let's see your craftsman block grinders

[LesserSon]

So jealous, BB!
I did my own double-take today at the flea. Picked up a second 1974 1/3hp, this time, with a quenching tray. When I got it home, I realized it’s just 2-1/2 months newer than my first one, plus the build date is my grandfather’s birthday (the first one missed my grandmother’s b-day by a couple weeks).
One striking difference between them is the 1/2” hex screws holding the cover on: the September ones have no slots, while the December ones do!
I started it up and it spun for half a minute after killing the power.

 

[kenc184]

Well, here it is, it runs nicely. Grey wheel looks to be full diameter, but the wire wheel is totally worn out. Going to fit my light deburring wheel to that side anyway.

While I was there I picked up this nice little number, paid top dollar for it, but I think under all that dirt it's in top dollar condition: Any guesses?

That's 155 lbs of goodness!

 

[trijeff]

Rock Island 577

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[kenc184]

Rock Island 577

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Damn, you're good!

 

[cajunfirehawk]

Merry Christmas

Blockheads!

​

 

[kenc184]

Rock Island 577

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Of course it WAS Jeffrey who sold it to me, so I should have said "seller excluded from competition!"

 

[trijeff]

Different Jeffrey ... I didn't sell that to you!

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[kenc184]

Different Jeffrey ... I didn't sell that to you!

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Hmmm, then once again "Damn, you're good!"

 

[Benryanuk]

Here’s mine.. 1950’s I think and I’m pretty good shape. This is the 6’ 1/4 hp version but works well for my needs so far. Really quiet and very little vibration.


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[DwightS]

Does mine qualify? It’s a 1/3 hp that belonged to my father. I have limited room in my 2-car garage so I’ve mounted it on a 3/4” plywood plate that I can mount on my Workmate.




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[kenc184]

What use are the "square" exhaust ports on the guards? Never seen a rectangular shop-vac hose!

Guess I could make an adapter out of sheetmetal?

 

[LesserSon]

What use are the "square" exhaust ports on the guards? Never seen a rectangular shop-vac hose!

Guess I could make an adapter out of sheetmetal?

I think they direct sparks and debris away from the operator. I think hooking standard vacuum equipment to it would invite fire. Hidden, smoldering fire.

 

[Rileysan]

My 3/4 hp Craftsman Commercial block started smoking today. A wire (or wires) definitely caught fire.

It wasn't under much of a load (just using the wire wheel) and it didn't make any noise or come to a stop. I leisurely shut it off, then unplugged it. The housing wasn't hot but it continued to smoke for a good minute or so.
I was using the lamp as well.

I'm bummed but I'll take it in to work and let one of our plant electricians take a look at it this week - they don't have nearly enough to do, LOL!

Oh, and that's a 1 hp block standing behind it
Brian

 

[exmaxima1]

Here’s mine.. 1950’s I think and I’m pretty good shape. This is the 6’ 1/4 hp version but works well for my needs so far. Really quiet and very little vibration.

It's quiet and smooth because it's a Pre-Block grinder made of heavy cast iron. The later Block models are alloy aluminum, 1/2 the weight, and more prone to vibration if the wheels get a little off balance.

 

[Rileysan]

I brought my 3/4 HP block into work today and our supervising plant electrician made me do all the work!

What we found is the starter windings had overheated - they are quite black (no pix)! After testing the internal switch and capacitor, he deemed it was ok to fire up. We started and stopped it at least a dozen times with no issue. He thinks the internal switch didn't shut off capacitive power and it pulled max amps until I turned it off, thus overheating (but not damaging) the starter windings.

I probably should replace the internal switch anyways. Can someone provide a recommendation?

Brian

 

[Rileysan]

Here's a bad picture taken with my phone

 

[cajunfirehawk]

My "Santa dropped off a block grinder pic;" thanks to the Elf that sent it!

​

 

[Benryanuk]

It's quiet and smooth because it's a Pre-Block grinder made of heavy cast iron. The later Block models are alloy aluminum, 1/2 the weight, and more prone to vibration if the wheels get a little off balance.

