torqueman2002
Well-known member
Due to Photo Buckets change in 3rd-party hosting policy, many/all images below may not appear. December 30, 2017
Due to a complete system failure at other sites, some of the threads, as well as pictures are not active/available. I regret the inconvenience.
Other CM Block grinder related threads:
"let's see your craftsman block grinders"
http://tinyurl.com/let-s-see-CM-block-grinders
"Vintage Craftsman "Block Motor" bench grinder info -"
http://tinyurl.com/CM-Block-motor-style-grinders
"Craftsman Block motor Bench Grinders - Restorations"
http://www.garagejournal.com/forum/showthread.php?t=325578
What is a Block grinder?
Important Update: March 24, 2020
<< I thought the other places refer to the block grinder as the ones with center band and end bells that look like a cube.
The prior aluminum ones have end bells shaped like a tombstone, or mailbox as you've mentioned. These should not be confused with "block grinder".
The aluminum tombstone/mailbox shaped grinders were patterned from the earlier 6" and 7" cast iron machines.
I don't think there's any question on manufacturers or dates (below is a thumbnail):
1954: Post-WWII Craftsman 7"x1" (with built in bulbs) & Dunlap 6"x3/4" grinders replaced by Packard built cast iron tombstone/mailbox shaped 6" & 7" grinders.
1961: Transition from centrifugal switch to relay and source code to Delco.
1964: Delco aluminum body tombstone/mailbox shaped 6" & 7" grinders replace the cast iron machines.
1969: 8"x1" grinder introduced.
~1975: Block shape designs replace the tombstone/mailbox style. Vibration improved with reinforced endbells.
~1981: Paramount source code replaces Delco.
~1984: Paramount minor changes to Delco block designs. 3-phase 8"x1" model introduced.
1990: Import grinder designs replace ball bearing models.>> per Brian Kachadurian, OWWM http://owwm.org/viewtopic.php?f=77&t=212610&p=1503646#p1503540
"... the classic Craftsman bench grinders that were manufactured for Sears by Paramount/Allegretti & Co. from the early 1960's to early 1980's. Affectionately known as "Block Motor" grinders because of their unique shape, these power tools have developed a large following among shop enthusiasts because of their legendary reliability, accuracy, and power.
The "Block Motor" grinder can be readily identified by the Sears manufacturer prefix of 397 or 257 (as in 397.XXXXX); which is stamped on the front label. Popular models include 1/4-HP, 1/3-HP, 1/2-HP, 3/4-HP, and 1-HP Industrial units."
Link to: "Vintage Craftsman "Block Motor" bench grinder info -" (source)
http://tinyurl.com/CM-Block-motor-style-grinders
"People always want to know what makes these things {CM Block grinders} so special; here's the reason. Look at those field windings. That is some VERY thick copper wire. When compared to a modern Chinese winding, these look GIGANTIC. The imports use very thin field wire. This is what makes these "block motors" so darn powerful and long lasting." Source - http://tinyurl.com/0-5-HP-CM-Block-Motor-FINISHED
There are different styles of Block grinders, here a few.
Early round top models ('mail box' style, some call them)
6" 1/4-HP m-397.19501
With CM CI stand.
6" 1/3-HP m-397.19580
A pair of 6" 1/3-HP Blocks
m-397.19410 on left, m-397.19580 on right.
397.19410 has an 'electric brake'.
7" 1/2-HP m-397.19590
8" 3/4-HP m-397.19670
Later flat top models.
6" 1/3-HP m-397.19391
Correct plastic eye shields, CM CI stand, and CM tool sharpening attachment.
3/4-HP m-397.19350
Before restore.
After
Note: Eye shields are from earlier round top model, power switch replaced with non-OEM.
1-HP m-257.191600
Before restoration.
After.
Note: Tool rests donated from 1/2 H.P. Model - 397.19470.
8" 1-HP m-257.191600
Showing HD base with quench tray and correct 3-piece tool rest, tool rest shaft.
Industrial and Commercial versions of the Block grinders.
"General speaking, the commercial grinders are rated for industrial use and dual voltage. The non-commercial grinders are usually single voltage 6" and some 7" for homeowner use." per Brian Kachadurian on OWWM.
6" 1/3-HP m-397.19580 Industrial Rated
7" 1/2-HP m-397.19440 Commercial
7" 1/2-HP m-397.19460 Commercial
8" 3/4-HP m-397.19670 Commercial
8" 3/4-HP m-397.19451 Commercial
"When Sears switched the 8" grinder to guard mounted tool rests in the 1980s, they look like the ones below.
