let's see your craftsman block grinders

[JZiggy]

I was noodling this morning about the energy involved in spinning grinding wheels. Anyone can look up the equations, but here are few assumptions:

density of wheel = 2.1 g/cc
Rotational speed = 3600rpm (377 rad/s)

I was especially curious about the difference between a standard 6x0.5" wheel and a "big" 8x1" wheel.

Rotational energy:
8" wheel = 624 Joules
6" wheel = 100 Joules

The 8" wheel weighs 3.75 pounds. To get a sense for 624 Joules, that is the same kinetic energy as that 3.75lb wheel traveling at 60mph!!

Also, if you assume a startup time of 2 seconds, it takes 312W (0.42HP) to get the 8" wheel to 3600rpm. I guess it makes sense that you'd need a 3/4 or 1HP "rated" motor to do that from a dead stop.

Anyway, fun with physics

 

[exmaxima1]

I found some pictures, while looking for answers to the cast v. steel tool rest question above.

That's interesting as neither of my deluxe base grinders had rubber between between the base and grinder. They are both rigidly mounted using the 4 inner mounting slots, and 5/16" bolts. But I just looked and I see that there are factory 1/4" holes to utilize the outer mounting slots as well, which is what you would need to employ the rubber grommets.

Both of my grinders are lacking the mounting holes in the guards for standard rests, so I know both are factory-equipped deluxe base models. I wonder if the rubber grommets are mainly in those grinders that added the deluxe base as an accessory?

 

[s14brent]

For the sticker I used a local print shop.

The eye shields while not perfect came out pretty good. I usually clean plastics by by using gradually finer grades of sandpaper. Then polish with Flitz, or Maas metal polish.
These however had some pretty deep spark burns. Sanding them out would have made the shields too thin.

So instead I soaked them in hot, but not boiling water and dish soap for about an hour.
Rinsed, and washed them really well with dish soap and water.

After they dried. I polished them with toothpaste. It works as a very mild abrasive. And does not scratch the plastic. Did a pretty good job on the yellowing.

I was not looking for perfection on the shields. As soon as the paint is fully cured. In about a week. The grinder will be seeing hard use.

WOW! I need to try this on mine, but I think I need to do some sanding on mine because of how "gritty" one shield is. great job man

 

[Reversepolarity]

WOW! I need to try this on mine, but I think I need to do some sanding on mine because of how "gritty" one shield is. great job man

That is why you soak for an hour before washing.
It loosens the grit.

Try that before sanding.

 

[s14brent]

That is why you soak for an hour before washing.
It loosens the grit.

Try that before sanding.

as i got it

before soaking in hot water/dish detergent for 1hr

after - got rid of the yellowing and most of the overspray with some scrubbing

sanded w/2k grit (took my time) wet sand and polished on a **** buffing wheel

not baaad!

 

[Reversepolarity]

as i got it

before soaking in hot water/dish detergent for 1hr

after - got rid of the yellowing and most of the overspray with some scrubbing

sanded w/2k grit (took my time) wet sand and polished on a **** buffing wheel

not baaad!

Nice job

 

[Reversepolarity]

Another thumbs up RP... what colors/paint did you use? Yours is getting me motivated to repaint my 3/4.

These are the paints I used.

 

[Kaervak]

Perusing craigslist as usual and found a couple blocks:


1/3HP for $40 in Brazil, IN
http://indianapolis.craigslist.org/tls/5405323591.html

1/2HP for $175 (way overpriced, but worth listing) in Noblesville, IN
http://indianapolis.craigslist.org/tld/5386287139.html

1/2HP for $100 with original stand in Fort Wayne, IN
http://fortwayne.craigslist.org/tld/5394247282.html

1/2HP for $75 in Greenpoint, NY
http://newyork.craigslist.org/brk/tls/5417304061.html

 

[CalsXS2]

Is a 1/2hp desirable. I found what looks like a nice one on a stand. Looks complete.

What is a price range on these things.

Problem is I really don't need another grinder right now. I have a cheap china made "Collins Tool" one. I can bog it down using the wire wheel. Don't know if I would want another 1/2hp.

