"Pre-Block" Grinders--Where's the Love?

[DDOPWD23]

Correct.

I have a vintage Woodward lamp mounted to the table. I added a snap-in female outlet to the back side of the center band on the grinder. It's wired into the grinder switch so the lamp turns on when the grinder is turned on. It really works great.

"Pre-Block" Grinders--Where's the Love?

The CAST IRON BLOCK GRINDERS...are probably the best BLOCK GRINDERS that were ever made. Yep, you're preaching to the choir. Welcome to the family! I will say that the terms used here and on the Block thread--and elsewhere--are not meant to be derogatory, just descriptive short-hand. We...

www.garagejournal.com

very nice and it does look like it serves its purpose well. Looks like you have it all mounted to a side mount table for an Emerson DP not sure what generation guessing 3 or 4.

 

[DDOPWD23]

Here is my grandfather’s 1/3 HP 1961. The last of the Packard built. You can see how it looked when I got it and that was all its years of service. I cleaned it up gave it new bearings and power cord and found the tool rests for it. You can see I changed the color to the current gold and brown. I will make another post for the 1/4 HP that I use for buffing and polishing. You can also see a 1/2 HP in the background as well but I have not restored that one yet.

 

[DDOPWD23]

Well finally got some time to restore this new to me 1957 1/2 HP grinder. It needed bearings really bad. I turned it on once to test it out and shut it right away. Someone also ground down a lot of the tool rests and I tried my best to put back what was taken away. All in all it’s a beast that I am glad I don’t have to lift anymore. That completes my collection restoration of those tools. I now have to move onto 5 CM DP two of them are 100 series and 2 are 150 series and the 5th one is a 1939 that I will be restoring as a wedding gift. Since guys usually don’t get tools put on the registry.

 

[Hanniballs]

Anyone have wiring info for 115.7397?

Damaged switch and frayed cord so I’ve never run it.

As received the neutral was switched and connected to black. Hot line in was connected to red. Capacitor was connected to red and white.

 

[FrankLee]

Anyone have wiring info for 115.7397?

Damaged switch and frayed cord so I’ve never run it.

As received the neutral was switched and connected to black. Hot line in was connected to red. Capacitor was connected to red and white.

The photos below are from a 115.6965; a '48 version of your model. Maybe you can make sense of them.

When re-wiring two-prong plugs on old motors and grinders with new grounded cords, I always connect hot directly to the switch.

 

[Hanniballs]

The photos below are from a 115.6965; a '48 version of your model. Maybe you can make sense of them.

When re-wiring two-prong plugs on old motors and grinders with new grounded cords, I always connect hot directly to the switch.

Awesome, thank you! Your pics confirmed what I was seeing when I disconnected my wires. I wasn’t sure if it was correct as received.

My grinder is now running, although needs new bearings.

 

[FrankLee]

I saw this photo in an estate sale ad. I saw that the left guard was broken off and went to check it out. It's a great parts machine if the price is right.

​

It was marked $30, but was day 2 of the sale and I snagged it for $20. I did find the broken left-side guard with a good left cover and discovered that the Vimco lamp shade was fubar.

I walked around some more and found the grinder pedestal stand. Ah... it's a no-brainer that the grinder broke when it fell over on the stand. It was very obvious that it was a long time since the grinder was on that stand. The stand came home with me too.

This will likely be a parts machine soon.

More pics after I got them home. It runs good and the rotor/arbor shaft is straight.

 

[Old Radar]

I walked around some more and found the grinder pedestal stand. Ah... it's a no-brainer that the grinder broke when it fell over on the stand.

You should have claimed the stand was obviously unbalanced--citing all the damage to the grinder--and gotten a further discount on it, too! Still, $35 for the pair is outstanding--you ****!

 

[FrankLee]

I bought another 115.7575 today. This one has a couple issues, but with parts from yesterday's buy, I'll have a very nice refurb.

 

[DDOPWD23]

I bought another 115.7575 today. This one has a couple issues, but with parts from yesterday's buy, I'll have a very nice refurb.

Nice! I used the 1957 one I restored to sharpen a lawn mower blade just to test it out and it was a joy to use. My grandfathers 1/3 HP will always be my favorite but man that 1/2 HP is a beast.

 

[FrankLee]

Nice! I used the 1957 one I restored to sharpen a lawn mower blade just to test it out and it was a joy to use. My grandfathers 1/3 HP will always be my favorite but man that 1/2 HP is a beast.

I like and prefer my '55, 1/3 hp too.

 

[FrankLee]

Is anyone 3D printing these shades?

Or found an acceptable substitute?

 

[FrankLee]

Apparently, grinders on pedestal stands falling over and breaking is not as uncommon as I thought.


