GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Show us your Custom Airgun Parts (TRICKS-N-TIPS) => Topic started by: sb327 on September 18, 2020, 10:22:31 PM
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This is a breech I’ve been messing with kinda just to see how hard it would be to make. I was originally gonna make it for my synrod and cut the bottom radius for it. I used a boring bar and that was a trick getting it true. I had to come at it from both ends. Then decided on a small tube complete build and recut the radius. Only this time I realized a core router bit (for wood) would be perfect. It worked great.
The reason I wanted to go with the sidelever is because it inherently pushes the pellet/slug past the tp and then retracts. (I think this is how most work, I could be wrong). I also like single shot, so I incorporated a removable brass piece (for caliber changes) that will get sealed inside and have the tp drilled into it. I will also seal the rear of barrel. The barrel hole is 1/2”.
The bolt raceway is a piece of 1/2” od x 3/8” id 4130 I had.
The breech is 6” overall, 6061 1 1/2” x 1” bar.
I haven’t drill/machined any bottom holes or start on the tube. I’ve got 3’ piece of tubing I will cut to length when I decide what length I’ll need.
I’ve got a disco valve, I probably need to look at the best mods for it. Or design my own.
Any suggestions appreciated on valving, hammer, etc.
Dave
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Nice work!
Most sidelevers are not made to retract past the TP, they will retract a very small amount to lock but rarely past the TP, as most production airguns have tiny ports there are no need to have a retracting sidelever anyway.
But there are no reason one could make it so it does retract.
Lloyd did make one in for a marauder.
https://www.youtube.com/watch?v=Cgl7H6FNJ2g (https://www.youtube.com/watch?v=Cgl7H6FNJ2g)
What calibers will this be in and what pressures will it be made for?
With a 1/2 barrel diameter I guess 9mm will be the biggest you will use?
The disco valve can be ported quite good but if you are going to make a new valve I would go for one that seals before the poppet so you have the whole tube diameters area around it and you can use bigger poppets then what the disco have in it's valve housing, (which is 1/2 around the poppet? idk there are some years I had one apart)
Another alternative if you still want to use a bigger tube (or can be used with a small tube too for that matter) is to make a "monoblock" and have a end plug on your tube that you threaded in it with either the valve in the "end plug" or have the valve in your "monoblock" (which will in this case be a "biblock" as it is two parts) so you bolt the upper straight down into it having two flat surfaces mating each other.
Making the mounting of the upper and the transfer port a much easier deal imo as there can be hard to find place to but good fasteners on a small tube.
(Lots of weight with the heavier barrel/breech that the two small bolts on a stock disco would be holding as an example)
As you are going with a custom build hammer strength will not be a problem, so I think you have good possibilities to get the performance you want. ;D
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I watched that video before making mine and I ended up pretty much with those lengths and angles. There is a point in the video where you can see the bolt in it’s forward most position then locked. I watched the pivot screw and it appears to come back quite a ways. He also writes a ‘probeless’ bolt was used, so I assumed flat front gets skirt past tp then gets back out of the way. Not sure if probed or probeless is better.
.25 will probably be as large as I go, possibly .30 but doubtful. My idea is to have things interchangeable, so I’ll probably stay with internal valve. If I do a monoblock, it might not lend too well to experimenting with different valves. Albeit it sure would make securing that receiver easier.
I will study some on this valve I have. Since I have it in hand, some mods make more sense now.
I have an mrod valve and large tube as well, still haven’t ruled that completely out. I also have the core bit for it. Would be a simple machine op.
3000 psi is my max on pressure that I will use. It’s 4130 tube.
I thank you for your input.
Dave
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Probless will give you the possiblity to use full bore portning.
So more power and a theoretical longer shoot string as you can go to lower pressures and still keep your velocity.
A disco valve should not be hard to port for a 1/4 exhaust port.
A marauder poppet is a common mod, but they will not handle the bigger throat diameters at 3000 psi (to soft).
Peek works good, if I remember right someone was using PET for poppet heads, there are probably plenty of driffent matrials one could use...
