Possible Homemade revamp of the Classic Trigger

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Croc
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Possible Homemade revamp of the Classic Trigger

Post by Croc » Thu Jun 14, 2012 10:37 pm

Hey guys, I was just thinking, what if it were possible to remake the trigger system from say... a CPS xxxx series blaster out of PVC? For example, using a 2.5 or 3 inch endcap, and drilling holes and using springs as needed? I just got thinking of it as I was looking at my CPS 2000 in a state of disrepair... the LRT I put in tends to like shooting the rear plug off if it's overpressurized.

Also, its been a long time. :goofy:

Andrew
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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Fri Jun 15, 2012 5:01 am

Firstly, welcome back (I know I wasn't around then but still).

As for the valve it's definitely possible, but I don't know how small we could make it.

Something along these lines would work, and might be an option either for trigger actuated homemades, or power mods for stock soakers where stock valves would break:
Image

The o-rings which seal the firing pin could be replaced with some sort of flexible but inextensible (EPDM?) diaphragm for less friction. The larger the diameter of the firing pull 'pin' is, in relation to the plunger, the less the effect of pressure making the valve harder to open, but the larger the valve will be.

Drenchenator's linear valve (you'll probably remember this) is also an option.
Last edited by Andrew on Fri Jun 15, 2012 8:49 am, edited 1 time in total.

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atvan
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Re: Possible Homemade revamp of the Classic Trigger

Post by atvan » Fri Jun 15, 2012 8:49 am

Andrew wrote:Firstly, welcome back (I know I wasn't around then but still).
haha^^^this :goofy:

The problem would be getting is small enough, as Andrew stated, and getting all the seals to work well. The problem with his design is there is no way to get back in there and replace any bad seals.

Did the linear valve ever work totally? I thought he was having problems with flow and leaks. It is a good concept though.
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Fri Jun 15, 2012 8:54 am

atvan wrote:The problem with his design is there is no way to get back in there and replace any bad seals.
You could use threaded adaptors to connect the two halves together, but then that will make the valve even larger. It depends on how much space is available really (whether it's used to replace a broken stock valve, or as a new valve for a homemade).
atvan wrote:Did the linear valve ever work totally? I thought he was having problems with flow and leaks.
Honestly, I've no idea. I don't think it was ever completely finished. Flow shouldn't be too hard to fix (the design optimises this anyway), it's the leaks that are the problem.

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atvan
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Re: Possible Homemade revamp of the Classic Trigger

Post by atvan » Fri Jun 15, 2012 9:11 am

His fist design had a tiny hole- very limiting. He was never able to get the full bore version to work at all IIRC.
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
Beware the Purple

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Re: Possible Homemade revamp of the Classic Trigger

Post by Croc » Sat Jun 16, 2012 2:34 pm

Yes, I do recall the linear valve, I was there while the prototype threads were everywhere :goofy: . It was an interesting design, but to get a decent flow the T would have to be massive. The hole had to not reduce the integrity of the pipe (5/8 could only really safely go to 7/16" on 1/2" PVC (OD 5/8" = 10/16"). In addition, it requires the purchase of parts from McMaster-Carr, which proves difficult as I am from Canada and they don't like shipping there to new customers. :goofy:

In addition, Schedule 40 PVC does not exist in sizes larger than 1/4" at local home improvement stores (Rona and the Canadian branch of Home depot), but is expensive in specialized plumbing stores.

My mechanical engineering course matter got me thinking about this again for some reason, and made me want to resume an old project. This is for a homemade, but I'm sure it could be adapted to be a replacement.

Now, on to the issue at hand... I'll make a drawing of what I was considering and upload it when I can. I'd make it with rubber washers instead of O-rings, as I don't really like the seal conditions for O-rings.