Can you guys give me any info on it. I think it's from the 70's?

Model# 397.19430

 

[Reversepolarity]

What are they asking?

 

[torqueman2002]

My comments are in red.

Is a 1/2hp desirable.
Yes.
However, it depends upon what you want to do with it.
A CM 1/2-HP m-397.19430 is a great grinder for home use: rust removal & cleaning of threads with a w. wheel or dressing tools, sharpening mower blades, ....
I found what looks like a nice one on a stand. Looks complete.

What is a price range on these things.
That really depends.
Like real estate:
Of course, it has to do with condition and completeness, some pieces are still available new, most are not.
Location, location, .... Really, there is a steady supply in SE Michigan and New England, and NYC areas, maybe LA. Other areas seem to have far fewer on CL.
Also, estate sale, CL, and eBay prices usually determine asking/selling prices, in ascending order.

Problem is I really don't need another grinder right now. I have a cheap china made "Collins Tool" one. I can bog it down using the wire wheel. Don't know if I would want another 1/2hp.
The 1/2-HP CM Block is not rated like a modern motor. It would be closer to a 1-HP made in China grinder.
I have yet to stall my 1/2-HP Blocks, doing the above operations.

Can you guys give me any info on it. I think it's from the 70's?
Post pictures, location, and intended use. That will allow us to give you a better idea.
Note: If you do buy a 45 year old electric tool, expect it will need:
power cord
bearings
wheels
power switch, maybe
paint, maybe
eye shield restoration, maybe
Model# 397.19430

Looking forward to your pictures.

 

[drivesitfar]

Cal: The new half hp grinders have about half the power as the old ones. It's the way they measure now that is different and we've talked about it quite a but here if you want to do some reading.

 

[Shiftless]

Cal: The new half hp grinders have about half the power as the old ones. It's the way they measure now that is different and we've talked about it quite a but here if you want to do some reading.

Drives:
Looks like you forgot to include the link to the horsepower article...

 

[McBrownie]

Drives:
Looks like you forgot to include the link to the horsepower article...

Post #6 on this thread has some interesting information.
http://www.bladeforums.com/forums/showthread.php/877192-Old-electric-HP-ratings-motors-vs-new-ones

And a quote from an article allegedly published by Rochester Institute of Technology, but the link is broken:

"A gasoline motor has a peak torque value for a given RPM (3600). It’s easy to peg that as a HP rating – measured torque at a fixed RPM. An electric motor produces torque in response to load. You load it, the RPM drops, and it draws more current and produces more torque. It’s more of a moving target, so you have to rate it, rather than the actual horsepower it produces, the horsepower it can produce at a given load before it melts."

 

[JZiggy]

Another helpful link about motor ratings with regard to thermal insulation. Most block grinder labels I have seen state they are "Class B"

http://www.motorsanddrives.com/cowern/motorterms4.html

 

[JZiggy]

Post #6 on this thread has some interesting information.
http://www.bladeforums.com/forums/showthread.php/877192-Old-electric-HP-ratings-motors-vs-new-ones

And a quote from an article allegedly published by Rochester Institute of Technology, but the link is broken:

"A gasoline motor has a peak torque value for a given RPM (3600). It’s easy to peg that as a HP rating – measured torque at a fixed RPM. An electric motor produces torque in response to load. You load it, the RPM drops, and it draws more current and produces more torque. It’s more of a moving target, so you have to rate it, rather than the actual horsepower it produces, the horsepower it can produce at a given load before it melts."

And actual produced horsepower is developed torque x the rpm at which it is developed (in radians/second)

So you can rate horsepower two ways:

1) The peak of the actual power curve, which is an upside down parabola. This is the right way to measure HP.

2) The maximum amperage the motor can draw (at stall!) times the voltage. So this is really giving you maximum power CONSUMED, not DEVELOPED. This is how small import motors can be given high ratings.

I'm not an EE, but this is my best understanding based on what I've read. Please correct as needed

 

[mtwaterguy]

Digging through some blocks, separating the keepers from the ones to sell, I came across this one. Out of all my 1/2 hp grinders this is the only one with the tray plug intact. Only my 3/4 & 1hp with the HD base have come this way. Anyone ever had a 1/2 hp with the HD base?