So in a .25 you could tune it up to around the 100-150 fpe range, could be a nice slug gun for 50gr acp bullets maybe?
I too have a 4130 7/8 tube and my tube is okay for 4500 psi.
So depending on your endplug/valve mounting it could be possible to expriment with higher pressures.
Here's a good thread about hammer weight and travel.
https://www.gatewaytoairguns.org/GTA/index.php?topic=99949.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=99949.0)
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I was just going with 3000 just because I’m used to that with my mrod. I may go to 3500 with this.
If I make my own valve, I think I will move that sealing point. I may also move the lugs back so I can use four and stay out of the exhaust area. I’ll try to scribble out what I have in mind later but I think your right on with your ideas and I appreciate the input.
Dave
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This is what I have in mind. Since it is a custom build, no sense boxing myself in just so a ‘stock’ valve will fit.
Let’s say I want to make 75-100 fpe with a .22 or .25, what throat and tp size would be good? And if I do a balance valve, what size to match up with throat?
Dave
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nice looking breech. Im made a bunch , never a sidelever.. As for porting , if its a slug gun you want full bore or close.. So assuming a 25 cal , youd have something like a . 300 throat , 1/8th stem , .250 TP
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1/8th stem is . 0122 sq inches
.300 throat is .076 sq inches
1/4 inch tp is .049 sq inches
SO
.076- .0122= .0638 flow through the throat , choking down into .049 in the transfer port
for balanced valves , half mine dont work so thats a bob question.
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Thanks
Bob gives an example in reply #546 of the simplified balance valve novel. It is pretty close to your suggestion. Is this still the ‘best’ way to configure one of these?
Will this be doable in a disco size tube?
I think Motorhead (Scott) had made some changes to this design as well. I will be trying to track down those threads too.
Dave
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Since I’m at work and can only study I think I have come up with some generalizations about bv’s.
1. They are more tune able by vent and bv chamber size than hammer strike.
2. They work within a smaller tune window than hammer tuning but have the advantage of opening large valves with less hammer force.
3. Maximum poppet lift is dictated by travel within the balance chamber then hammer bounce/crash occurs.
4. A bv can ‘blow open’ and ‘hold’ open, but offers nothing to closing force
5. The tuning of the ‘hold’ open is what gives us dwell
With these things in mind, could we limit the travel within the chamber to just the cracking distance, run a large vent to speed the neutralizing of the bv, extend the poppet stem back out to allow hammer movement (dwell) and ‘float’ the balance chamber not only a touch radially (for machining tolerance) but also allow it to travel with the poppet away from valve seat. If the bv gets negated as soon as valve cracks, then we might possibly have a larger tuning window without altering the valve itself.
I scribbled it down. Just a thought.
Dave
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If you have so little travel the hammer will knock it open and bounce back not giving your more dwell and so a longer valve stem will not do anything and it would be harder to tune.
Also there are a risk of breaking something when it slams in the stop like that?
Just some guesses from my part, I can very well be wrong.
Also the big throat you have to compesate for the low lift (less then 1/4 of the area) seems to be counterproductive for the purpose of a balanced valve which is mainly to be able to use less hammer force.
With a bigger throat it will soon have has much force on it as a convential valve even with it's balance chamber.
Also you need to fit the bigger balance chamber in your valve body which will take up some area in a 7/8" tube.
One solution to that could be to place the chamber behind the poppet instead.
For full bore portning in. 25 with a. 30" OD poppet you have 210lb holding close at 3000psi
If a convential valve is used the bobs rule of thumb recomendations a 1" travel and 100g as the hammer weight for 100 fpe, which is maybe doable depending on the setup.
Many seems to use a balance chamber of 50% the poppet (about. 21" on. 30" poppet) area so that would be 105lb of closing force with a. 30" poppet and more with a bigger one like in your example.
One could also go with a bit smaller poppet and a. 25" exhaust port, taking the lb down just below 200lb.
