat or stem head . My disco I turned the stem head down to .400 and stem to .71 but that is regulated to 1800 . I'm not using peek though so I don't think I should push it any farther.
Valve stem reduction certainly should only be done safely and relative to the force reduction on the poppet opening cycle being done. IDK the disco's poppet head stock diameter or the seat surface, but .4" seems huge, I'd imagine if the poppet head were .4" and the seat were anything less than .28" that you could reduce that poppet head much further. A .03 overlap should be plenty especially if regulated @ 1800 psi. So if you have a .28" throat a .34" poppet would be fine at 1800 psi
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You used a HSS drill blank to make that valve stem? Is the stem just pushed in to a drilled hole in the peek poppet?
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You used a HSS drill blank to make that valve stem? Is the stem just pushed in to a drilled hole in the peek poppet?
Correct, I drilled the hole to around ~.122" so I could press the .125" stem in (my method of pressing was tapping it in with a hammer) I didn't grind down / reduce the stem until after it was all prepped. My depth could of likely been greater as I think I only went about 40-50% into poppet where I think stock they go in about 80% of the depth of poppet, but with me doing it by hand, less seemed like more.
The Stem where it was pressed in got hit with a quick notch going around the stem twice, and then hit with red lock tite prior to being pressed or in my case hammered in. The toughest part was centering the hole and staying concentric, this took me about 3 tries to get how I liked. I started with 12 inches of peek, and still have 8 inches left! Compared to my delrin attempts, I started with 12 inches, and have only 4 inches left! Lol...I got extremely lucky on the peek or just better with practice...I like to think the latter.
I obtained a flat surface on the poppet by just enlarging a dremel's sanding disc hole to accept the .125" stem, putting the poppet into my dremel with the sanding disc on it, and holding the sanding disc up by hand as flat as I could with one hand and the dremel as straight as I could with the other. I repeated the same with water on the disc (180 grit disc) and then repeated it again with some Ultimate Compound. End result was a very glass like smooth surface.
The most work involved in modding valve seats / poppets is attention to detail and prep. If you have a lathe then you're golden. I think I spent about 1-2 hrs on both my custom valve seats prepping them to be as smooth as glass, where as prepping the poppet (sanding seating surface) only took <5 minutes.
To install the washer center I used a bit with tape around it which was JUST under the size of my throat (throat .2255, taped bit = .224/.225, so when it was slide down into the valve it really only has one way to fit...I slipped the washer over the taped bit and I then applied the glue. The taped bit functioned as an alignment /install tool. After pressing it firmly into place I used two small allen wrenches/skinny objects to hold it in place as I pulled out the taped bit. I cleaned up the glue that got squished out with q-tips, and then sat a 13/32" bit on it to add a little weight as it cured...There are MUCH better choices for glue opposed to what I used, what I use is rated to 3500 psi and is called E6000. There is a better glue I can't think of the name, and MUCH better alternatives to either that are rated for 5000+ psi...but I am regulated @ 2000 psi or under and curiosity has me hedging bets...The reason I would use a flexible glue is because due to impact over time, glues like JB Weld or of the like that dry entirely hard are prone to cracking, I speak from experience in very LOW impact situations...let alone in a pcp air rifle, the area of the new seat = .418" - .225" = .193"...what that means is my poppet has around 100 lbs of force against it at 1900 psi, where as the seat has 61 lbs, for a combined 160 lbs...the amount of flex in the glue is likely retained at its max even when the valve is open with 61 lbs of force + the force of air passing through it, having absolutely no ill effects. In essence I have no concern that flexible glue flexes in any negative manner.
-Matt
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I'll add in costs for this fairly AWESOME mod...
Peek Material 1/4" x 1 foot (could maybe find it cheaper?) = 12.50$ (ebay)
.125 HSS Blanks (could be found cheaper I am sure) = 7$ for 3 (1 bit makes 2 poppets) (ebay)
Brass washer (forget size but they come at around .43" OD x .21" ID , 10 pack = 1$ (home depot)
For around 21$...I would do this again in a heart beat, in fact I have enough material to do it at least 6 times for 21$, so 3.50$ per valve...I already had the glue from other projects, but if add in that costs (5$) then 26 / 6 = 4.33 per valve...take it further and add in my custom tooling (washer with sand paper glued to it to create valve seat surface seen in earlier posts) you can bring the cost up another .25 cents in total...if you don't have a dremel and acquire a harbor freight one for 9$ then you're still under 6$ per valve! Don't call me cheap though, just call me frugal :)
I love frugal mods that rock my world! :)
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I think the stock head of the stem was .428 I'll have to measure again . But it looked like there is metal on the inside of the stem head looks like if I take it down farther it will expose the metal. This is on the disco otherwise I would have taken it down farther