GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: sb327 on October 13, 2021, 10:50:08 AM
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I've got a build going that is inspired by the lines of the Leshiy2.
It will be a single shot with PP700 style breech, only a little more robust.
It will be using my pilot type valve I've posted about before. I have done some extensive testing with it and it responds superbly to my solenoid actuator. It has allowed me to drop operating voltage down to 24v. I am using a short solenoid, about 1" long. I can run it with two 470uf caps. I'm still using the arduino nano to control dwell based on potentiometer input.
The pilot valve as designed does not use blow closed or sail effect to close. It relies on pressure at the stem to pull valve closed. This makes it easier for the solenoid to hold valve open. It does have a fill from empty spring that adds a little but is negligible compared to stem force.
I've got most of the frame, breech block, valve and plenum whittled out. The grip frame will house most of the electronics (hopefully). I want to run a single 18650 lithium (3.7v) inside the front of frame under barrel. The grip will attach via a pic rail on bottom of frame.
The butt will handle the gauge, fill port and bottle mounting.
Dave
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I forgot to mention the reg will be at back of plenum and mount to butt.
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Looking good-watching... 8)
Jesse
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Got the reg body and reg/bottle connections on the butt. Lot of cutting left to do on it. Starting to take a little shape. The cutout grip pattern is to see how much room I’ll have for the electronics.
Dave
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Still have the shoulder cut to make. Got to think on that a bit. Got the main lightening cuts and the gauge and fill port done.
Dave
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8)
Jesse
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very cool./. i guess that pilot idea proved reliable on the last build..
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Most excellent!!
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Thank you gents.
Rob,
It proved perfect for the solenoid idea. The valve acts a lot like an on/off. I can set the height it opens. Dwell how long I want and let it close. It closes pretty quick partly due to the ‘hammer’ of the smaller solenoid is super light. It took quite a bit of testing and head scratching, but I think it’s worthy of a nice, classy build.
Dave
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I was able to get all the controls tucked into the grip. This grip is hickory because I had some in the rafters. I want to make a grip from micarta.
Dave
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.
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This is really cool!
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Most impressive build.
Will be great to see the final project
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big capacitor in there, wheres the battery go?? i likely missed it
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David, you have some MAD SKILLS! That is an incredible electronic PCP build! Kudos to you and I hope it goes smoother than expected! Looking forward to you finishing the build.
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Thanks again fellas,
It will use an 18650 rechargeable lithium. It will hide inside the front of the receiver. I still have quite a bit of fabbing to do. I need an on/off switch, battery connection cap and plug, barrel/shroud, trigger, etc. The list keeps going, lol.
Dave
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very cool.
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I love how sleek you're being able to get it-just awesome work!
Jesse
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I got my lw barrel, 23”. It is the .630” diameter one so I only had to turn about .005” off.
Made a trigger and guard.
Lots left to do but was tired of working on it and decided to shoot a bit. Nothing exciting, pebbles and golf balls at 50.
Fun shooter.
Dave
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it looks INSANELY awesome ! hows the sealing on the swing breech holding up?
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8)
Jesse
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Very impressive! I will be reading up on your "pilot type valve".
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Someone making their own equipment is always impressive. I look forward to reading more.
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Thank you gentlemen.
As I said, I’ve still got quite a bit left to do on this one. I need to make a shroud, finish out the trigger guard and butt. Then I think I will powder coat everything flat black. Maybe leave a few shiny bits here and there.
Then I’ll be going back to my test setup and testing different variations to the pilot valve. I want to gain a little more control than what it currently has. I’m sure playing with different sizes of the valve, vent, etc. will give different results. I need to figure out what does what.
Dave
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I haven’t had a chance to work on this much. Mainly just shooting it some. My kids got me a Hawke 3-12 and I bought a knockoff brand bi-pod. First Hawke I’ve owned and am impressed.
Dave
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I have a hawk endurance. I gotta say…I like the clarity. But mine doesnt tract at different ranges even without touching the zoom function, i have it fix at 14 power. I have it on my Crown, replaced that with Bug Buster…good til 150 yards with nsa 17grns.
cool project! whats your max fpe now? I would love to be able to build something like that electronic hammer like yours!!!!
