I recently acquired a somewhat rusty used Rockwell 6" bench grinder
(model No 23-612 F573 G6-202-17 1/3 HM 115vac single phase, 3250 rpm).
It is in the process of getting new bearings (the old ones tick when
running, probably due to bits of metal in the grease).

This unit is old-time US, made of cast iron, and weighs a ton. And runs
smoothly, except for the ticks.

The mystery is the wheel flanges. The arbor is 0.500" diameter, and the
wheel flanges (that hold the grinding wheel) are die-cast aluminum alloy
and are about 0.425" thick along the arbor shaft, and are equipped with
two keyslots spaced 180 degrees apart. In the arbor shaft there was a
0.095" diameter by 5/16" deep radial hole with a spiral pin pressed in,
with the tip sticking out, and engaging one of the two keyway slots
(which are 0.117" wide) of the inner flanges. The spiral pins had
largely sheared off, and had chewed a groove and raised a divot on the
inside of the flange, where the radial pin rested. Both sides were
equally affected.

I was able to drill the pin stubs out without damaging the arbor shaft,
using a 0.088" diameter HSS drill in a hand drill, using black sulfur
oil.

My first thought was that this should have been a woodruff key, but the
keyslot is halfway between the standard sizes. But I could mill a
woodruff key slot in the shaft and widen the keyslot in the flange
washer.

My second though was that the original design probably had a single
close-fitting but loose pin that went all the way through the arbor, and
engaged both keyslots.

My third thought was to wonder why the scroll pins both sheared off.
They don't lead that hard a life, so what happened? Maybe I don't want
to make this too strong.

My fourth thought was to observe that few modern bench grinders have
such pins or keys. What problem did they solve?

Comments?

Joe Gwinn

On Mar 4, 5:57*pm, Joseph Gwinn wrote:
I recently acquired a somewhat rusty used Rockwell 6" bench grinder
(model No 23-612 F573 G6-202-17 1/3 HM 115vac single phase, 3250 rpm).
It is in the process of getting new bearings (the old ones tick when
running, probably due to bits of metal in the grease).

This unit is old-time US, made of cast iron, and weighs a ton. *And runs
smoothly, except for the ticks.

The mystery is the wheel flanges. *The arbor is 0.500" diameter, and the
wheel flanges (that hold the grinding wheel) are die-cast aluminum alloy
and are about 0.425" thick along the arbor shaft, and are equipped with
two keyslots spaced 180 degrees apart. *In the arbor shaft there was a
0.095" diameter by 5/16" deep radial hole with a spiral pin pressed in,
with the tip sticking out, and engaging one of the two keyway slots
(which are 0.117" wide) of the inner flanges. *The spiral pins had
largely sheared off, and had chewed a groove and raised a divot on the
inside of the flange, where the radial pin rested. Both sides were
equally affected.

I was able to drill the pin stubs out without damaging the arbor shaft,
using a 0.088" diameter HSS drill in a hand drill, using black sulfur
oil.

My first thought was that this should have been a woodruff key, but the
keyslot is halfway between the standard sizes. *But I could mill a
woodruff key slot in the shaft and widen the keyslot in the flange
washer.

My second though was that the original design probably had a single
close-fitting but loose pin that went all the way through the arbor, and
engaged both keyslots.

My third thought was to wonder why the scroll pins both sheared off.
They don't lead that hard a life, so what happened? *Maybe I don't want
to make this too strong.

My fourth thought was to observe that few modern bench grinders have
such pins or keys. *What problem did they solve?

Comments?

Joe Gwinn

The only 6" grinders I've worked with haven't been that elaborate.
Usually had pressed steel washers on each side just large enough to
stay on the cardboard washers on the wheel, the inner sides abutted a
shoulder on the arbor, friction was the only thing that kept things
from spinning on the arbor. Never had a problem with that. So I
think your arbor is overengineered unless it was intended for driving
some other gizzy as well as doing grinding duty. Might be the pin
engaged with a flex shaft attachment or something similar. You could
probably put the thing back together sans pins and it'd work fine as a
grinder.

Stan

Stanley Schaefer fired this volley in news:9f7cc9e0-
:

So I
think your arbor is overengineered unless it was intended for driving
some other gizzy

I'll agree, and go further with that thought.

Spiral pins are easy to remove (as opposed to roll pins).

There is no apparent reason for that pin to be easily removable, unless
it's intended to be removed.

Lloyd

In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Stanley Schaefer fired this volley in news:9f7cc9e0-
:

So I
think your arbor is overengineered unless it was intended for driving
some other gizzy

I'll agree, and go further with that thought.

Spiral pins are easy to remove (as opposed to roll pins).

Yes. These were roll pins (look like a fat letter C, not a two-turn
spiral). There wasn't enough left to grab and pull the pin stub out.


There is no apparent reason for that pin to be easily removable, unless
it's intended to be removed.

I agree with both of you, but still Rockwell went to some trouble and
expense to put those pins and key slots in, so they must have thought it
necessary or at least quite desirable. The question is why. What
problems were they solving?

Joe Gwinn

Joseph Gwinn fired this volley in news:joegwinn-
:

What
problems were they solving?


Pretty simple. The fact that they were roll pins somewhat suggests they
were NOT designed to be removed.

So, they were simply enforcing that the face of the friction washer would
be the ultimate yield point if something slipped, rather than having the
washer slip on the shoulder of the shaft.

