Sorry for making the 100th topic about homemade questions, but I can't find the answers to these anywhere :huh:

1. 1/2" or 3/4" pumps? Is the extra effort worth it to pump up the PC faster?

2. 2" or 3" PC's? Which is the best volume for the price?

3. Single chamber or double? Is the extra pumping worth the overall result?

Price is not a major issue here, but I would like to keep the total price as low as possible still making sure it gets 50+ feet range and pretty large output.

1) Which pump volume you want depends completely on two factors: how strong you are and how powerful your water gun is. If you're comfortable with 3/4", then by all means use it! While you're at it, make the first homemade pump that pumps on both strokes. I'm very surprised that no one has done that yet (hint: it's much easier than you think). Storm has had pumps like that for a long time.

2) In the future, don't rely on people like me to answer questions like this. These math ones are very easy to figure out for yourself. Just open up a calculator program and use the volume of a cylinder equation, v = l * pi * r^2. Divide the cubic inches by 61 and you'll get the capacity in liters accurately.

5 feet of 4 inch pipe costs $20.51. This pipe contains 753.99 cubic inches of space. 753.99 / 20.51 = 36.67. One dollar buys you 36.67 cubic inches of space in this pipe.

5 feet of 3 inch pipe costs $14.41. This pipe contains 424.12 cubic inches of space. 424.12 / 14.41 = 29.43. One dollar buys you 29.43 cubic inches of space in this pipe.

Obviously, the 4 inch pipe is the best deal for capacity. Of course, volume increases exponentially as radius increases, so this was no surprise at all.

This information was obtained from McMaster by the way. They're just about the best website to do research into parts because they explain nearly everything if you don't know.

3) This again is opinion. I make chambers as large as possible if they are rubber CPS because the power will remain the same no matter how much I pump. On air pressure, I acknowledge that larger chambers will mean more pumping. That usually doesn't matter to me, but I did make a single chamber APH to compare to my other one at the time. The dual chamber APH is more useful to me.

Hope I answered your questions! If you have any more, feel free to ask.

Pump on both strokes? Well, I suppose you could have two pumps, stacked on top of eachother, each pumped with the same handle. One would be backwards... but I have a feeling this isnt what you had in mind (I wish I had my old Storm 600 :angry: ).

On McMaster, once you chose the ID, it requires you to choose a size of OD. Which will fit standard 4" fittings? I think I'll see what they have at the hardware store and do the math there.

Edit: I'm probobly looking at the wrong section anyways. Could somebody tell me how to get to plain PVC pipe?

Plumbing section, white pipe that is marked PVC on each fitting. Make sure you get pressure rated pipe, an example is if the pipe in question says "260 psi @ 73 degrees" on it. While fittings don't have that marked, most are pressure rated and you can tell by how hard they feel. Non-pressure fittings look different, feel weaker, etc.

As for the other things, the math related ones are self explanatory, the pump size is fully up to you, and the dual chamber vs single is also up to you. I personally prefer single chamber because of low pumping, but do you want longer shot time and more pumps or less shot time but less pumps?

At McMaster, I always first specify schedule. I don't want anything larger than schedule 40 pipe most of the time. I then work from there. I have not seen a part where you must specify ID and OD, only OD. They do have a good guide on the size of PVC pipe if you are confused. 4 inch PVC pipe has an OD of 4.500 inches last time I checked. The actual ID of schedule 40 is something like 4.068, but for all intents and purposes that is close enough to 4.

Also, from what I know, a larger schedule only makes the ID smaller. The pipe still will be labled 4 inch, but the ID will be smaller. They do this so that you can use schedule 40 and schedule 80 parts together. The ID changes can get confusing sometimes. I bet you didn't know that schedule 40 1/2 inch pipe actually had an ID of 5/8 inches. Most schedule 80 1/2 inch pipes have an ID of 1/2 inch unless they use a stronger plastic. Weird stuff really, but to most it doesn't matter.

You should rely first and foremost on your local hardware store's plumbing section as Duxburian said. That will be the easiest to access and probably will be cheaper because tax usually is lower than shipping. Sadly, not every hardware store keeps a good stock of pressure-rated pipe, and you should never use anything else. The fittings they put by the PVC are more than likely pressure-rated. The fittings they put by the sewer pipe are never pressure-rated but similarly sized. If you are unsure whether or not a fitting is right, ask someone at the store about it.

I have heard (somewhere) that the ID is actually slightly bigger than what the pipe says, which is rather... unusual.

@Doom: About the single/double chamber, how much shot time does your APH on, say, a 1/4" nozzle? (any idea about the output?) And your single chamber?

I'll have to get back to you on that. I'm not sure at the moment, but I will go test outputs tommorow if it is not raining.

Well here's a question that's easier to answer: How is the shot time on the riot blast? Is it ~1 sec. or is it longer due to the huge PC size?

The riot blast shot time varies really. It depends very much on how many times I pump the APH. Typically it is one second or less, so when taking the famous "50X" output I rounded up to 1 second shot time.

