Lathe Wiring, Motor to Dewhurst Fwd - Rvse Switch


Postby maximat » Sun Dec 30, 2007 5:36 pm

How do all, Hope Christmas was a safe one for all of you DIY people.
Maximat here again with another Motor / Lathe problem.
So here we go,

Crompton / Brookes 240v Motor.
BHP - 1/6
Ph - 1
Rated - Cont.
.._..--.._.. - 50

Wiring terminals inside motor cover plate are as. T, A2, A, Z, E, Info inside plate states "to reverse rotation interchange Black and Blue Motor Leads at terminal A & AZ".

At present the 240 is wired as, Blue to A2.
Brown to A.
Gr/Ye to Earth !!

Terminals are wired as, A2 to Black going to motor windings
A to Black going to motor windings but also connected with fixed wire to Z
T to nothing at present.
E to Earth

Question is...I want to use a "Dewhurst and Partner" Reversing drum Switch...any thoughts on how to connect it up ??, I have read that four leads are needed to exit the Motor ? can you get 4 core ?..then what ??.


If anyone can help it will be much appreciated indeed, small byte-size diagrams are (hopefully) below of the Motor terminals, and a pic of the interior of the Dewhurst if that helps.

Please can you help me..again, really pathetic Lathe man need Help please.
Happy New Year to you all, cheers..Maximat (Ian)

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Postby 333rocky333 » Mon Dec 31, 2007 12:18 am

You can get 3 core and earth, and 4 core and earth in both flexible and solid cable.
As well as swa 4 core with steel earth.
Sleeve the cores to relevant colours for purpose if necessary.

You may be better though with single cables and earth in flexi conduit for mechanical protection to suit the work enviroment

All easily obtained up to about 2.5mm, as used for 3 phase and neutral and fan controls etc.
Bigger sizes available to order

As for connections i will pass for now
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Postby sparx » Mon Dec 31, 2007 7:15 pm

Hi, Maximat,
The unused T term is prob. a thermal cut out in the winding core so can be ignored, it's only any use if using a full blown starter.
Without getting too involved in the type of motor it sounds like a 'capacitor start & run' type.
If this is so then as well as two wires going to external capacitor from A & Z there will be 4 wires going in to motors winding a 'run' winding and a
'start' winding. You need to be able to reverse the connections to the 'start' pair, ie remove them from the terms. they are on, extend them out as a pair, then add a pair of wires to their original terms so you then have 4 wires in 2 pairs which can be reversed. I would use a domestic 'Intermediate' light sw, off load in workshop to prove system then try to get drawing of proposed reversing sw. and compare operation of contacts with int.sw ops.
The' Start' winding should be the ones the manufacturers drawing (in lid?)show,
good luck,
SPARX
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Postby 333rocky333 » Mon Dec 31, 2007 7:44 pm

sparx

Nice work
I thought that too but was not 100% sure

One question though
Would the motor need to be powered off first each time and allowed to stop rotating first.

would there be a problem if the winding was SWITCHED OVER whilst motor still rotating or the supply was still on to it.

Just worried in case he blows motor or winding.

Is it the same one he has cherished 30 years!
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Postby 333rocky333 » Mon Dec 31, 2007 8:42 pm

Dont the lathe need adapting also, so the chuck DONT spin off!!!!
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Postby sparx » Tue Jan 01, 2008 9:26 pm

Hi all good ? rocky, yes if switched over at speed would probably blow fuse, I assumed it is a wood lathe, & as with mine does not use a chuck as such just 'dogs' to drive spindles etc & my 'face plate locks on so rotation not a prob.
My metal turning lathe has inbuilt reversing by gears &/or it's variable speed & reverse motor Very old AC 'repulsion' motor Circa 1940's.
chuck never undone yet ....ummm wonder why.....must check!
regards SPARX
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