Threads would be pointless, unless you make it a longer valve, in which case it'd be a bit more difficult to build, and you'd want to leak proof it, using Teflon tape or something of the sorts, making it difficult to open. Unless it's screwed together, it needs to have a really solid construction, strong springs and a good seal on the first build. Rubber washers would work in place of an O-ring there, so long as there is a washer and nuts holding it in place. It would also not require much in terms of strength dealing with pressure either, as it is only water going through it, it does not need to withstand pressure in excess of the pressure of water, if I'm not mistaken. The Super Soaker ones are over-engineered to prevent any possible failure, and have tons of screws or are just epoxied together. (Correct me if I'm wrong in assuming the CPS 2000 was the first with that trigger system) The only issue with screws is you need to make it watertight, and thus need some form of O-ring or something somewhere wrapped around the entire circumference being held between the halves, creating a watertight seal.

A possible material for the actuator is a bolt, either threaded all the way or just part of the way(Threaded partway would seem ideal as rubber washers could then be used to create the seal). There would be one internal spring to maintain the seal and close the valve after trigger release, and there would also already be something to pull on, being the head of the bolt. I'm not sure if including a trigger torque arm as they do in their design is necessary, but if so that would be figured out while prototyping.

The output would likely need creation of linear flow, so straws and maybe screens to hold them in place would help. Somewhere on SSC(dating myself there) there's an article about a stream laminator, of which the design would be similar for the nozzle.

For a prototype, I was considering 3" PVC for space to work with things, with two NPTs on one side, and a 3/4" CPVC threaded adaptor, as that is what I have laying around. I was designing this for a homemade CP system (Which once again is lost somewhere in SSC, something about a sideways CPH) as they did in the old days, as I have some LRT left over from when I repaired my CPS 2000's bladder. Although now that I think about it, the size of washer would be ridiculous for a 3/4" hole, thus requiring me to think smaller (3/8"-1/2") pipe would be ideal, or simply installing a NPT right in the valve itself. I'm not sure, but it'd require lots of production cares such as making sure that the PVC for the output is flush with the inside of the endcap such as to improve the flow. That and smoothing the output intake, such as to once again increase the flow rate. (Curse you fluid mechanics... making me think of this scientifically)

For future creations though, I have seen some waterproof water conduits, which would work wonderfully with vinyl tubes (Not that there's anything wrong with NPT connections, these just look cool and adapt to different sizes, clamping around them). I was also considering figuring out the pressure that makes the SS PRVs work, as it would help to prevent bladder bursting issues, and could be tuned to different situations.

The only real downside to the design really is the dead space and not exactly linear flow of the water, but it could work very well if executed properly.

A friend of mine is printing parts of a RepRap (3D printer) for me when he gets his working, so I could possibly be drawing something up in CAD and fabricating a prototype of sorts at a later date.

[EDIT 6/18/2012] Attached the file with an explanation to the end of this post. Black large parts are rubber washers. Same style of seal is created both ways, this is just an alternative. Sorry about the small size, it's legitimately drawn on a 2x2" sheet of paper.
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Drawing-1.jpg
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Last edited by Croc on Mon Jun 18, 2012 9:18 pm, edited 1 time in total.

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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Sat Jun 16, 2012 4:06 pm

I believe your referring to JLspacemarine's laminator.
Croc wrote:Now, on to the issue at hand... I'll make a drawing of what I was considering and upload it when I can. I'd make it with rubber washers instead of O-rings, as I don't really like the seal conditions for O-rings.
I think I get what you mean. To use a washer clamped between nuts on the bolt. Would that be acting like an o-ring (probably not, I don't see how that could be any better), would it be clamped at the edges (like a diaphragm) or would it be resting against part of the valve and sealing under the pressure of the water? I should be able to see what you mean with a pic of your idea in front of me.
Croc wrote:Threads would be pointless, unless you make it a longer valve, in which case it'd be a bit more difficult to build, and you'd want to leak proof it, using Teflon tape or something of the sorts, making it difficult to open.
They would give the valve a huge amount of dead space but would allow the valve to be taken apart. If you have access to a 3D printer, or moulding facilities, designs can get a whole lot more compact and be easier to maintain. I wasn't aware 3D printers could make strong pressure rated components yet (although I could still do with one ready for uni next year :goofy: ). They'd be fine for a prototype but plastic moulding would be the way to go for the finished product. Unfortunately such equipment is costly.
Croc wrote:I was also considering figuring out the pressure that makes the SS PRVs work, as it would help to prevent bladder bursting issues, and could be tuned to different situations.
I was under the impression that their release pressures differed over a variety of blaster models and marks. You can buy adjustable PRV's and set them to whichever pressure you need (although the point of constant pressure is of course to keep the pressure almost constant, so it'll take careful adjustment to release exactly when the PC is full.
Croc wrote:I'm not sure if including a trigger torque arm as they do in their design is necessary, but if so that would be figured out while prototyping.
That would depend entirely on what pressure you want to achieve, and how strong the trigger mech is, so you can find out either by physically testing (with a newton meter?) or using stress analysis (CAD would help here).