Although my grinders have a mere shoulder, _I_ would rather have them
slip on the paper washer than to slip on the shaft -- if they ever
slipped; which they have not.

LLoyd

Lloyd E. Sponenburgh wrote:
....
So, they were simply enforcing that the face of the friction washer would
be the ultimate yield point if something slipped, rather than having the
washer slip on the shoulder of the shaft.

Although my grinders have a mere shoulder, _I_ would rather have them
slip on the paper washer than to slip on the shaft -- if they ever
slipped; which they have not.

How do you know that they haven't slipped? G

In fact, Joe posted that his flange is scored from it slipping on the
shaft and the pin's stub cutting it.

BTW - the talk has been "flanges" and I say "flange", cause only the
inner flange is/was pinned, right? Varying thickness of wheels would
prohibit pinning the outer flange. Oh, wait ... "flanges" could mean
the 2 inner ones (both sides).

Bob

Bob Engelhardt fired this volley in
:

How do you know that they haven't slipped? G

I know because I routinely change wheels. I normally keep an 80-grit
alumina wheel on one side, and a knotted brush on the other.

The brush never comes off until it wears out, but sometimes I mount a
greenstone on the wheel side.

LLoyd

Bob Engelhardt fired this volley in
:

I guess that you're assuming that if it had slipped, it would have
scored the arbor and you would have noticed. I'm not sure that I would
assume that.

It's academic to me - so what if it slips?

I guess you've never properly installed a stone, or at least not noticed
what's what between the stone and flange washers!

If it had slipped, the paper washers would have been abraded.

(Paper what? You don't use them?)

And if it had slipped, then there's the potential for the stone's
becoming loose on the arbor, which could be dangerous.

Lloyd

Lloyd E. Sponenburgh wrote:

I guess you've never properly installed a stone, or at least not noticed
what's what between the stone and flange washers!

If it had slipped, the paper washers would have been abraded.

(Paper what? You don't use them?)

And if it had slipped, then there's the potential for the stone's
becoming loose on the arbor, which could be dangerous.

Lloyd, you're not paying attention - I've been talking about the wheel &
flanges slipping together on the arbor. No relative motion between
them. A condition that you referred to: "... _I_ would rather have them
slip on the paper washer than to _slip on the shaft_ [my emphasis} --
if they ever slipped; which they have not" and which started this whole
exchange when I replied to it.

And yes, I do "properly" install stones with paper washers. Actually,
I've never thought that paper was enough of a cushion and I've always
cut my washers from thin cardboard (e.g., cereal boxes).

Also, apparently you didn't notice my "G" following my query about
whether you would know if it slipped. I.e., it was more a of rhetorical
question; I never intended it to provoke a debate leading to a snobbish
"I guess you've never properly installed ...".

Bob

Bob Engelhardt fired this volley in
:

Also, apparently you didn't notice my "G" following my query about
whether you would know if it slipped. I.e., it was more a of
rhetorical
question; I never intended it to provoke a debate leading to a snobbish
"I guess you've never properly installed ...".


Ok. Sorry.

(but PS... thin cardboard IS paper. The stuff cereal boxes is made from
is called "chipboard", nominally 0.018" thick. (lot of paper-tech in
fireworks)

LLoyd

In article
,
Stanley Schaefer wrote:

On Mar 5, 11:54*am, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
Bob Engelhardt fired this volley
:

How do you know that they haven't slipped? G

I know because I routinely change wheels. *I normally keep an 80-grit
alumina wheel on one side, and a knotted brush on the other.

The brush never comes off until it wears out, but sometimes I mount a
greenstone on the wheel side.

LLoyd

That's been my experience as well, swap from a fine alumina wheel to a
carborundum or green wheel and back. There's only been indents in the
cardboards from the pressure of the nut on the washers, no signs of
slippage.

I have no idea why those pins would show signs of shearing, the only
thing I could think of is bubba jamming big chunks of truck body in
there and stalling the wheel(s) out.

Bubba was my first theory. My second was to wonder if it was just 35
years of starts pecking away.


In the process of googling, I came up with this site:
http://vintagemachinery.org/members/detail.aspx?id=296
For the members here that have an interest in vintage tools, this has
a bunch of pdfs, exploded drawings and manuals. Also has a 1978
exploded drawing of the 23-612, Rockwell Int. Some of the other sites
I've found had the same thing under the Delta name. None of them show
pins in the arbors. Not really enough detail in the drawing to see if
there were keyways in the flanges. There are a few spares available,
though. Looks like they decided that pins weren't needed in the later
versions for driving wheels around.

This drawing looks exactly like the unit I have, and there is no part
number for a removable pin. But as you say, one cannot tell from the
drawing.

I like the part about making people replace the whole motor unit if a
bearing goes bad. There is nothing magical inside. I am going to
replace both bearings.

Joe Gwinn

In article ,
wrote:

On Mon, 05 Mar 2012 08:21:09 -0500, Joseph Gwinn
wrote:

In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Stanley Schaefer fired this volley in news:9f7cc9e0-
:

So I
think your arbor is overengineered unless it was intended for driving
some other gizzy

I'll agree, and go further with that thought.

Spiral pins are easy to remove (as opposed to roll pins).

Yes. These were roll pins (look like a fat letter C, not a two-turn
spiral). There wasn't enough left to grab and pull the pin stub out.


There is no apparent reason for that pin to be easily removable, unless
it's intended to be removed.

