"Requiem", my first homemade... made from Copper!

[Aurum]

Hey, im new to the site (i wont go into details, ive done that in the general section).

After finding out most PVC parts used in homemade guns are hard to find here in the UK, ive decided to follow in the steps of Insanitys_Engineer and hisCopper Watergun.

Ive looked at his designs, and I will be making something similar. Ive even already sourced the parts, i just have to buy them now. The piping will be mostly 15mm, and all valves and parts are built for compression, so once i get Copper PC together, imagaine to pressure...

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Here's a simple plan, as close to my current designs as possible:
(notice the long barrel... who says sniping in water fights is impossible?)


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Yeah, i know i havent included the Water Tank or the PC in this diagram, but his is just showing the bulk of the design. The water tank will most probably be a 5L water bottle carried in a backpack.

The PC will probably be a 0.5L or 1L drinks bottle at first, but i will upgrade it to a large diameter copper pipe (blanked) via (a) reducer(s) eventually, possibly dual Copper PCs eventually. Its metal, it can take the pressure
(I may even attach a pressure gauge to test it if things work well! PVC, you;ve met your match in British Copper Engineering!)

[Aurum]

Just posting to say thepage is now updated... also, i'd like to ask...

Does anyone have a better idea for the nozzle? of course a drilled blanking disc would work, but it there any way i can have a small nozzle piece instead? Unfortunatly, i cant just use more reducers as 10mm copper pipe is as small as you can go i think...

Any ideas from UK people?

[Ben]

Looking good. My only suggestion would be to eliminate the barrel--it doesn't improve performance or accuracy and makes the water gun longer.

You've already done more than half the work.

Edit: Missed your second post. I'm fairly certain you can find smaller brass piping if you want something smaller (I don't know if they have this in the UK). You'll need a coupler with a threaded female end and a bushing to reduce the size, but other than that it's straightforward. There's other options too I'm sure, but that's how I would do it.

[Aurum]

Thanks very much. Yeah, ive just read your reply on the Sniping thread, i see now where the design is wrong.

Brass parts eh? I'll look into this ASAP

[Silence]

Welcome to the forums, since I haven't seen your other thread yet!

That looks like a solid design, and thanks for the clear diagram. Only two problems caught my eye:

• The long barrel, which Ben has already pointed out.
• The wide pump. 22 mm is definitely too wide. For the record, 3/4" is much worse than 1/2", and that's about equivalent to 22 mm to 15 mm. 15 mm should be the maximum bore you use for the pump. Pressure = force / area, so if you pump with a given amount of force, increasing the area reduces the maximum pressure you can generate. And area increases as the square of diameter.

[Aurum]

So i should use 15mm for the pump section as well?

OK, in that case, the pump rod will be stopped from entering the Tee joint by the handle: the rod will be shorter then the pipe, and ill keep the pump handle chunky. i was planning on making the handle from ducktape

oh, seconds thought, put a 15mm-10mm reducer on the end to stopp the pump from comming loose. Yaaay, i think this is going well design-wise.

Im still having trouble finding a suitable nozzle though, i may have to sick with the drilled blanking disc


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EDIT:
New diagram

[Silence]

Yes. Sorry, I kinda evaded the point. 15 mm is best for the pump.

If you want to stop the pump from entering the tee, you could use an appropriately-sized washer sandwiched in between the pipe and the tee. If you look at the image in this page from the APH water gun guide, you'll see there's a washer in that location. I couldn't find a washer that fit precisely, so I had to sand down one that was slightly larger. You may have better luck with your parts, or maybe you could cut a washer from a piece of plastic.

That said, your handle method would work, too. I was actually lucky with my handle; the aluminum rod I had was short, but it already had two screw holes tapped in the end. I drilled a hole for the rod in a wooden dowel, drilled two holes, and screwed in two bolts to hold the wood on.

With your 10-15 mm reducer, you may want to use a removable pump handle. Or at least do all your testing first. You'll have to slide in the plunger/rod, add the reducer, and then add the handle to the rod, in order to make sure everything fits. That's a little obvious though and I'm being long-winded here.

Metal pipe nipples have been suggested for nozzles. They're probably what you're using for your water gun anyway: short lengths of tubing with male screw threads on either end. You could get, say, a 5 mm pipe nipple and an appropriate reducer. The advantage is that the walls are perfectly parallel, which reduces turbulence from the nozzle itself.

[aEx155]

Why didn't you just use 22 mm pipe for everything? That would certainly increase performance. Also, if you went with 15 mm pipe for everything, why did you increase the pump diameter? With that size, the area would be ~1.85104787", which is similar to 3/4" PVC (I think). Wouldn't that make it too hard to pump?

If I were you, I would switch everything in your diagram around. (as for the pipe diameters.)

EDIT: Oops, didn't see SilentGuy's post. I just restated what he said.

[Ben]

The cheapest and best thing he could do would be using 22 mm for everything past the last check valve and it'd increase his performance without affecting the pump. I did something similar in my APH design and I highly suggest it. It saves money with smaller pipes when larger pipes don't make sense or aren't needed.

[Aurum]

OK, to set some things striaght, i couldnt find a metal pipe nipple with would fit the copper fittings.

Also, thanks for the tips on the pump construction, much obilged.
As for using 15mm, i find its cheaper than 22mm, and i dont want to spend alot on my first prototype, i'll save the money for when i need to rebuild an improved version once testing of this first model is complete

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edit: didnt see that last post
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So i should stick with 15mm, but use 22mm for the latter half of the gun, ie the PC and ball-lever nozzle etc

[Ben]

So i should stick with 15mm, but use 22mm for the latter half of the gun, ie the PC and ball-lever nozzle etc

That's exactly what I mean. You'd get the higher performance from the 22 mm pipe without the cost of a water gun made entirely of 22 mm pipe.

[Silence]

Yep, 15 mm pipe is much lighter and cheaper. And it actually makes a big difference with copper. Whereas basic PVC pipe cost just a few cents or dollars for a 5-foot length, I'd imagine metal pipe costs quite a few euros/pounds per meter.

I didn't seem to get much of a boost from using larger diameter tubing. It probably doesn't make a difference for nozzles that are much smaller than the barrel anyway, but maybe it does for larger nozzles.

[Ben]

That's what I meant. For the same diameters you should have similar performance but you also get the option to have larger diameters with larger pipe.

[Drenchenator]

Aurum, what are you using for the chamber? You mentioned a copper PC, something I don't think anyone has done before. From what I remember larger diameters of copper pipe are very expensive, but then again that doesn't necessarily mean that you can't use it.

[Aurum]

i was in B&Q the other day (big warehouse for building, gardening, DIY etc) and i was checking prices.

You can get 2 Meters of Copper 15mm (or 22mm) for around £5.35 (or £5.75). So roughly thats £2.50 per metre on average, which is again roughly $5.00 a meter

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edit: sorry, drenchenator, didnt see your post

Well, for the time being its only going to be a plastic bottle like Insanitys_engineer's model, but once ive got the main sections of the gun working im going to upgrade the PC to something copper, also, so the overall pressure doesnt mean the PC will be the part most likely to burst, as plastic bottles are most definatly weaker than your average metal.

Imagine, a fully metal watergun. I could be a pioneer... and with the spare parts (some parts im buying come in packs of 10) i could build multiple models at reduced costs. maybe sell them to the rest of you through this website? if you want... But fantasys aside, i think i'd better stick with a)finishing the gun and b)making sure it works first