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Re: Possible Homemade revamp of the Classic Trigger

Post by atvan » Sat Jun 16, 2012 6:16 pm

The torque arm is likely very useful- remember that the pressure chamber helps hold the valve closed.

For inspiration, the Mad Ghost from nerfhaven includes a brilliantly done pull valve based on the concept that if you take a check valve and flip it around, half of the work is already done for you.
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
Beware the Purple

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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Sun Jun 17, 2012 5:12 am

That's not a bad idea actually. The leak would need fixing for water blaster purposes (especially with smaller nozzles), the flow would need improving (use 45° elbows instead of 90° elbows), and it would be better if the check valve was pulled open from the other side (again improving flow on the exit side of the valve) but otherwise an interesting concept with definite potential.

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Re: Possible Homemade revamp of the Classic Trigger

Post by Croc » Sun Jun 17, 2012 10:23 pm

Andrew wrote:
Croc wrote:I was also considering figuring out the pressure that makes the SS PRVs work, as it would help to prevent bladder bursting issues, and could be tuned to different situations.
I was under the impression that their release pressures differed over a variety of blaster models and marks. You can buy adjustable PRV's and set them to whichever pressure you need (although the point of constant pressure is of course to keep the pressure almost constant, so it'll take careful adjustment to release exactly when the PC is full.
That is correct, I was referring more to the systems containing rubber bladders, how much pressure they give at, which is generally the same for all of them as they are likely all just the same thickness of rubber for certain years. For example if the valve releases at 50 psi for a wall thickness of 1/8", and then for a 1/16" wall, 40 psi, then I would just have to figure the thickness of the LRT (I think it is 1/8"), and plug it into the calculation.
Andrew wrote:
Croc wrote:I'm not sure if including a trigger torque arm as they do in their design is necessary, but if so that would be figured out while prototyping.
That would depend entirely on what pressure you want to achieve, and how strong the trigger mech is, so you can find out either by physically testing (with a newton meter?) or using stress analysis (CAD would help here).
I was only considering not using one as the torque arms in the valves themselves are relatively small (and not to mention not attached to the valves all the time). Although I guess it is indeed such a manner that compared in size it is approximately half that of the valve height itself, and that is using the refined Super Soaker valve design. So it could be useful but testing is indeed important. Spring loading ball valves is just way too difficult for the time and effort, as 90 degrees is a long distance for a spring to be working. For a 2" model, a torque arm would be 1 inch approximately, probably mounted by some really dodgy means such as carefully cut PVC and all that jazz but it could well work. Just like how I fixed a penny modded Maverick's loading pin with a nail that just so happened to fit through the slot. That bad boy isn't going to break any time soon.
atvan wrote:The torque arm is likely very useful- remember that the pressure chamber helps hold the valve closed.

For inspiration, the Mad Ghost from nerfhaven includes a brilliantly done pull valve based on the concept that if you take a check valve and flip it around, half of the work is already done for you.
Andrew wrote: That's not a bad idea actually. The leak would need fixing for water blaster purposes (especially with smaller nozzles), the flow would need improving (use 45° elbows instead of 90° elbows), and it would be better if the check valve was pulled open from the other side (again improving flow on the exit side of the valve) but otherwise an interesting concept with definite potential.
My only issue with using NIC designs in water guns, is that their triggers are created for a compressible gas instead of an incompressible liquid. The amount of turbulence in that design in comparison to the old SS valves is very ridiculous. The pressure required for opening a valve like that with an air-air interface is minimal compared to air-water, and i'd be concerned about leaks for sure with that setup. The sheer hydrostatic pressure acting on the valve would make it nearly impossible to actuate without a rather massive mechanical advantage.

