I was gifted a basic ("Professional Woodworker" brand) lathe with a
dead 3/4 horse motor. I have an old Dayton 3/4 horse motor (which is
much bigger and heavier than the one in the lathe) which I'd like to
use for the lathe, but the spindle on the "new" replacement motor is
maybe 1/16" too large for the pulley from the dead motor.
How should I go about getting the pulley on the motor? Should I crank
up the motor and just use sandpaper on the spindle until the pulley
fits or what? I'm hesitant to try to drill out the pulley because I
don't want to make the hole off center and ruin a mostly irreplaceable
Also, since the "new" motor is so much larger than the dead one, I
have to relocate the motor to below the lathe's motor enclosure...
would one of those link belts be a good option for connecting the
pulleys or should I just go to an auto parts store and try to find an
appropriate size belt there?
Any recommendations on where to go for one?
Rather than a flat side section on the spindle like most motors I've
seen, my motor has a notch cut out of the spindle in which a small
square metal peg was inserted.
I have no idea. There is no plate of any kind on the original motor,
and aftermarket support of this brand of machine appears to be pretty
slim. The replacement is a 1750rpm, and I'm pretty sure a machine of
this level wouldn't spin at the 3000rpm mark.
http://www.mcmaster.com/ (my preferred online "go to")
http://www.grainger.com (my preferred local "go to")
or do a Google search for "sheave" any your city location and it may
bring up some local outlets.
A square key fits in the notch and mates with a similar notch in the
sheave to prevent the sheave spinning on the shaft. If you check the
motor dataplate, find the frame size, and compare it to the entries in
a NEMA frame chart, it will give you the diameter of the shaft and the
dimensions of the notch. Or, since the key slots are standardized
based on the shaft diameter, you can just get one that matches from
the same place you get the sheave.
For example a motor with a NEMA 56 frame has a 5/8 dia shaft which
takes a 3/16 square key. See for example:
Any keyed sheave/pulley fitting that shaft would also have a 3/16
keyway. Here's an example
Note the description and specs indicate that the sheave has a keyway.
A 12" length of 3/16 keystock from Grainger is about 95 cents if you
want to cut your own.
Local hardware for a start, motor shops and/or auto parts places and
other industrial distributors.
There's always the online route of McMaster-Carr, Grainger, et al, but
ordinary items like this shouldn't be any problem locally.
That's typical keyed way -- more than likely 3/16". Key stock or precut
keys are a dime at the hardware store or may well come w/ the pulley.
That's why I asked -- if you had a common 3450 rpm motor, I was betting
the original was likely 1725.
The only 4 step pulleys I can find have minimum sizes ranging from
1/4" larger than the original at the smallest step to 1/2" larger at
the largest step. I know that will yield a higher overall rotation
speed, but does anyone out there think it will be any more dangerous
Also, after measuring, I discovered that the original pulley bore is
1.5cm! I'm glad I came here for help, because I hadn't even thought
about this thing being metric! The pulley steps on the original are 4,
5, 6, and 7 cm, and the replacement ones will be 1-3/4", 2-1/4",
2-3/4", and 3-1/4".
The speed difference will be the ratio of the diameters--I didn't do 'em
all, but the first is roughly 11%; I wouldn't worry at that difference.
The other choice still, of course, is to get the existing pulley rebored
at a machine shop--depending on whether you have a local kind-hearted
retiree w/ a shop in his basement you might get it done pretty
inexpensively; commercial shops tend to be pretty pricey.
No, I haven't. I'm not sure it would be worth it. It's not a very
impressive specimen, and I think it would probably cost me more than
$20 to have repaired, which is what a new belt and pulley would cost
Here's a photo of the old motor and the "new" one, side by side:
Something tells me that the 3/4 hp I'd get from the Dayton brand motor
would be better than the 3/4 hp the unbranded one would give me.
I was under the impression that small motor repair was generally a
comparatively expensive proposition. If I'm going to be out around
$20, wouldn't it be better to have a more robust motor driving things
than repair something that's already broken down once?
And to Tom:
I'm not 100% sure on my measurements. I've been using the "inside the
house" tape measure, which sometimes doubles as a toy for my 2 year
old son, so you're most likely right in that it's 14mm. I would hope
the motor would have that information on it, but I'm learning to not
expect too much from these cheap imports. :-)
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