lafester
Well-known member
In the context of old grinders I think size is a legitimate factor.
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let's see your craftsman block grinders
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McBrownie
Well-known member
This tool lets you change between 120v and 115v. I have no idea what the efficiency and power factors are for old electric motors. Or, new ones for that matter.
https://www.inchcalculator.com/amps-to-horsepower-calculator/
https://www.inchcalculator.com/amps-to-horsepower-calculator/
Old Radar
Well-known member
I almost posted a similar calculator yesterday but since I didn't understand those same factors, I gave it up. I just now played around with McBrownie's link--it has a horsepower to amps calculator--and I used that to manipulate those unknown factors to come up with the known amperage for my 1/2hp pre-block. Unfortunately, when I substituted the 1/4 and 1/3hp into the calculator it did not spit out the rated amps for those machines--in fact, it reversed them. It said the 1/4hp should be 3.5 amps and the 1/3hp should be 4.66 amps.
Is there an Electrical Engineer in the house who can explain this in layman's terms???
Is there an Electrical Engineer in the house who can explain this in layman's terms???
Outlawmws
Well-known member
Mathematically, that should be correct (1/4 is smaller than 1/3)
The amperage on the box is determined by the MFG/Eng and the HP number by Marketing - so all bets off there. Usually the smart $$ in on the amps, not the HP
The amperage on the box is determined by the MFG/Eng and the HP number by Marketing - so all bets off there. Usually the smart $$ in on the amps, not the HP
McBrownie
Well-known member
I worked for a company that made electrical switches for power tools years ago. I remember an electrical engineer expressing displeasure, shall we say, about horsepower testing. We did temperature rise and amperage testing all of the time, but my sense was that horsepower testing and ratings may have been a bit of black art. I'm not an engineer, so can't add a whole lot more than that. Other than this:
Here is the label for my late 1960's (1967?) 3/4hp industrial rated:
View media item 58956
And my early 1970's (plastic eye shields, but metal toggle switch) 1/2hp commercial capacitor start.
View media item 40851
Both are really nice grinders and smooth running, but the 3/4hp definitely has more power. The difference is obvious. However, the 1/2hp allegedly draws more amps. It also states a "NEMA Rating". So, peak amperage? Amperage under load? Who knows. All I can say for sure is that the 3/4hp has more "grunt" on start up and does not bog down as easily.
Here is the label for my late 1960's (1967?) 3/4hp industrial rated:
View media item 58956
And my early 1970's (plastic eye shields, but metal toggle switch) 1/2hp commercial capacitor start.
View media item 40851
Both are really nice grinders and smooth running, but the 3/4hp definitely has more power. The difference is obvious. However, the 1/2hp allegedly draws more amps. It also states a "NEMA Rating". So, peak amperage? Amperage under load? Who knows. All I can say for sure is that the 3/4hp has more "grunt" on start up and does not bog down as easily.
ooba tooba
Well-known member
- Joined
- Jan 13, 2014
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- 744
Picked up 2 today. A nice solid old Baldor, and this old Craftsman for a grand total of $105. They both started up and ran quiet no smoke. Here’s the Craftsman. Last pic I found on the web when I typed in the model number, so made by Packard (a division of GM) in the 30s?
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ooba tooba
Well-known member
- Joined
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- 744
Also, the restored one has no brass tag like mine...? And the on/off switch is vertical whereas mine is side to side. Only differences I spot. Could mine possibly be earlier or later? Anyone know about that numbered brass tag?
torqueman2002
Well-known member
When I worked at Rochester Products div. of GM, the machines had brass tags similar to your grinder's tag.
They had alpha-numeric numbers stamped. AMxxxxx
"AM", I was told, stood for amortized machine.
Our department took requests for repairs of production machines: presses, lathes, assembly lines; all recorded and dispatched based on the AM-number.
They had alpha-numeric numbers stamped. AMxxxxx
"AM", I was told, stood for amortized machine.
Our department took requests for repairs of production machines: presses, lathes, assembly lines; all recorded and dispatched based on the AM-number.
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Bigblockyeti
Banned
The brass tag is almost certainly a very old asset tag for whatever company owned it. When I bought my Delta drill press with a repulsion induction motor, it had a brass asset tag riveted to the motor with a number and it was at one point, probably when brand new, owned by PictSweet farms.
I am absolutely not an engineer, but one informal test of efficiency that would produce some numbers would be decibel output. Might be more straightforward than setting up to duplicate heat-rise testing. There are apps for phones. Noise is waste.
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IMHO noise output is going to depend on too many factors and won't be a good metric of "efficiency." Something along the lines of current draw under a specific motor load would be more instructive.
