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[wadsworthj]

Looking for info on the water pump static dive system, as featured in the book,
"simply model submarines", as it gives no details of what type of valve they mention
or where it would be positioned.
Many thanks in advance.

Cheers    John.w.

[Subculture]

You should also get the book 'Model Submarine Technology' by Norbert Bruggen (also by Traplet), that goes much further into the nitty gritty technical stuff.

It doesn't really matter where you site the valve, just so long as there is one there. It can be between the pump and the outlet, or the pump and the bag

The type of valve you need- there are three possible approaches.

1. A servo controlled pinch valve. You run silicon tubing to your pump, as this is very squishy it can easily be pinched up. Using one of the servo arms as a cam, the hose can be pinched off using either a blunt plate (think guillotine, but not sharp) or a ball bearing. If you use the latter method, you'll probably need a little more pressure, so it's usually advised that a standard sized servo is used and that it's ballraced. I use the guillotine type pinch valve with a little 9 gram servo. Works perfect. You need to make sure the hose is unpinched when storing the boat, else the hose can get damaged.

2. A ball valve. Festo do miniature ball valves which are designed for pneumatics, but work equally well with water, as the materials are non corrosive. You have to modify your servo to operate over an extended 180 degree range to use these. The valves cost about £8.

3. Solenoid actuated valve. OTW use a solenoid valve in their modules, but it's quite a bulky item. If you have the room, no big deal. Some have used Clippard valves, which are quite small. Unfortunately they're designed for gas not water, and they corrode if you don't strip them down after a sailing session and dry them out thoroughly.

[Davy1]

Hi John,

Some more information would help us.(Page Number/Are we talking vented or pressure tanks systems etc ?)

Some basic information here (Although I see that heading for pressure tanks systems is missing (Richard!!  ))

http://associationofmodelsubmariners.com/diving-systems-part-1.php

David

[wadsworthj]

Hi.
   The info required is as follows, page 16, pressure tank.
Cheers and thanks   John.

[Subculture]

Whoops- the festo valve requires 90 degrees of movement, not 180.  Al's hobbies sell them, although they're a bit more expensive than some other suppliers-

http://alshobbies.com/shop/lookupstock.php?pc=6432

Another link with a bit more information on ballast systems-

http://www.heiszwolf.com/subs/tech/tech01.html

An advantage of the sealed tank is that it doesn't pressurize the rest of the boat, which makes life easier for your shaft seals, bellows etc. The disadvantage is that the tank needs to be bigger to deal with the free air space you require (not a big deal), it needs to be strong to deal with the much greater (about 30x) pressures, and you probably want to think about fitting at least one baffle to prevent sloshing. You might also want to check that your pump is capable of making the pressure required, especially if you're running it on half volts.

[wadsworthj]

Hi Subculture.
                  Thanks for the info, so much clearer now, with a good picy,
not a million miles away from the one installed in my washing machine set up.
Bags of info is helping me plow a course through this mine field, many thanks
im begining to see the wood for the trees.

cheers john.

[Subculture]

Think your washing machine is a bit different from any I have worked on!

Have gander Look at post 69 on this thread- http://www.modelboatmayhem.co.uk/forum/index.php?topic=33589.50

I think Mark has copied the Sheerline design. I'll post some pictures of the mini pinch valve I made when I get a chance- not at home at the moment. It's slightly different to Mark's, and was made from a few scraps of copper sheet.

[Davy1]

Yes the Heizwolf picture is better than p 16 (which was written by Steve, who also did the one on the AMS site!)

BTW I see that pressure tanks are not covered very well in Norbert Bruggen's  book either. (p44)

Have you had a look at the discussion on the AMS site for pump and valve selection?

http://www.theassociationofmodelsubmariners.com/t286-pumps-geared-variety

I am very keen on the pressure tanks system and use it in almost all my subs. I use a glass fibre tank containing baffles which was moulded using a soft drink bottle as a former!
I would be cautious about selecting pumps. The red ones have been very good for our hobby. A lot of people will recommend scrap yards, Halfords, ebay etc etc as sources of supply. But do these same people actually sail their submarines much? (I'm sailing again tomorrow - and I intend to be bringing it back too!)

All the best,

David

[wadsworthj]

Thanks for pointing me to the picy of the pinch valve, very usefull info,
i could fabricate one of these, without too much trouble, un fortunately i
do not have a lath, or the room to put one, unlessits in the bedroom!!
i live in a flat, and my workshop is a broom cupboard, but i manage.
Many thanks again its all helpfull, as its my first venture into subs.

