Quiet submersible pump

[Neale]

Hey, Kit - is that a cooling system or a pressure washer? I hasten to add that I am joking...

But seriously, I'm inclined to think that cooling requirements are over-estimated, at least for the typical home-built machine. I would prefer to avoid 240V submersible anyway - mains and water don't mix and although clearly the pump is designed to run like this, why do it at all if not needed? My 12V low-flow pump running on 5V gives more a trickle than a flow, and that's through some metres of 4 or 5mm pipe. However, the combination of narrow pipe, low flow rate, and length mean that there is quite a lot of water cooling going on in the pipe, so the water going back round via a 10litre bucket is still fairly cool. Some few degrees above ambient, maybe 10deg if I've been working for a while, but I've never noticed it much higher than that.

[JAZZCNC]

But seriously, I'm inclined to think that cooling requirements are over-estimated, at least for the typical home-built machine. I would prefer to avoid 240V submersible anyway - mains and water don't mix and although clearly the pump is designed to run like this, why do it at all if not needed?

100% agree, the typical Water cooled spindle requires very little water to cool it. Every machine I build/sell uses a 24v submersible pump in a simple tank of water and for 99% of users this is more than enough, for users who are running jobs lasting multiple hours or days then we offer an upgrade with an aluminium tank, radiator and twin fans but it still uses the same water pump. Obviously, for people like kit who live in very hot countries, this will be slightly different but still, they don't need a massive flow of water.

Re 240v pump, then again 100% agree, in fact, our spindles come supplied with a 240Vac pump which we replace with a 24Vdc pump because I don't like water and mains voltages together. So have a nice box full of 240vac pumps if anyone wants a cheap pump....Lol

[Kitwn]

Neale,

Joke appreciated, but it's a very modest sized aquarium pump. I don't think any other voltage option was available locally when I set up this machine back in remote Western Australia and delivery times for mail-order were typically anything over 14 days so I used what I could get. Plus I spent most of my working life mixing up to 40,000V with water so perhaps I'm biased.

But think on this: The 240V brushless pump motor coils are fully encapsulated in plastic, the heavy duty 3-core mains cable is fixed in place and I don't often hold it in my hand. It doesn't get bent and twisted every day or trodden on and if the 240V does escape through the pump it will connect to the cooling circuit which is flowing through the spindle which is solidly bonded to mains earth and I have an RCD in my shed mains supply.
Now compare that installation to the cheap-shit 2-core mains lead on your wife's/daughter's/granddaughter's hairdryer.

Link to previous discussion on cooling pumps and the effect of pipe diameter on flow rate:
http://www.mycncuk.com/threads/12791...cooled-spindle

[f750]

Thank you all for your reply's, the new pump arrived today and I have fitted and run the pump. Nor really needed today as it is quite cool today but the pump felt cooler and a lot quieter.

Cheers Tony