Like ackuric did in this thread, but with a. 216" exhaust.
https://www.gatewaytoairguns.org/GTA/index.php?topic=127676.40 (https://www.gatewaytoairguns.org/GTA/index.php?topic=127676.40)
So there are many ways to skin a cat and all of them could probably work with enough effort...
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I saw now that the balance chamber did float with the poppet.
So what I said before is not right, just me miss understanding your design...
Seems like it could be a good idea.
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So an update.
Got my valve, tube and a 22lr barrel done. And a grip. Everything looks very utilitarian right now. Still need a foregrip and stock.
I used glass filled pei (supposed to be similar to peek, not an expert on the stuff, it was cheap on eBay as machine shop drops). Cut the face at 10 degree concave and it seems to hold fine. I used the glass filled for the same reason Scott uses it, because of its compressive strength. I used a .058” hole though the face of valve to balance chamber. I can adjust balance piston fore and aft to adjust volume. Piston is free to float towards muzzle end.
I have 3 8-32 shcs, a 10-32 from top (through breech), and another 8-32 through grip anchoring the valve in place.
Fill port and gauge plug is threaded with oring at minor id.
Barrel is 25 3/4” long.
I’m testing springs now. Hammer is a stock Crosman 7/8”. A factory 2240 spring will crack it at 2600 but bounces bad. Best spring that has worked so far is a short (2” to give free flight) spring of .039” wire, 10 pitch. Still think I’m getting just a little bounce with it.
Will post more pics shortly.
Dave
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The pvc on the barrel is to mount my chrono.
And the allthread out the back is to cock the hammer until I decide how I want to tie it in to the bolt.
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very cool love the skeletonized valve.. Question , did you also make the trigger asembly and frame ?? that looks awesome
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I did. 3-d printed the ar grip.
Here’s a couple of in progress pics of grip frame.
I had a sketch on the side of it with a different kind of sear setup but didn’t go with that style. It’s all made from scraps.
Dave
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excellent work , i know how time consuming that can be . I made an entire 3d printed grip frame and aluminum trigger components for it.. pain in the a--
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Fantastic work! Love the concept of the past-center latchup to clear the TP, never thought of that before. Looks mighty cool, especially the flat-front trigger. Jim, I might be wrong but my impression of the intent of the limited poppet stroke on Bob's balanced valve was to prevent bottoming out in the balance chamber. I believe he found that with the length of the stem exposed equal to the available stroke in the balance chamber, the poppet still bottomed out due to it's own momentum taking it past the rear of the valve. I think that the dwell was supposed to be governed by the hammer mass, the idea (I think) being that the balance of spring force/stroke was supposed to leave the hammer decelerating/stopping just shy of the rear of the valve, and due to it's weight/momentum takes a tiny moment to begin to reverse. I do remember that he found that power dropped when he had too much hammer energy, as the hammer ended up bouncing off of the back of the valve. I may be waaay off base, have never built nor tuned a PCP yet; just done a lot of reading. Hope that might help somehow, even a blind squirrel gets a nut now and again,
Jesse
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Since I’m at work and can only study I think I have come up with some generalizations about bv’s.
1. They are more tune able by vent and bv chamber size than hammer strike.
2. They work within a smaller tune window than hammer tuning but have the advantage of opening large valves with less hammer force.
3. Maximum poppet lift is dictated by travel within the balance chamber then hammer bounce/crash occurs.
4. A bv can ‘blow open’ and ‘hold’ open, but offers nothing to closing force
5. The tuning of the ‘hold’ open is what gives us dwell
With these things in mind, could we limit the travel within the chamber to just the cracking distance, run a large vent to speed the neutralizing of the bv, extend the poppet stem back out to allow hammer movement (dwell) and ‘float’ the balance chamber not only a touch radially (for machining tolerance) but also allow it to travel with the poppet away from valve seat. If the bv gets negated as soon as valve cracks, then we might possibly have a larger tuning window without altering the valve itself.
I scribbled it down. Just a thought.
Dave
Hey Dave, again, I'm NO expert as I've never built nor modded a PCP yet, but I think:
Quote-"1. They are more tune able by vent and bv chamber size than hammer strike."