 

[torqueman2002]

Digging through some blocks, separating the keepers from the ones to sell, I came across this one. Out of all my 1/2 hp grinders this is the only one with the tray plug intact. Only my 3/4 & 1hp with the HD base have come this way. Anyone ever had a 1/2 hp with the HD base?

Yet another variation on the CM Block grinder.

I reviewed 21 pictures of 1/2-HP Blocks, and they all have the knock-out for the quench tray removed.

New one to me.

 

[Bobioz1]

I have a 397 19580 with the tray and lamp knock outs still intact. It just means it didn't come with them.

 

[CalsXS2]

Well ****. I missed that one. It went for $50. I emailed him and it had only been on there 9 minutes. He said he had 5 guys in front of me.

 

[McBrownie]

Well ****. I missed that one. It went for $50. I emailed him and it had only been on there 9 minutes. He said he had 5 guys in front of me.

Someone named CalsXS2 said on the previous page, and I quote!

"Don't know if I would want another 1/2hp."


Do you know now?

 

[torqueman2002]

I have a 397 19580 with the tray and lamp knock outs still intact. ...

Me too.

Those 1/3-HP m-397.1958x Blocks came in a number of varieties.

To keep price down, some were sold with out lamps and quench trays, while others had the 'extras'.

.... It just means it didn't come with them.

The 3/4 and 1-HP HD models with the quench tray knock-out in place, came mounted on a separate base with integrated quench tray and some with integrated tool rests.

I have 4 pictures of the 1/2-HP m-397.19440, none have the knock-outs in place, and I haven't seen any 1/2-HP like that on this forum before.

So mtwaterguy, I wonder if yours once had a HD base?

 

[bfm336]

Picked up this 1/2HP today - $50

It makes a slight metallic sound when it starts and it doesn't continue long after turning off - although that could be the buffing wheel on it.

Is there a tutorial anywhere on here for a refurbishing? Or common issues FAQ?

 

[torqueman2002]

Picked up this 1/2HP today - $50

It makes a slight metallic sound when it starts and it doesn't continue long after turning off - although that could be the buffing wheel on it.

Is there a tutorial anywhere on here for a refurbishing? Or common issues FAQ?

Nice price on a Block with CM stand.

To get started - check the 1st link in my Signature, I've pulled together some links and resources on these Block grinders.

We'd like to see how you proceed, and are happy to answer any questions.

If you get stuck, don't force anything.

 

[torqueman2002]

Well ****. I missed that one. It went for $50. I emailed him and it had only been on there 9 minutes. He said he had 5 guys in front of me.

That's fast!

There's another, better 1 with your name on it out there for you.

 

[Bobioz1]

Me too.

Those 1/3-HP m-397.1958x Blocks came in a number of varieties.

To keep price down, some were sold with out lamps and quench trays, while others had the 'extras'.


The 3/4 and 1-HP HD models with the quench tray knock-out in place, came mounted on a separate base with integrated quench tray and some with integrated tool rests.

I have 4 pictures of the 1/2-HP m-397.19440, none have the knock-outs in place, and I haven't seen any 1/2-HP like that on this forum before.

So mtwaterguy, I wonder if yours once had a HD base?

Page 77 post 1530 and page 146 post 2907 are 1/2-HP with tray knock-outs in place. mtwaterguy's looks more econo (never had a tray), than deluxe with a missing heavy base. JMO

 

[exmaxima1]

Page 77 post 1530 and page 146 post 2907 are 1/2-HP with tray knock-outs in place. mtwaterguy's looks more econo (never had a tray), than deluxe with a missing heavy base. JMO

+1
Factory grinders with deluxe bases did not have guard-mounted rests, or even threaded holes for them.

 

[torqueman2002]

Page 77 post 1530 and page 146 post 2907 are 1/2-HP with tray knock-outs in place. mtwaterguy's looks more econo (never had a tray), than deluxe with a missing heavy base. JMO

Bobioz1 - that took some research, nice investigation.

Kool!