I agree with both of you, but still Rockwell went to some trouble and
expense to put those pins and key slots in, so they must have thought it
necessary or at least quite desirable. The question is why. What
problems were they solving?

Joe Gwinn
Greetings Joe,
I think they were just avoiding a shoulder on the shaft. And since
they were using a pin and cast washers why not cast in slots for the
pin?

The shaft has a substantial shoulder, upon which the big flange washer
rests. The pin is in a machined keyslot, and does not prevent motion
along the shaft. Only rotation is prevented, and only for the two inner
flange washers (nearest to the motor).

I suppose they could have cast the slot in, but they didn't, and they
use only one of the two keyslots, so my guess is that they simplified
the attachment but left the washers alone because they already had the
molds and tooling.

Joe Gwinn

In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Joseph Gwinn fired this volley in news:joegwinn-
:

What
problems were they solving?


Pretty simple. The fact that they were roll pins somewhat suggests they
were NOT designed to be removed.

Certainly. But my theory was that the original design had a pin through
the shaft so the pin could engage both slots in the washer. Although my
guess is that the pin was loose, trapped by the washer, it could have
been a roll pin pushed all the way through as well.


So, they were simply enforcing that the face of the friction washer would
be the ultimate yield point if something slipped, rather than having the
washer slip on the shoulder of the shaft.

That makes sense. Prevents damage to the shoulder and washer.


Although my grinders have a mere shoulder, _I_ would rather have them
slip on the paper washer than to slip on the shaft -- if they ever
slipped; which they have not.

Given that both pins were partly sheared, it was certainly trying to
slip.

Joe Gwinn

On Mon, 05 Mar 2012 20:59:53 -0500, Joseph Gwinn
wrote:

In article ,
wrote:

On Mon, 05 Mar 2012 08:21:09 -0500, Joseph Gwinn
wrote:

In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Stanley Schaefer fired this volley in news:9f7cc9e0-
:

So I
think your arbor is overengineered unless it was intended for driving
some other gizzy

I'll agree, and go further with that thought.

Spiral pins are easy to remove (as opposed to roll pins).

Yes. These were roll pins (look like a fat letter C, not a two-turn
spiral). There wasn't enough left to grab and pull the pin stub out.


There is no apparent reason for that pin to be easily removable, unless
it's intended to be removed.

I agree with both of you, but still Rockwell went to some trouble and
expense to put those pins and key slots in, so they must have thought it
necessary or at least quite desirable. The question is why. What
problems were they solving?

Joe Gwinn
Greetings Joe,
I think they were just avoiding a shoulder on the shaft. And since
they were using a pin and cast washers why not cast in slots for the
pin?

The shaft has a substantial shoulder, upon which the big flange washer
rests. The pin is in a machined keyslot, and does not prevent motion
along the shaft. Only rotation is prevented, and only for the two inner
flange washers (nearest to the motor).

I suppose they could have cast the slot in, but they didn't, and they
use only one of the two keyslots, so my guess is that they simplified
the attachment but left the washers alone because they already had the
molds and tooling.

Joe Gwinn
Well then I'm stumped. If the pins only prevent rotation then maybe
some engineer though it was a good idea. I have never seen a grinder
like this and have never needed a pin to prevent wheel rotation
Eric

There doesn't seem to be a good reason for the pins. Maybe the only way to
find out what problem (real or imagined) Rockwell designers thought they
were addressing, would be to find some advertising literature from the time
when this type of "feature" was introduced.

Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable to me,
but I assume someone thought it would be a good idea.

If there were wrench flats (or pin spanner holes) on the inner wheel flanges
to fit a wrench when removing and replacing the shaft nuts, I could see some
perceived practical use for the pins, but then only really useful if the
nuts were nylock types (any type of locking nut is not actually required for
mounting grinding wheels), because grinding wheel nuts don't require
significant torque to make the mounting secure.

I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough to
figure out the right direction to turn the nuts, or not confident in having
the nuts just snug enough to firmly secure the grinding wheel.

I've also seen wheels with significant gouges in them, so if an accidental
jam on one side caused the motor's rotor to stop, it's possible the other
wheel could continue to rotate, but that's still not likely to unscrew the
nut from the arbor threads.

--
WB
..........


"Joseph Gwinn" wrote in message
...
I recently acquired a somewhat rusty used Rockwell 6" bench grinder
(model No 23-612 F573 G6-202-17 1/3 HM 115vac single phase, 3250 rpm).
It is in the process of getting new bearings (the old ones tick when
running, probably due to bits of metal in the grease).

This unit is old-time US, made of cast iron, and weighs a ton. And runs
smoothly, except for the ticks.

The mystery is the wheel flanges. The arbor is 0.500" diameter, and the
wheel flanges (that hold the grinding wheel) are die-cast aluminum alloy
and are about 0.425" thick along the arbor shaft, and are equipped with
two keyslots spaced 180 degrees apart. In the arbor shaft there was a
0.095" diameter by 5/16" deep radial hole with a spiral pin pressed in,
with the tip sticking out, and engaging one of the two keyway slots
(which are 0.117" wide) of the inner flanges. The spiral pins had
largely sheared off, and had chewed a groove and raised a divot on the
inside of the flange, where the radial pin rested. Both sides were
equally affected.

I was able to drill the pin stubs out without damaging the arbor shaft,
using a 0.088" diameter HSS drill in a hand drill, using black sulfur
oil.