So i spent a bit of time digging around the block thread to find parts for my "block" bench grinder. Checked ebay. Nothing. I have a Sears/Craftsman 397.19391 that I want to restore/get in working order but I require parts to replace those that are missing.
Anyone have this particular model that I can ****** up for the parts? I can toss some money your way (Not much but some). Or, if you are aware of any models that are compatable with this model of grinder?
Anyone have this particular model that I can ****** up for the parts? I can toss some money your way (Not much but some). Or, if you are aware of any models that are compatable with this model of grinder?
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Old Radar
Well-known member
I hate to say it, but unless this particular grinder has some deep sentimental value, I'd look for one that didn't start quite so deep in a parts vacuum and use this one for parts. IMHO you'll spend much more for parts than this little 1/4hp is worth.
Old Radar
Well-known member
I meant to touch on this last week but got distracted. I haven't seen a 1/4 or 1/3 hp to compare either, but here are my two 1/2hp models.
This is mostly for those who have never seen a Pre-Block next to a Block (in this case a CM Commercial Round Top). The Pre-Block is a full two inches wider measured from the outside of the wheel guards. The motor housing is full inch wider while the armatures are virtually the same length. Granted, the Pre- is mounted on its base that combines the tool rests and quenching tray, so it looks taller, but without it, they are the same height.
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lafester
Well-known member
Those look great! But... You really need two pre blocks back to back.I meant to touch on this last week but got distracted. I haven't seen a 1/4 or 1/3 hp to compare either, but here are my two 1/2hp models.
This is mostly for those who have never seen a Pre-Block next to a Block (in this case a CM Commercial Round Top). The Pre-Block is a full two inches wider measured from the outside of the wheel guards. The motor housing is full inch wider while the armatures are virtually the same length. Granted, the Pre- is mounted on its base that combines the tool rests and quenching tray, so it looks taller, but without it, they are the same height.
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whateg01
Well-known member
That's a pretty sweet looking setup! I'm rearranging the shop now as part of my effort to get the Newport mill in. Part of that is consolidating the grinding, sanding, drilling to one corner. What you have is clean looking! I especially like the riveted look for the plate to drum!
Dave
Really? I see.
bubinga
Well-known member
torqueman2002
Well-known member
It's hard for me to tell if your Block is a 1/4 or 1/3-HP; and I don't have a model 397.19391 in my collection of owner manuals. (Which are free to download PDF copies, see link below).
The publications also include old catalogs, manuals, parts list and historical documents for many manufacturers. http://vintagemachinery.org/mfgindex/detail.aspx?id=222&tab=3
If there isn't a copy of the owner's manual (they include a parts breakdown) for your model, try cross referencing the part number on the RH wheel guard with other models, then you can look-up the p/n of your missing bits 'n pieces and/or know what models can be donors for your Block.
Good luck.
PM me.
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lafester
Well-known member
You just need to be patient and watch ebay, but the parts you find are going to be more expensive then your complete grinder will be worth in the end.
damon18
ALLIANCE MEMBER
Is there a model timeline for block grinders somewhere?
A recent post here by Hartunian made me wonder about the different versions of 397.xxxxx 1/3 HP block grinders.
Mine is a 397.19580
https://www.garagejournal.com/forum/showpost.php?p=8135863&postcount=11812
and Hartunian posted one that was 397.19391
https://www.garagejournal.com/forum/showpost.php?p=8486741&postcount=2
Both 1/3 HP but completely different nameplates. Same motors and other accessories?
A recent post here by Hartunian made me wonder about the different versions of 397.xxxxx 1/3 HP block grinders.
Mine is a 397.19580
https://www.garagejournal.com/forum/showpost.php?p=8135863&postcount=11812
and Hartunian posted one that was 397.19391
https://www.garagejournal.com/forum/showpost.php?p=8486741&postcount=2
Both 1/3 HP but completely different nameplates. Same motors and other accessories?
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lafester
Well-known member
You can look through the catalogs to get a timeline. I think the 1/3 round top came out in the mid 60s and the flat top in the early 70s.
The lamp, eye shields, tool rests and quench trays are interchangeable.
You could swap the entire wheel guards between the two if you wanted but the inner and outer parts are not compatible.
The lamp, eye shields, tool rests and quench trays are interchangeable.
You could swap the entire wheel guards between the two if you wanted but the inner and outer parts are not compatible.
Outlawmws
Well-known member
Speed will be 3450 +-.. look under on the sheet metal plate for a year. That may require taking it off if its inside.
"Replacement Eye protection" you mean the plastic guards on the machine? watch Eprey for something compatible, but you can also get a place like Tap Plastics to cut some Lexan if the frames are there.
