Variable speed 9" disc grinder build

[rmack898]

Nice work.
Having just finished a batch of parts with black oxide for the first time and being very pleased with the results, I highly recommend it for your steel parts.
Anodized aluminum always looks great.

 

[melsdad]

Things are coming together now! Got the base plate and motor riser block complete.

 

[melsdad]

I was able to assemble most of the parts today. The last part is the table and to get the magnets installed in the hub.

 

[mzayd3]

how did you machine the slot for the table pivot clamps? looks terrific! nice work:goodjob:

 

[melsdad]

I had the slots cut on a wire E.D.M machine. That's not cheating is it....lol

I would have needed a slitting saw about 6" in dia. To clear the arbor and get the depth I needed. I didn't have that and i didn't want to bandsaw the slots and risk messing them up at this point.

 

[melsdad]

Got the table finished this morning. Except for the slot for the bevel gage. That will be later.

Cutting the recess in the table



Releaving the underside of the table so it can be tilted to 45 deg. And be close to the disc.



Axle mounted to the table


In position

 

[Arkie]

That's pretty interesting how you built the table. I guess trunnions would be the standard way, but they might be harder to machine.

Do you have any shots or a description about how you made the disc? I'm thinking about building one of these grinders to complement my 2 X 72.

 

[melsdad]

The discs took a good bit of time. I had them lazer cut out of 1/4" steel plate. They were not very flat so they needed to be surface ground. To get something flat that is not flat takes planning. You can't just put a disc on the magnet and grind it. You need a surface plate and a variety of shim stock. With a dial indicator on the disc you need to shim the gaps under the plate all around till the needle is dead still. Then those shims need to be transferred to the magnet in the same location. I ground the discs till they cleaned up. Now when flipped over and cleaned up both sides should be flat.

You can see the shims under the disc in these pictures.



Alll cleaned up

 

[melsdad]

Once the discs were flat I trued them on lathe. I grabbed the o.d. in a 6 jaw chuck and bored the I.d. of the discs to a slip fit of the aluminium hub. The I made a fixture that mastered off of the I.d. and turned the o.d. of the discs to 8.875 dia. My thinking was that a standard sheet of sand paper can eeasily be applied and trimmed with a razor flush to the disc.

I also turned a 30 deg. Relief bevel on the back side of the discs for clearance when grinding inside corners.

The fixture




Disc held in place with a 4" washer.


Cutting the bevel


Fiinished product

 

[pineyfolks]

Excellent build and very well documented.