My first thought was that this should have been a woodruff key, but the
keyslot is halfway between the standard sizes. But I could mill a
woodruff key slot in the shaft and widen the keyslot in the flange
washer.

My second though was that the original design probably had a single
close-fitting but loose pin that went all the way through the arbor, and
engaged both keyslots.

My third thought was to wonder why the scroll pins both sheared off.
They don't lead that hard a life, so what happened? Maybe I don't want
to make this too strong.

My fourth thought was to observe that few modern bench grinders have
such pins or keys. What problem did they solve?

Comments?

Joe Gwinn

On Mar 5, 8:25*pm, "Wild_Bill" wrote:
There doesn't seem to be a good reason for the pins. Maybe the only way to
find out what problem (real or imagined) Rockwell designers thought they
were addressing, would be to find some advertising literature from the time
when this type of "feature" was introduced.

Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable to me,
but I assume someone thought it would be a good idea.

If there were wrench flats (or pin spanner holes) on the inner wheel flanges
to fit a wrench when removing and replacing the shaft nuts, I could see some
perceived practical use for the pins, but then only really useful if the
nuts were nylock types (any type of locking nut is not actually required for
mounting grinding wheels), because grinding wheel nuts don't require
significant torque to make the mounting secure.

I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough to
figure out the right direction to turn the nuts, or not confident in having
the nuts just snug enough to firmly secure the grinding wheel.

I've also seen wheels with significant gouges in them, so if an accidental
jam on one side caused the motor's rotor to stop, it's possible the other
wheel could continue to rotate, but that's still not likely to unscrew the
nut from the arbor threads.

--
WB
.........

"Joseph Gwinn" wrote in message

...



I recently acquired a somewhat rusty used Rockwell 6" bench grinder
(model No 23-612 F573 G6-202-17 1/3 HM 115vac single phase, 3250 rpm).
It is in the process of getting new bearings (the old ones tick when
running, probably due to bits of metal in the grease).

This unit is old-time US, made of cast iron, and weighs a ton. *And runs
smoothly, except for the ticks.

The mystery is the wheel flanges. *The arbor is 0.500" diameter, and the
wheel flanges (that hold the grinding wheel) are die-cast aluminum alloy
and are about 0.425" thick along the arbor shaft, and are equipped with
two keyslots spaced 180 degrees apart. *In the arbor shaft there was a
0.095" diameter by 5/16" deep radial hole with a spiral pin pressed in,
with the tip sticking out, and engaging one of the two keyway slots
(which are 0.117" wide) of the inner flanges. *The spiral pins had
largely sheared off, and had chewed a groove and raised a divot on the
inside of the flange, where the radial pin rested. Both sides were
equally affected.

I was able to drill the pin stubs out without damaging the arbor shaft,
using a 0.088" diameter HSS drill in a hand drill, using black sulfur
oil.

My first thought was that this should have been a woodruff key, but the
keyslot is halfway between the standard sizes. *But I could mill a
woodruff key slot in the shaft and widen the keyslot in the flange
washer.

My second though was that the original design probably had a single
close-fitting but loose pin that went all the way through the arbor, and
engaged both keyslots.

My third thought was to wonder why the scroll pins both sheared off.
They don't lead that hard a life, so what happened? *Maybe I don't want
to make this too strong.

My fourth thought was to observe that few modern bench grinders have
such pins or keys. *What problem did they solve?

Comments?

Joe Gwinn- Hide quoted text -

- Show quoted text -

OK, have a look at this:
http://www.acetoolrepair.com/parts-r...or-23-249.html

This is a long-shaft buffer, it HAS roll pins. So maybe what it is is
something that's been converted or a special order item. Can't think
of another explanation. Looks like the pins drive the inner flanges,
then there's a pin that drives some sort of hub for each buffing
wheel.

Stan

Stan

Maybe.. can't tell much from the sketchy drawing.
The pins look like stops for the spacer tubes, to me (assuming no shoulder
on arbor shaft for the spacer tube to fit up to).. whereas Joe stated his
grinder arbor shaft does incorporate a shoulder.

--
WB
..........


"Stanley Schaefer" wrote in message
...

OK, have a look at this:
http://www.acetoolrepair.com/parts-r...or-23-249.html

This is a long-shaft buffer, it HAS roll pins. So maybe what it is is
something that's been converted or a special order item. Can't think
of another explanation. Looks like the pins drive the inner flanges,
then there's a pin that drives some sort of hub for each buffing
wheel.

Stan

Stan

Wild_Bill Inscribed thus:

There doesn't seem to be a good reason for the pins. Maybe the only
way to find out what problem (real or imagined) Rockwell designers
thought they were addressing, would be to find some advertising
literature from the time when this type of "feature" was introduced.

Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable
to me, but I assume someone thought it would be a good idea.

If there were wrench flats (or pin spanner holes) on the inner wheel
flanges to fit a wrench when removing and replacing the shaft nuts, I
could see some perceived practical use for the pins, but then only
really useful if the nuts were nylock types (any type of locking nut
is not actually required for mounting grinding wheels), because
grinding wheel nuts don't require significant torque to make the
mounting secure.

I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough
to figure out the right direction to turn the nuts, or not confident
in having the nuts just snug enough to firmly secure the grinding
wheel.

I've also seen wheels with significant gouges in them, so if an
accidental jam on one side caused the motor's rotor to stop, it's
possible the other wheel could continue to rotate, but that's still
not likely to unscrew the nut from the arbor threads.

