Sunday, 2 May 2010

New last!

Halloween has been and gone and although we are nearly half way through 2010 I've decided to start a new project.

My 7 year old son, Josh loves a water fight. So we've decided to make the water gun from hell.
After some research I found this design which I thought would meet my usual criteria of fun and danger.

The design calls for high pressure PVC piping which is incredibly expensive in the UK for some reason. The only people who sell it at a low cost per metre insist upon you buying a crate of 5m lengths.

In the end I got my supplies from koi fish suppliers here. This pipe is rated PN9 which is good for 131PSI in old money.

Here is a picture of the parts I ordered:

The T piece and the 4" to 2" and 2" to 1" reducers next to it are to allow me to connect the screw cap end set (at the top left hand side) via the 1" pipe at the bottom. This screw cap is to be the inlet to top up the water. This differs somewhat from the linked design but as the availability of parts are is limited here, a compromise was the only solution.

I have a feeling I will be requiring some custom fittings for this project, so I dusted off my lathe. It has not been run for 10 years but it's still in running order. It comes complete with thread cutting gears, but only if I want to produce Whitworth threads.

The final part of this project is to be a solenoid valve to control flow. The original design uses a ball valve but this is both cumbersome and slow to respond. I intend to use a small MPU to control a 12V solenoid. If this responds fast enough, I should be able to have several modes selectable with a push button:

  • Single shot.
  • 3 shots rapid.
  • Full auto.
  • Continuous.
This all depends upon the performance of the solenoid I've ordered. They don't publish the operational frequency. I'll just have to give it a go.

Here's a pic of the one I ordered:

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