I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not buying
a balancer, but could build something. Or just spin it up and see how
it does? Thanks.

Pete Keillor

"Pete Keillor" wrote in message
...

I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not buying
a balancer, but could build something. Or just spin it up and see how
it does? Thanks.

Pete Keillor

================================================== =======
[Ed]

Static balance is easy. Turn a shaft that just fits the bore. Rest it on two
knife edges (I like razor blades, if the device is light, but that's
overkill here). It will rotate until the heavy side is down.

At 3800 rpm, with a lathe-turned wheel, you probably aren't going to have
dynamic balance (wobble) problems. Those are more difficult with home-built
gadgets.

--
Ed Huntress

"Pete Keillor" wrote in message
...
I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running
on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not
buying
a balancer, but could build something. Or just spin it up and see
how
it does? Thanks.

Pete Keillor

If you haven't already cut the shaft to length you could turn the
other end to 1/4" and spin the shaft and pulley with a fast drill, a
variable speed one to accelerate it slowly and carefully. If the shaft
is long enough the pulley will rotate smoothly around the combined
center of gravity of it and its end of the shaft. You could carefully
touch a laundry marker to the shaft to mark the light, high side and
feel the amount of vibration.

-jsw

On Wed, 6 Aug 2014 12:48:44 -0400, "Jim Wilkins"
wrote:

"Pete Keillor" wrote in message
.. .
I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running
on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not
buying
a balancer, but could build something. Or just spin it up and see
how
it does? Thanks.

Pete Keillor

If you haven't already cut the shaft to length you could turn the
other end to 1/4" and spin the shaft and pulley with a fast drill, a
variable speed one to accelerate it slowly and carefully. If the shaft
is long enough the pulley will rotate smoothly around the combined
center of gravity of it and its end of the shaft. You could carefully
touch a laundry marker to the shaft to mark the light, high side and
feel the amount of vibration.

-jsw

Good idea. Since the shaft is cut, I can adapt your idea by chucking
in a 3/4" 5C collet in my Hardinge mill, set it up for high speed, and
use the VFD to bring it up slowly. Should be able to get a sense of
an out of balance condition. More rigid, but with enough overhang, it
should work.

I also thought of not drilling the opposing holes completely, and
deepening as indicated.

Thanks.

Pete

"Pete Keillor" wrote in message
...
On Wed, 6 Aug 2014 12:48:44 -0400, "Jim Wilkins"
wrote:

"Pete Keillor" wrote in message
. ..
I'm to the point of turning the drive wheel for the belt grinder
I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running
on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to
help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not
buying
a balancer, but could build something. Or just spin it up and see
how
it does? Thanks.

Pete Keillor

If you haven't already cut the shaft to length you could turn the
other end to 1/4" and spin the shaft and pulley with a fast drill, a
variable speed one to accelerate it slowly and carefully. If the
shaft
is long enough the pulley will rotate smoothly around the combined
center of gravity of it and its end of the shaft. You could
carefully
touch a laundry marker to the shaft to mark the light, high side and
feel the amount of vibration.

-jsw

Good idea. Since the shaft is cut, I can adapt your idea by
chucking
in a 3/4" 5C collet in my Hardinge mill, set it up for high speed,
and
use the VFD to bring it up slowly. Should be able to get a sense of
an out of balance condition. More rigid, but with enough overhang,
it
should work.

I also thought of not drilling the opposing holes completely, and
deepening as indicated.

Thanks.

Pete

The lathe is NOT a good idea. I couldn't find a clear, short article
on Critical Speed to explain what happens. A loosely restrained hand
drill will let the spinning shaft and pulley find their own center of
rotation while the shaft and pulley may whip around dangerously in the
lathe.

"Jim Wilkins" wrote in message
...
"Pete Keillor" wrote in message
...
On Wed, 6 Aug 2014 12:48:44 -0400, "Jim Wilkins"
wrote:

"Pete Keillor" wrote in message
...
I'm to the point of turning the drive wheel for the belt grinder
I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide,
running
on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to
help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not
buying
a balancer, but could build something. Or just spin it up and
see
how
it does? Thanks.

Pete Keillor

If you haven't already cut the shaft to length you could turn the
other end to 1/4" and spin the shaft and pulley with a fast drill,
a
variable speed one to accelerate it slowly and carefully. If the
shaft
is long enough the pulley will rotate smoothly around the combined
center of gravity of it and its end of the shaft. You could
carefully
touch a laundry marker to the shaft to mark the light, high side
and
feel the amount of vibration.

-jsw

Good idea. Since the shaft is cut, I can adapt your idea by
chucking
in a 3/4" 5C collet in my Hardinge mill, set it up for high speed,
and
use the VFD to bring it up slowly. Should be able to get a sense
of
an out of balance condition. More rigid, but with enough overhang,
it
should work.

I also thought of not drilling the opposing holes completely, and
deepening as indicated.

Thanks.