Isn't it possible that the idea is to hold the stone at one end whilst
tightening the nut at the other. A cross pin would achieve that aim.

--
Best Regards:
Baron.

On Mar 6, 3:16*pm, Baron wrote:
Wild_Bill Inscribed thus:





There doesn't seem to be a good reason for the pins. Maybe the only
way to find out what problem (real or imagined) Rockwell designers
thought they were addressing, would be to find some advertising
literature from the time when this type of "feature" was introduced.

Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable
to me, but I assume someone thought it would be a good idea.

If there were wrench flats (or pin spanner holes) on the inner wheel
flanges to fit a wrench when removing and replacing the shaft nuts, I
could see some perceived practical use for the pins, but then only
really useful if the nuts were nylock types (any type of locking nut
is not actually required for mounting grinding wheels), because
grinding wheel nuts don't require significant torque to make the
mounting secure.

I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough
to figure out the right direction to turn the nuts, or not confident
in having the nuts just snug enough to firmly secure the grinding
wheel.

I've also seen wheels with significant gouges in them, so if an
accidental jam on one side caused the motor's rotor to stop, it's
possible the other wheel could continue to rotate, but that's still
not likely to unscrew the nut from the arbor threads.

Isn't it possible that the idea is to hold the stone at one end whilst
tightening the nut at the other. *A cross pin would achieve that aim.

--
Best Regards:
* * * * * * * * * * * * * Baron.- Hide quoted text -

- Show quoted text -

On that sort of grinder, you don't really need to hold the stone at
all when screwing on the nut. It ends up wherever it ends up and you
true it after everything is tightened up.

I still say that cross pin is for driving something other than a
grinding wheel.

Stan

In article
,
Stanley Schaefer wrote:

On Mar 5, 8:25*pm, "Wild_Bill" wrote:
There doesn't seem to be a good reason for the pins. Maybe the only way to
find out what problem (real or imagined) Rockwell designers thought they
were addressing, would be to find some advertising literature from the time
when this type of "feature" was introduced.

Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable to me,
but I assume someone thought it would be a good idea.

If there were wrench flats (or pin spanner holes) on the inner wheel flanges
to fit a wrench when removing and replacing the shaft nuts, I could see some
perceived practical use for the pins, but then only really useful if the
nuts were nylock types (any type of locking nut is not actually required for
mounting grinding wheels), because grinding wheel nuts don't require
significant torque to make the mounting secure.

I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough to
figure out the right direction to turn the nuts, or not confident in having
the nuts just snug enough to firmly secure the grinding wheel.

I've also seen wheels with significant gouges in them, so if an accidental
jam on one side caused the motor's rotor to stop, it's possible the other
wheel could continue to rotate, but that's still not likely to unscrew the
nut from the arbor threads.

--
WB
.........

"Joseph Gwinn" wrote in message

...



I recently acquired a somewhat rusty used Rockwell 6" bench grinder
(model No 23-612 F573 G6-202-17 1/3 HM 115vac single phase, 3250 rpm).
It is in the process of getting new bearings (the old ones tick when
running, probably due to bits of metal in the grease).

This unit is old-time US, made of cast iron, and weighs a ton. *And runs
smoothly, except for the ticks.

The mystery is the wheel flanges. *The arbor is 0.500" diameter, and the
wheel flanges (that hold the grinding wheel) are die-cast aluminum alloy
and are about 0.425" thick along the arbor shaft, and are equipped with
two keyslots spaced 180 degrees apart. *In the arbor shaft there was a
0.095" diameter by 5/16" deep radial hole with a spiral pin pressed in,
with the tip sticking out, and engaging one of the two keyway slots
(which are 0.117" wide) of the inner flanges. *The spiral pins had
largely sheared off, and had chewed a groove and raised a divot on the
inside of the flange, where the radial pin rested. Both sides were
equally affected.

I was able to drill the pin stubs out without damaging the arbor shaft,
using a 0.088" diameter HSS drill in a hand drill, using black sulfur
oil.

My first thought was that this should have been a woodruff key, but the
keyslot is halfway between the standard sizes. *But I could mill a
woodruff key slot in the shaft and widen the keyslot in the flange
washer.

My second though was that the original design probably had a single
close-fitting but loose pin that went all the way through the arbor, and
engaged both keyslots.

My third thought was to wonder why the scroll pins both sheared off.
They don't lead that hard a life, so what happened? *Maybe I don't want
to make this too strong.

My fourth thought was to observe that few modern bench grinders have
such pins or keys. *What problem did they solve?

Comments?

Joe Gwinn- Hide quoted text -

- Show quoted text -

OK, have a look at this:
http://www.acetoolrepair.com/parts-r...or-23-249.html

This is a long-shaft buffer, it HAS roll pins. So maybe what it is is
something that's been converted or a special order item. Can't think
of another explanation. Looks like the pins drive the inner flanges,
then there's a pin that drives some sort of hub for each buffing
wheel.

Hmm. Maybe. The motor unit et al are the same. The buffer's roll pins
are 1" long and go all the way through, with 1/4" sticking out on either
side. By contrast, on the grinder, the hole is blind, and the pin
sticks out a bit less than 1/8". But maybe.

Joe Gwinn

In article ,
"Wild_Bill" wrote:

Maybe.. can't tell much from the sketchy drawing.
The pins look like stops for the spacer tubes, to me (assuming no shoulder
on arbor shaft for the spacer tube to fit up to).. whereas Joe stated his
grinder arbor shaft does incorporate a shoulder.