Cool thanks!


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[jonshonda]

My "Santa dropped off a block grinder pic;" thanks to the Elf that sent it!

​

Somehow I had a feeling you were going to buy that. I also had a feeling it was put up for sale on GJ because the seller knew the firehawk couldn't resist!

 

[454ragtop]

Ugly 1/2 HP for sale in CT https://newlondon.craigslist.org/tls/d/norwich-bench-grinder-5-horse-power-on/6779985210.html

 

[kenc184]

Somehow I had a feeling you were going to buy that. I also had a feeling it was put up for sale on GJ because the seller knew the firehawk couldn't resist!

Wow, that looks unused. Too nice to use unfortunately!

 

[jonshonda]

Wow, that looks unused. Too nice to use unfortunately!

It will sit on a nice shelf (likely behind a glass case) in a climate controlled room. We should all be so lucky as that grinder!

 

[Rileysan]

I brought my 3/4 HP block into work today and our supervising plant electrician made me do all the work!

What we found is the starter windings had overheated - they are quite black (no pix)! After testing the internal switch and capacitor, he deemed it was ok to fire up. We started and stopped it at least a dozen times with no issue. He thinks the internal switch didn't shut off capacitive power and it pulled max amps until I turned it off, thus overheating (but not damaging) the starter windings.

I probably should replace the internal switch anyways. Can someone provide a recommendation?

Brian

*bump*

Any input on why my started coils got hot? Should I replace the internal switch or something else?

Brian

 

[tym]

*bump*

Any input on why my started coils got hot? Should I replace the internal switch or something else?

Brian

Personally, if the wire got hot enough that the insulation blackened, I'd consider the winding compromised and not trust it.

That said, I'd err on the side of caution and replace both switch and cap.

 

[kenc184]

*bump*

Any input on why my started coils got hot? Should I replace the internal switch or something else?

Brian

How does the starter winding disengage? Often times - like on my crappy yet reliable 35 year old Taiwan 6" grinder it's a centrifugal switch. Seems like the only way the starter winding could get hot would be if it does not disengage. So whatever element causes it to disengage, be it centrifugal switch or something else, should be inspected and replaced if necessary.

 

[Rileysan]

How does the starter winding disengage? Often times - like on my crappy yet reliable 35 year old Taiwan 6" grinder it's a centrifugal switch. Seems like the only way the starter winding could get hot would be if it does not disengage. So whatever element causes it to disengage, be it centrifugal switch or something else, should be inspected and replaced if necessary.

Tym, the starter windings are not insulated, though they are in close proximity to some that are. Visually, it doesn't appear that anything else was affected. The only area that was blackened was the starter windings themselves, which I can't say what was actually burning.

Ken, that was the assessment made by our plant electrician - that it must be some sort of centrifugal switch, but we couldn't get it to fail. The switch activated then released the capacitor every time we tried it. He had a home made pigtail with which he used an ammeter to test the amp draw at startup and while running full speed.

In my previous post, I inquired about where to find a replacement switch for this model. Can anyone recommend one?

Brian

 

[torqueman2002]

....
... it must be some sort of centrifugal switch...
In my previous post, I inquired about where to find a replacement switch for this model. Can anyone recommend one?

Brian

Brian, what is the model number?

Almost every Block that does not have a relay, uses a centrifugal switch (CS). Note: I was mistaken, the 1/4-HP model I was thinking of and pictured in a following post, does have a CS, but no capacitor. The relay is a replacement for the CS, who's function is to power-up the start-up windings (thin wires and lots of EMF) when power is first turned on and only long enough to get the arbor spinning to about 75% of operating speed.

The CS is located in the RH End Frame and ASFAIK are no longer available.

However, they operate like a set of ignition points and can be cleaned/burnished.

The other part of the CS system is a 'governor' with weights that swing out at a calibrated speed to activate arms and a bushing that pulls away from the switch to open the start-up winding circuit, removing voltage to the start-up windings.

