Taking apart split-phase fractional HP motors isn't complicated, take some
pics with a digital camera if desired.

If the shaft is rusty, clean it up first with some shinin' cloth or
equivalent.

The end bells (case ends) should be marked with a file notch or prick punch
just to make re-assembly easier.. the power cord and oilers, etc (if
equipped) will then be in the same orientation as before.
There aren't any parts in these types of motors that will pop out and fly
away, only an occassional shim washer that may fall on the floor, if not
paying attention.

Remove one end bell (after removing the end-to-end case screws, and remove
the rotor.. it's that easy.

The shaft will cut fairly easily, although there will be some irregularity
due to the interrupted cut from the keyway slot.
Taking very slight finish cuts will generally correct the irregularity.

Re-assembly of these motors is also fairly simple. Add some oil to the felt
pads if the motor has the sleeve type bearings.
Put the rotor back in, and position the end bell for assembly, aligning the
mark. The bell may require some pressure to seat it in the case, and
removing any sharp edges from the mating surfaces will generally make
re-assembly very easy. Apply some candle/crayon wax or dry bar soap as a
lube and push the bell into the case.
Install the case screws and snug them a little, then begin to tighten them
gradually, crossing the the case diameter with each subsequent screw/nut, a
couple of turns each until the end bells are fully seated.

Spin the shaft by hand, and if the rotor doesn't coast a little, use a
little percussive tuning to align the bearings with the shaft for nearly
perfect alignment, by thumping the end bells with a chunk-o-wood, then
rechecking the rotor spin/coast.
When the rotor coasts, indicating very good alignment, finish tightening the
case screws.

Forget about the keyway since the pulley doesn't have one.. fill it with a
section of key stock (or other piece of steel or brass stock that fits the
slot) that's been filed down to the shaft diameter, but with a flat spot for
the setscrew to bite on.
Use a better/high quality setscrew (with an end that will bite/seat securely
in the piece of key stock) of an appropriate length that will engage all of
the threads in the pulley.
A drop or two of medium loctite/threadlocker on the setscrew will likely be
worthwhile.

Filing the shaft to size wouldn't be difficult if one could fabricate a
fixture with front and rear roller guides that straddle the shaft to prevent
filing the shaft off-center or tapered.
I've seen such single-roller guides as lathe attachments in old lathe
books.. which were apparently intended to keep the file flat/parallel to the
workpiece surface (spindle center axis), not for filing to a specific
diameter.
This sort of fixture would then need to be rigidly attached to the motor
base to attain the desired results.

It would be far less effort to disassemble the motor and turn the shaft on a
lathe either between centers (if needed for the shaft length), or chucked at
the back end (with a protective wrap of aluminum flashing, for example, to
prevent marring the bearing surface) with the output shaft centered at the
tailstock end.
Absolute precision isn't required on a low speed drill press motor shaft.

It's not likely that one will ever encounter a precision ground shaft on a
general purpose, utility-type motor.

As for the subject of smaller motors.. most fractional HP AC induction
motors (not including universal AC/DC types) are generally about the same
size as far as shaft to mounting surface. The rotors are longer in higher HP
ratings, but the cases are often the same diameter size.
Shaft sizes change with HP ratings.. it's not very common to see a 1/4 HP
motor with a 5/8" (but sometimes a 1/2") shaft.

The entire process of machining the motor shaft in a lathe and mounting the
finished motor with pulley, would probably only take an hour, and likely
less time for many experienced home shop metalworking types.

The only small issue with using this motor as intended would be that it may
be worthwhile to add a fiber or smooth thrust washer on the back end shaft,
since the motor will be oriented in shaft-up vertical position.
It wouldn't be required for motors with ball bearings, but may prevent
startup/shutdown noises in sleeve-bearing type motors.
A properly selected size of a single ball bearing placed in the closed back
end bell shaft bearing pocket (with a small dollop of grease) could also
take care of the issue.

Note: the shaft's end play shouldn't be reduced to zero.. an improvised
thrust bearing should only give the back end of the shaft something to rest
on.

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


"Searcher7" wrote in message
...
I decided to get back to putting together an old table top drill press
that had never been used. I proceeded to connect the AC and the pulley
to the motor shaft, only to find out that the pulley has an I.D. of
1/2" and the motor shaft has O.D. of 5/8". (This explains why the
previous owner never finished it).

Outside of trying to find another pulley set I was wondering if I
should look into machining the present motor pulley by boring the
1-1/2" I.D. long from 1/2" diameter to 5/8" diameter.

Also, the pulley has a set screw, and the motor shaft has a key-way.
The problem is that the set screw *may* be too small for the key-way,
in which case I'd also have to re-drill for a larger set screw.

And all this after I figure out whether this would be best done on a
lathe or a mill, and then how to work hold for both operations.

I'd appreciated any advice on whether a project like this is
plausible, or should I just keep my eyes open for a pulley set that
fits.

Thanks.

Darren Harris
Staten Island, New York.