J&S 540 on VFD

I have the chance to buy a Jones and Shipman 540 surface grinder. It is not a "P" model with power rise and fall for the wheelhead.

My question is can it be run on one VFD inverter or will I need one for wheelhead and one for hydraulics ?

Some VFDs are OK to run 2 motors together, some aren't. But generally you don't want to be connecting a stationary motor to an already-operating VFD, so unless the machine can operate correctly with motor motors always running simultaneously, you would need separate VFDs.

Do the motors need to start and stop independently?

When you run 2 motors simultaneously, there are some settings you need to change, such as disabling the thermal protection. Details in the manual...

Thanks Muzzer if I go ahead with the machine I will use two. Normal operation is to start the hydraulics and leave on. Wheel only normally stopped when changing or setting up. I will take a couple of test pieces to try the machine when I go to inspect it.

Almost sounds as if you could get away with just one from what you say. Might not be too expensive either way eg these boys.

I guess you may need to make provision for the coolant tank motor as well?

Chris Gunn

That's usually a piddly small motor and can be connected across the main motor. This is what I did on my Bantam. The only slight downside is that the flow rate varies with the motor speed but I simply adjust the valve to compensate. It's hardly critical.

On the Bridgeport clone I used a (single phase) Grundfoss central heating pump because it didn't come with a coolant pump. That works very nicely too.

For a coolant pump I'd wire it with capacitors as described in the book Electric Motors in the Home Workshop **LINK**

I did this mod on a Ferret tool grinder, it works fine as long as you don't want to start with a big load on.

You can also make 440V contactors work with an in line capacitor by making up a tuned circuit, don't ask me how to work out the capacitor, I'm getting too old!

No coolant tank with this one, I will most likely use the shop vacuum as a dust extractor.

I am surprised there is no coolant tank, I remember them having quite a big unit with a settling tank to separate the grinding dust. I am not sure what work you intend to do, but I would have thought coolant is essential to get the best out of the machine. I ran one for 6 months during my apprentiship on production work and coolant was always on.

Chris Gunn

Chris, if I do have the machine it is only for the odd job where a ground finish is required instead if milling. Grinding "dry" I have done for over 50 years, the only grinders I used coolant on where the bigger surface grinders and cylindrical grinders where the coolant is essential. I will be grinding things like motorcycle cam followers and small parts.

I did a lot of dry grinding as well. It was more the norm but there was one hell of an extraction unit fitted that served the entire grinding area. Around a dozen machines.

I found out that the suction was enough to suck up a rather large flying diamond. Actually I think it was really a piece of poorly mounted glass intended to catch people out.

Some of the woodworking extraction units use AC motors and are much quieter than other types.

I'll include cylindrical and bore grinding dry. Coolant was hardly used.

John

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Edited By Ajohnw on 19/08/2016 08:57:32

I've found that one can easily reconnect a coolant pump into Delta and run it one a single phase supply by connect a 4 micro farad across a pair of terminals and the 240 volt to the vacant terminal and any one of the already used terminals. Also the dust is unpleasant to say the least so coolant improve finish and controls the dust.John

I served my time at a manufacturer of high speed rotary printing machines where grinding was the norm to finish large precision rollers plus many surface ground parts, and coolant was used for everything. Not only did this keep the dust down and allowed good metal removal rates but also ensured the finish was good with no burning on the surface. I remember that if the coolant was off on the J&S, one could get a brown scorch mark on the surface taking a thou cut, so coolant was the norm.

Chris Gunn