If you open the bottom cover of a Block with a CS, there will be 2 wires to/from the CS on the RH End Frame.

The problem can be when removing the RH End Frame, the RH bearing is stuck to the arbor and will be drawn out with it.

This is a problem because the CS is screwed to the End Frame, the bearing is behind it and will break the fiber mounting of the CS, ruining the CS.

I have gotten around this, by cutting the CS wires.

Good luck and feel free to post pictures and ask questions, we will do our best to get it running reliably.

 

[Rileysan]

Brian, what is the model number?

Almost every Block that does not have a relay, uses a centrifugal switch (CS). The relay is a replacement for the CS, who's function is to power-up the start-up windings (thin wires and lots of EMF) when power is first turned on and only long enough to get the arbor spinning to about 75% of operating speed.

The CS is located in the RH End Frame and ASFAIK are no longer available.

However, they operate like a set of ignition points and can be cleaned/burnished.

The other part of the CS system is a 'governor' with weights that swing out at a calibrated speed to activate arms and a bushing that pushes on the switch to open the start-up winding circuit, removing voltage to the start-up windings.

If you open the bottom cover of a Block with a CS, there will be 2 wires to/from the CS on the RH End Frame.

The problem can be when removing the RH End Frame, the RH bearing is stuck to the arbor and will be drawn out with it.

This is a problem because the CS is screwed to the End Frame, the bearing is behind it and will break the fiber mounting of the CS, runing the CS.

I have gotten around this, by cutting the CS wires.

Good luck and feel free to post pictures and ask questions, we will do our best to get it running reliably.

The Model # is: 397.19671
3/4 HP Craftsman Commercial

AFAIK, it is completely original. I bought it from the son of the original owner ~18 months ago, and it has worked flawlessly that whole time.

We took the bottom off at work (myself under the instruction of our 70 year old plant electrician supervisor). He pointed out the starter coil wires being black and then went about testing the cap and switch.

Perhaps this is where I'm wrong. The "switch" I'm referring to is located near the bottom cover and is held in place by a single screw to the frame. The light is also wired into it. Perhaps I've been talking about a relay?

From your description, it sounds like the centrifugal switch isn't visible from the bottom.

I'll try to take it apart this weekend.

Brian

 

[tym]

Tym, the starter windings are not insulated, though they are in close proximity to some that are. Visually, it doesn't appear that anything else was affected. The only area that was blackened was the starter windings themselves, which I can't say what was actually burning.

I doubt it's bare wire; there's got to be some kind of insulation (it may be thin/translucent like on magnet wire) and likely that's what burned and blackened from the heat. You might be able to find some kind of shellac or thin spray epoxy that would be suitable to apply as a poor-man's "re-insulation" to prevent future shorts.

 

[torqueman2002]

I'll make my comments in RED.

The Model # is: 397.19671 3/4 HP Craftsman Commercial. Thanks, I have a similar model: 397.19670. See pics below.

The "switch" I'm referring to is located near the bottom cover and is held in place by a single screw to the frame. The light is also wired into it. Yes, that is the power switch. Perhaps I've been talking about a relay? I don't thinks so. See the pics below.

From your description, it sounds like the centrifugal switch isn't visible from the bottom. Correct, see the pics of a different model below.
....

I doubt it's bare wire; there's got to be some kind of insulation (it may be thin/translucent like on magnet wire) and likely that's what burned and blackened from the heat. Yes, it appears to be bare copper, but has some sort of insulation - varnish/shellac?

You might be able to find some kind of shellac or thin spray epoxy that would be suitable to apply as a poor-man's "re-insulation" to prevent future shorts. Yes, this guy is worth saving.

3/4-HP, m-397.19670, round top, Heavy Duty base

Inside of bottom, showing cap, power switch, and relay. Centrifugal Switch (CS) not employed in this model.

1/3-HP, m-115.7966, round top, pre-Block, mfg date 2 59.