"Replacement Eye protection" you mean the plastic guards on the machine? watch Eprey for something compatible, but you can also get a place like Tap Plastics to cut some Lexan if the frames are there.
bagged89s10
Well-known member
I was cleaning my garage and forgot I had this center section for a 1/3”HP or 1/2” HP block. I think both use the same center piece but now I can’t remember which model it’s from. it’s stripped and ready for paint. If anyone needs it, let me know.
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harley jim
Well-known member
That is identical to my 3/4 hpI was cleaning my garage and forgot I had this center section for a 1/3”HP or 1/2” HP block. I think both use the same center piece but now I can’t remember which model it’s from. it’s stripped and ready for paint. If anyone needs it, let me know.
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Outlawmws
Well-known member
I don't see a need to at all. Steel wool will easily remove the tiny amount of surface rust in seconds...
inigomontoya
Member
Hey ya'll. Im a garbage man and someone had this Craftsman block grinder out on the curb. Made in '74 according to the stamp on the cover underneath. Took it home and she fired right up. Was covered in old paint splatter and light rust just about everywhere. Decided to give it a refurb. Unfortunately I didn't get many before pictures. Went ahead and replaced the bearings with Timken sealed ones. Switch was feeling a bit crunchy so I disassembled it and cleaned out all the old dielectric grease and put some new in there. Good as new. Replaced the sheet metal screws for the cover with new. There was some damage to the casings due to some caveman trying to sharpen a lawnmower blade a time or two I suspect. Painted with Rustoleum self-etching primer and Rustoleum hammered spray paint in black and gray. Hammered to obscure some of the damage. Got a new sticker from mattblast and it looks great. Still need to get a good wire wheel and some replacement grommets from Lowes. Thank you all for all the information on these.
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Looks great! Do you have the eye shields, spark arrestors, and tool rests?
inigomontoya
Member
Thanks! I have the tool rests but not the spark arrestors or eye shields. Is there a source for those items? I'm not above getting something made for another grinder that can be adapted. If you noticed, there are additional holes drilled in the guards at the top. The previous owner had a big piece of lexan attached to these points with screws. I may put that back on unless I find something suitable to replace it.
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Many of those 70s-era "block" grinders by Craftsman had clear plastic eyeshields, so fashioning something out of Lexan wouldn't be too far off base.
Spare parts come up now and then. I do have a spare set of spark arrestors and mounting hardware--if you're interested, contact me.
Thank you! I was definitely overthinking that.
torqueman2002
Well-known member
This may help.
Eye Shield Kit, Bench Grinder, Replacement --> http://www.garagejournal.com/forum/showpost.php?p=3323239&postcount=465
Eye Shield Kit, Bench Grinder, Replacement --> http://www.grainger.com/product/DAYTON-Eye-Shield-KIt-5PZP2
L-bracket --> https://www.mcmaster.com/1556a26
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bagged89s10
Well-known member
So since this had rust on it, is there anything I can do to prevent rust in the future? I'm a little unsure as this is obviously internal. Can I paint the shaft or the middle section? I wouldn't paint where the bearings would seat as that doesn't seem like a good idea.
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Those are your “before” pics, right? I hope you are not handling it with bare hands. The salts from your skin will remain where you have handled it, absorbing moisture from the air and causing it to rust more.
It’s the shaft itself you’re concerned with, right? The shaft is blued, which if clean should be sufficient protection in a dry shop with steady temperatures.
IMHO, this is a mountain/molehill concern. If your shop is dry, it will be okay. If your shop is damp, paint isn’t going to do much good, but I can easily imagine it doing harm.
My dad’s shop is partly sub-grade in the side of a hill. With the doors and windows all closed it’s around 60° in there in summer. But he frequently opens the bay doors in the summer to get equipment in and out, and 80° air goes in there and the moisture condenses on every metal surface. It does not take long for steel to get surface rust in those conditions.
It’s the shaft itself you’re concerned with, right? The shaft is blued, which if clean should be sufficient protection in a dry shop with steady temperatures.
IMHO, this is a mountain/molehill concern. If your shop is dry, it will be okay. If your shop is damp, paint isn’t going to do much good, but I can easily imagine it doing harm.
My dad’s shop is partly sub-grade in the side of a hill. With the doors and windows all closed it’s around 60° in there in summer. But he frequently opens the bay doors in the summer to get equipment in and out, and 80° air goes in there and the moisture condenses on every metal surface. It does not take long for steel to get surface rust in those conditions.
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I wasn't trying to make a big deal out of nothing. I was just asking if there was something simple I could do to help prevent rust is all.