Mine:




Here's an active fb listing:
https://www.facebook.com/marketplace/item/925149606317324




Another I spotted online recently.


Another broken wheel guard here:

https://www.garagejournal.com/forum/threads/pre-block-grinders-wheres-the-love.339921/post-8884320

12/22/2025

Another casualty due to gravity. It's interesting that all these I posted have been broken on the left side.

 

[twistedstang]

I picked up my first vintage grinder yesterday. A 1958 1/3 horse on a pedestal. I snagged the 1957 1/4 horse on the way home. The tag on the 57 is super crispy. I can see these becoming addictive.

 

[DDOPWD23]

Finally got a pedestal. The price and location were just right $50 and 15 minutes away. I’ll just have to clean it up and paint it to match all the others. The Delco just free to place on it.

 

[ching0n]

May I suggest a 'nomenclature' change from pre-block/block/mailbox/tombstone? I think '115's' and '397's' may be a better identifier for users. I don't think there's any cast iron 397's and 397 round and flat tops are all aluminum AFAIK.
Basically:
115
397 RT
397 FT

Moving on, I picked up a 1/4 115, it's got a centrifugal switch and noticed it came w/o finger washer beneath the guards. Unlike other cast 115's, it also came w/o the double stamped washer or felt dust shield. Is this normal for the 1/4? 115.19500

I was hearing a scraping spinning it by hand so tore it apart thinking a wire was rubbing against the rotor but may have been the centrifugal switch itself. I don't hear the switch clicking off on speed down so that's got me a bit concerned.

 

[FrankLee]

May I suggest a 'nomenclature' change from pre-block/block/mailbox/tombstone? I think '115's' and '397's' may be a better identifier for users. I don't think there's any cast iron 397's and 397 round and flat tops are all aluminum AFAIK.
Basically:
115
397 RT
397 FT

I think something was tried before to eliminate that other term, but it failed. Unfortunately, I think we're stuck with it. I just don't use it myself.

I believe there was a 397 cast iron model.

Moving on, I picked up a 1/4 115, it's got a centrifugal switch and noticed it came w/o finger washer beneath the guards. Unlike other cast 115's, it also came w/o the double stamped washer or felt dust shield. Is this normal for the 1/4? 115.19500.

It should have a spring washer and end caps (#12 in the parts diagram), but no felt washers.

http://vintagemachinery.org/pubs/222/16769.pdf

I was hearing a scraping spinning it by hand so tore it apart thinking a wire was rubbing against the rotor but may have been the centrifugal switch itself.

The scraping sound is very likely the cent switch.

I don't hear the switch clicking off on speed down so that's got me a bit concerned.

It should click. Were both springs (#25) present on the governor assembly?

 

[Old Radar]

May I suggest a 'nomenclature' change from pre-block/block/mailbox/tombstone? I think '115's' and '397's' may be a better identifier for users.

Welcome to the thread and to the debate. You are hardly the first and won't be the last to bring up this topic or suggest alternative nomenclature. Peruse the previous pages in the thread--it's a popular subject--one episode starts in the middle of page 6 and goes on for a bit.
Not to dismiss your suggestion out of hand (you're free to identify them as you wish) but most humans tend to rely on visual cues and assign common-place names to inert objects to serve as memory clues to identify objects--even if not always clear-cut or accurate. The use of model numbers is less common unless you are talking about R2D2 or C-3PO.

 

[ching0n]

I think something was tried before to eliminate that other term, but it failed. Unfortunately, I think we're stuck with it. I just don't use it myself.

I believe there was a 397 cast iron model.


It should have a spring washer and end caps (#12 in the parts diagram), but no felt washers.

http://vintagemachinery.org/pubs/222/16769.pdf

The scraping sound is very likely the cent switch.


It should click. Were both springs (#25) present on the governor assembly?

I think there's also a 267 or 257 model so I may have the round head aluminums pegged wrong.

I found a single bearing spring washer though don't recall which side it was on (likely the correct one). Both springs are there on the governor, lots of white oxide on the I'm guessing galvanized body (hopefully not cadmium). Perhaps the switch isn't as audible as in newer grinders? I'll take some resistance measurements of the start winding but it had no trouble starting.

I also might've confused surface rust on the cast iron w/factory 'rust brown' paintjob for lack of a better name. The center sheet piece was pitted to hell so figured the cast was also rusted. Upon closer inspection, there is some but looks like it's mostly oxidized painted finish. Makes sense to offer if anticipating damp environments like a farm.