In addition, I'd be wary of putting the valve so far back (NIC homemade guns can have the trigger anywhere really as air flows nicely. Water guns behave much differently :goofy:)

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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Tue Jun 19, 2012 1:54 am

Croc wrote:For example if the valve releases at 50 psi for a wall thickness of 1/8", and then for a 1/16" wall, 40 psi, then I would just have to figure the thickness of the LRT (I think it is 1/8"), and plug it into the calculation.
Ah OK, I understand now. You want to find the approximate release pressure for a given thickness to calculate the release pressure for a homemade of a different thickness. Even so, there is some variance in PRV activation pressure within the same model of blaster, so it would be wise to test a few and take an average pressure for a given thickness.
Croc wrote:I was only considering not using one as the torque arms in the valves themselves are relatively small (and not to mention not attached to the valves all the time). Although I guess it is indeed such a manner that compared in size it is approximately half that of the valve height itself, and that is using the refined Super Soaker valve design. So it could be useful but testing is indeed important. Spring loading ball valves is just way too difficult for the time and effort, as 90 degrees is a long distance for a spring to be working. For a 2" model, a torque arm would be 1 inch approximately, probably mounted by some really dodgy means such as carefully cut PVC and all that jazz but it could well work. Just like how I fixed a penny modded Maverick's loading pin with a nail that just so happened to fit through the slot. That bad boy isn't going to break any time soon.
Sounds like the way to go. As for spring loading ball valves, rotary springs are the most effective, as the always apply all of the force in the same direction as the motion of the valve handle, no matter what angle the valve is opened by. Such springs are used in commercially available spring-return ball valves (which, in comparison with that handle mounted spring-pin system, is a much more realistic design to be used in homemade water blasters).
Croc wrote:
:goofy: I wrote:That's not a bad idea actually. The leak would need fixing for water blaster purposes (especially with smaller nozzles), the flow would need improving (use 45° elbows instead of 90° elbows), and it would be better if the check valve was pulled open from the other side (again improving flow on the exit side of the valve) but otherwise an interesting concept with definite potential.
My only issue with using NIC designs in water guns, is that their triggers are created for a compressible gas instead of an incompressible liquid. The amount of turbulence in that design in comparison to the old SS valves is very ridiculous. The pressure required for opening a valve like that with an air-air interface is minimal compared to air-water, and i'd be concerned about leaks for sure with that setup. The sheer hydrostatic pressure acting on the valve would make it nearly impossible to actuate without a rather massive mechanical advantage.

In addition, I'd be wary of putting the valve so far back (NIC homemade guns can have the trigger anywhere really as air flows nicely. Water guns behave much differently )
I appreciate it isn't the best design for flow, and you'd be correct in saying that it's unsuitable in it's current design and position, but by:
  • Using 45° elbows instead of 90° elbows
  • Placing the elbows and firing pin on the PC side of the valve (turning it into a conventional pull valve)
  • Connecting the front of the valve to a straight pipe and nozzle (maybe even a laminator)
  • Adding a small torque arm
  • Using a larger diameter check valve
  • Find some way to seal everything :goofy: (firing pin exit hole, the hole drilled into the check valve to mount the firing pin screw/nail etc.)
then it mightn't be too bad as a homemade water blaster valve. It would certainly be simpler than some of the other options for a trigger based homemade.

Sealing any homemade valve usually poses some kind of problem, so, if adapted well, this could, in theory, make a cheap-ish option for trigger actuated homemade firing valves.

