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Help re: motor & Dewhurst switch wiring for Boxford lathe please?

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David Sheppard 104/12/2019 17:41:13
4 forum posts
3 photos

I wonder if anyone can help me with a wiring query re: the above please? I have tried searching the forums but can’t find an answer to my specific setup.

I have recently purchased a Boxford CSB lathe with a Gryphon single phase motor and a Dewhurst type A switch and I am keen to connect the latter to the motor but am unsure of the connections required.

The motor currently runs in the wrong direction for my installation but I don’t know if the reversing switch was connected to this motor in the past.

On taking off the terminal cover on the motor there are three terminals numbered 1, 2 & 4 on the mounting board (from top to bottom). The incoming live was connected to terminal 1 and the incoming neutral to terminal 4.

There are internal motor wires connected and labelled as follows:

Terminal 1 - one unlabelled black wire

Terminal 2 - three black wires, labelled Z1, T1 and one unlabelled

Terminal 4 - Two black cables labelled T4 & T8.

The Dewhurst switch has three brown conductors labelled 1, 2 & 3 and there is an earth.

If anyone can guide me as to how to connect up the Dewhurst switch it would be much appreciated!

Thanks in anticipation,



JohnF04/12/2019 20:23:08
1013 forum posts
143 photos

David i am sure others will be along to advise but I can send you a wiring diagram for a Myford & a Dewhurst switch which will probably be helpful-- if you want it please PM me with your email address


David Sheppard 104/12/2019 20:56:52
4 forum posts
3 photos

Thanks John.

You have PM.


Paul Lousick04/12/2019 23:05:39
1501 forum posts
572 photos

David, do a search in the box above for " Dewhurst ". lots of previouse posts on MEW. Im not an expert but not all single phase motors are reversible.


Edited By Paul Lousick on 04/12/2019 23:06:03

David Sheppard 105/12/2019 09:45:12
4 forum posts
3 photos
Posted by Paul Lousick on 04/12/2019 23:05:39:

David, do a search in the box above for " Dewhurst ". lots of previouse posts on MEW. Im not an expert but not all single phase motors are reversible.


Edited By Paul Lousick on 04/12/2019 23:06:03

Thanks Paul.

i have done quite a bit of searching but can’t find anything in relation to the specific type of motor that I have. Whilst Gryphon motors are quite common I haven’t been able to find any reversing details for a motor with three terminals like mine.

I wonder if you are right in that this motor is one of those that is not reversible?


Emgee05/12/2019 10:08:06
1652 forum posts
224 photos

David, the switch wiring instructions are useless to you unless you know which terminals have the start and run windings.
I suggest you start by removing the 2 screws holding the paxolin connection plate, move this to see if there is a centrifugal switch fitted. If there is the connections to the switch will be live and 1 end of the start winding, the other end of the start winding can be found by removing 1 of the wires connected from the posts where 2 are connected, a low resistance meter will indicate the other end of the start winding.
You need to identify each cable on the terminal connection board before connecting to the Dewhurst.

If you don't feel confident working with the terminations then best find a local well informed electrician.


Oldiron05/12/2019 10:24:51
483 forum posts
22 photos

David. You may get better results if you Google "brook gryphon 1 phase motor reversing".

I did and found a lot of info in the Images section.

Also is a useful source of info as is YouTube.

Hope this helps.


David Sheppard 105/12/2019 11:52:37
4 forum posts
3 photos

Thanks both for your comments/suggestions.

Emgee - that’s really useful re how to ID the start windings.

Oldiron - I hadn’t seen the Instructables website before - looks really useful. I had done quite a bit of googling before coming on here but hadn’t been able to find info re my specific motor. I hope that I have enough now to be getting close to a solution!

Thanks again everybody - I’ll report back in due course but may not be for a few days as I now have an old motorbike that’s not starting today that requires my attention!!


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