Note: The stamped steel arms are basically the same as on some of the 7" grinders." per Brian Kachadurian on OWWM.
8" 1-HP m-257.192190 Industrial
Grinder Safety
'Ring Test' - Checking grinding stones for hidden cracks.
Important - The 'Ring Test' is primarily applicable to vitrified bonded wheels.
http://tinyurl.com/Grinding-Wheel-RingTest-Norton
http://www.youtube.com/watch?feature=player_embedded&v=NDtL4gisZYo
"How to Perform a Ring Test on a Grinding Wheel." - pdf file.
http://www.nortonindustrial.com/upl...ents/Safety - Ring Test a Grinding Wheels.pdf
Grinder Safety
Note: Has good set-up and operation guidelines.
http://tinyurl.com/Pratice-Safe-Wire-Wheeling
Norton Grinding Do's and Don'ts
https://tinyurl.com/Norton-Dos-Donts
Grinder & Abrasive Wheel Gory Safety Training from SafetyVideos.com
Grinder Basics
'Introduction to the bench grinder, a machinists tips and tricks'
{Crazy music, but good grinder information.}
{Go to end for more good videos - B&W Machine Tools}
Grinding Wheel Failures Can Lead To Serious Injury Or Death
http://www.georgiainjurylawyerblog.com/2009/05/grinding_wheel_failures_can_le.html
Grinding on the Side of the Wheel?
http://www.homemodelenginemachinist.com/f19/grinding-side-wheel-8635/
Use aluminum oxide wheels for all types of steels.
Use silicon carbide green wheels for tungsten cabide and non-ferrous metals such as brass, bronze and aluminum.
If you grind non ferrous metal on the same stone, then dressing the stone before reverting to ferrous is a must.
Old grinding stones | Are they safe to use?
http://www.garagejournal.com/forum/showthread.php?t=357111
Blotters... What Good Are They?
http://magna-matic.com/pdf/norton/Safety - Blotters - What Good Are They.pdf
The daily grind: Test your knowledge on grinder safety
http://www.reliableplant.com/Read/26801/daily-grind-test-knowledge-safety
Bench Grinder Basics - March 1990 Popular Mechanics.
http://tinyurl.com/79k26ma
As always, comments, suggestions, corrections, links to Block grinders are welcome.
Due to a complete system failure at other sites, some of the threads, as well as pictures are not active/available. I regret the inconvenience.
Other CM Block grinder related threads:
"let's see your craftsman block grinders"
http://tinyurl.com/let-s-see-CM-block-grinders
"Vintage Craftsman "Block Motor" bench grinder info -"
http://tinyurl.com/CM-Block-motor-style-grinders
"Craftsman Block motor Bench Grinders - Restorations"
http://www.garagejournal.com/forum/showthread.php?t=325578
What is a Block grinder?
Important Update: March 24, 2020
<< I thought the other places refer to the block grinder as the ones with center band and end bells that look like a cube.
The prior aluminum ones have end bells shaped like a tombstone, or mailbox as you've mentioned. These should not be confused with "block grinder".
The aluminum tombstone/mailbox shaped grinders were patterned from the earlier 6" and 7" cast iron machines.
I don't think there's any question on manufacturers or dates (below is a thumbnail):
1954: Post-WWII Craftsman 7"x1" (with built in bulbs) & Dunlap 6"x3/4" grinders replaced by Packard built cast iron tombstone/mailbox shaped 6" & 7" grinders.
1961: Transition from centrifugal switch to relay and source code to Delco.
1964: Delco aluminum body tombstone/mailbox shaped 6" & 7" grinders replace the cast iron machines.
1969: 8"x1" grinder introduced.
~1975: Block shape designs replace the tombstone/mailbox style. Vibration improved with reinforced endbells.
~1981: Paramount source code replaces Delco.
~1984: Paramount minor changes to Delco block designs. 3-phase 8"x1" model introduced.
1990: Import grinder designs replace ball bearing models.>> per Brian Kachadurian, OWWM http://owwm.org/viewtopic.php?f=77&t=212610&p=1503646#p1503540
"... the classic Craftsman bench grinders that were manufactured for Sears by Paramount/Allegretti & Co. from the early 1960's to early 1980's. Affectionately known as "Block Motor" grinders because of their unique shape, these power tools have developed a large following among shop enthusiasts because of their legendary reliability, accuracy, and power.