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Re: Possible Homemade revamp of the Classic Trigger

Post by atvan » Tue Jun 19, 2012 9:00 am

Seeing your picture Croc, That washer idea is clever, but you still have to seal against the pin. That part is always going to be a pain- small holes that need to let something to slide seem very difficult to seal properly, especially under pressure.
DX wrote:In the neanderthal days of K-modding, people would lop off the whole PRV
Well, not that much soakage.
Beware the Purple

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Re: Possible Homemade revamp of the Classic Trigger

Post by Croc » Tue Jun 19, 2012 9:59 pm

atvan wrote:Seeing your picture Croc, That washer idea is clever, but you still have to seal against the pin. That part is always going to be a pain- small holes that need to let something to slide seem very difficult to seal properly, especially under pressure.
The washer would be slightly too small for the shaft, thus sealing the valve, and then the second (metal) washer would push against it and cause a seal on the surface the hole is in. Slight positional tuning would be necessary but I think it would work. It'd also allow a certain degree of slop with hole sizes and such. In theory, it works perfectly, I'll have to find some parts lying around to test it out. And maybe draw it in CAD. Just for visualization sake.
Andrew wrote:
Croc wrote:I was only considering not using one as the torque arms in the valves themselves are relatively small (and not to mention not attached to the valves all the time). Although I guess it is indeed such a manner that compared in size it is approximately half that of the valve height itself, and that is using the refined Super Soaker valve design. So it could be useful but testing is indeed important. Spring loading ball valves is just way too difficult for the time and effort, as 90 degrees is a long distance for a spring to be working. For a 2" model, a torque arm would be 1 inch approximately, probably mounted by some really dodgy means such as carefully cut PVC and all that jazz but it could well work. Just like how I fixed a penny modded Maverick's loading pin with a nail that just so happened to fit through the slot. That bad boy isn't going to break any time soon.
Sounds like the way to go. As for spring loading ball valves, rotary springs are the most effective, as the always apply all of the force in the same direction as the motion of the valve handle, no matter what angle the valve is opened by. Such springs are used in commercially available spring-return ball valves (which, in comparison with that handle mounted spring-pin system, is a much more realistic design to be used in homemade water blasters).
The springs you're describing are coil springs, and yes I know they are "super-effective" at their task, but they are rather costly and difficult to set up if the valve does not already include it. Also, on that ball valve, that's one thick spring... And probably the weakest they could get away with. If I am not mistaken, they would require far more force to open than their manual counterparts, and thus incorporating a trigger becomes pointless when you have a torque arm the size of your forearm attached to the valve for easier opening. (Although that handle mounted system could potentially be easier to open)
Andrew wrote:I appreciate it isn't the best design for flow, and you'd be correct in saying that it's unsuitable in it's current design and position, but by:
  • Using 45° elbows instead of 90° elbows
  • Placing the elbows and firing pin on the PC side of the valve (turning it into a conventional pull valve)
  • Connecting the front of the valve to a straight pipe and nozzle (maybe even a laminator)
  • Adding a small torque arm
  • Using a larger diameter check valve
  • Find some way to seal everything :goofy: (firing pin exit hole, the hole drilled into the check valve to mount the firing pin screw/nail etc.)
then it mightn't be too bad as a homemade water blaster valve. It would certainly be simpler than some of the other options for a trigger based homemade.

Sealing any homemade valve usually poses some kind of problem, so, if adapted well, this could, in theory, make a cheap-ish option for trigger actuated homemade firing valves.
You kind of disprove the usefulness of this valve (In the water weaponry community) before you even list possible ways of using it here, as with homemade water guns, are you not going for the best flow? However, the design is ingenious for something simple like a Nerf gun (Don't tell me some are complex. I know. But every Nerf gun has the same size darts it must accept, and that makes designing easier IMHO), however it is not too useful for water weapons, where valves must pretty well be strictly open or closed for the best flow and performance, the more instant the better.

Also, if you haven't already, look at the drawing a few posts up. It roughly outlines what I was going to do with the washers. Probably gluing the output side washers together as well.

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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Wed Jun 20, 2012 7:58 am

Croc wrote:You kind of disprove the usefulness of this valve (In the water weaponry community) before you even list possible ways of using it here, as with homemade water guns, are you not going for the best flow? However, the design is ingenious for something simple like a Nerf gun (Don't tell me some are complex. I know. But every Nerf gun has the same size darts it must accept, and that makes designing easier IMHO), however it is not too useful for water weapons, where valves must pretty well be strictly open or closed for the best flow and performance, the more instant the better.