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I haven’t stretched this one out to see what kind of power it’ll make. In developing the valve, tuning down was the hardest to get. Full power was relatively easy. Right now I’m shooting 18 grain pills at around 900ish.
I like the reticle on this scope, it can be illuminated but I doubt I ever use that feature.
Dave
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Dave,
I must have missed out on your electronic builds. Can you point me to a diagram or elaborate how it works? I would like to tinker on the arduino hammer stuff. Its very interesting!
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I’ll try to sketch everything up and post it in the next couple of days.
Dave
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it will be very interesting to learn! thank you
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I am interested in to see as well how the electronic trigger works.
I would like to make one remote to trigger my Impact trigger for BR.
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I am interested in to see as well how the electronic trigger works.
I would like to make one remote to trigger my Impact trigger for BR.
Triggering a trigger remotely can be quite simple. A solenoid of sufficient size with corresponding power supply and momentary switch are all that’s really needed.
A more complicated but more efficient means, I have drawn below. Not complicated or expensive really but more intricate than the first option. You can simply increase the size (capacitance) of the capacitor until it reliably fires. If you put a small boost converter in there, you can adjust voltage up to the same effect (just don’t go over capacitor rated voltage.
If you wanted to guarantee as little disturbance as possible, a gearmoter/stepper actuator would possibly be better. Not sure.
Dave
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Here is a basic flow/component diagram of my control system. All these components are really cheap and all but the battery and solenoid fit in my grip.
I am not claiming everything here works perfect/as planned but it keeps getting closer and my results to date are still encouraging.
I will post my arduino sketch (program) later today, hopefully.
Dave
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and my sketch (code, program)
its really pretty simple, is kind of cluttered with leftover lines but is working
I have a new code but haven't got all the kinks worked out, it has some safety considerations in it
If you are an arduino guy, please don't beat me up too bad, I'm just a novice when it comes to the computer stuff
Dave
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Eventually I would like to input tank pressure as a variable and compensate the drop via dwell time, this would eliminate the need for a reg. Just kinda dreaming on that one.
Dave
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your potentiometer reads 0-5volts.. Which is odd, is it hall effect ?? or did you mean 0-5k ohms ? anyway , awesome gun and thanks for making it open source to the forum.EDIT , i see now in the diagram it says ohms, and volts was a typo in the code
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your potentiometer reads 0-5volts.. Which is odd, is it hall effect ?? or did you mean 0-5k ohms ? anyway , awesome gun and thanks for making it open source to the forum.EDIT , i see now in the diagram it says ohms, and volts was a typo in the code
It is a 10k ohm pot, it is tied to the 5 volt reference voltage of the arduino and the ground of the arduino. The wiper of the pot sends 0-5volts (depending where it is set) back to the arduino on an analog in pin. The arduino analog to digital converter converts that voltage to an integer between 0-1023.
Hope that clears it up.
Dave
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ok .,,, that makes more sense..hows the gun reliability wise soo far ?
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Reliability has been surprisingly good. I’m running a glass filled pei poppet so it seeps from time to time. I want to switch to peek but just haven’t done it. Got a stick of it beside my lathe just waiting.
I’m just messing with fiddly stuff right now, like getting the wires on the battery the correct length, etc.
I’m still working on my 54 Chevy ls conversion as well and my main focus has been on it. I’m about to run out of pretty weather for it though.
On the build though, my next major project is going to be setting up some sensors and seeing if I can catch dwell time actual vs pellet exit from barrel. I think I can catch that with an oscilloscope. There is a portion of my dwell time (programmed) that is just to accelerate the ‘hammer’ of the solenoid and open the valve. You can see in my mapping strategy I started the dwell time at 3500 uSec (3.5 milliseconds). That is what testing showed to be lowest I could go and still open valve.
You don’t happen to know what a reasonable time open for a valve is? Or anyone else reading. That may be a Bob question.
Dave
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i dont know honestly thats a Bob question .., but already finding the lowest possible setting to crack the valves seems like a really good starting point .
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Not really any update but I’m playing with data gathering. Not sure how to go about it really.
I put a piece of thin wire across the muzzle that breaks when a pellet hits it. That is the yellow channel on my oscope.
I have a hole in my receiver that I put a piece of wire in between the hammer/solenoid that gets smashed when I pull the trigger.