As far as I understand it, the whole point of the pressure vent to the balance chamber is to eliminate any "balancing" force after the valve has cracked open, reducing required hammer strike only at the moment full pressure is holding the poppet closed. If you think about it, after a poppet is off it's seat, only the stem area is open to atmospheric pressure creating a net closing force. Minus any "sail" effect of the airflow around the poppet. IIRC, if the vent is made too large, you rapidly lose any advantage to it being balanced at all.
Quote-"4. A bv can ‘blow open’ and ‘hold’ open, but offers nothing to closing force"
Again, that's the point of the vent. It takes the valve back to the "unbalanced" state soon after the poppet lifts off it's seat.
Quote-"5. The tuning of the ‘hold’ open is what gives us dwell"
Correct to some degree, as the speed at which the balance chamber fills regulates how long the valve is actually "balanced", changing it back to acting like any other valve. To big a vent will negate the point of balancing. Like I said in my last post, I believe hammer weight is supposed to be the main variable determining dwell.
I find the arrangement in your drawing interesting, as it might/should have exactly the same effect while giving a longer possible stroke.
Obviously, you've got it shooting and that's what counts, just offering my two wooden coins in hopes that my ramblings may help in some obscure way. Don't mean to come across sounding like I know what I'm talking about, 'cause I wouldn't know whether or not I do... just read a lot on here while it was all being developed, and tried to understand it.
Keep up the good work, again, I don't want to sound like I'm some kind of expert, just hoping that my messed up understanding of things might give someone else an idea/insight even if it's through something I've gotten wrong.
Respectfully,
Jesse
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Thanks for the replies. I really appreciate constructive feedback.
My understanding of the need for a balance valve comes from an excessively high cracking force, usually due to higher pressure, larger valve, or a combination of the two. One that makes the hammer/spring combo obnoxious. Obviously what one encounters when seeking more power.
If all we ‘need’ is a reduction in cracking force, my thought was, how do we negate the ‘side effects’ of the bv.
That is my goal to try to eliminate and still have a lower cracking force.
So far.....
1. Cracking force is low. I can open the valve at 3000 with a 2240 spring/hammer.
2. I have no failures to close.
3. Hammer bounce is bad with light springs and preload. Typical from what I have been reading.
Those are things I know for sure. Things that are showing promise but not enough testing done
1. Wide range of tuning with hammer strike
2. Quite a bit of power.
Once I get hammer/spring combo figured out, my ‘goals’
1. 100fpe
2. External tuning to keep light slugs under 1000 FPS
I don’t have enough data yet to say I have reached those goals but testing, so far, has been very promising.
Thanks for the replies and encouragement.
Dave
Here are a couple of slugs I have been testing with. The top is a 45gr Lyman with gc base. It drops at .224. The bottom is one I made a mold for while doing some load developing. It is considered a powder coat bullet. It measures .223.
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Sounds like it's all running good, hope you reach your goals! I really like that breech... Might be an obvious question, but what holds the lever closed? Is it spring pressure once the toggle goes past center? Anyhow, thanks for sharing! Really cool to rival some .22 LR loads with a BB gun... 8)
Jesse
Edit-If you haven't found Motorhead's BV thread yet, here's a link:https://www.gatewaytoairguns.org/GTA/index.php?topic=167384.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=167384.0)
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Thanks. Testing has shown my goals are not out of reach. It IS cool to rival a Lr since I have spent years messing with the 22. I have built several on the Lr platform. Singles to br bolt actions. My designs.
I have read Motorheads thread (although he doesn’t believe so and was less than encouraging in his reply in Bob’s house). I do appreciate his and others work in this area. The work and testing in this area and the documentation has been priceless. My ideas/changes are only to satisfy my own ideas/questions. I like to build. And I LOVE to shoot.
Dave
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Thanks. Testing has shown my goals are not out of reach. It IS cool to rival a Lr since I have spent years messing with the 22. I have built several on the Lr platform. Singles to br bolt actions. My designs.