Also, if you haven't already, look at the drawing a few posts up. It roughly outlines what I was going to do with the washers. Probably gluing the output side washers together as well.
The reason I stated that it was not the best design for flow, is because no pull valve design offers the best flow. Ball valves offer one of the best designs for flow, as there is no (well, OK, very little) interruption in the pipe diameter or direction, if the correct valve is used. If this check valve-based valve has no use in the water warfare community, surely the standard pull valve has little more? Bringing us all the way back to ball valves. :goofy:

As for the drawing of your design, I agree with atvan that the washer is going to be very difficult to seal around the pin. Yes the hole will be smaller than the pin diameter, but that (if you're not careful) will introduce a hell of a lot of friction (rubber having a reasonably high coefficient of friction as is), unless regularly and heavily lubricated. If the seal between the washer and pin is too tight, you'll need a stronger spring inside the pull valve, making it harder to open (not to mention the pressure forcing the valve shut when pressurised). Stock CPS blasters tend to have pretty easily opened valves, so not much force is needed to open the trigger. It's only when pressurised that they really become harder to open (or even fail to open at all if heavily power modded).

However, if you can get that area to seal (and you're right there is no reason why you shouldn't if you design and build it carefully) without introducing too much friction and resistance to trigger pull when fully pressurised (bearing in mind homemades tend to run at higher pressures than stock blasters) then this valve could be a good option for those wanting triggers on their homemades, at the slight expense of range.

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Re: Possible Homemade revamp of the Classic Trigger

Post by wetmonkey442 » Wed Jun 20, 2012 8:11 am

^I've always been of the impression that flow doesn't really affect performance at the scale that most homemades operate at.

True, reducing turbulence and optimizing flow should be what every homemade aspires to, but I fear that too much focus has been placed on flow. For example, I would rather use a pull valve than a ball valve during the course of a long water war (ie more than one hour long), simply because a ball valve becomes tiresome and impractical to use. Long term ergonomics over slight performance gains is my mentality! I mean, the CPS 2000 is the gold-standard for many enthusiasts, and it features a regular old-fashioned pull valve. We can match it in terms of power (as Ben as showed us countless times), but we haven't yet matched it in useability. I think a homemade pull valve might be an excellent step in that direction.
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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Wed Jun 20, 2012 1:09 pm

There have been more usable homemades created in the past, one of the post practical of which (DR-4 Riptide) featured a ball valve. There is no reason why future homemades can't feature trigger actuated ball valves. A pull valve would no doubt be easier to trigger actuate and, if usability is more important to the builder than range/power, it is a perfectly good option. The other benefit of ball valves is they are readily available and work well as they are. No problems trying to seal them, or making them open/close (unless you do want a trigger).

Making a valve from scratch can be challenging, but if it works would provide a viable alternative to ball valve for more user-friendly homemade blasters.

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Re: Possible Homemade revamp of the Classic Trigger

Post by Croc » Thu Jun 21, 2012 10:23 pm

Andrew wrote: The reason I stated that it was not the best design for flow, is because no pull valve design offers the best flow. Ball valves offer one of the best designs for flow, as there is no (well, OK, very little) interruption in the pipe diameter or direction, if the correct valve is used. If this check valve-based valve has no use in the water warfare community, surely the standard pull valve has little more? Bringing us all the way back to ball valves. :goofy:

As for the drawing of your design, I agree with atvan that the washer is going to be very difficult to seal around the pin. Yes the hole will be smaller than the pin diameter, but that (if you're not careful) will introduce a hell of a lot of friction (rubber having a reasonably high coefficient of friction as is), unless regularly and heavily lubricated. If the seal between the washer and pin is too tight, you'll need a stronger spring inside the pull valve, making it harder to open (not to mention the pressure forcing the valve shut when pressurised). Stock CPS blasters tend to have pretty easily opened valves, so not much force is needed to open the trigger. It's only when pressurised that they really become harder to open (or even fail to open at all if heavily power modded).
The seal could actually be properly made with the right lubricant, for example an oil based lube on the walls of the valve would prevent water from getting anywhere near the exterior of the valve. It may be slightly harder to create a seal with washers, but in the long run, the valve will be much more reliable, and easier to maintain than O-rings.

