Wolf bench grinder

[Lurker]

I bought this 8” grinder about six years ago with the intention of refurbishing it.
A house move and other stuff got in the way.
This morning I bought it from the store shed into the workshop, it’s so heavy it was just within my capability but it made me puff a bit
I intend to rewire it with a new cable and NV switch, but I gingerly powered it up before I started doing anything.
It was a bit slow in getting going but it is a heavy load, the thing was it went backwards! Bugger! I switched off at the socket and it took ages to become stationary, so the bearings are good! I started it up twice more and this time it turned in the right direction.
Any idea why it would do this?

 

[Lurker]

Any idea what the black rectangle in the right hand photo is?
Given the overall weight , I’m wondering if it’s a lump of iron, it’s not lead as it’s not soft enough.

Edit: box has wires going in and out, I have decided not to disturb it/ them.
I wonder if the motor is basically a three phase that the Wolf factory repurposed for single phase.

 

[Woodbloke]

The original Wolf kit is really solid. I still use a Wolf 'Saphire' power drill bought in the mid 70's. I even saw somebody giving it some big welly trying to drill a large 'ole in masonry; he didn't burn out the motor out but did completely knacker his drill bit - Rob

 

[DaveL]

Jim,
It probably has the capacitor for starting the motor in it. Depending on the type of motor there could be two in there.

 

[Jonathan]

Another thought….is it’s a transformer?

 

[AndyT]

Don't forget that Bob 9Fingers left us his detailed notes about motors:

Induction_motors_Issue3.pdf

drive.google.com

 

[Trevanion]

As Dave said, the box is likely housing the start capacitor for the motor, which may be what's causing your polarity issue if it has become degraded, as it's not giving enough initial power to the winding to make it rotate in the correct direction.

 

[Lurker]

When it went in the wrong direction, I immediately thought capacitors.
I am now slowly rewiring between other jobs and hopefully it’s actually ok.
Just for fun, I’m going to put it on the bathroom scales to see how much it weighs.
I am going to build a castor mounted plinth for it as I certainly can’t lift it onto the bench when I need it like I do with my current one.

Edit:42kg !

 

[Guineafowl21]

I have a similar Wolf 8”, rescued, literally, from the scrapheap (£10!). The black box is an old Dubilier capacitor which might need replacing.

The motor is a permanent split capacitor type, so you’ll need a run-type motor capacitor of the same uF and voltage ratings.

The old capacitor might contain nasty PCBs (polychlorinated biphenyls), so take care when handling and disposing.

 

[Lurker]

Update.
I have rewired it:
Cord set from a washing machine.
New cable strain relief.
Shrink wrapped the rubber wires.
added an extra earth point
Fitted NVR switch.

Dressed the wheels, which look nearly new.
I may strip paintwork and re spray, but will leave that until the warmer months.

It still occasionally (1 in 10 starts ) runs backwards but there’s plenty of power at the wheel when in use.

 

[AndyT]

Nice one. Very satisfying to rescue something so big and solid.

 

[Pete Maddex]

Update.
I have rewired it:
Cord set from a washing machine.
New cable strain relief.
Shrink wrapped the rubber wires.
added an extra earth point
Fitted NVR switch.

Dressed the wheels, which look nearly new.
I may strip paintwork and re spray, but will leave that until the warmer months.

It still occasionally (1 in 10 starts ) runs backwards but there’s plenty of power at the wheel when in use.

Pictures?

Pete

 

[Lurker]

Pictures?

Pete

Nothing really to see, use your imagination