Leshiy2 inspired build

[sb327]

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

[darkcharisma]

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?

[sb327]

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

[sb327]

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

[Spacebus]

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.

[sb327]

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

[AlanMcD]

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!

[sb327]

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

[Spacebus]

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.

[sb327]

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

[JuryRigger]

Looking very, very cool... Performing fantastically as well 
Jesse

[Rob M]

awesome , looks as good as ano