J&S 540 on VFD

This topic has 13 replies, 6 voices, and was last updated 19 August 2016 at 10:01 by Chris Gunn.

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17 August 2016 at 08:48 #251090
Chris Evans 6
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@chrisevans6
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 ?
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17 August 2016 at 08:48 #32762
Chris Evans 6
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@chrisevans6
17 August 2016 at 12:47 #251120
Muzzer
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@muzzer
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…
17 August 2016 at 13:26 #251127
Chris Evans 6
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@chrisevans6
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.
17 August 2016 at 13:51 #251128
Muzzer
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@muzzer
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.
17 August 2016 at 20:42 #251183
Chris Gunn
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@chrisgunn36534
I guess you may need to make provision for the coolant tank motor as well?

Chris Gunn
17 August 2016 at 20:48 #251185
Muzzer
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@muzzer
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.
17 August 2016 at 21:28 #251195
duncan webster 1
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@duncanwebster1
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!
17 August 2016 at 22:39 #251216
Chris Evans 6
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@chrisevans6
No coolant tank with this one, I will most likely use the shop vacuum as a dust extractor.
18 August 2016 at 10:20 #251279
Chris Gunn
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@chrisgunn36534
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
19 August 2016 at 07:30 #251426
Chris Evans 6
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@chrisevans6
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.
19 August 2016 at 08:51 #251437
Ajohnw
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@ajohnw51620
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
19 August 2016 at 08:53 #251438
john fletcher 1
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@johnfletcher1
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
19 August 2016 at 10:01 #251458
Chris Gunn
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@chrisgunn36534
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
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