The "Block Motor" grinder can be readily identified by the Sears manufacturer prefix of 397 or 257 (as in 397.XXXXX); which is stamped on the front label. Popular models include 1/4-HP, 1/3-HP, 1/2-HP, 3/4-HP, and 1-HP Industrial units."
Link to: "Vintage Craftsman "Block Motor" bench grinder info -" (source)
http://tinyurl.com/CM-Block-motor-style-grinders
"People always want to know what makes these things {CM Block grinders} so special; here's the reason. Look at those field windings. That is some VERY thick copper wire. When compared to a modern Chinese winding, these look GIGANTIC. The imports use very thin field wire. This is what makes these "block motors" so darn powerful and long lasting." Source - http://tinyurl.com/0-5-HP-CM-Block-Motor-FINISHED
There are different styles of Block grinders, here a few.
Early round top models ('mail box' style, some call them)
6" 1/4-HP m-397.19501
With CM CI stand.
6" 1/3-HP m-397.19580
A pair of 6" 1/3-HP Blocks
m-397.19410 on left, m-397.19580 on right.
397.19410 has an 'electric brake'.
7" 1/2-HP m-397.19590
8" 3/4-HP m-397.19670
Later flat top models.
6" 1/3-HP m-397.19391
Correct plastic eye shields, CM CI stand, and CM tool sharpening attachment.
3/4-HP m-397.19350
Before restore.
After
Note: Eye shields are from earlier round top model, power switch replaced with non-OEM.
1-HP m-257.191600
Before restoration.
After.
Note: Tool rests donated from 1/2 H.P. Model - 397.19470.
8" 1-HP m-257.191600
Showing HD base with quench tray and correct 3-piece tool rest, tool rest shaft.
Industrial and Commercial versions of the Block grinders.
"General speaking, the commercial grinders are rated for industrial use and dual voltage. The non-commercial grinders are usually single voltage 6" and some 7" for homeowner use." per Brian Kachadurian on OWWM.
6" 1/3-HP m-397.19580 Industrial Rated
7" 1/2-HP m-397.19440 Commercial
7" 1/2-HP m-397.19460 Commercial
8" 3/4-HP m-397.19670 Commercial
8" 3/4-HP m-397.19451 Commercial
"When Sears switched the 8" grinder to guard mounted tool rests in the 1980s, they look like the ones below.
Note: The stamped steel arms are basically the same as on some of the 7" grinders." per Brian Kachadurian on OWWM.
8" 1-HP m-257.192190 Industrial
Grinder Safety
'Ring Test' - Checking grinding stones for hidden cracks.
Important - The 'Ring Test' is primarily applicable to vitrified bonded wheels.
http://tinyurl.com/Grinding-Wheel-RingTest-Norton
http://www.youtube.com/watch?feature=player_embedded&v=NDtL4gisZYo
"How to Perform a Ring Test on a Grinding Wheel." - pdf file.
http://www.nortonindustrial.com/upl...ents/Safety - Ring Test a Grinding Wheels.pdf
Grinder Safety
Note: Has good set-up and operation guidelines.
Norton Grinding Do's and Don'ts
https://tinyurl.com/Norton-Dos-Donts
Grinder & Abrasive Wheel Gory Safety Training from SafetyVideos.com
Grinder Basics
'Introduction to the bench grinder, a machinists tips and tricks'
{Crazy music, but good grinder information.}
{Go to end for more good videos - B&W Machine Tools}
Grinding Wheel Failures Can Lead To Serious Injury Or Death
http://www.georgiainjurylawyerblog.com/2009/05/grinding_wheel_failures_can_le.html
Grinding on the Side of the Wheel?
http://www.homemodelenginemachinist.com/f19/grinding-side-wheel-8635/
Use aluminum oxide wheels for all types of steels.
Use silicon carbide green wheels for tungsten cabide and non-ferrous metals such as brass, bronze and aluminum.
If you grind non ferrous metal on the same stone, then dressing the stone before reverting to ferrous is a must.
Old grinding stones | Are they safe to use?
http://www.garagejournal.com/forum/showthread.php?t=357111
Blotters... What Good Are They?
http://magna-matic.com/pdf/norton/Safety - Blotters - What Good Are They.pdf
The daily grind: Test your knowledge on grinder safety
http://www.reliableplant.com/Read/26801/daily-grind-test-knowledge-safety
Bench Grinder Basics - March 1990 Popular Mechanics.
http://tinyurl.com/79k26ma
As always, comments, suggestions, corrections, links to Block grinders are welcome.
Last edited:
, to mbsinmich! 