I have read Motorheads thread (although he doesn’t believe so and was less than encouraging in his reply in Bob’s house). I do appreciate his and others work in this area. The work and testing in this area and the documentation has been priceless. My ideas/changes are only to satisfy my own ideas/questions. I like to build. And I LOVE to shoot.
Dave
whats the barrel length ??
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The twist too; if you would for future reference when you get to checking accuracy. Will be watching,
Jesse
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Barrel is 25 3/4”. According to Bobs ‘lofty goal’ formula, I will be pushing it to get to 100fpe. If my figuring is correct, I will have to be just a touch over 50% of ‘possible’ fpe with that bbl and a reasonable pressure (2600 I think is what I figured it at). And from my understanding, above 50% is difficult.
I will have to check to make sure on the twist, I kind of assumed 16. It would be nice to find a larger longer 22 short barrel (20twist) as Knifemaker seems to be killing it with that twist. I’ll let you know. It’s an old mossberg takeoff.
Dave
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Barrel is 25 3/4”. According to Bobs ‘lofty goal’ formula, I will be pushing it to get to 100fpe. If my figuring is correct, I will have to be just a touch over 50% of ‘possible’ fpe with that bbl and a reasonable pressure (2600 I think is what I figured it at). And from my understanding, above 50% is difficult.
From what I've read and understand; above 50% cannot be achieved, with the proviso that the bullet weighs half the FPE. Bob has another article that deals with that aspect better on another forum, but I'm not sure if it's okay to link to it. Just re-read that article, and he breaks down the how's and why's. Basically, exceeding it has never/cannot be achieved if you stick with a bullet weight of half the FPE, as the formula is written. If you up the bullet weight to over 50% of the FPE predicted, you can exceed the 50% "lofty goal" FPE formula prediction. Whether or not that will get you as far as you need it, I don't know :-\. Don't know what bullets you intended to run in the future, but that might be something to consider. If you wish, I will PM you a link.
Jesse
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Pretty sure the link your referring is the same I’ve studied. I can still play with the pressure. 2600 is not set in stone.
It’s a fun challenge for sure.
Dave
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Good deal, will be watching.
Jesse
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The barrel is a 16 twist.
I got some pics of the valve apart while I had it out for machining the tube and breech to allow bolt to cock the hammer.
I have been able to get 90fpe with 2900 psi, after that it just seems to waste more air. I think with this barrel and and 44 grain bullets, I may be at my max. 90fpe seems pretty stout for a .22 though.
My next days off I’ll be trying some bench shooting to see where it likes to be set for accuracy.
And address putting some kind of stock on it.
Dave
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90fpe is serious power in 22 , nice job!
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Fantastic! If the accuracy is there, you've got a sweeeeet long range mini-sniper... Man but you've got me wishing that I had my shop together.... Thanks for sharing, nice pics of the valve.
Jesse
PS- Once you get your final tune down, please share the shot strings. That's a lot of power out of a small tube, will be cool to see how many good shots you can squeeze out of it 8).
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I can’t imagine getting more than 3 shots. ;D
It’ll be an air hog for sure.
I’ll definitely post accuracy results. I will also play with valve dwell to see how the valve design does with tunability.
Dave
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I replaced the barrel on this with a 30” liner. I am getting 101.3 fpe @ 2750 psi. I didn’t try higher pressure as I was shooting tethered and that’s what my reg is set to.
I need to order some tubing to tension my new ‘barrel’. Right now the liner is in aluminum tube of 5/8” diameter except for the last 3”. Loctited.
Once tensioned, I want to play with velocity vs accuracy. Then I am going to play with some porting to dump some pressure off the base of the slug upon exit. But I have to get a baseline first in case my porting screws up accuracy.
Anyway, just an update.
Got another project going while I wait on tube for this one.
Dave
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very nice.. Question , i may have forgotten , how many ccs do you have onboard total?
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It’s right at 170cc’s. 10.46”^3
Not much!
I forgot I added a piece of tube for a buttstock. Cut some holes in the side to be able to adjust preload. Gonna make a ‘scale’ on it so I can see where it’s set. That’s why the paper is taped to that area.