Rubber may have a large coefficient of friction, but the direction of travel does not involve frictional forces at all. The friction would oppose the motion, being... well away from the surface, meaning no friction and only hydrostatic forces to overcome, being if the valve was full of water, and the water could go nowhere because it is creating the seal.
Andrew wrote: However, if you can get that area to seal (and you're right there is no reason why you shouldn't if you design and build it carefully) without introducing too much friction and resistance to trigger pull when fully pressurised (bearing in mind homemades tend to run at higher pressures than stock blasters) then this valve could be a good option for those wanting triggers on their homemades, at the slight expense of range.
I believe (Don't quote me on this one, I'm unsure if it is true) that the SS valves have only the rubber washer at the output, and a machined hole that is just the right size for the metal to go through. That's what it looks like to me at least. Also, refer to the friction comment earlier, only resistance to trigger pull from the liquid is necessary. I can imagine this needing a few pumps before anything pressure related happens when it is initially installed.
wetmonkey442 wrote: I've always been of the impression that flow doesn't really affect performance at the scale that most homemades operate at.

True, reducing turbulence and optimizing flow should be what every homemade aspires to, but I fear that too much focus has been placed on flow. For example, I would rather use a pull valve than a ball valve during the course of a long water war (ie more than one hour long), simply because a ball valve becomes tiresome and impractical to use. Long term ergonomics over slight performance gains is my mentality! I mean, the CPS 2000 is the gold-standard for many enthusiasts, and it features a regular old-fashioned pull valve. We can match it in terms of power (as Ben as showed us countless times), but we haven't yet matched it in useability. I think a homemade pull valve might be an excellent step in that direction.
Good to see a familiar face :goofy:

Yes, I think I'm still working in the old school homemade mindset, where a laminar flow will result in better performance, but I sometimes wonder if the turbulent flow created by a pull valve might make it be a little better than the fully laminar flow, especially as it operates at a constant pressure, not with varying air pressures where the flow drops off even faster as you lose some of the energy from pressurization, at least it is a constant flow.

I agree that the CPS 2000 is the standard, where the usability and performance were maximized. Now we only need to find a way to create our own CPS 2000 and have it approximately similar dimensions (I dont know if including a reservoir in a design is wise or not, but it'd be an interesting experiment), and compare them side by side.
Andrew wrote: There have been more usable homemades created in the past, one of the post practical of which (DR-4 Riptide) featured a ball valve. There is no reason why future homemades can't feature trigger actuated ball valves. A pull valve would no doubt be easier to trigger actuate and, if usability is more important to the builder than range/power, it is a perfectly good option. The other benefit of ball valves is they are readily available and work well as they are. No problems trying to seal them, or making them open/close (unless you do want a trigger).

Making a valve from scratch can be challenging, but if it works would provide a viable alternative to ball valve for more user-friendly homemade blasters.
Honestly, I don't see the DR-4 Riptide being too... build-able by the community. Yes, it is a very interesting blaster, yes it does work well, but with the plates and many ordered parts, I do not see much of the gun being available to the general community, especially if ordering parts and making plates is not too feasible.

Building a valve will be very challenging, as there is nothing to start with. Everything coming from scratch requires more precision, more places to go wrong. In creating the valve itself, the output hole and the trigger rod will have to be perfectly aligned to ensure a good seal. I'd likely think clamping the two parts together would be easiest for making those matching parts. Or, if they're being printed, just making sure the CAD drawing has the proper dimensions and all.

