Quote Originally Posted by m_c View Post
If you're just using a basic impeller pump, can you add a flow control valve? A pair of mole grips/small g-clamp/pipe clamping pliers would also work for testing purposes.
Or would increasing the depth of water work, so there's not quite as much disturbance from the flow?
It's actually a diaphragm pump intended for use in caravans with a pressurised accumulator to damp out pressure pulses. We do have a control valve - a little clamp with an adjustable screw! The pump output splits; part goes through a deionising filter to keep the conductivity of the water down and the rest goes through the jet playing on the cutting area. It's possible to juggle the relative flows but it's an adjustment that I have not played with. Depth of water is a bit critical - too low and it doesn't flood the work (sparking is much more effective under water or the right kind of oil, believe it or not), too high and the splashing ends up in the electronics. Bad news - the machine's first outing came to an end during the first cut when spillage on to the control panel shorted out something critical which meant a new PC board was needed. A good question to which I do not have the answer is, "but why did non-conductive water short something out?" It just did!