Craftsman 1/4 HP Bench Grinder m-115.19500 - pre-Block style

These era CM grinders are heavy, well built, and appear on CL from time to time at fair (this one was $40) to inexpensive (I've paid as little as $15) prices.

I am in the process of restoring some other Block motor style grinders, but at least 1 other GJ member is in the process of restoring what appears to be the same model as this one. I tore this down to detail what maybe involved. Restoration will follow, but later rather than sooner.



It wasn't until I had it in the truck and was headed back to SE Michigan that I realized it was painted in the Ohio State team colors : Scarlet and Grey | UofM's big rival.


Here it is.










A common problem with this style eye shield is the tabs that hold the glass in place break-off easily. This pair has a tab pop riveted at the top. They will be replaced with small machine screws and nuts.


No date code on the bottom plate.


It has a 3-conductor power cord/plug, but the ground conductor is not connected at this end.


The cracked wires and sw cold-solder joints will be replaced and done properly.


Note: I am not 100% comfortable with the placement of the washers (felt & spring) and shims. The LH bearing is very 'dirty'. Leading me to believe the flt washer is out of position. Before re-assembly, a parts manual will be consulted, if available. This guy has been 'updated' with new colors and who knows what else was disturbed.

RH wheel guard removed - showing order of shim, felt washer, and shim with cup for felt washer.



LH wheel guard removed - showing order of shim, felt washer, shim with cup for felt washer, and spring washer.



Front and rear views, ready for removal of castings, after removal of {4} through nuts and bolts.



Close up of RH arbor/shaft. The surface marks will be removed to allow inner bearing race to slide over for removal. I will use 240 and 500 Emory cloth.


Close up of LH arbor/shaft. The surface just needs a light touch to remove oxidation/swarf to allow inner bearing race to slide over for removal.


The LH casting with the bearing was removed 1st. This allows easier removal of start-up centrifugal switch assembly that is screwed to the RH casting.


View of c. switch, one mounting screw, the 2 'white' wires to the c. switch - 1 from start-up stator (windings) & 1 from common conductor of power cord.

Another view of 'white' conductor from start-up stator (winding). Note: the wire insulation is brittle and has cracked. The wire will be cut at the c. switch and a new length spliced in, to replace the section that is no longer serviceable.


Diagram of motors.


The 'white' start-up stator (winding) conductor was cut, allowing the removal of the stator (windings).


View showing c. switch with start-up stator (winding) conductor cut, lower right corner.


View showing c. switch and RH casting after rotor removal.


Detail of RH casting, showing shoulder/ridge on inner edge of bearing mounting. The bearing must be removed with the RH casting. Therefore, the surface of the arbor/shaft must be smooth and free of obstructions.



Detail of LH casting, showing NO shoulder/ridge on inner edge of bearing mounting. The bearing can be removed with the LH casting or left on the arbor/shaft.


The bearings will be replaced, they felt and sounded like an old roller skate wheel.

I will be back later, much later, after blasting and painting the bits 'n pieces, and replacing the consumables.

Thanks for looking.

TM: amazing detail and pictures showing all parts to your pre-block. even though it's only a 1/4 HP i bet it had more power than the 1/2 HP versions you can buy new today. plus since it is opposing team's colors good thing it won't come anywhere near the 3/4 of Big Blue your Michigan grinder i dearly would like to hear run (how about a YouTube video of it revving up?).

just curious if you weren't taking all the pictures and making all the notes how long would it take you to take a block down all the way like you do? most of us would have problems with several of the steps especially removing the bearings so what are your secrets? slow and steady or do you also use a BFH?