Andrew
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Re: Possible Homemade revamp of the Classic Trigger

Post by Andrew » Fri Jun 22, 2012 4:02 am

Croc wrote:Rubber may have a large coefficient of friction, but the direction of travel does not involve frictional forces at all. The friction would oppose the motion, being... well away from the surface, meaning no friction and only hydrostatic forces to overcome, being if the valve was full of water, and the water could go nowhere because it is creating the seal.
Are you sure? If the washer is pinching the firing pull pin, then there is a reaction force between the pin and rubber washer, creating a frictional force equal to μR (when on the point of slipping) in a direction perpendicular to the reaction force (i.e along the firing pin and in the direction you are pulling the pin). It will depend on how tightly the washer seals against the pin and how well lubricated it is. I'd have thought a silicone based lubricant would be better than an oil based lube, as certain fractions of oil (mainly around the petroleum grade fractions) can degrade the natural rubber, or latex, used in CPH's. That's why Vaseline (petroleum based) is only really any use in APH pumps with Buna-N, EPDM or other synthetic rubber o-rings (or diaphragms in LPDH's).
Croc wrote:It may be slightly harder to create a seal with washers, but in the long run, the valve will be much more reliable, and easier to maintain than O-rings.
I agree that washers will provide easier maintenance and reliability long-term, and they will be a hell of a lot easier to mount in the valve in the first place. No cutting grooves into the pin (which provides a weak point in the pin anyway) and finding they aren't deep enough, or in fact too deep to work properly.
Croc wrote:I believe (Don't quote me on this one, I'm unsure if it is true) that the SS valves have only the rubber washer at the output, and a machined hole that is just the right size for the metal to go through. That's what it looks like to me at least. Also, refer to the friction comment earlier, only resistance to trigger pull from the liquid is necessary. I can imagine this needing a few pumps before anything pressure related happens when it is initially installed.
I'll be honest, I'm not sure about this myself. Maybe someone with a broken beyond repair (SEAL??) pull valve could dismantle it further (with a dremel maybe?) to see exactly what seals where and gain a bit more insight into how exactly the pull valves work under the pressures they do.
From my experience with bearings there is always something in between the moving rod and the static tube to seal the system. In a propeller shaft (admittedly it has rotary rather than reciprocating motion) there are usually two options. The first method uses a grease cup to squeeze grease into the stern tube to seal and lubricate the shaft. The other uses bearings which let some water pass into the hull of the boat (between the prop shaft and housing) to lubricate the shaft (the water is removed via a bilge pump). Bearing in mind the hydrostatic head of a foot or so of water is a lot less than the pressure attained by a stock CPS blaster, I really can't see how it holds the pressure without even a dribble of water passing around the pin, unless there is something sealing it.
Croc wrote:Honestly, I don't see the DR-4 Riptide being too... build-able by the community. Yes, it is a very interesting blaster, yes it does work well, but with the plates and many ordered parts, I do not see much of the gun being available to the general community, especially if ordering parts and making plates is not too feasible.
I see what you mean about the Riptide. Some of the community may well struggle to source all of the parts (myself likely to be one of them, LRT being the hardest for me) but they could make substitutions or changes to the design as necessary (the plates may be a struggle to change). Alternatively, people could buy cheap water blasters (seen a few with tracked pumps aswell), gut them, and fit there own components into the blaster making use of the casing. Space may be an issue, unless you buy a fake CPS-style super soaker style blaster, but compact valves like the pull valve will allow greater room for other components. If I get around to building another homemade (or would it be technically classed as a mod?), I'd probably do something like this to make it more usable. That reminds me, there was a post a long time ago on SSCentral about a homemade based inside the casing of a leaf blower.

What we really need now is a prototype (as you suggested the reprap would be good for that) so we can work out all of these little issues, and see how many of them noticeably affect the performance of the finished valve.

EDIT:
This one (not suggesting everyone should make a leaf blower based water blaster but it does demonstrate my point :goofy: ).

Croc
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Re: Possible Homemade revamp of the Classic Trigger

Post by Croc » Fri Jun 22, 2012 3:54 pm

I might just buy some threaded parts or see what I have lying around and try to crudely hash together a prototype when I next encounter mr. dude, as him and I would have probably a better chance of creating a device with proper quality and such (I tend to be the cut twice measure once kind, wonder if engineering has changed that) :goofy:

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