I like uncovering the history of these Blocks.

Please don't misunderstand me. My aim is to peel away at these simple, yet interesting machines, with their many variations.

I'll make my comments in Red.

Well I got another 1/2 hp Com'l Craftsman block grinder m-397.19460 for free with my $75 pedestal! ....

.... 1/2HP Commercial m-397.19440 ....

+1
Factory grinders with deluxe bases did not have guard-mounted rests, or even threaded holes for them.
Here's Go Blue! when I brought it home.

And after the restore. I used the existing threaded holes, to mount the missing tool rests.

Go Blue! has been a research/restore project since I brought it home.

During the tear-down, I found OEM CM wire wheel and grinding stone, and several missing parts as can be seen in the 1st picture.

As the blue paint was removed, only a corner of the label remained, so the model number was MIA, so-to-speak. The label was generated based upon testing of this Block and 2 known 1-HP m-257.191600 Blocks with HD quench trays.

So, I guess it's possible a PO swapped out bits 'n pieces to get it to the point where I picked it up.

However, during the research/restore period, I did not find anyone on this site, OWWN, or other tool sites, with information to suggest Go Blue! is not as-built from the factory.

My take on m-397.19460 and m-397.19440 above, is they may have been separated from HD bases, they do exhibit other missing bits 'n pieces.

I wonder if either of them have manufacture dates, which could lead to the CM Tool catalog for that year.

I could be convinced either way, as I have not seen a flat top 1/2-HP Block mounted on a HD quench tray.

Isn't the stuff fun?

 

[Bobioz1]

Not to pick nits but Davefr doesn't show a round top 397 19460. The label says 397 19440 and its a flat top. Can't post a smiley for some reason or I would.

 

[G20-Budo]

My links:
"Craftsman Block motor Bench Grinders - What's the Fuss? (resource information)"
http://tinyurl.com/CM-Block-Grinders-Resources
http://tinyurl.com/The-Torqueman-YouTube-Channel
http://tinyurl.com/CM-Block-Grinder-Parts

torqueman,

I just wanted to say THANK YOU for all of the work you've put into documenting the parts, paint, etc for these block grinders! You've done a stellar job!

I WILL be using the great resources you've provided for us here in the near future as I clean up my block and get some of those rubber feet for it, etc.

 

[GirchyGirchy]

I'm an idiot, ignore post!

 

[torqueman2002]

Not to pick nits but Davefr doesn't show a round top 397 19460. The label says 397 19440 and its a flat top. Can't post a smiley for some reason or I would.

Thanks, fixed it.

And here you go, 1 simile face. Use it as your own.

 

[torqueman2002]

torqueman,

I just wanted to say THANK YOU for all of the work you've put into documenting the parts, paint, etc for these block grinders! You've done a stellar job!

I WILL be using the great resources you've provided for us here in the near future as I clean up my block and get some of those rubber feet for it, etc.

You are welcome.

It doesn't feel like work and it keeps me out of the bars.

 

[Reversepolarity]

Picked up the replacement sticker at the printers today.
She did a great job.
Now to put this grinder to work!

 

[G20-Budo]

Picked up the replacement sticker at the printers today.
She did a great job.
Now to put this grinder to work!

Holy ****, that looks like new!

Great job!

 

[JZiggy]

Picked up the replacement sticker at the printers today.
She did a great job.
Now to put this grinder to work!

Tell us more about that sticker! What material?

 

[Reversepolarity]

Tell us more about that sticker! What material?

Sticker is vinyl with clear over lamination.

I told her I needed it to be durable. This is what she suggested for the application.

 

[G20-Budo]

Sticker is vinyl with clear over lamination.

I told her I needed it to be durable. This is what she suggested for the application.

So, you shot clear coat over the sticker after it was made and applied to the grinder, or they put some kind of clear coating on it before you got it?

What was the cost if you don't mind me asking.

 

[torqueman2002]

Picked up the replacement sticker at the printers today.
She did a great job.
Now to put this grinder to work!

Excellent!

 

[s14brent]

Picked up the replacement sticker at the printers today.
She did a great job.
Now to put this grinder to work!