Always good to 'hear' from you drivesit.

drivesitfar said:

TM: amazing detail and pictures showing all parts to your pre-block. even though it's only a 1/4 HP i bet it had more power than the 1/2 HP versions you can buy new today. plus since it is opposing team's colors good thing it won't come anywhere near the 3/4 of Big Blue your Michigan grinder i dearly would like to hear run (how about a YouTube video of it revving up?).
YouTube video ....? It's on the list then. Now, I need to take the next steps in this new fangled digital world. What ever happened to DOS 1.2 !??!
just curious if you weren't taking all the pictures and making all the notes how long would it take you to take a block down all the way like you do? most of us would have problems with several of the steps especially removing the bearings so what are your secrets? slow and steady or do you also use a BFH? I find I spend at least as much time to document/post, as I spend in the garage/shop working on the project. But, to answer your question for this project the tear down would probably have taken about 3/4 of an hour or a bit more. This was pretty straight forward and not too badly rusted up. The greatest amount of time was spent smoothing out the RH arbor/shaft so the bearing could be removed. I use a small hammer to persuade the well Kroiled pieces apart. The 2 in the picture below on the left, are used for working on British cars!
The greatest amount of time I spend is in the prep for reassembly - media blasting, electrical repair/recondition/modification, priming/painting.

Click to expand...

Almost forgot, I definitely need to conceal this guy's identity from Go Blue, until he's been converted to friendlier colors!

I'm adding some pictures of the grinding wheel assembly for reference.

RH side.

Sounds good, thanks.

I get the style, the quality of the motor, but what about the tool rests? Will you retro fit something better? Do you care?

I do a lot of free hand grinding, so maybe it doesn't matter too much to me, but there are times when I need a good stiff, straight square tool rest. Like when I dress wheels. Will you machine new ones? Are these better then they look?

My POS 8" Woodcraft slo speed grinder came with cast steel tool rests that will not sit square. But they were easily machined and are now half way decent.

Sorry I didn't realize this thread was 6 months old.

Hi Adam, I'll make my comments in Blue.

Adam.C said:

I get the style, the quality of the motor, but what about the tool rests? Will you retro fit something better? Do you care?
I will use the OEM tool rests, this little guy wit be used for cleaning of small fasteners, once fitted with wire wheels.
I do a lot of free hand grinding, so maybe it doesn't matter too much to me, but there are times when I need a good stiff, straight square tool rest. Like when I dress wheels. Will you machine new ones?
I don't plan to.
Are these better then they look?
They are just stamped steel and not intended for precision work.
My POS 8" Woodcraft slo speed grinder came with cast steel tool rests that will not sit square. But they were easily machined and are now half way decent.

Sorry I didn't realize this thread was 6 months old.
It's OK, I posted some pics recently, because there was a question about the spacers used on the arbor/shaft.

Click to expand...

Yours is actually two years older than my 1959 model; good to see both coming together.
Thanks again for all the info.

I found a source for arbor spacers; OD is 0.75" vs. 1.00" (OEM).

http://www.aluminumspacers.com/

Aluminum Spacer 3/4 OD x .509 ID x 3/4 Long AS75-22-48
Aluminum Spacer 3/4 OD x .509 ID x 1/2 Long AS75-22-32
Aluminum Spacer 3/4 OD x .509 ID x 1/8 Long AS75-22-8

torqueman2002 said:

I found a source for arbor spacers; OD is 0.75" vs. 1.00" (OEM).

http://www.aluminumspacers.com/

Aluminum Spacer 3/4 OD x .509 ID x 3/4 Long AS75-22-48
Aluminum Spacer 3/4 OD x .509 ID x 1/2 Long AS75-22-32
Aluminum Spacer 3/4 OD x .509 ID x 1/8 Long AS75-22-8

Click to expand...

In my experience, that spacer is one of the most critical parts for holding the wheels true. It should be a slip fit (not .509") and ideally made of something harder than aluminum. Have you tried these spacers? Do they work ok for this application?

exmaxima1 said:

In my experience, that spacer is one of the most critical parts for holding the wheels true. It should be a slip fit (not .509") and ideally made of something harder than aluminum. Have you tried these spacers? Do they work ok for this application?

Click to expand...

Good feedback.

No, I haven't tried them, I haven't found any steel, etc. ....

I prefer OD of 1.0", but have searched several places.

Any ideas?

I picked one of these up today. Oh how I wish the pictures on this post still worked.