I got a clean pdf from Vintage Machines, and it's clear.

http://vintagemachinery.org/pubs/detail.aspx?id=2319

Joe Gwinn

In article ,
wrote:

On Mon, 05 Mar 2012 20:59:53 -0500, Joseph Gwinn
wrote:

In article ,
wrote:

On Mon, 05 Mar 2012 08:21:09 -0500, Joseph Gwinn
wrote:

In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Stanley Schaefer fired this volley in
news:9f7cc9e0-
:

So I
think your arbor is overengineered unless it was intended for driving
some other gizzy

I'll agree, and go further with that thought.

Spiral pins are easy to remove (as opposed to roll pins).

Yes. These were roll pins (look like a fat letter C, not a two-turn
spiral). There wasn't enough left to grab and pull the pin stub out.


There is no apparent reason for that pin to be easily removable, unless
it's intended to be removed.

I agree with both of you, but still Rockwell went to some trouble and
expense to put those pins and key slots in, so they must have thought it
necessary or at least quite desirable. The question is why. What
problems were they solving?

Joe Gwinn
Greetings Joe,
I think they were just avoiding a shoulder on the shaft. And since
they were using a pin and cast washers why not cast in slots for the
pin?

The shaft has a substantial shoulder, upon which the big flange washer
rests. The pin is in a machined keyslot, and does not prevent motion
along the shaft. Only rotation is prevented, and only for the two inner
flange washers (nearest to the motor).

I suppose they could have cast the slot in, but they didn't, and they
use only one of the two keyslots, so my guess is that they simplified
the attachment but left the washers alone because they already had the
molds and tooling.

Joe Gwinn
Well then I'm stumped. If the pins only prevent rotation then maybe
some engineer though it was a good idea. I have never seen a grinder
like this and have never needed a pin to prevent wheel rotation

But that engineer had to convince his penny-pinching boss to spend the
money. Not to mention the boss's boss. They had to have had a reason.

Joe Gwinn

In article ,
"Wild_Bill" wrote:

There doesn't seem to be a good reason for the pins. Maybe the only way to
find out what problem (real or imagined) Rockwell designers thought they
were addressing, would be to find some advertising literature from the time
when this type of "feature" was introduced.

Yes, but it seems like a lot of work to find that one ad. Maybe someone
will know where to look.


Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable to me,
but I assume someone thought it would be a good idea.

Why is a 0.096" diameter hole in a 0.500" shaft a problem? This does
not seem large compared to the shaft.


If there were wrench flats (or pin spanner holes) on the inner wheel flanges
to fit a wrench when removing and replacing the shaft nuts, I could see some
perceived practical use for the pins, but then only really useful if the
nuts were nylock types (any type of locking nut is not actually required for
mounting grinding wheels), because grinding wheel nuts don't require
significant torque to make the mounting secure.

There are no such holes. Just RH and LH 1/2-20 hex nuts.


I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough to
figure out the right direction to turn the nuts, or not confident in having
the nuts just snug enough to firmly secure the grinding wheel.

Yes, but no such damage seen.


I've also seen wheels with significant gouges in them, so if an accidental
jam on one side caused the motor's rotor to stop, it's possible the other
wheel could continue to rotate, but that's still not likely to unscrew the
nut from the arbor threads.

This could be - Bubba at work. But I don't see any other evidence. The
wheels are quite worn, one 6" stone being worn to maybe 4", but no big
gouges in stone or metal.

Joe Gwinn




"Joseph Gwinn" wrote in message
...
I recently acquired a somewhat rusty used Rockwell 6" bench grinder
(model No 23-612 F573 G6-202-17 1/3 HM 115vac single phase, 3250 rpm).
It is in the process of getting new bearings (the old ones tick when
running, probably due to bits of metal in the grease).

This unit is old-time US, made of cast iron, and weighs a ton. And runs
smoothly, except for the ticks.

The mystery is the wheel flanges. The arbor is 0.500" diameter, and the
wheel flanges (that hold the grinding wheel) are die-cast aluminum alloy
and are about 0.425" thick along the arbor shaft, and are equipped with
two keyslots spaced 180 degrees apart. In the arbor shaft there was a
0.095" diameter by 5/16" deep radial hole with a spiral pin pressed in,
with the tip sticking out, and engaging one of the two keyway slots
(which are 0.117" wide) of the inner flanges. The spiral pins had
largely sheared off, and had chewed a groove and raised a divot on the
inside of the flange, where the radial pin rested. Both sides were
equally affected.

I was able to drill the pin stubs out without damaging the arbor shaft,
using a 0.088" diameter HSS drill in a hand drill, using black sulfur
oil.

My first thought was that this should have been a woodruff key, but the
keyslot is halfway between the standard sizes. But I could mill a
woodruff key slot in the shaft and widen the keyslot in the flange
washer.

My second though was that the original design probably had a single
close-fitting but loose pin that went all the way through the arbor, and
engaged both keyslots.

My third thought was to wonder why the scroll pins both sheared off.
They don't lead that hard a life, so what happened? Maybe I don't want
to make this too strong.

My fourth thought was to observe that few modern bench grinders have
such pins or keys. What problem did they solve?

Comments?

