I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my drill
press and fits on the outside of the shaft to mill it down?

Thanks !
JCD

pogo wrote:

I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my drill
press and fits on the outside of the shaft to mill it down?

There are rotabroaches that are 1/2" ID but it would be nearly impossible to use
one in a drill press and have the shaft come out concentric with its axis. You
are in deep doodoo, pal. Suggest you buy a motor arbor that bolts on which
effectively does what you need, rather than wrecking your motor. - GWE

"Grant Erwin" wrote: (clip) it would be nearly impossible to use one in a
drill press and have the shaft come out concentric with its axis. You are
in deep doodoo, pal. (clip)
^^^^^^^^^^^^^^^^^
Not necessarily, Grant. Maybe he is building a vibrating table.

pogo wrote:
I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my drill
press and fits on the outside of the shaft to mill it down?

You could bore out your existing sheave. Purchase a long 1/2" steel
bolt, the body of which is a tight 'slip fit' to your sheave.

(One that looks like the second from the left in:
http://www.fhwa.dot.gov/environment/...833/fig069.jpg)

Cut off the bolt threads. Cross drill the body of the bolt off center
about 1" from the cut end, (start with a center drill. Size this to fit
a sharpened 1/8" tool blank. End drill and tap the axial center of the
body to accomodate a 1/4" clamp screw. (Use a 'pulley tap')

Adjust the tool blank to protrude say 0.0615" above the body of the bolt
and liberally apply cutting oil. clamp the sheave in your vise using
blocks of wood to spread out the force. Insert your new piloted boring
tool and crank it through the bore of the sheave with your 1/2" breaker
bar or long handle ratchet. Use an adjustable reamer in your power drill
to open up the ID for a cold slip fit to your motor shaft.

Viola! one properly sized sheave.

--Winston

"Grant Erwin" wrote in message
...
pogo wrote:

I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my
drill
press and fits on the outside of the shaft to mill it down?

There are rotabroaches that are 1/2" ID but it would be nearly impossible
to use one in a drill press and have the shaft come out concentric with
its axis. You are in deep doodoo, pal. Suggest you buy a motor arbor that
bolts on which effectively does what you need, rather than wrecking your
motor. - GWE

Grant, you are personally responsible for stifling the creative process
here, not to mention the chance for some good video footage. We need to
encourage people to "Pee on the electric fence" for themselves. God knows,
I've done it myself enough and I'm a better man for it!

It's called a file

Winston wrote:
pogo wrote:
I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my
drill
press and fits on the outside of the shaft to mill it down?

You could bore out your existing sheave. Purchase a long 1/2" steel
bolt, the body of which is a tight 'slip fit' to your sheave.

(One that looks like the second from the left in:
http://www.fhwa.dot.gov/environment/...833/fig069.jpg)

Cut off the bolt threads. Cross drill the body of the bolt off center
about 1" from the cut end, (start with a center drill. Size this to fit
a sharpened 1/8" tool blank. End drill and tap the axial center of the
body to accomodate a 1/4" clamp screw. (Use a 'pulley tap')

Adjust the tool blank to protrude say 0.0615" above the body of the bolt
and liberally apply cutting oil. clamp the sheave in your vise using
blocks of wood to spread out the force. Insert your new piloted boring
tool and crank it through the bore of the sheave with your 1/2" breaker
bar or long handle ratchet. Use an adjustable reamer in your power drill
to open up the ID for a cold slip fit to your motor shaft.

Viola! one properly sized sheave.

Or clamp the boring bar (toolholder) on the vise movable jaw. Bolt the
motor to the bench such that the shaft is exactly parallel to the vise
screw axis. Run the motor while using the vise screw to move the tool
along the shaft.

The usual tool that acts like an inverted drill bit to turn something
down

is a lathe

i cant think of many ways to rig a tool up


On Wed, 29 Mar 2006 22:34:33 -0500, "pogo"
wrote:

I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my drill
press and fits on the outside of the shaft to mill it down?

Thanks !
JCD

The name of the "inverted drill" you are looking for is called a
Hollow Mill. Check industrial suppliers like MSC.

No, it is called a hollow mill :-), but the chances of successfully
using it by hand for this purpose is very low. Better to take the motor
apart and get someone to turn the shaft or as others suggested, use a
stepdown adapter or bore the pulley.
to see one goto http://www.kbctools.com/usa/main.cfm and check out the
bottom of page 80, they show both solid and adjustable hollow mills

daniel peterman wrote:
It's called a file

"machineman" wrote in message news:AmTWf.13843$B_1.12999@edtnps89...
No, it is called a hollow mill :-), but the chances of successfully
using it by hand for this purpose is very low. Better to take the motor
apart and get someone to turn the shaft or as others suggested, use a
stepdown adapter or bore the pulley.
to see one goto http://www.kbctools.com/usa/main.cfm and check out the
bottom of page 80, they show both solid and adjustable hollow mills

THIS is the kind of answer I was hoping for. Thanks very much!

I figured I'd end up needing to remove the shaft to do anything to it.

Thanks !

Yeah - that's what my initial thought was, too.
Thanks !

"Brent Philion" wrote in message ...
The usual tool that acts like an inverted drill bit to turn something
down

is a lathe

i cant think of many ways to rig a tool up


On Wed, 29 Mar 2006 22:34:33 -0500, "pogo"
wrote:

I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my drill
press and fits on the outside of the shaft to mill it down?

Thanks !
JCD

Cool! I will do so!
Thanks!

"Scott" wrote in message oups.com...

The name of the "inverted drill" you are looking for is called a
Hollow Mill. Check industrial suppliers like MSC.

I would like to make sure that you know that there are shaft
adaptors that are sold commercially.

Yep and I understand that that is probably the best over-all solution.
But thanks for the help!
JCD

There are rotabroaches that are 1/2" ID but it would be nearly impossible to use
one in a drill press and have the shaft come out concentric with its axis.

Yep - I figured that! I seem to figure out a lot of this stuff *after* I post the questions!

You
are in deep doodoo, pal. Suggest you buy a motor arbor that bolts on which
effectively does what you need, rather than wrecking your motor. - GWE

Yes, and good idea!
JCD

It's called a file

Thanks. You da man.

most of the other advise is right on, but - a long time ago I did
something similar by running the motor and bringing a grinding wheel
(powered and running in opposite direction) up against the shaft -
worked well enough for my purposes, though certainly not very high
precision


On Wed, 29 Mar 2006 22:34:33 -0500, "pogo"
wrote:

I'd like to grind a 5/8" shaft on a motor down to 1/2", but have no real
metal shop - just a drill press & mitre saw.
Is there something like an inverted drill bit, that I could put in my drill
press and fits on the outside of the shaft to mill it down?

Thanks !
JCD

Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com
*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

William B Noble (don't reply to this address) wrote:
most of the other advise is right on, but - a long time ago I did
something similar by running the motor and bringing a grinding wheel
(powered and running in opposite direction) up against the shaft -
worked well enough for my purposes, though certainly not very high
precision


snipped


Me too, and more than once in my life.

I'm assuming that you didn't head for a shaft adaptor because it would
extend the shaft further than your application can accept.

Depending on what you're trying to do, if it's just a small die cast
v-belt pulley or something similarly imprecise that you intend to put on
the shaft, then carefull application of a flat file with the motor
running and FREQUENT checking of the diameter at several points along
the length you are reducing will probably be good 'nuff.

If you're going to be spinning a larger diameter weighty load you'd be
better off biting the bullet, taking the rotor out and bringing it
somewhere where it would just be "the matter of a moment" to have it
turned to size on a lathe.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."