Help/advice with Myford motor and switch

[bazmak]

On my Myford restoration thread i have almost finished no 3.Looked at and cleaned up the motor
This one is wired directly to a 3 pin plug and not thru a forward/reverse switch.As i have very limited electrical knowledge i would like help and advice. With a screw on spindle and being able to reverse thru the tumbler
gears i think reverse is not really needed. I have never used it and can think of no reason to.?
However as i have to obtain a switch and if the motor is able to be wired for forward and reverse then that
i shall do.I beleive that if the motor has 4 conns then this can be done.I have posted photos of the motor
Question,can the motor shown be reversed and if so where can i get a suitable reversing switch.Any advice
most welcome and if we get there a wiring diagram. Many thanks Barry

 

[goldstar31]

On a contentious note( for some people), do you really want to reverse the running of the spindle?

In my experience, chucks tend to unscrew--- or do on old Myford lathes

And yes, Dewhurst switches are apparently, regarded as unsafe!

Regards

N

 

[bazmak]

Hi Norm,as i stated in my post is reverse really needed and why did Myford always supply f/rev drum switches
I will be happy to fit a forward on/off switch but just needed the thoughts of others first

 

[goldstar31]

Barry

In another world, I represented the local electrical supply industry in court cases.
It's rather nice to have had their pension cheques for the last--- 35 years so 35 times 12 months. Whey hey but regulations change and so for the Dewhurst switches. Safer to have a certified electrician in this newer world

Meanwhile, 'By Jove how the money rolls in- rolls in!'

N

 

[Charles Lamont]

Just making absolutely sure: there is no label inside the terminal cover?

 

[goldstar31]

Let's say- I actually have a similar Hoover on my ML10- but I'm not taking it to bits.


My ML10 handbook gives the information for the English Electric motors-- which have numbered terminals as follows:-

1 and 4 Starting winding
2 and 3 Running winding

I accept NO Responsibility as previously stated-- very firmly.

 

[Blogwitch]

Hi Baz,

When I upgraded (downmotored) my Atlas 10F to a half horse four pole (to slow it down) I used this type of switch to do the honours and it worked perfectly for many years.

These seem to be out of stock at this time but should be available somewhere in your country or china.

http://www.chesterhobbystore.com/nvr-switch---with-forward-reverse-switch-5761-p.asp

Hope t5his helps

John

 

[RM-MN]

That motor seems to be a "split phase" motor with a start winding and a run winding. To reverse one you would reverse the wiring to the start winding. The cover plate for the wires should have the wiring shown on it so you know which is the start winding. Here is an article about how it is done.

https://woodgears.ca/motors/reversing.html

 

[bazmak]

thanks rm-mn.The terminals 1,3,4 and 6 are connected to the windings but the power supply
is only connected to the 3 and 4.In a split phase motor would the power be connected to the start windings or run windings ?
I would get an answer by conn the power to terminals 1 and 6 to see if the motor reverses. but might not like the answer
I dont really need or want reverse so may take the safe option and just fit a stop/start switch

 

[WOB]

There are a few occasions where spindle reverse is nice to have. One is spring winding( assuming you can slow down the spindle sufficiently). I prefer to watch the coils forming when the wire feed is over the top and away from the chuck. Another use is power tapping with the tap in the tailstock chuck. Much more convenient to back out the tap under power. Now, my lathe has a threaded spindle, but it also has a VFD for speed control. The lowest spindle speed is 50 RPM which makes the above operations easy. If your lathe cannot run slow enough, then I agree with your option to just use a stop-start switch. If you do go to VFD drive sometime in the future( I recommend it highly), all the control functions will be implemented thru the VFD control circuits and this much improves lathe operational flexibility.

WOB

 

[redhunter350]

Hi Barry , first I am not an electrician and knowledge is limited to simple electrics
However I have run a Myford with a Dewhurst switch for over 50 years and no problems , now on VFD why I waited so long goodness knows! As far as reverse IMO yes go for it if only for the reasons already stated, yes chucks can unscrew but it’s rare if fitted correctly and you are sensible with material removal rates etc
You can add preventative measures to the chuck mounting as well if you wish
As for wiring I have a diagram I can send you if you message me on my email it’s actually from the Myford book
Cheers John

 

[bazmak]

Thank you all for your advice and i am slowly getting there. Thank you Charles for telling me to look inside the conn. cover
Barely visible and only readable with a jewellers loupe but its there. The motor is reversable but i have decided to go the simple
route and fit a comm. slide on/off switch and just have forward. Just need to recable the motor and fit the switch.Any advise
on the conn for the switch ?? Motor fitted and lathe up and running

 

[RM-MN]

thanks rm-mn.The terminals 1,3,4 and 6 are connected to the windings but the power supply
is only connected to the 3 and 4.In a split phase motor would the power be connected to the start windings or run windings ?
I would get an answer by conn the power to terminals 1 and 6 to see if the motor reverses. but might not like the answer
I dont really need or want reverse so may take the safe option and just fit a stop/start switch

The incoming power is always connected to the run windings. The start windings are momentarily connected to control the direction and to give the motor the initial spin up, then disconnected automatically by a governed switch internally. I think you need a double pole, double throw switch so you can control which way the current flows through the start windings a the same time power is connected to the run windings. Someone else will have more info on that as it has been years since I have done that.