View of CS-governor. At start up, the black bushing is pushing the CS points closed, powering the start-up coils (thin wires). At a calibrated speed ~75% of full speed, the weights spin out and pull the bushing away from the CS, opening the points and start-up coil circuit.

If this assembly is 'sticky' it can prevent the CD points from opening and providing power to the start-up coils too long and potentially burning them up.

View of CS, and RH bearing behind the CS.

View of a different 1/4-HP pre-Block - CS, RH bearing stuck to arbor shaft. Red and white wires visible on the right are connected to a black wire that comes from the NO side of the power switch.

View of CS contacts/points. At start-up through ~75% final speed, the CS governor bushing pushes on the CS contact/point assembly, closing the contacts, and providing power to the start-up winding/coil.

 

[cajunfirehawk]

I'll make my comments in RED.

3/4-HP, m-397.19670, round top, Heavy Duty base


Inside of bottom, showing cap, power switch, and relay. Centrifugal Switch (CS) not employed in this model.


1/3-HP, m-115.7966, round top, pre-Block, mfg date 2 59.


View of CS-governor. At start up, the black bushing is pushing the CS points closed, powering the start-up coils (thin wires). At a calibrated speed ~75% of full speed, the weights spin out and pull the bushing away from the CS, opening the points and start-up coil circuit.

If this assembly is 'sticky' it can prevent the CD points from opening and providing power to the start-up coils too long and potentially burning them up.

View of CS, and RH bearing behind the CS.

View of a different 1/4-HP pre-Block - CS, RH bearing stuck to arbor shaft. Red and white wires visible on the right are connected to a black wire that comes from the NO side of the power switch.

View of CS contacts/points. At start-up through ~75% final speed, the CS governor bushing pushes on the CS contact/point assembly, closing the contacts, and providing power to the start-up winding/coil.

As always the plethora of Block knowledge from the Torque Monster flows like water in the streets!

Thanks Mike, HAPPY NEW YEAR!

 

[cajunfirehawk]

It will sit on a nice shelf (likely behind a glass case) in a climate controlled room. We should all be so lucky as that grinder!

Well you know you can always use just one more 1hp minty block grinder...

 

[Rileysan]

As always the plethora of Block knowledge from the Torque Monster flows like water in the streets!

Thanks Mike, HAPPY NEW YEAR!

You aren't kidding!

Thank you very much for the detailed information and photos! I could not have asked for a better explanation!

Brian

 

[torqueman2002]

You are welcome. I am glad I can help.

I just wish I had a spare stator/coil assembly to offer, as I think a re-wind will be very expensive.

 

[torqueman2002]

As always the plethora of Block knowledge from the Torque Monster flows like water in the streets!

Thanks Mike, HAPPY NEW YEAR!

Thank you, but I'm not worthy of such high praise.


And yes! A Happy and Safe New Year!

 

[tommyp]

So was in the process of putting together a sandblast cabinet for my shop I stumbled across this guy on facebook for $25. Its bigger brother in the background in a 1/2hp commercial I bought off a widow a bunch of years ago.It has been flawless. Great machine.

View media item 89461
Snatched it up for a little project for my oldest and I. My son took it apart and we started to blast the casting. Found that one of the side plates was cracked. Going to try to tig it up at work this week. I haven't welded on aluminum casting but going to give it a go. If not will try to find a replacement for it.

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View media item 89462
My son wanted it blue. So we put down some self etching primer and then shot some royal blue rustoleum.

View media item 89458
View media item 89457
Have a label coming for it from the awesome mattblast. My son was thinking he wanted to paint the center metallic silver but I am thinking flat black maybe the way to go. I feel weird making it so different than original but it should come out cool.

 

[bubinga]

That blue paint job looks great, almost looks like powder coat.
Are those "pre blocks"?

 

[tommyp]

Are those "pre blocks"?

Thanks, I guess technically tombstones? Not sure.

 

[bubinga]

Thanks, I guess technically tombstones? Not sure.

 

[tommyp]

Got the flat black on the center section. I think I like it.

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