Using a pneumatic cylinder to reset bolt, i.e. no bolt spring idea

[Aliens-8-MyDad]

mspaint of course.

[the electrician]

well I did some measuring and some preliminary tests.

the standard operating psi is in fact 400 psi, and the lvl 10 operating psi is about 470 psi

I did some tests removing the bolt spring and replacing it with a bumper that would stop the bolt from going too far forward. I calculated the bolt movement to be about .943"

this means the power piston in the middle of the bolt was not really coming out of the power tube tip. it is about .033" away from coming out. so I increased the bolt movement a bit to make the bolt piston come right out to the edge of the power tube tip, for this test.

so with a standard bolt, no spacer, no spring, and the operating psi at 400, my velocity increased from an average of 280, to and average of 310 fps. not near what I hoped.
I imagine that would only yield a decrease in operating pressure of about 20-25 psi. I don't know for sure yet, but it won't be much.

well atleast it's something.

the next test will be to increase how far the bolt piston comes out of the power tube, and do some more tests.

after doing some calculations, the operating psi would have to be reduced to about 275 to actually gain efficiency due to the amount of air that would be used to hold the bolt back when deleing the sear altogether.

the new ICD freestyle gun I believe holds some of the answers we are looking for. I'm looking to get my hands on one and take some measurements, or find someone that can do it.

[GordDesigns]

All this sounds very interesting, but can I add my 2 cents in?

Question 1; With the actuation of the bolt as you describe, how do you field strip the marker now?

Question 2; How do you stop it chopping balls up?

I just thought of a way to do the ball chopping solution. Use dual LPR's set to different pressures, one to open the breech and the other to load the ball.

Inventing is fun, yes.

[the electrician]

my design idea will not change the "field strip ability" of the marker at all. it would be a single acting type cylinder design. it would only have one sealed side. the dump chamber air would still push the bolt forward, the cylinder air just returns the bolt. you could still just pull the valve and bolt assembly out like normal,and the one sided cylinder can stay in the gun body. not that I ever pull the valve out in the middle of a game anyway. I usually squeegie out the barrel if there is a break.


as far as chopping goes, the use of a single-acting cylinder instead of a spring would create different force characteristics on the ball. the spring starts out with very little opposing force, and has more and more when it is being compressed while the bolt is moving forward.

with the cylinder, it starts with the most force it's going to have, and then as the air is exhusted, it rapidly looses all it's force that is opposing the forward movement of the ball.

so it's opposite in it's force characteristics. it just might naturally stop on a ball. and if the time is taken to refine the design, it could be engineered to be approximately the same force as the lvl 10 applies to a ball. being that this design is electronic, and has a specific cycle time, the ball would be pinched for the time of one set cycle, and then the bolt would reset.


so dual LPRs are not necesarry, and I prefer the use of flow controls, if it ever comes down to it in the design of anything else. alot less complicated, and a smaller set-up.

[the electrician]

alright, for those following or interested.

I did some more tests on the gun with a bumper instead of the spring. as before, the bumper keeps the bolt from moving too far. I shortened the bumper, almost a 1/16". this should let the bolt move a bit farther forward, hopefully letting the dumpchamber air out abit better, and showing an increase in velocity.

now I did notice that I don't want the bolt to go too far, it will go past the front end of the sear, and when the sear comes back, it will be able to come up behind the bolt jamming the bolt forward and letting the sear come all the way up. this will cause the on/off pin to let air into the dump chamber and out the bolt with no stopping it. I've heard the sound before and it is painful. the only real point to letting the bolt move farther forward is to let the bolt piston come out and a bit away from the power tube tip. later on, when I've found the proper opeing amount, I can hash out how far the bolt should move for the new design, and I will probably be shortening the power tube tip when it is re-designed, along with the shorter blt stroke.

so the rest stayed the same, just a shorter bolt bumper.
the results were an average fps of 320fps. so only a gain of another 10 fps from the previous tests. but now that total has gone up to a difference of 40 fps average between the original 280 and the now 320fps.

so next I lowered the pressure from the original 400 psi, until the velocity came back down to an average of 280 fps.

I then put the operating psi rig on the end of the valve and gassed it back up. it went down to 355 psi. better than I expected for sure.