Pete

The lathe is NOT a good idea. I couldn't find a clear, short article
on Critical Speed to explain what happens. A loosely restrained hand
drill will let the spinning shaft and pulley find their own center
of rotation while the shaft and pulley may whip around dangerously
in the lathe.

Or mill, I posted fast to stop you. Don't spin it with anything until
I find a better explanation.

"Jim Wilkins" wrote in message ...

"Pete Keillor" wrote in message
...
I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not buying
a balancer, but could build something. Or just spin it up and see how
it does? Thanks.

Pete Keillor

If you haven't already cut the shaft to length you could turn the
other end to 1/4" and spin the shaft and pulley with a fast drill, a
variable speed one to accelerate it slowly and carefully. If the shaft
is long enough the pulley will rotate smoothly around the combined
center of gravity of it and its end of the shaft. You could carefully
touch a laundry marker to the shaft to mark the light, high side and
feel the amount of vibration.

-jsw

================================================== ========
[Ed]

One-plane (static) balancing is generally considered plenty for this type of
job:

http://www.mpta.org/MPTA%20B2c%202011.pdf

(page 4)

That's just a knife-blade job, as I described. Make sure the knife blades
are DEAD level. The back sides of two hacksaw blades should be plenty
sensitive. Just stroke them with a stone or some wet-dry to make sure
they're smooth.

--
Ed Huntress

On Wednesday, August 6, 2014 2:36:15 PM UTC, Pete Keillor wrote:
\


Any suggestions on how to balance this for a hobbyist? I'm not buying

a balancer, but could build something. Or just spin it up and see how

it does? Thanks.



Pete Keillor

I would probably just spin it up and see how it does. But this has come up before in this group.

Take a look at " Orthoganol balancing - twinwheel grinders " back in 09. It is a really good thread started by Jim Pentagrid.

Dan

On 8/6/2014 2:00 PM, Ed Huntress wrote:

One-plane (static) balancing is generally considered plenty for this
type of job:

http://www.mpta.org/MPTA%20B2c%202011.pdf

(page 4)

That's just a knife-blade job, as I described. Make sure the knife
blades are DEAD level. The back sides of two hacksaw blades should be
plenty sensitive. Just stroke them with a stone or some wet-dry to make
sure they're smooth.


My home made belt grinder has a DC motor with a max speed of 6000 rpm.
With the pulleys that I made, the 6" x 2" contact wheel can run at 4000
rpm. This 10% over the threshold for 2 plane balancing in Ed's
reference. It was balanced with the knife-blade method and does not
show any imbalance.

I gotta admit that I hardly ever run at max speed, which is a belt speed
of 6000 fpm.

Bob

"Ed Huntress" wrote in message
...
"Jim Wilkins" wrote in message ...
"Pete Keillor" wrote in message

Any suggestions on how to balance this for a hobbyist? ...
Pete Keillor

[Ed]

One-plane (static) balancing is generally considered plenty for this
type of job:

http://www.mpta.org/MPTA%20B2c%202011.pdf

(page 4)

That's just a knife-blade job, as I described. Make sure the knife
blades are DEAD level. The back sides of two hacksaw blades should
be plenty sensitive. Just stroke them with a stone or some wet-dry
to make sure they're smooth.

--
Ed Huntress

Yeah, go with that. For a quick check maybe you could roll the shaft
on two parallels on the mill table, shimmed as level as you care to.

The only difficult part of making a static balancer is drilling an
accurately centered conical recess that doesn't have a small flat in
the center. A split-point drill might work.
-jsw

On 2014-08-06, Pete Keillor wrote:
I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not buying
a balancer, but could build something. Or just spin it up and see how
it does? Thanks.

Hmmm ... if you make the screw enough bigger (and perhaps an
Allen head cap screw (if you have hollow ends and hubs within that),
you could compensate for the mass missing from the drum surface. Then
no need to drill an extra hole opposite. Maybe add a nut for locking
and extra mass, too.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

The pulley is aluminum and presumably the set screws will be some kind of
steel alloy so they are three times the density of the aluminum, which
should make up for the "missing" volume from the threads and hex key socket.
They might even be too heavy. Considering how close they are to the shaft,
I bet the balance will be pretty much dead on with just the two plain set
screws. If you set up the knife edges it would be interesting to check the
pulley before you drill and tap the set screw holes, just to make sure it is
dead on, and then you could see if the set screws change anything.

-----
Regards,
Carl Ijames

"DoN. Nichols" wrote in message
...

On 2014-08-06, Pete Keillor wrote:
I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not buying
a balancer, but could build something. Or just spin it up and see how
it does? Thanks.