Guess my coffee hadn’t kicked in when I took these pics, they not so good for detail. :o
Dave
She’s a skinny girl with long legs! She needs to plump up a little!
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Kewl 8)
Jesse
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Boy that’s a lot of power in .22. Nice build . Best I’ve hit by modding another platform has been 70fpe in .223 but I couldn’t live with the poor shot count. That’s without a BV with quick closing . It was all brute force and ignorance.
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Thanks. I doubt it’ll be accurate and it sure as heck isn’t efficient but it was a goal I set.
I’m really curious to see though!
Dave
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With these things in mind, could we limit the travel within the chamber to just the cracking distance, run a large vent to speed the neutralizing of the bv, extend the poppet stem back out to allow hammer movement (dwell) and ‘float’ the balance chamber not only a touch radially (for machining tolerance) but also allow it to travel with the poppet away from valve seat. If the bv gets negated as soon as valve cracks, then we might possibly have a larger tuning window without altering the valve itself.
An interesting thought worth animating ;)
(https://i.imgur.com/mP6MEMe.gif)
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Thanks a bunch!
I think the biggest benefit of this design is that it is easy to get to work. Or I just got really lucky the first go around.
I’ve was able to get over 100fpe with an easy cocking bolt. Plus I can slow it way down with the hammer spring adjusted low.
Still more to do on this project as well.
Thanks again,
Dave
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Just finding this thread .... Sorry If something I had said was a negative to your creative process, was never my intent. Generally i share my experience/s on a given subject sharing what learned to save others from taking wrong turns or wasted effort.
Respectfully,
Scott S
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Updated animation, there was a little glitch in the first iteration that was bothering me:
(https://i.imgur.com/h8LyBLs.gif)
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Just finding this thread .... Sorry If something I had said was a negative to your creative process, was never my intent. Generally i share my experience/s on a given subject sharing what learned to save others from taking wrong turns or wasted effort.
Respectfully,
Scott S
I’m not sure exactly which time your talking about?
The time mentioned in this thread is here
https://www.gatewaytoairguns.org/GTA/index.php?topic=178479.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=178479.0)
You basically attempted to negate every single GENERALIZATION I made, proceeded to claim I had not done my homework and then left. Without offering anything in the way of insight into what my actual thread was about.
Or the most recent time here
https://www.gatewaytoairguns.org/GTA/index.php?topic=175248.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=175248.0)
Where you pointed out that I basically had too many dynamic orings for the valve to be consistent when I had already stated that consistency with that design was awesome. Again leaving without offering any possible solution for stated problems.
I respect your work and appreciate you sharing it. It has helped me a lot to get where I am. I believe I have shown that respect multiple times across my posting here. I will continue to credit your work.
I would just appreciate if you would give me a little credit as well and try to understand my ideas.
Thanks for your reply,
Dave
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dave ,from the animation , it appears that the balance chamber is partially floating if struct from behind , in the sense it can allow the spool to bottom out and still function.. is this correct ?? if so , its actually quite interesting
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it appears that the balance chamber is partially floating if struct from behind , in the sense it can allow the spool to bottom out and still function.. is this correct ??
That is how I understood it, a balanced valve that can be cracked open by a weaker hammer, but once it's open it essentially behaves like a normal poppet, moving as one part.
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which makes a great deal of sense since the cracking force is the issue , moreso than the dwell .
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That is exactly what it does. You can hit as hard as you want and nothing bottoms out.
(Yes, within reason)
But if you hit it light, the large vent allows quick closing.
Now to be honest, I have not yet got to test all the features of this valve. I am not going to say that something ugly might not rear it’s head.
Dave
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Dave , you have a lot of good ideas.. Well , lets put it this way , a lot of people have a lot of ideas, But having the machine skills to execute AND the good ideas is a rare combo ..
Of all the challenges in airgun machining and design , reinventiing the valve is by far the hardest.( i still want to see how the umarex hammer valve works since we know its a Qev that self closes somehow )
Jack also has some awesome ideas that he can pull off ..