It's funny too, when you test fire the gun to get a velocity reading, the bolt actually bounces back almost all the way. hell, sometimes it reset itself! it resets itself almost everytime when you shoot it up in the air. I think if I time the solenoid energize time right. I can catch it almost everytime while testing. not very useful for actaul useage, but nice when testing to not have to stop and reset the bolt :)

as I mentioned before, I removed the power tube spacer, so that the bolt has to move farther forward before it starts to vent, and waste air. I believe this helps a little bit. I haven't tested how much, but I think when I redesign the power tube tip, I will try and incoporate a sealing o-ring into the end of the power tube tip. this way the gas is not released until right after the breech closes, making for less blowback, and a bit less waste.

perhaps an o-ring on the out side of the power tube tip, a bit further back, could help seal the interior of the bolt, to keep air from leaking out the back. this may not be necessary, that would have to be a separate study. it could posibbly help efficiency, or hurt it due to the added friction slowing the bolt down, and making the bolt reset cylinder use more air.

there are advantages, and disadvantages I see to using and intergrated bolt/bolt reset cylinder.
the advantages are that it takes up the space that the spring was occupying anyway, and it doesn't need that much more space. it makes it possible to machine a new bolt out of aluminum, making it much lighter and faster responding. it would not have any binding affects on the bolt. with the removal of the sear, there is more room to incorporate a 4-way solenoid valve with manifold, keeping the design very tight.


the disadvantages are that it is going to need alot of force to hold the bolt back, if there is no sear. this means consuming more air. so the lower the operating pressure a can be taken, without increasing the bolt piston dia., the better.

when the marker is first gassed up air has to travel through the lpr, through the solenoid valve, and into thebolt reset cylinder, to hole the bolt back BEFORE the air flows through the main valve reg, into the on/off, push the on/off down and fill the dump chamber.
if not preoperly setup, the gun could potential fire, everytme it if first gassed up.

granted the dump chamber air has to fill a much larger space before the pressure can create force on the bolt piston, but the air is moving faster into the dump chamber due to its higher pressure. proper design should be able to avoid this potential problem.

[SlartyBartFast]

when a mag fires a ball, the chamber does not go all the way down to atmosheric pressure. it goes down to about 50 or 60 psi. if it went all the way down, it would take up more air and time just to get it back up to usable pressure.

That's a key point that really has been missed. Using the current bolt and chamber design with a ram retun would create a Mag that had the same horrid efficiency firing paint as it does when dry firing.

The bolt piston/level 10 and dump chamber would need to be redesigned and sized to operate at a pressure that would allow for good eficiency when the chamber is dumped to atmospheric pressure.



-- I'm trying to catch up after three weeks of vacation.

[the electrician]

you control the time the bolt stays forward through the energize time of the solenoid valve. so you control when it comes back. it doesn't just stay forward for some unknown time.

anything dumped out of the chamber, after the air has been discharging for approx. 3 msec, is wasted air, and does not affect or increase velocity.

so you should be able to keep the residual pressure close to the same by reducing the energize time (people like to call it "dwell") of the solenoid right before the point of where there is a velocity drop. this should leave you with about the same residual pressure.

the same technique I've used in setting the times on my electro-cocker.

you bring up a good point. I've not mentioned it, but I have been thinkin' about it.

I'm dying to get some bolt info off of a freestyle to apply to my flow calculations. it would really help with the "feasibility study" that needs to be done before anything is fabricated.
nobody seems to be intersted in helping so far.

[SlartyBartFast]

so you should be able to keep the residual pressure close to the same by reducing the energize time (people like to call it "dwell") of the solenoid right before the point of where there is a velocity drop. this should leave you with about the same residual pressure.

Then you are really just changing the way the Mag functions for no reason other than to make a change.

The ram would also have to provide more force than previously considered in this thread.

The end result would be a Mag that functions exactly the same, but in a more complex fashion with more moving parts. Additionally, it'll be somewhat less efficient since the ram is using air.

[the electrician]

no.

you didn't read my posts.

run the numbers on consumption. the lower you can get the operating psi, and keep the same size dump chamber, the more efficient it will be, and the deeper you can shoot into the tank(the more air you can use in the tank) and, the lower the operating pressure, the less air consumed by the bolt reset cylinder.
I know exactly how much force the bolt reset ram would have to produce.
read my posts, I'm not pulling numbers out of the air, and I wouldn't bother if it made the mag less efficient.


run the numbers yourself, and you can see what I mean.

[the electrician]

alright, again, for those who are interested...


I did some more tests and finally got my flow rate calculation spread sheet done.

this time the tests were about sealing up two of the three "leak points" of the mag bolt design. the three points are:

1) the leaking of air around the bolt piston after it moves away from the power tube piston o-ring, and moves forward up the power tube. (I believe this to be the smallest leak due to the movement of the bolt causing the air to expand anyway, and the close tolerances at this point.)

2)the leaking that occurs out of the back of the bolt, around the outside of the power tube when the bolt has moved far enough forward to release the air from the dump chamber. fairly significant due to the .015" difference between the power tube OD and the inside of the bolt. (atleast on my gun)

3) the leaking that occurs in the breech due to the lack of a bolt tip o-ring, and the loose tolerances between breech size and bolt size.In my ULE body, there is a .014" difference here too.

