looks like I used a 12.5 Uf 440v on this one.

I have done several conversions to single phase of fractional HP motors by just putting a capacitor across one of the windings in delta configuration. As long as no great starting torque is required the motor will start slowly and then run up to speed in a couple of seconds. I have a Clark T&C grinder, a Pollard high-speed drill and a diamond faced wheel grinder configured like this and they all run perfectly well. The capacitors I used came out of old florescent light fittings. I suspect a suds pump requires no great starting torque so you should be OK by doing this. I got the capacitor values from the Workshop Practise series book 'Electric Motors'. There is a table in there that gives the size of run capacitors for motors of various power and also start capacitors if you wanted to add a bit more circuitry for greater starting torque.

ME published a simple electro-mechanical circuit that I designed, circa 1993, which was based on the support circuit given in Electric Motors but which allowed a 3-phase machine to start and stop using the original start/stop buttons. I have a 3-phase Boxford 8" shaper working on single-phase with all original switch gear still in place but re-wired/modified to include my support circuit. I similarly converted a power hack-saw and it worked fine too.

Is the lathe running on a VFD? The added load of the suds pump would probably not be noticed by a VFD and all would be normal, except if you are running at a low speed. Suck it and see.

I've used a 4 micro farad at 400 volts ex 4 foot fluorescent light fitting for my Harrison/Colchester friends, that was 5/10 years ago and they are still working OK. For those who don't know, connect capacitors in parallel to increase capacitance value and in series to decrease. So, two 4 in series equals two micro farad and same pair in parallel equals eight. All capacitors should be tested at their working voltage 400, not the 9 volts of most digital multimeter John

By placing two or more capacitors in parallel you are effectively increasing the plate area and so increasing the effective capacitance. When placed in series, you are increasing the distance between the plates and this reducing the effective capacitance.

What,s wrong with using a pump from a scrap washing machine ?

Been using one of those on my bandsaw for the last 10 years or more, simple, cheap, effective.

Good morning Andrew,

You are not missing anything, I simply mentioned this in case it might be of interest to others.

A tank is no problem, on old cooking pot will serve well enough.

Please accept my apologies for any upset, just convert .

For reasons I never understood, chemical engineers where I worked used to control flow from centrifugal pumps by by-passing some of the output back to the input rather than throttling the output. Then came vfd but the electrical chaps had to be dragged kicking and screaming, their objection being something to do with waveform.