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One thing that does have to be within a certain region is the valve travel before bv bottoms out.
Bob expressed some concern about that in the other thread and I made that adjustable. I had thought originally as small as possible but he pointed out, basically, that it needs some movement to afford time for the chamber to fill. He was correct and I had to increase that distance from my original .020” guesstimate to around 3x that. Iirc
I think for those first trying to build a bv, this design does seem to be forgiving.
Just so there is no confusion if looking at the animation and comparing to my actual valve. Scott (Motorhead) pointed out in one of his threads that making the forward end of the bv the piston and the poppet the cylinder, you take advantage of the strength of materials as well as afford a better spot for your oring. Mine is made like Scott’s and the animation depicts it reversed. The concept is the same.
Dave
Jacks got a really fantastic idea I can’t get out of my head because I want to try it!!!!
I’ve even sketched it out and trying to figure out the easiest machining operations.
I’ve got too many unfinished guns/ideas as it stands!!!
Now you bring up the hammer. I just figured it was like the af? Is it not?
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nope .. takes 2 lbs of force to cock the gun and it dumps 105cc HPA chamber tucked away in the stock per shot.. So its not a tophat design or anything similar , its something new .. Some blend of a QEV and a typical BV.. Ive made a few balanced designs , none were a huge success, mostly because i tend to " overbalance " looking for the lightest possible unseating force. I made one where it would randomly go semi automatic.. that was interesting and quite startling. MY interest now is more spool related with no stem , where the seat force is almost zero but has an oring on the tapered seat.. Gotta get back to it , had some early success a few weeks ago bbut it was hard to externally trigger ( similar design to your electric solenoid gun)
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I’ll have to see if I can figure out this hammer design. I love new ideas and out of the box thinking.
Your soft seal poppet idea I believe is achievable. I will enjoy seeing how it works.
My first valve attempt on here was a failure but for me a success because I learned a lot of the basics along the way. Still learning.
Dave
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the 2 tapers are aluminum , but the oring creates the seal , heres a pic of it early on , both sides of the spool are sealed ,but the bias is closing force + spring
(https://live.staticflickr.com/65535/50493040181_1ce3969eee_z.jpg) (https://flic.kr/p/2jVU2Gi)20201015_152244 (https://flic.kr/p/2jVU2Gi) by murphyrobert9 (https://www.flickr.com/photos/56743574@N07/), on Flickr
SO it still takes a hammer strike to PULL it open, but that same hammer has to release the Pullstud also or its a dump valve
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(https://live.staticflickr.com/65535/50494404341_b12edfbb3e_z.jpg) (https://flic.kr/p/2jW22di)20201016_092157 (https://flic.kr/p/2jW22di) by murphyrobert9 (https://www.flickr.com/photos/56743574@N07/), on Flickr
maybe this makes more sense , but doesnt show the oring in the taper.
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Does the valve travel inside the round bar to the right?
Dave
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Does the valve travel inside the round bar to the right?
Dave
yes , it has an oring roove inside the tube to the right , that seals the spool .. SO the poppet side of the spool is .440 and the right side is .375 sliding through a static seal. the " pullstud" to the far right is connected directly to the spool.. SO very little force is needed to unseat the valve , reseating is the spring and the slight diamter differential ( the air fed into the chamber being restricted also aids in the valve closing
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I will continue to watch the progress and say no more. Having been at home for the last 2 weeks with COVID-19 being exposed by a dear friend who did not know he had it, and His passing this morning from complications, I'm in no mind set to elaborate further.
Best of luck on this project !! wish i was thinking clear enough to follow along and offer positive encouragement or suggestions.
Scott
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the 2 tapers are aluminum , but the oring creates the seal , heres a pic of it early on , both sides of the spool are sealed ,but the bias is closing force + spring
Very nice, I see a P17 valve next to it, inspiration?
i still want to see how the umarex hammer valve works since we know its a Qev that self closes somehow
If it is a QEV then surely it can't be that much of a mystery? By not having the piston as a perfect seal the pilot chamber should refill as soon as the pilot valve closes and reseal the outlet.