Hmmm ... if you make the screw enough bigger (and perhaps an
Allen head cap screw (if you have hollow ends and hubs within that),
you could compensate for the mass missing from the drum surface. Then
no need to drill an extra hole opposite. Maybe add a nut for locking
and extra mass, too.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703)
938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Wed, 06 Aug 2014 17:43:38 -0400, Bob Engelhardt
wrote:

On 8/6/2014 2:00 PM, Ed Huntress wrote:

One-plane (static) balancing is generally considered plenty for this
type of job:

http://www.mpta.org/MPTA%20B2c%202011.pdf

(page 4)

That's just a knife-blade job, as I described. Make sure the knife
blades are DEAD level. The back sides of two hacksaw blades should be
plenty sensitive. Just stroke them with a stone or some wet-dry to make
sure they're smooth.


My home made belt grinder has a DC motor with a max speed of 6000 rpm.
With the pulleys that I made, the 6" x 2" contact wheel can run at 4000
rpm. This 10% over the threshold for 2 plane balancing in Ed's
reference. It was balanced with the knife-blade method and does not
show any imbalance.

I gotta admit that I hardly ever run at max speed, which is a belt speed
of 6000 fpm.

Bob
This one will be very similar speeds.

On Thu, 7 Aug 2014 11:19:57 -0400, "Carl Ijames"
wrote:

The pulley is aluminum and presumably the set screws will be some kind of
steel alloy so they are three times the density of the aluminum, which
should make up for the "missing" volume from the threads and hex key socket.
They might even be too heavy. Considering how close they are to the shaft,
I bet the balance will be pretty much dead on with just the two plain set
screws. If you set up the knife edges it would be interesting to check the
pulley before you drill and tap the set screw holes, just to make sure it is
dead on, and then you could see if the set screws change anything.

-----
Regards,
Carl Ijames

"DoN. Nichols" wrote in message
...

On 2014-08-06, Pete Keillor wrote:
I'm to the point of turning the drive wheel for the belt grinder I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not buying
a balancer, but could build something. Or just spin it up and see how
it does? Thanks.

Hmmm ... if you make the screw enough bigger (and perhaps an
Allen head cap screw (if you have hollow ends and hubs within that),
you could compensate for the mass missing from the drum surface. Then
no need to drill an extra hole opposite. Maybe add a nut for locking
and extra mass, too.

Enjoy,
DoN.

Thanks to everybody for the suggestions. I'm out of town and didn't
have access for a while. It's the wife's business junket, but spouses
were invited, so who in their right minds wouldn't get out of Texas in
August to Park City, Utah. Got in some very pleasant hiking.

I now plan to use the knife edge idea originally mentioned by Ed, then
depending maybe add extra set screws if needed or drill opposite.
Probably just spin it first, but the disc would be near the mill
spindle on the 3/4" shaft which is pretty short, 10" back through the
collet. No worries about whipping. If it seems smooth enough,
that'll be it. The idler and contact wheels should not be a problem
because they run on their own bearings and are uniform.

Pete Keillor

"Pete Keillor" wrote in message
...
On Thu, 7 Aug 2014 11:19:57 -0400, "Carl Ijames"
wrote:

The pulley is aluminum and presumably the set screws will be some
kind of
steel alloy so they are three times the density of the aluminum,
which
should make up for the "missing" volume from the threads and hex key
socket.
They might even be too heavy. Considering how close they are to the
shaft,
I bet the balance will be pretty much dead on with just the two
plain set
screws. If you set up the knife edges it would be interesting to
check the
pulley before you drill and tap the set screw holes, just to make
sure it is
dead on, and then you could see if the set screws change anything.

-----
Regards,
Carl Ijames

"DoN. Nichols" wrote in message
...

On 2014-08-06, Pete Keillor wrote:
I'm to the point of turning the drive wheel for the belt grinder
I'm
building for my son. It'll be 6061 Al, 6" dia. x 2" wide, running
on
a 3/4" keyed shaft, and turn up to 3800 rpm. I figure I'll put a
setscrew on the key and another at 90 deg., which will require
drilling from the circumference. I can drill holes opposite to
help
balance.

Any suggestions on how to balance this for a hobbyist? I'm not
buying
a balancer, but could build something. Or just spin it up and see
how
it does? Thanks.

Hmmm ... if you make the screw enough bigger (and perhaps an
Allen head cap screw (if you have hollow ends and hubs within that),
you could compensate for the mass missing from the drum surface.
Then
no need to drill an extra hole opposite. Maybe add a nut for
locking
and extra mass, too.

Enjoy,
DoN.

Thanks to everybody for the suggestions. I'm out of town and didn't
have access for a while. It's the wife's business junket, but
spouses
were invited, so who in their right minds wouldn't get out of Texas
in
August to Park City, Utah. Got in some very pleasant hiking.

I now plan to use the knife edge idea originally mentioned by Ed,
then
depending maybe add extra set screws if needed or drill opposite.
Probably just spin it first, but the disc would be near the mill
spindle on the 3/4" shaft which is pretty short, 10" back through
the
collet. No worries about whipping. If it seems smooth enough,
that'll be it. The idler and contact wheels should not be a problem
because they run on their own bearings and are uniform.

Pete Keillor

Does an unbalanced flycutter or boring head make your mill vibrate?
-jsw