Joe Gwinn

In article , Baron
wrote:

Wild_Bill Inscribed thus:

There doesn't seem to be a good reason for the pins. Maybe the only
way to find out what problem (real or imagined) Rockwell designers
thought they were addressing, would be to find some advertising
literature from the time when this type of "feature" was introduced.

Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable
to me, but I assume someone thought it would be a good idea.

If there were wrench flats (or pin spanner holes) on the inner wheel
flanges to fit a wrench when removing and replacing the shaft nuts, I
could see some perceived practical use for the pins, but then only
really useful if the nuts were nylock types (any type of locking nut
is not actually required for mounting grinding wheels), because
grinding wheel nuts don't require significant torque to make the
mounting secure.

I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough
to figure out the right direction to turn the nuts, or not confident
in having the nuts just snug enough to firmly secure the grinding
wheel.

I've also seen wheels with significant gouges in them, so if an
accidental jam on one side caused the motor's rotor to stop, it's
possible the other wheel could continue to rotate, but that's still
not likely to unscrew the nut from the arbor threads.

Isn't it possible that the idea is to hold the stone at one end whilst
tightening the nut at the other. A cross pin would achieve that aim.

Perhaps, but no easy way to grab the flange washer. I usually use a
vice grips to keep the stone from rotating.

Joe Gwinn

I agree.. searching for the actual purpose/intent of a short-lived decades
old design feature could result in a huge waste of time.

We'll await the day when someone poses the question: Who was asking about
pins in the bench grinder shaft arbors, because..

All we might do at this point is speculate.. and someone probably nailed it,
as there are always good ideas found here, IMO.

--
WB
..........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

There doesn't seem to be a good reason for the pins. Maybe the only way
to
find out what problem (real or imagined) Rockwell designers thought they
were addressing, would be to find some advertising literature from the
time
when this type of "feature" was introduced.

Yes, but it seems like a lot of work to find that one ad. Maybe someone
will know where to look.


Putting a thru hole that size in a 1/2" shaft doesn't seem reasonable to
me,
but I assume someone thought it would be a good idea.

Why is a 0.096" diameter hole in a 0.500" shaft a problem? This does
not seem large compared to the shaft.


If there were wrench flats (or pin spanner holes) on the inner wheel
flanges
to fit a wrench when removing and replacing the shaft nuts, I could see
some
perceived practical use for the pins, but then only really useful if the
nuts were nylock types (any type of locking nut is not actually required
for
mounting grinding wheels), because grinding wheel nuts don't require
significant torque to make the mounting secure.

There are no such holes. Just RH and LH 1/2-20 hex nuts.


I've seen used bench grinder arbor threads that have been chewed up by
someone using a plier on them, apparently by someone not smart enough to
figure out the right direction to turn the nuts, or not confident in
having
the nuts just snug enough to firmly secure the grinding wheel.

Yes, but no such damage seen.


I've also seen wheels with significant gouges in them, so if an
accidental
jam on one side caused the motor's rotor to stop, it's possible the other
wheel could continue to rotate, but that's still not likely to unscrew
the
nut from the arbor threads.

This could be - Bubba at work. But I don't see any other evidence. The
wheels are quite worn, one 6" stone being worn to maybe 4", but no big
gouges in stone or metal.

Joe Gwinn

In article ,
"Wild_Bill" wrote:

I agree.. searching for the actual purpose/intent of a short-lived decades
old design feature could result in a huge waste of time.

We'll await the day when someone poses the question: Who was asking about
pins in the bench grinder shaft arbors, because..

All we might do at this point is speculate.. and someone probably nailed it,
as there are always good ideas found here, IMO.

Actually, speaking of speculation, it occurs to me that the worn-down
stones may be the clue: Maybe a user was leaning into the wheels to
grind faster, and what was carrying the resulting torque was the inner
flanges and roll pins. As I recall, the arbor nuts were snug but not
overly tight. If the wheel was able to rotate on the shaft under such
heavy use, the nuts would have become very tight, perhaps too tight.

Joe Gwinn



WB
.........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

[snip]

I've also seen wheels with significant gouges in them, so if an
accidental
jam on one side caused the motor's rotor to stop, it's possible the other
wheel could continue to rotate, but that's still not likely to unscrew
the nut from the arbor threads.

This could be - Bubba at work. But I don't see any other evidence. The
wheels are quite worn, one 6" stone being worn to maybe 4", but no big
gouges in stone or metal.

Joe Gwinn

A+, good conclusion Joe.. why all the mystery? heheh

I think you meant to state 1/3 HP rating in the OP.. so it's likely to stall
before crushing the grinding wheels, me thinks.
(however, 1/3 HP is much more powerful than today's 3/4+ HP "ratings")
--
WB
..........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

I agree.. searching for the actual purpose/intent of a short-lived
decades
old design feature could result in a huge waste of time.

We'll await the day when someone poses the question: Who was asking about
pins in the bench grinder shaft arbors, because..

All we might do at this point is speculate.. and someone probably nailed
it,
as there are always good ideas found here, IMO.

Actually, speaking of speculation, it occurs to me that the worn-down
stones may be the clue: Maybe a user was leaning into the wheels to
grind faster, and what was carrying the resulting torque was the inner
flanges and roll pins. As I recall, the arbor nuts were snug but not
overly tight. If the wheel was able to rotate on the shaft under such
heavy use, the nuts would have become very tight, perhaps too tight.