(https://i.imgur.com/2rfRU0e.gif)
Here is a very early ( 2010! ) prototype valve I had made with the same concept using a schrader valve as a pilot and hooked up to a 100 psi air line:
https://www.youtube.com/watch?v=xKq4ktpplMA (https://www.youtube.com/watch?v=xKq4ktpplMA)
The piston was a thick rubber disk fitted loosely in the cylinder with a weak spring to reset it.
Having been at home for the last 2 weeks with COVID-19 being exposed by a dear friend who did not know he had it, and His passing this morning from complications, I'm in no mind set to elaborate further.
Sorry for your loss Scott and best wishes for your own affliction, here's to hoping you pull through unscathed.
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I will continue to watch the progress and say no more. Having been at home for the last 2 weeks with COVID-19 being exposed by a dear friend who did not know he had it, and His passing this morning from complications, I'm in no mind set to elaborate further.
Best of luck on this project !! wish i was thinking clear enough to follow along and offer positive encouragement or suggestions.
Scott
Understood.
We have all been effected by this &^^& in a negative way.
Hope you stay healthy.
Sincerely,
Dave
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On the qev, can the exhaust run down the barrel? Have the minor poppet seat to a throat in major poppet, maybe?
Would make it a pull stem rather than push and may even afford some adjustability by how far the minor poppet came out because the major will be chasing it. ????
Interesting
Dave
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Jack youre correct about the p17 baseline idea.. When i made a few p17 pcps , I couldnt tune them to close , so i branched off ... As for the QEV hammer valve, I know people have complained about a blast from the breech area during firing , SO it very well could be aa piloted QEV .. Im guessing the gun is plumbed a bit differently though , as the tank is directly behind the breeech.. no one has opened one up to verify as of yet
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Is this the hammer valve?
https://patentimages.storage.googleapis.com/ac/a7/52/177a326b9c7f46/US20180195831A1.pdf
Don’t have much time right now to make sure
Dave
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nice , while i dont fuly understand the diaghram , i dont see why theyd file a patent for any of the other guns. ( and it was filed 2017
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Does the valve travel inside the round bar to the right?
Dave
yes , it has an oring roove inside the tube to the right , that seals the spool .. SO the poppet side of the spool is .440 and the right side is .375 sliding through a static seal. the " pullstud" to the far right is connected directly to the spool.. SO very little force is needed to unseat the valve , reseating is the spring and the slight diamter differential ( the air fed into the chamber being restricted also aids in the valve closing
So something like this?
Dave
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thats exactly right dave ... Furthermore , I think it would need a metered supply from res , either choked by adjustment , or a secondary poppet much like discussed in the huben thread. I never hooked up a large supply of air to it , So no clue if it would reset while having air flowing inward.
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This is only a suggestion. It looks complicated at first but it’s not. You can make this thing adjustable real easy.
Take a look at this. I will comment more in a bit. I have some machining suggestions that will make life easier.
Dave
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i see what you mean , have the balance hole through the spool , and a second set of partial seals at the right side of the spool So the return pressure assists with closing the valve , and can be a metered port via small threaded set screw hole. ( or metered by the pullstud itself
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Yeah, I would just use the pullstud to meter. For simplicity sake.
Now we don’t need to forget, when testing, valves react differently when they are pushing a pellet vs dry fire. Especially valves that are dependent on throat pressure. Not saying it won’t cycle but it is affected.
Dave
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Now compare the previous to this....
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yours is hammerless, and appears to be bias open, not shut?
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That’s Jacks.
Biased closed.
Hammer opened.
This design actually uses the vent to INCREASE closing force.
A regular bv uses the vent to negate the opening force the bv subtracts from the closing force.
This design does have the easy opening effect of a normal bv as well but with enhanced closing. Keep in mind this design is still theoretical.
Dave
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i see now that its biased closed.. and this is the one where the idea of a metered inlet was tossed around. or a secondary poppet ( gettting mixed up with all the aniimations lol
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Me too