Go to Enzed they have all that sort of gear. Cant remember how much but I dont remember it being too over the top.

jim

Thanks Hoop & Skinny for the pointers. Your right about Cloudmaker, they're not cheap thats why I'm after something 2nd hand or a fridge compressor which I'm told works well ... anybody?.

Thanks Kaos,

I didnt quite understand what you meant by the 'you never want to vacuum more than about 30-40% even lower' statement. I also know nothing about air bleeders (as you suggested for the intake) can you explain that further? I was planning on using a vacuum switch on the system in conjunction with a gauge so that I could pre determine a point where the pump switches on and off based on the amoumt of vacuum in the system (see http://www.acp-composites.com/acp-vbes.htm for the switch). I expect that this is the ideal setup rather than using a timer
Another option is that you make your own vac switch using a syringe, spring & microswitch but I havent figured out yet how to have a buffer on the system to stop switch continuously switching on/off (maybe someone can suggest something)

Crashdum,
not a good idea to have the pump that switch on and off.
You need to keep the pump running all the time, and just need to have a leak somewhere to maintain the needed pressure
and that the pump is not doing a complete vacum and crush the board.
Very simple way of doing this , is to have a little system with a screw that you screw in more or less to change the leak.


you could check my setup..I used a fridge compressor (with a vacum gauge to check the pressure)

http://www2.cwr.uwa.edu.au/~berthot/shape/shapewindsurf/IMGA0053.html

good luck!!
By the way what are you making ??? windsurf board?surf board? kite board?

ok so I suppose a switch that could be ok if it only kick in at 3hg below.
I guess for a kite board you use some kind of herex/divinicel core (or clark foam) or similar
so maybe it doesn't matter as much if the pressure vary a bit ( compare to the first vacum stage
polystyrene foam for a windsurf board).

As for the fridge pump that get too hot, it does depend on the quality of the pump (ie fridge).
I 've used some that were ok...but yes on a hot summer day have top be carefull sometime
Kaos69 glued a little plastic pot on the fridgecompressor it self and cool it down but putting ice in the pot.. (good system)
, In my case I just set a little home fan in front of the compressor.

good luck, I 'll make a kite board soon too as I still have some divinicell leftovers....

Check out this site.

ww25.dream-models.com/eco/vacuumpump.html

Me and a mate just finished one of these a few weeks ago. The advantage of this one is that the pump cuts in and out automatically as the pressure drops, also the pressure can be adjusted by altering the tension in the spring.

We almost electrocuted ourselves when we mistook the active for the earth. But apart from that it works a treat.

Cost about $50 to make

I use a similar system, with a big old gas bottle as reservoir.
It's important that the motor is not turned on and off too quickly, it can cause big sparks across the contacts and burn them out or fuse them together. My system stays on for at least 5 seconds, which works ok but I'd prefer it to be longer. It stays off for between 1 and 10 minutes, depending on how good the seal is.
A fridge compressor works fine like this without special cooling, but a friend of mine borrowed my last system, holed his bag so that the motor ran continuosly, and burnt it out.
I have a vague memory of having to add a non return valve on one system, not sure if it was a fridge compressor

decrepit

Decrepit is right, the reservoir is the way to go!!

When i first tried my pump it didnt have a reservior, it would cut in and out quite frequenly and would only run for a fraction of a section before it built up pressure and switched off again.

I was worried that it would burn out the pump so i added a reserviour to the main vacuum line. I actually made one out of an old kite pump, i removed the handle and the shaft, sealed the top and had a line in and a line out.

Now the pump holds the vacuum for much longer and when it does cut in, it runs for a more substaintial amount of time (about 3-4 seconds). I was also a bit worried that the kite pump wouldnt be able to withstand the vacuum, but it hangs in there fine.

Yep, line in is all you need, with a "T" junction, or if it's easier, line in, line out, would be just as good.
just makes the pump work long enough for the initial surge current to die down, before switching off.
So position of the sensor is also important, the further away from the pump (vacuum line wise) the better. If you use in & out from the resevoir, the out line wouldn't be a bad place for the sensor.

If it switches off while the current is high, it can produce big voltages (back EMF) as well as switching off a high current. If you can achieve 5 secs on that would be great, less than 2 secs may be a worry. Can't give you an exact safe time, you'd need to talk to an electrical engineer. But I'm sure it's to do with pump speed, as long as the pump has reached full speed + a little bit for good measure, should be OK.
5 mins on sounds good. I'd be happy with that, it'll go even longer with the resevoir.

decrepit