I tried sealing, or improving the seal, in the two main areas. the breech leak, and the back of the bolt leak.

I did this by simply cleaning the surfaces I wanted to seal with acetone, then I applied electrical tape to the power tube tip, and the bolt tip. the electrical tape is super33, and is a consistent .007" thickness. I carefully applied it and cut it to seam together without overlapping. on the bolt tip I did the same, and cut it down to be about an 1/8" ring around the bolt, like an o-ring would be. I know this is crude, but it happened to be the perfect thickness, and worked quite well for the testing purposes.

I had left the gun at 355 psi from the previous tests, along with the other test components that yeilded the other gains.(see first test) I put the gun together and used the same procedures as before.

it showed a consistent 320 fps again. I fired about 20 shots over the chrono, all ranging between 316 and 324. it was shooting a steady 280, at the same psi, same barrel, same paint, right before I did these tests.

after reducing the psi to get it down to an average of 280fps, I degassed it and put on the test gauge rig to get a reading. 310 psi !

as you can guess, I'm prettyy happy about that. I've been able to reduce the mag operating pressure by almost 100 psi, and I haven't had to change the bolt piston dia. to do it.

I've sealed the leaks, let the bolt move a bit farther forward(open up the restriction between power tube tip and bolt piston) and let the bolt move forward faster, to reduce the bolt piston leakage, increasing the pressure upon the main release.

I don't know if will get much better , without increassing the bolt piston. I don't want to increase the bolt piston size. even though it would obviously increase flow capabilities, it would also increase the force needed to hold the bolt back. this would increase air consumption, and possibly the flow capabilities of the solenoid valve needed to control the bolt reset cylinder design I want to use.

the reason I say I don't know how much lower it can go is because of the info obtained by the freestyle design, and the expansion of the air inside the mag power tube and bolt.

the freestyle, does not control the supply air. it is stated that it runs on about 260 psi, Hellbore said that he has been able to modify his to run on 220 psi. but because it does not shut off the supply air while firing a ball, the air does not lose pressure as the bolt moves forward and realeases air to the ball. the air does not really have to expand.

in a mag, the on/off cuts of the supply air. so when the bolt moves forward, the air in the dunp chamber expands into the power tube, then into the bolt, before it can act upon the ball. it only has so much to work with, so the air expands, and the pressure drops. if you calculate the expansion area, then the pressure drop, it is fairly significant. the air is down to about 200 psi by the time it acts on the ball. so I'm not sure how much lower it could go with this particular bolt design. something might have to be done with the flow capabilities of the bolt design....hmm

...ideas anyone?

[SlartyBartFast]

...ideas anyone?

We're FULL of ideas.

I've sketched a blow-forward design that would use a piston, chamber, bolt, and a custom multiport valve.

The valve could be actuated manually, or driven by air pressure from a solenoid valve.

No spring or sear required, zero resistance to bolt forward travel, chamber pressure holds the bolt back before firing.

Now, if only I had the time and access to a machine shop....

[the electrician]

I was actually looking for ideas on how to get more air to the ball through the bolt in a mag.

but new gun design ideas are always interesting :)

[ScatterPlot]

You're doing these tests without a bolt spring, right? I cant remember if you said these latest ones were or not.

[the electrician]

that's right, no bolt spring. there is a bumper, made out of rubber, around the bolt. it is cut to a specific length to let the bolt travel a bit farther forward than what I think it is able to travel under normal conditions. if you tried it without the bumper, the bolt would go too far forward and sear would be able to come up all the way, behind the bolt.

the bolt almost resets itself. I have to make sure it all the way back before loading another ball to test fire over the chrono.

funny, the gun is operating at about 310 psi. it sounds like it's shooting weak, like it's turned down way too far, you know the sound(quieter). but yet it shoots 280,282,284,281,284 over the chrono. kinda strange.

I want to see if I can go lower ewith the pressure.

[undescriptive]

so basically if we could get a VERY accurately matched bolt stem and power tube tip (thousandths of an inch) so you could dispence with the o-rings (and use heavy grease instead) wouldn't that increase the efficiency any?

as has been said, make the bolt out of ALuminium (making the efficiency better due to less mass?)but rather than making the bolt move all the way out, couldn't the bolt stem be machined with holes in, thus making the dump vent at a precise time?

in theory, doesn't the bolt on have to move 0.7 inches? less movement = less total force. s wouldn't that be an advantage? - or am I just talking out of my backside as usual??

enough of my mad raving... I'll leave this to the Pros "go Electrician!"