I need to come up with better triggers for my oscope, so if this has been done before, I’m open to suggestions.
Dave
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This is off topic. But seeing all electrical toys you have….is there a way to measure the pressure of a shot cycle between the exhaust and the back of pellet? or can we just convert a sound signal to graphs and approximate the pressure?
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I’ve thought about how one might go about that but that’s about as far as I got. Pressure sensing gets a bit tricky due to the response/polling intervals of most gauges.
I haven’t dismissed it, just haven’t come up with a clever (cheap) way to do it.
Dave
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Ok, I made a pretty big step towards getting an adjustment window I like. My passage for air to the throat was limited to 3 flats I filed on the 1/8” pilot poppet rod. I open those up some more with the dremel and turned the rod itself down some more. This quicker dumping let me open my vent up a little more as well.
Now, what I thought before was hammer travel time (when I mentioned minimum dwell setting) was also part dump/opening time. I can now open the valve with a ~2 millisecond pulse. According to my last shot string, I achieved 774fps@2071uS and 1037fps@3518 uS.
Anything past that 3.5millisecond setting, I didn’t achieve any significant gains. This is a 23.75” barrel and pressure was ~2180psi.
Pellet was JSB 18.13.
Anyway, long way to go but a significant step.
Dave
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Ok, I made a pretty big step towards getting an adjustment window I like. My passage for air to the throat was limited to 3 flats I filed on the 1/8” pilot poppet rod. I open those up some more with the dremel and turned the rod itself down some more. This quicker dumping let me open my vent up a little more as well.
Now, what I thought before was hammer travel time (when I mentioned minimum dwell setting) was also part dump/opening time. I can now open the valve with a ~2 millisecond pulse. According to my last shot string, I achieved 774fps@2071uS and 1037fps@3518 uS.
Anything past that 3.5millisecond setting, I didn’t achieve any significant gains. This is a 23.75” barrel and pressure was ~2180psi.
Pellet was JSB 18.13.
Anyway, long way to go but a significant step.
Dave
Are you saying that you can effectively control dwell with the solenoid? That's pretty incredible and it should allow you to swap barrels and compensate dwell accordingly, or adapt the valve setup to different calibers.
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Here is the shot string. This was done with main poppet travel @ 1/16”.
You can see, the higher the dwell setting, the less significant returns in velocity. Obviously this is something Bob has been teaching us as well, so it gives me confidence that my valve is responding more ‘as expected’.
Spacebus, I’m getting closer (pretty close now) to effectively controlling dwell with a small solenoid. So yes. I do hope it can be scaled over different calibers and such. In my last post, the very small poppet is the only part I control, the larger poppet is controlled by the pilot poppets control of air flow.
Dave
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I'm sure you know this, but the "returns in velocity" as the dwell goes up are very dependent on the mass of the projectile as a key variable in the equation. If you ran the same test with 34 grain JSB Beasts you would likely see the returns continue . . .
Your work on this is simply fantastic!
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I'm sure you know this, but the "returns in velocity" as the dwell goes up are very dependent on the mass of the projectile as a key variable in the equation. If you ran the same test with 34 grain JSB Beasts you would likely see the returns continue . . .
Your work on this is simply fantastic!
That’s a good point, I need to put that in my notes to run that test. Might be interesting to simply change my reg pressure to accommodate the larger weight projectile as well. Lots left to do but I enjoy the challenge of this.
Dave
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I'm sure you know this, but the "returns in velocity" as the dwell goes up are very dependent on the mass of the projectile as a key variable in the equation. If you ran the same test with 34 grain JSB Beasts you would likely see the returns continue . . .
Your work on this is simply fantastic!
I've noticed the same thing in my testing with different weight slugs in my .45 Challenger. "Theoretically" I should be able to hit 500 FPE with a 244 grain slug and a 305 grain slug, but so far I am not able to match the FPE with the 244. I'm going to try sizing the lighter slugs to see if that helps, but the 305's are also twice the length of the 244's, which might be part of why I'm getting better ME with the larger/longer slugs.
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Holidays are eating up my shop time. I did get some powder coat on the receiver and made a free float mount.
Just a tiny update.
Dave
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Looking very, very cool... Performing fantastically as well :D
Jesse
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awesome , looks as good as ano