 

[ching0n]

Welcome to the thread and to the debate. You are hardly the first and won't be the last to bring up this topic or suggest alternative nomenclature. Peruse the previous pages in the thread--it's a popular subject--one episode starts in the middle of page 6 and goes on for a bit.
Not to dismiss your suggestion out of hand (you're free to identify them as you wish) but most humans tend to rely on visual cues and assign common-place names to inert objects to serve as memory clues to identify objects--even if not always clear-cut or accurate. The use of model numbers is less common unless you are talking about R2D2 or C-3PO.

I'm mostly coming at it from chassis codes in vehicles but dunno if the differences are such to make this method foolproof.

 

[DDOPWD23]

I would agree on the nomenclature to identify them but I am also new here. Franklee is right, when Deleco took over from Packard electric in 1962 they used cast iron construction for the 1962 & 1963 model years. Those years used the craftsman crown for the first time on the stator band for the bench grinders and continued the brown and gold color scheme. Then went to the cast aluminum and the gray on gray color scheme in 1964.

Feel free to correct me if I am wrong since I wasn’t even alive then and it’s just my own research that I have done.

 

[ching0n]

I would agree on the nomenclature to identify them but I am also new here. Franklee is right, when Deleco took over from Packard electric in 1962 they used cast iron construction for the 1962 & 1963 model years. Those years used the craftsman crown for the first time on the stator band for the bench grinders and continued the brown and gold color scheme. Then went to the cast aluminum and the gray on gray color scheme in 1964.

Feel free to correct me if I am wrong since I wasn’t even alive then and it’s just my own research that I have done.

I went back a few pages and found that indeed there's a few iron block 397's from the 60's. They appear to be rated lower amperage but believe these were relay start so wonder if the centrifugal switch eats up some of the efficiency in the earlier models, causing the added amp draw? Would need to convert one to relay start and measure amp draws I guess.

 

[DDOPWD23]

Yes you are correct, when Delco took over they got rid of the centrifugal switch and used a sensing relay. You are right there is a big difference in amp draw. I had both 1/2 HP grinders and the Packard one would draw 7 amps and the Delco would draw 4.4 amps. Doing the math for the 7 amp draw that would work out to be a 49% efficiency which I find it hard to believe. Unless they were just under rating the true power of the motors.

 

[ching0n]

what fits through the factory grommet 14/3 or 16/3? For the 1/4 hp

 

[DDOPWD23]

what fits through the factory grommet 14/3 or 16/3? For the 1/4 hp

Either will work. I used 14/3 though and I like the power cords to be long. I went with this from Amazon and I used it for 1/4, 1/3, and 1/2 HP builds.

https://a.co/d/hJkD6Wj

 

[ching0n]

Either will work. I used 14/3 though and I like the power cords to be long. I went with this from Amazon and I used it for 1/4, 1/3, and 1/2 HP builds.

https://a.co/d/hJkD6Wj

I got impatient so used a fairly thick jacketed 9' 18/3 from a PC PSU. A bit thin gauge but ampacity's enough for this, I usually worry more about the overall thickness being too small. Runs fairly smooth w/o the stones but a bit wobbly w/them installed (I can see the stones spins in a bit of an orbit for some reason. I'll probably tear into it again to grease the contacts, locktite a few things, repack the bearings (anyone have a how-to?, manual says it's doable) & maybe paint the center sheet metal. I like the rat-rod look right now.

I can hear the centrifugal switch now but maybe was expecting it at higher RPM when I was listening for it before. Is it normal for these or is it sticking?

 

[DDOPWD23]

You might have to dress the wheels but I would buy new ones since you can’t really trust the used ones from the previous owner.

 

[ching0n]

You might have to dress the wheels but I would buy new ones since you can’t really trust the used ones from the previous owner.

yeah, it's what I figured...I just didn't think the wheels would be so out of round given they wear as they spin. I ordered a unitized fiber wheel as well as a burnishing wheel. Might pick up a wire wheel and stone @ HF tomorrow.

.... I'll probably tear into it again to grease the contacts, locktite a few things, repack the bearings (anyone have a how-to?, manual says it's doable)

on repacking:

 

[ching0n]

yeah, it's what I figured...I just didn't think the wheels would be so out of round given they wear as they spin. I ordered a unitized fiber wheel as well as a burnishing wheel. Might pick up a wire wheel and stone @ HF tomorrow.


on repacking:

Tore it apart again and I couldn't figure out how to take off the grease shields (different design than above).

Here's what I did:
There is a tiny gap between the inner race and the shield (towards motor side). Take off bearings, shoot some carb cleaner into that gap and/or soak bearings in gasoline (per manual) so you can dissolve the old grease. Dry out, using grease in a tube (or syringe or grease gun with needle injector) press and use pressure to inject into the gap, repeat until dry noise when spinning disappears and you get some drag from the grease. I'm pretty sure mine had a larger gap than the one below (check yours before using solvent to remove old grease). You could bypass the cleaning and just add more grease and/or maybe drop a few drops of synthetic oil in there to re-soak the binder that could be dry.