Joe Gwinn



WB
.........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

[snip]

I've also seen wheels with significant gouges in them, so if an
accidental
jam on one side caused the motor's rotor to stop, it's possible the
other
wheel could continue to rotate, but that's still not likely to unscrew
the nut from the arbor threads.

This could be - Bubba at work. But I don't see any other evidence.
The
wheels are quite worn, one 6" stone being worn to maybe 4", but no big
gouges in stone or metal.

Joe Gwinn

In article ,
"Wild_Bill" wrote:

A+, good conclusion Joe.. why all the mystery? heheh

Because most modern grinders omit the anti-rotation feature.

I wonder if Baldor grinders have anti-rotation or not.


I think you meant to state 1/3 HP rating in the OP.. so it's likely to stall
before crushing the grinding wheels, me thinks.
(however, 1/3 HP is much more powerful than today's 3/4+ HP "ratings")

I think I did mention that it's 1/3 HP. Maybe they had bigger ponys
back then.

Anyway, we have a conculsion: The anti-rotation feature will be
retained, or improved. The alternatives are the through-pin and the
woodruff key.

Joe Gwinn



"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

I agree.. searching for the actual purpose/intent of a short-lived
decades
old design feature could result in a huge waste of time.

We'll await the day when someone poses the question: Who was asking about
pins in the bench grinder shaft arbors, because..

All we might do at this point is speculate.. and someone probably nailed
it,
as there are always good ideas found here, IMO.

Actually, speaking of speculation, it occurs to me that the worn-down
stones may be the clue: Maybe a user was leaning into the wheels to
grind faster, and what was carrying the resulting torque was the inner
flanges and roll pins. As I recall, the arbor nuts were snug but not
overly tight. If the wheel was able to rotate on the shaft under such
heavy use, the nuts would have become very tight, perhaps too tight.

Joe Gwinn



WB
.........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

[snip]

I've also seen wheels with significant gouges in them, so if an
accidental
jam on one side caused the motor's rotor to stop, it's possible the
other
wheel could continue to rotate, but that's still not likely to unscrew
the nut from the arbor threads.

This could be - Bubba at work. But I don't see any other evidence.
The
wheels are quite worn, one 6" stone being worn to maybe 4", but no big
gouges in stone or metal.

Joe Gwinn

I have 3 good bench grinders (or 5 maybe).. and I now feel a sudden urge to
drill holes in the outboard ends of the arbors, for installing safety
(cotter) pins in them to eliminate the possiblility of having the wheels
spinning the nuts off and running across the floor.

The idea's probably already been patented, so probably not much potential
for it being a rewarding feature.

--
WB
..........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

A+, good conclusion Joe.. why all the mystery? heheh

Because most modern grinders omit the anti-rotation feature.

I wonder if Baldor grinders have anti-rotation or not.


I think you meant to state 1/3 HP rating in the OP.. so it's likely to
stall
before crushing the grinding wheels, me thinks.
(however, 1/3 HP is much more powerful than today's 3/4+ HP "ratings")

I think I did mention that it's 1/3 HP. Maybe they had bigger ponys
back then.

Anyway, we have a conculsion: The anti-rotation feature will be
retained, or improved. The alternatives are the through-pin and the
woodruff key.

Joe Gwinn

On 3/9/2012 9:54 PM, Wild_Bill wrote:
I have 3 good bench grinders (or 5 maybe).. and I now feel a sudden urge
to drill holes in the outboard ends of the arbors, for installing safety
(cotter) pins in them to eliminate the possiblility of having the wheels
spinning the nuts off and running across the floor.

The idea's probably already been patented, so probably not much
potential for it being a rewarding feature.

It might be personally rewarding in a non-remunerative way for you not
to have those wheels go flying across the shop floor.

In article ,
"Wild_Bill" wrote:

I have 3 good bench grinders (or 5 maybe).. and I now feel a sudden urge to
drill holes in the outboard ends of the arbors, for installing safety
(cotter) pins in them to eliminate the possiblility of having the wheels
spinning the nuts off and running across the floor.

The problem is rather the inverse, grinding drag causing the nuts to
become overly tight, in the extreme breaking the wheel (not that I've
ever heard of this happening on a bench grinder).

The nut won't unscrew all the way because once the wheel can spin
freely, it is no longer able to turn the nut.


The idea's probably already been patented, so probably not much potential
for it being a rewarding feature.

I plan to use a shopmade "feather key" (made from 1/8" square keystock)
on the inboard sides, nearest to the motor), with the top of the key
narrowed to fit the 0.115" keyways in the flange washers.

I was going to use a woodruff key, but they are weaker than square keys,
and milling the lengthwise groove is easier than making the recess for a
woodruff key, especially because one needs to go right up to the
shoulder upon which the flange washer rests.

Joe Gwinn


--
WB
.........


"Joseph Gwinn" wrote in message
...
In article ,
"Wild_Bill" wrote:

A+, good conclusion Joe.. why all the mystery? heheh

Because most modern grinders omit the anti-rotation feature.

I wonder if Baldor grinders have anti-rotation or not.


I think you meant to state 1/3 HP rating in the OP.. so it's likely to
stall
before crushing the grinding wheels, me thinks.
(however, 1/3 HP is much more powerful than today's 3/4+ HP "ratings")

I think I did mention that it's 1/3 HP. Maybe they had bigger ponys
back then.

Anyway, we have a conculsion: The anti-rotation feature will be
retained, or improved. The alternatives are the through-pin and the
woodruff key.

Joe Gwinn