Cool! With a 50x blast, how big an area can it cover? Is it laminar until about 20 feet or is it a straight riot blast that soaks everything up to 30 feet?

Edit: Just thought of another question. What about the material used for pumps? Can you cut aluminum dowels with a hacksaw? And will the wooden ones rot or break down after being in contact with water for so long?

You can actually get more than 50x, my dual chamber APH has ~60x because the pcs are very large. While impressive, the riot blast doesn't go very far. Mine doesn't spread all that much, it stays laminar for most of the way.

I use wooden dowels, although they rot if you don't coat them with a protective seal. I'm still looking for that, in lieu of one I have been taking out the pump shaft after using the guns.

You could probably cut the aluminum with a hacksaw, but I would reccommend something stronger.

Sadly, I don't have anything stronger than a hacksaw :( so I may have to go with wooden dowels.

About the pumping on both strokes, has anyone done this on a homemade? That sounds like something interesting ;)

You can cut metal with a hacksaw! That's what it was meant for. I only use a hacksaw for everything I do. ;)

Ok then, I think I'll use aluminum.

@Dux: I tried PMing you a while ago, but you never answered. Can I use this pic for a link to the homemades section on my website? I would be willing to cite you if you wish.

Storm on the SSC forums has done it I think, so send him a PM or Email.

If you get wooden dowels, get 5/8" if you are using 3/4" PVC, less than 1/2" if you are using 1/2" OD PVC.

3/4" OD O-rings fit perfectly over a 5/8" dowel placed in a 3/4" pipe.
5/8" OD O-rings fit perfectly over a less-than-1/2" dowel placed in a 1/2" pipe.

The dowel has to be less than 1/2" if it's going in a 1/2" PVC pipe [1/2" PVC has ID 5/8", hence the 5/8" O-rings] Otherwise the dowel with O-rings on it won't fit in the pipe.

Lots of similar numbers, but it is simpler than it looks in that explanation. If you do get dowels, look for something to spray on to coat the wood and protect it from rotting. I plan on finding some kind of wood protection today at Lowe's, since I've had several pumps start to rot.

Aluminum could be better since it won't rot, but if it damages your hacksaw blade, stop cutting.

Oh, so is that what he meant by Storm? Oops :rolleyes:

As long as you cite the source, feel free to use anything on the site.

Eventually, all blades will get dull, hacksaw ones included. Alluminum is a very easy metal to cut, so I don't think that any damage should occur. Part of the hacksaw design is a replaceable blade anyway, so any damaged blades could easily be replaced.

I'll make a drawing to explain this to you later today. It's a very easy concept, but sadly not too many people know about it. You might have to shorten your pump a bit to design it to use this, but it will have more volume despite the shortening.

I'm actually very interested in this concept. Will it work with a tracked pump?

Maybe having a 1/2" pump within a 3/4"? Or maybe something like this?

Uh why are you guys talking about high-output riot blast's when all of you play 1hk? :huh: During 1hk super high-output like that is not needed

If people are grouped together, you can use a riot blast to "kill" several at once. Although a high range horizontal fan blast would be more useful. Maybe if you cut three or so 1/4" overlapping holes in an endcap to make a kind of fan nozzle. Except then you would have to have some kind of way to make sure when you screw it on, it will be aligned horizontally.

I have always been thinking about making "custom homemade nozzles" out of end caps. B)

End caps are what are used for most homemade nozzles, and multi nozzle mods to stock guns.

As for riot blasts, I don't generally use those in a war since they waste water, but they are an impressive feature to have. Homemade riot blasts can have extremely high output since they can dump a huge pc [or more than one] in under 1 second.

If you want a homemade fan blast, drill a whole bunch of small holes in the cap in a line, double checking that it is horizontal when screwed on.

I may try the double pumping method as illustrated on the previous page, hopefully it works well.

Are there any topics on the double pumps? I searched SSC and didn't see any.

The double pump design you posted M is correct. Just remember, you don't need more than one check valve even on this design. ;)

Ah, yes because they could both draw from the same one. Would you use plastic tubing or pipe? Tubing would be cheaper and you wouldn't need to cement all the parts, but that might make it a little cluttered.

I think a double pump may complicate things. But, I have a perfect idea for it. For the longest time I've wanted to make a turret, but the problem is pressure. This designed will cut down time pumping.

I've made a design for the double pump, keeping it as compact as possible. I plan to assemble the gun whenever I find the time to.

After thinking about that, if you only used one check valve, what's to keep the water from just going around in a circle, and not into the PC's? I think you really so need two <_<

Is there a picture somewhere on how double pumps work? It seems M figured it out, but there's not a diagram or picture, so I would like to know how.

Thanks.

If by double pumps you mean a pump that pumps on both strokes, I am sure that m15399 could make a graphic describing the concept. It really is quite simple really. There essentially are two pumps with a single rod between them. Once you see the image, I am sure you'll understand how they work immediately.