Cheers   John.w.

[thegrimreaper]

@ wadsworthj for what its worth you can get by without a lathe the WTC in my vanguard is fabricated from sheet plexiglass that the end plates were cut from using a jigsaw then a hole drilled dead centre and a bolt passed through the bolt was then fastend into the chuck of a drill that was wedged into the jaws of a work bench  and a file lightly held to the edge until within an exceptable tolorance then fine wet & dry used to hone them to a fine finish. the finished endplates work brilliantly. the pinch valve is just a block of plexiglass with a hole drilled through for the silicon tube and a second hole drilled 3/4 of the way into the block to except a brass plunger.

hope this helps with your thinking.

Regards Mark

[Subculture]

The whole idea with a waterpump system, is that you don't require a lathe to get a working system together. You do need to be proficient with hand tools, but most modelmakers are anyway, else you're in the wrong hobby!

[Albion]

@ wadsworthj for what its worth you can get by without a lathe the WTC in my vanguard is fabricated from sheet plexiglass that the end plates were cut from using a jigsaw then a hole drilled dead centre and a bolt passed through the bolt was then fastend into the chuck of a drill that was wedged into the jaws of a work bench  and a file lightly held to the edge until within an exceptable tolorance then fine wet & dry used to hone them to a fine finish. the finished endplates work brilliantly. the pinch valve is just a block of plexiglass with a hole drilled through for the silicon tube and a second hole drilled 3/4 of the way into the block to except a brass plunger.

hope this helps with your thinking.

Regards Mark

I previously used your method, but here's my new disc maker. the cutting tools can be reversed for cutting internal holes or external discs. Designed for wood but goes through plastic materials quite nicely. this photo shows the saddles to hold a WTC, but i also used this method to build a piston tank tech rack.

[Subculture]

You're a braver man than I- I'd be worried about that digging in.

[thegrimreaper]

Nice looking tool Albion but prey tell where would one aquire one of them from. I think that the idea would be to run the drill at a very slow speed Andy mind you I bet your arms ache after a while

Regards Mark

[Subculture]

It's a trepanning tool. I have one, but it has the tool on one side only.

[wadsworthj]

Hi Guys.
           A trepannig tool is used for cutting skulls, grusome!!!
I have used tank cutters in a pillar drill and it works well,
but antool like the one shown, is infinatly variable, exellent.
I think that this kind of tool can be found amoung wood working shops etc.
But thanks for the hint.

Cheers    John.W.

[g4yvm]

[Davy1]

Just looking in on this one again to confirm that you don't need a lathe to produce pinch valves etc. Lathes are useful but only become really necessary if you start to need grooves for O ring etc.

David

[Subculture]

Here are a couple of pictures of the little pinch valve I made for the Holland to replace the troublesome Clippard valve originally fitted. Space was tight in this model, so I had to use a miniature 9 gram servo to get it to fit, which thankfully was more than up to the job.

The valve is shown minus the silicone tubing for clarity, it's important to use the thinner walled silicone tubing which squishes up easily. If you want to use thicker tubing you may need a stronger servo.

The pinch valve was made out of some thin copper sheet scraps, with a polycarbonate plate. I made the hole square(ish) to encourage the tubing to squish up flat, but note the small gap with the valve closed to allow for the tubing wall thickness. It's important to ensure all edges where the tubing comes into contact are thoroughly deburred and well rounded, else you will have made an effective guillotine!! 

I've tested this valve to 30psi and it remained tight. That's way beyond what is required for the system sued in the Holland. A sealed tank will make much higher pressures, but I have no reason to doubt this valve would remain tight in that instance.

[Davy1]

It is good to see you actually building something, Andy, but that design will not give you much silicone tube life - split it and the boat sinks.
I will stick to the alternative designs, I think.

David

[Subculture]

I thought originally it would cut into the hose over time. Time will tell, but it's been in use for over a year now with no signs of distress on the hose so far.

It's not terribly clear in the photos, but the pinch blade has a radius on it as the sheet is folded over, so there is nothing to cut into the hose.

I should add that I always release the valve when the boat is stored, but I think you should do that with all pinch valves anyway.

[AL 1]

im sure you would be able to find out how to do it properly on the AMS website

[Patrick Henry]

im sure you would be able to find out how to do it properly on the AMS website

You most certainly would...ask and ye shall receive.


Rich

[Subculture]

Well I see nothing here except my design.

[Patrick Henry]

Hmm...

(a) Well, we're not on the AMS forum, are we?
(b) You haven't asked anything...


Rich