Eagle No2 Surface Grinder

I've just bought an old Dronsfield Eagle no 2 Surface Grinder, and I
need a little bit of help with the electrics (bear with me here, as I'm
more than a bit electrically dyslexic).
The item was sold as 3-phase, has a Brook 'Gryphon' motor labelled as
3-phase, but only appears to run on 3 wires. Wiring from the motor goes
into a standard MEM 15 amp isolator mounted on the machine but has only
one red, one blue, and one yellow wire.
I've always known the 3-phase machinery we use in the factory to have 3
lives, a neutral, and an earth.
Now I know this thing must be around 40 years old, although it's in
surprisingly clean and unworn condition, but were 3 phase wiring or
motors this different back then?
Ultimately I want to run it off single phase in the garage.
Thanks
Peter
Reply to
Peter Neill
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3 Phase comes in two forms 1. the motor you have but that is missing the earth which you could add seperately and 2. the one you describe which has a neutral. The neutral is only used if your grinder has the added need of single phase electrics i.e. a lamp would be powered by the neutral and one of the other phases.
Martin P
Peter Neill wrote:
Reply to
Campingstoveman
No Peter that's right. Red, Blue, Yellow are the 3 phases. Earth should be bonded to the frame of the machine.
What you know as three phase in your factory is actually three phase and neutral. Neutral is only needed if you have to run 240 volt single phase equipment like portable electric tools.
-- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
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Reply to
John Stevenson
Martin & John, thanks for that info. If I can trouble you both again, do you think a a motor of this age would be compatible to run off a phase convertor, and if so, could you point me in the direction of a reasonably priced item? The motor is 1hp with a speed of around 1450rpm. Thats as much as I could read off the nameplate without de-mounting it. Electrics are a curse with me. I've always considered myself to be reasonably mechanically competent, but the moment I'm faced with much more than a 3-pin plug I draw a total blank. Thanks
Peter
Reply to
Peter Neill
Peter, No reason why this shouldn't run off a phase converter. try these people, no connection but I have had some converters from them with no problems.
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-- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
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Reply to
John Stevenson
Peter
Did you buy this at Grabors sale today? Was it any good?
Before you go further have a look at the motor in detail. On the motor itself take off the cover and see if it has 3, 4 or 6 terminals. This tells you whether you can run on a converter or a cheaper inverter. If you want email me photos ( if you can) and I'll help.
Regards
Charles
Reply to
Charles Ping
Thank you Charles, I will pull the motor tomorrow and have a look, as it's set too far inside the base to easily check other wise. I may well take you up on your kind offer of help. I didn't get it from the Grabor sale, it was a buy from e-bay actually. I'd been looking for a small grinder for a litle while and was lucky that this came up at the right price.
The sale today was a bit mad. I think I'll avoid public auctions in future and stick to tenders, the pricing was so unpredictable. Used Bridgeports(without any tooling) went for over =A32000, while a CNC Hurco went for well under =A31000, and a lovely J&S 1400 grinder complete with 18" eclipse mag chuck only fetched =A3200.
One scrap dealer had a field day buying all 3 15metre high by 3metre dia aluminium silos for less than =A32000. An HP plotter that I was prepared to pay =A3500 for went for =A31300, and when you add on the 10% buyers premium and vat this was only =A315 less than a new one. I did come away with an A-frame gantry and hoist for =A340, but other than that the day was a bit of waste. The Fritz Werner eventually went for =A3270.
John, thanks for that link. I'll take Charles' advice once I've shown him the motor and then follow it up.
Regards
Peter
Reply to
Peter Neill
Sounds a bit mad - a J&S 1400 for £200 is ok though....
An A frame and hoist eh? What weight capacity?
Regards
Charles
Reply to
Charles Ping
The chain block is only 1/2 tonne rated, but the A frame itself is very substantial and uses sections twice the size of the 1Tonne+ gantry we use at work. The nice thing about it though is that it's almost garage/workshop size, with an overall height of around 7ft and a width between the frame of about the same. I need to break it down into sections and get a van before the end of next week to get it out of the place now. I haven't got a use for it yet, but it was so cheap I couldn't resist it. Kevins 'workshopping' hobby syndrome strikes again:)
Regards
Peter
Reply to
Peter Neill
I ran my old capco grinder (similar size & vintage) on a couple of large capacitors. You loose a bit of power from the motor, but grinders don't need lots of power anyway as your usually only taking fractions of a thou off. You often find these older motors are permanently wired in star mode, which will mean a bit of digging about in the windings to find and disconnect the star point.
Regards
Kevin
Reply to
Kevin Steele
I've found a similar motor in single-phase that could be used, but it's 1.5hp rather than the 1hp 3-phase that's currently on the machine. It shouldn't need that much power as I'll never (rough) grind more than 3 thou' anyway at the maximum, but is there any reason that I shouldn't fit this on? I remember reading somewhere, on Tony Griffiths' lathe site I think, that if you're replacing a 3-phase with a single phase motor you need an increased power rating of betwen 30-50% to maintain the same performance. All advice appreciated.
Peter
Reply to
Peter Neill
Shouldn't be a problem to go for 1.5 HP. IMHO it's more important to get an easy swap than have the exact power match.
Charles
Reply to
Charles Ping

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