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Old MKVII motor

Posted: Tue Aug 13, 2019 9:36 am
by bigk01
I haven’t torn into it yet, but I was using my ‘67 mkvii last week with a small wire wheel in the chuck, when one time when I went to turn it on it wouldn’t run in the forward rotation. It just hums and vibrates.

It seems to run fine in reverse.

I’m hopeful that it’s maybe just the switch.

I would appreciate any thoughts or suggestions from the experts before I take it apart.

K

Re: Old MKVII motor

Posted: Tue Aug 13, 2019 10:06 am
by JPG
bigk01 wrote:I haven’t torn into it yet, but I was using my ‘67 mkvii last week with a small wire wheel in the chuck, when one time when I went to turn it on it wouldn’t run in the forward rotation. It just hums and vibrates.

It seems to run fine in reverse.

I’m hopeful that it’s maybe just the switch.

I would appreciate any thoughts or suggestions from the experts before I take it apart.

K
Leave the motor alone!

Dive into the switch(not a pleasant task).

Do NOT do the hum test often nor 'longly'.

The contacts lose their spring with use/age.

VERY carefully 'form' the spring contacts.

If arcing has eroded the contacts, all bets are off.

Re: Old MKVII motor

Posted: Tue Aug 13, 2019 3:53 pm
by bigk01
Thanks for the reply.
Believe me the last thing I want to do is mess with the motor.
As soon as I get a little time, I will pull the headstock and try to rebuild the switch.
Thanks again,
K

Re: Old MKVII motor

Posted: Tue Aug 13, 2019 6:29 pm
by beeg
You don't need to pull the headstock. Just undo the nut holding the switch. BEFORE ya disconnect the switch, take a pic so ya know where the wires go back to.

Re: Old MKVII motor

Posted: Tue Aug 13, 2019 8:46 pm
by JPG
beeg wrote:You don't need to pull the headstock. Just undo the nut holding the switch. BEFORE ya disconnect the switch, take a pic so ya know where the wires go back to.

ALL 8 or nine wires???? :D

Re: Old MKVII motor

Posted: Tue Aug 13, 2019 11:28 pm
by beeg
JPG wrote:
beeg wrote:You don't need to pull the headstock. Just undo the nut holding the switch. BEFORE ya disconnect the switch, take a pic so ya know where the wires go back to.

ALL 8 or nine wires???? :D
YES!

or the next question will be "WHERE do these wires connect." :D :D

Re: Old MKVII motor

Posted: Wed Aug 14, 2019 12:07 am
by everettdavis
beeg wrote:
JPG wrote:
beeg wrote:You don't need to pull the headstock. Just undo the nut holding the switch. BEFORE ya disconnect the switch, take a pic so ya know where the wires go back to.

ALL 8 or nine wires???? :D
YES!

or the next question will be "WHERE do these wires connect." :D :D
I can help with that just a bit. https://www.shopsmith.com/ss_forum/view ... 90#p185690

Follow the My Google Drive link, select the "Mark VII - 1960's vintage" folder

When you start seeing things like these..... download what you need. It's Free

There are even some blank motor wiring diagrams in case your colors are different that allow you to define what you have. Pictures are good, but colors sometimes get sketchy.

Everett
Mark VII Stuff.png
Mark VII Stuff.png (192.77 KiB) Viewed 18087 times

Re: Old MKVII motor

Posted: Thu Aug 15, 2019 1:19 am
by StevenAyres
bigk01 wrote: one time when I went to turn it on it wouldn’t run in the forward rotation. It just hums and vibrates.
I had the same experience shortly after I started using my VII. After checking out the wiring carefully, I narrowed the problem down to the start capacitor. Mine was a GE motor.

Re: Old MKVII motor

Posted: Thu Aug 15, 2019 8:13 am
by JPG
StevenAyres wrote:
bigk01 wrote: one time when I went to turn it on it wouldn’t run in the forward rotation. It just hums and vibrates.
I had the same experience shortly after I started using my VII. After checking out the wiring carefully, I narrowed the problem down to the start capacitor. Mine was a GE motor.
Ah, but, his only fails in ONE direction, hence the switch is de prime suspect.

Re: Old MKVII motor

Posted: Sat Aug 17, 2019 8:59 am
by bigk01
Thanks again to everyone who has replied.
I just took a quick look and I can’t see anyway to get at the switch without talking the headstock off the rails. It doesn’t look like the motor cover will drop between the lower tubes.
Am I missing something?
It’s a little tough wrestling the headstock by myself, but I have done it before.