Custom

[Legion]

I cad'ed up the bolt. Its pretty easy to build. Anyone with a lathe and a mill should be able to build it.

[Z50]

Is there a reason you cannot drill your forward ports in a venturi as opposed to forcing the gases to make two 90 degree turns into a more restricted channel than they are in?

My other suggestion would be to add an O-ring grove on the spring shelf since you are allowing your expanding gas to ride behind it in an open manner.

[Legion]

Is there a reason you cannot drill your forward ports in a venturi as opposed to forcing the gases to make two 90 degree turns into a more restricted channel than they are in?

Actually no there isn't, and that may be a better route to go. it would add an extra step in the machining process but wouldn't be terribly difficult and would certainly add better flow charateritics. Here is the revised bolt

My other suggestion would be to add an O-ring grove on the spring shelf since you are allowing your expanding gas to ride behind it in an open manner.

Also a good idea and while adding friction would improve efficency i would imagine.

[duckman]

looks like what I was trying to describe. By chance would anyone know where to get ahold of a set of flow charts that give Pressure/volume ratios as they pertain to paintball?

[y0da900]

There isn't any all inclusive chart, as every system will have different flow dynamics making things more or less efficient. The average system runs on roughly 200 inch pounds of pneumatic energy*.

Take volume (cubic inches) times pressure (psi) and it will normally come out to approximately 200, more for less efficient systems, less for more efficient.


* I remember Have Blue having a page about this somewhere, but I can't seem to find it anymore, but that is what I remember being the average number.



Legion, have you had a chance to look at that file yet, I'm not sure how helpful it will be as nothing is drawn to manufactureable dimensions, it is all conceptual.

[dukie]

Are you going with a sear asembly? Or with 2 on/offs?

With a sear assembly, the bolt acts as both a piston and an on / off, and that pin out the back of your bolt acts the same as the core in the automag bolt ( both piston and on/off to retain the pressure in the dump chamber until the sear is released, then to move the bolt forward ). Although with a sear your bolt would be much easier to manufacture, with only the cost of adding length to the valve train.

With 2 on/offs the bolt no longer needs the on/off function, it simply needs to act as a piston the move the ball and close the breach. It does not retain pressure, and only needs to seal well enough to move forward when the dump chamber is opened. I can't see what the pin is doing for you if you are going this route.

BTW I have decided to slap one of these together myself out of delrin or similar to test my alternate design ( running on very low pressure obviously). Since small cheap pneumatic valves and actuators are so popular these days, both designs could really be revolutionary.

[Legion]

Legion, have you had a chance to look at that file yet, I'm not sure how helpful it will be as nothing is drawn to manufactureable dimensions, it is all conceptual.

I was able to look at it, though i haven't had enough time to real go through it yet. it was very very detailed and obviously you put a lot of thought into it.

Take volume (cubic inches) times pressure (psi) and it will normally come out to approximately 200, more for less efficient systems, less for more efficient.

Based on my calculations of a maximum of 400 psi we get 785 (1.25 x .5 x 3.14 = 785) More than three times the energy nessisary with that system.And this isn't figuring in the chamber around the power tube. That may seem like a waste but realisticly we could run a much lower pressure where the extra volume will come in handy. Most likely we will operate at closer to 200 psi.

With 2 on/offs the bolt no longer needs the on/off function, it simply needs to act as a piston the move the ball and close the breach. It does not retain pressure, and only needs to seal well enough to move forward when the dump chamber is opened. I can't see what the pin is doing for you if you are going this route.

A searless model is very attractive.
My biggest concern is that without a sear all off the tolerances would have to be much much tighter. Im not sure a average garage shop can hold those tolerances. A sear allows for a cetain amount of slop. I guess all we can do is start test and see what we come up with. I am cading up and cam level sear version and a dual on/off no sear version.

BTW I have decided to slap one of these together myself out of delrin or similar to test my alternate design ( running on very low pressure obviously). Since small cheap pneumatic valves and actuators are so popular these days, both designs could really be revolutionary.

I really think thats great im swamped with customer work and mamba stuff but when i get some free time i'll follow suit. Please post your work im very interested to see it.

[dukie]

Originally Posted by Legion

A searless model is very attractive. My biggest concern is that without a sear all off the tolerances would have to be much much tighter. Im not sure a average garage shop can hold those tolerances. A sear allows for a cetain amount of slop. I guess all we can do is start test and see what we come up with. I am cading up and cam level sear version and a dual on/off no sear version.

I agree to disagree ! lol

Damn I seem to be talking an awful lot for a new guy here. I'm really not trying to usurp your thread here.

What say we build them up and swap prototypes so that we can both make improvements? Personally I would like to have another engineer / machinist / player go over my design hands on.

Interested?

[Legion]

I'm really not trying to usurp your thread here.

Certainly not, you are adding valued input. Which is exactly what i wanted.

[y0da900]

I can hold the tolerances just fine for a searless system, and my lathe isn't set up the best, I don't even have the tailstock offset fixed yet because I don't own a dial indicator.

Searless also makes it a much easier design for people to make that have a lathe, but no mill. If someone only has one of the two machines, my guess is that they would have a lathe first, but that is only a guess.

I think that allowing adequate clearances and relying on o-rings will be a lot easier than a home shop being able to make and properly harden a sear. I don't think that a sear made of a metal that can be comfortably cut with a (home shop sized) mill would hold up real well without being hardened, which doing consistently may be difficult. There is always the heat cherry red and drop in oil/water method, but I doubt that is overly repeatable.