Shopsmith Forums

How did you ascertain a defective motor by rotating the saw blade and how did you 'confirm' that?

The damage done to the speed control is typically mashing of the teeth on the quadrant gear(porkchop) and deformation of quadrant gear pivot legs.(fixable)

The later induction motor is 1 1/8 HP and is a direct replacement. I would not 'upgrade' until I had determined it is necessary.

If your 'confirmation' was due to it not running, look for why before assuming it requires replacing.

Now the belt running on the idler shaft may be an indication of the control sheave missing the bearing etc. on the end that rides on the quadrant gear. A pix will confirm that. Also fixable!

Welcome!!!!

JPG wrote:How did you ascertain a defective motor by rotating the saw blade and how did you 'confirm' that?

The damage done to the speed control is typically mashing of the teeth on the quadrant gear(porkchop) and deformation of quadrant gear pivot legs.(fixable)

The later induction motor is 1 1/8 HP and is a direct replacement. I would not 'upgrade' until I had determined it is necessary.

If your 'confirmation' was due to it not running, look for why before assuming it requires replacing.

Now the belt running on the idler shaft may be an indication of the control sheave missing the bearing etc. on the end that rides on the quadrant gear. A pix will confirm that. Also fixable!

Welcome!!!!

JPG... thanks for the quick response! As always, good questions are the first step to good solutions!

When I hand rotated the blade at the estate sale I felt significantly varying degrees of resistance during the course of each revolution. A follow-up powered check of the motor in my shop resulted in (very) slight initial rotation and then full stop. The o/o switch is good and all external wiring and connectors are undamaged.

Without going any deeper than the removal of the headstock covers, my inspection showed the sheaves moving in what appeared to me to be a smooth and even manner when I rotated the Speedial. The belts show no sign of "trauma", i.e. burned or abraded sections. The catch here, of course, is that this is new ground for me so I may not really know what it is I'm looking at/for.

I believe my next course of action should be to start watching some of the numerous videos noted on the SS forum (the "sawdust series" sounds promising) to get a good baseline of general knowledge about the Mk5. I like to do do my own maintenance, but I'm also a firm believer in "physician- first, do no harm", so I'll proceed slowly. I also remember the advice given to me by one of my first "sea daddys" when I joined the Merchant Marine years ago- "before you beat yourself half to death trying to solve a problem, first take a minute and find out if someone else already has".

I must say at the outset that I am extremely impressed with the SS community. I knew SS had a loyal following, but I had no idea it was so vast and wide ranging.

Cheers,

The differing resistance was likely due to belt deformation(they had taken a 'set').

If the motor was not humming loudly when it 'stopped', it likely had a sudden power interruption.

I would check the switch and wiring (electrical continuity).

An ohmmeter would be helpful!

Finally verify the bearing and wire loop are present on the end of the control sheave hub.

JPG wrote:The differing resistance was likely due to belt deformation(they had taken a 'set').

If the motor was not humming loudly when it 'stopped', it likely had a sudden power interruption.

I would check the switch and wiring (electrical continuity).

An ohmmeter would be helpful!

Finally verify the bearing and wire loop are present on the end of the control sheave hub.

JPG- Alas, the motor did hum heartily after stopping (until I opened the switch), and a continuity check of all switch related wiring was positive. Your mention of deformed belts being responsible for varying resistance to rotation never occurred to me (thanks, I've learned something already!) so I double checked them for pliability and they were ok. No funeral plans yet, but the future does not appear all that rosy for the old motor.

Cheers,

Dave

Check to see if the spring-loaded centrifugal motor start contacts return to the closed position and don’t have an obstruction between them. Without them closing the motor start windings are disconnected and the motor will hum trying to start from the run windings which it cannot do.


Some have an external motor start relay whose contacts can fail etc.

Everett

Humming is actually a good sign(as long as the duration was short). Jerking then humming is how they act when the start circuit is ineffective.

Start a new thread and we can proceed from there.

Hi JPG

From reading around, I see you're the expert on '60s era Mark VII so as a new owner, I have a question: on the lower sheave (at the motor) I understand there's to be a spring that needs to be pulled apart to expose the hole for the oil. I see a case over that spring, as shown in the exploded view as well. Any advice on the best way to take that case off so I can lubricate it?

thx
Ash

Same as Mark V. Pull the spring away from the sheave side to expose the oil hole.

Also snag the restored Mark VII Owners Manual in the Mark VII Folder BR following the My Google Drive link.

Everett

I got that manual, so thank you Everett. On there, I see an exploded view that has a case over the spring with a retainer ring. Am I to take the retainer ring off and expose the spring and _then_ pull it apart to expose the hole for the oil? Or am I misunderstanding something?

Specifically, on that manual on your Google Drive, on pg 46, Fig 88 shows how to oil that spring. And on pg. 54, item #21 is the case over the spring.

I hope that clarifies!

The oil hole is on the same area of the idler sheave as it is on the control sheave. Put it in high speed mode and turn it off. (Yes you will manually rotate the quill with machine off to wind it down to slow before turning it back on. In fast, the spring is not compressed tightly and you can pull it back without taking it off.

See a photo of the control sheave for where to look for the hole. If you have it in slow mode, that spring is so compressed there is no room to pull spring back.

Everett