Also, in my model, there's a spring washer on the left side behind the shield & an end cap that I'm fairly certain sets a pre-load. Manual says that when removing the shields, one must run these end caps bolted down.

Lastly, despite being held together by 4 bolts, it is possible to bolt together w/a mild twist, to avoid this, perform final bolt down with grinder sitting on a flat surface, preferably without the bottom cover/feet in place. Once I was done, I ended up w/a tiny transient induction hum similar to an oscillating fan swinging by. I can't remember if it was there before but it's possible a lack of torque or induced twist when bolting the whole thing together is the culprit. I had already applied thread lock & tightened the nuts so fixed the twist w/a mallet & could hear the noise change as I did it. Maybe next tear down I'll look into it, I was not liking how easily the lacquered cloth covered wiring was fraying so that may be the next 'upgrade'.

 

[ching0n]

I like and prefer my '55, 1/3 hp too.

Is there a particular reason for it? I'm on the hunt for a larger unit and wondering if I should pass 1/2 hp for 1/3 hp instead. How 'bout the one w/the built in tray, does that one fall short to the regular 1/3?

 

[DDOPWD23]

I would agree with Franklee. I have all three HP grinders, each one set up for a different task. 1/4 is for polishing and buffing. 1/3 has a wire wheel and a 180 grit fiber wheel and the 1/2 has 34 grit and 100 grid grinding wheels. If I had to choose HP grinder and get three of them it would be the 1/3. Just is a well rounded grinder and has all the power you will need to get any job done that a garage hobbits.

 

[FrankLee]

I bought another 115.7575 today. This one has a couple issues, but with parts from yesterday's buy, I'll have a very nice refurb.

I've got a bit of work to do yet on the eye shields, but wanted to post a video of the grinder running. It is SO smooth!

I generally don't reinstall the original stones, but they rang nicely.

 

[DDOPWD23]

Looking and sounds just like mine. Did you repaint that with the ACE hardware gray paint or the Kyrlon matte dark Pearl?

 

[FrankLee]

That is the Krylon Matte Dark Pearl.

 

[DDOPWD23]

Awesome, I’m going to order some now. That looks just like the craftsman blue gray. I can’t order the ACE hardware color online. I have to go to the store and there isn’t any near where I live. I can order the krlyon and get it deliver.

That is the Krylon Matte Dark Pearl.

 

[FrankLee]

Krylon MDP is available at Lowes. Bulk discount on six or more.

 

[DDOPWD23]

Already ordered and going to be delivered later today. I won’t be home till the 22nd so it will just be there waiting for me.

 

[ching0n]

did the old iron blocks come w/vitrified aluminum oxide or carborundum stones? My tags are FUBAR.

 

[ching0n]

I picked up a 6" 1/2hp aluminum block grinder for a song. It needs some love but wheel guards look swappable w/the iron blocks. If yours are damaged or lost, it might get you spark guards, eye guards, and tool rests....I'll confirm later today. Stator looks about the same size as my iron block 1/4 hp.

I think it would be a good idea to take some resistance readings & gauge size of the windings and start keeping track of them, might help figure out which is "best".

FWIW, it weighs about half as much despite "being double the power" but runs very smooth. I think the amp draw is on the same ballpark (tag is sun damaged) but that's not the whole story as I suspect there's some efficiency gain not having to spin a centrifugal switch around.

 

[ching0n]

I picked up a 6" 1/2hp aluminum block grinder for a song. It needs some love but wheel guards look swappable w/the iron blocks. If yours are damaged or lost, it might get you spark guards, eye guards, and tool rests....I'll confirm later today. Stator looks about the same size as my iron block 1/4 hp.

I think it would be a good idea to take some resistance readings & gauge size of the windings and start keeping track of them, might help figure out which is "best".

FWIW, it weighs about half as much despite "being double the power" but runs very smooth. I think the amp draw is on the same ballpark (tag is sun damaged) but that's not the whole story as I suspect there's some efficiency gain not having to spin a centrifugal switch around.

Here's a ballpark of the size for 1/4hp iron block and 1/2hp aluminum block, roughly same volume:


aluminum guard casting is same left or right, bolt pattern is same w/added benefit of 3 extra holes (6 total) allowing for more angle options:



The end cover clearance is an issue though (if you want to use), you need about 1/4" more which can be easily resolved by shimming the guard's 3 bolts w/some bushings/nuts/washers: