I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).

Thanks,
Bob

Bob Engelhardt writes:

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).

The boring should be fine, but you may need a keyway broach and bushing to
recut the keyway.

Bob Engelhardt wrote:

I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).

I sure hope it's OK; I've done it a few times. :-)

But use the lathe (or mill, if that's how you're doing it) to stroke the
keyway deeper. It's a very useful thing to know how to do, and it's easy,
and the tooling is inexpensive.

Grant

--
Posted via a free Usenet account from http://www.teranews.com

Grant Erwin wrote:
Bob Engelhardt wrote:

I'm putting a new motor on my lathe that has a bigger shaft than the
old pulley. I'm planning on boring out the old pulley (another
1/8"), but I want to make sure that this is not a Bad Idea before I
do. Is it OK?

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).

I sure hope it's OK; I've done it a few times. :-)

But use the lathe (or mill, if that's how you're doing it) to stroke the
keyway deeper. It's a very useful thing to know how to do, and it's easy,
and the tooling is inexpensive.

Grant

Really . I use a boring bar set on center , with a cutter ground
square on the end . Tedious ...
--
Snag

On Jan 25, 9:12*pm, Terry Coombs wrote:
Grant Erwin wrote:
Bob Engelhardt wrote:

I'm putting a new motor on my lathe that has a bigger shaft than the
old *pulley. *I'm planning on boring out the old pulley (another
1/8"), but I want to make sure that this is not a Bad Idea before I
do. *Is it OK?

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).

I sure hope it's OK; I've done it a few times. :-)

But use the lathe (or mill, if that's how you're doing it) to stroke the
keyway deeper. It's a very useful thing to know how to do, and it's easy,
and the tooling is inexpensive.

Grant

* *Really . I use a boring bar set on center , with a cutter ground
square on the end . Tedious ...
--
* *Snag

It goes faster if you saw or chisel the slot deeper first. The key
bottoms in the shaft, not the pulley, so you can afford small
mistakes.

Enco keyway broaches have worked well for me. I make the bore guide
and mill its slot a few thousandths shallower than the height of the
first tooth. It doesn't need a shoulder but must be at least as long
as the hole through the hub, for support.

Lacking better tools you can sand or grind the teeth off the faces of
a file and cut the slot deeper with the edge.

Jim Wilkins

Terry Coombs wrote:

Grant Erwin wrote:

Bob Engelhardt wrote:

I'm putting a new motor on my lathe that has a bigger shaft than the
old pulley. I'm planning on boring out the old pulley (another
1/8"), but I want to make sure that this is not a Bad Idea before I
do. Is it OK?

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).


I sure hope it's OK; I've done it a few times. :-)

But use the lathe (or mill, if that's how you're doing it) to stroke the
keyway deeper. It's a very useful thing to know how to do, and it's easy,
and the tooling is inexpensive.

Grant

Really . I use a boring bar set on center , with a cutter ground
square on the end . Tedious ...

Yup, me too. Well, I do a slightly more sophisticated grind - there's some
relief built in - but basically it's crank the apron towards the headstock,
pull it back out, crank the topslide .005" or so towards you, repeat ..
actually it doesn't take that long, a few minutes. I don't think Bob's
going to go into production, this sounds like a one-off to me.

Grant

--
Posted via a free Usenet account from http://www.teranews.com

On 2008-01-26, Bob Engelhardt wrote:
I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Well -- the first question is what will you use to do the
boring? I would want to do it on a lathe, taking the time to truly
center it in a 4-jaw chuck. (And I might use an old belt to fill the
outer V-groove so the chuck jaws are less likely to damage the pulley.

Just drilling it will probably cause the hole to be off center,
because of the keyway providing less resistance to the drill than the
rest of the pulley body. I certainly would not want to do it in a drill
press -- unless I had a piloted drill with just the right size pilot and
flute diameter.

So -- I hope that you have another lathe to use for the boring,
or a creative way to drive the exiting lathe while its pulley is not on
the motor. :-)

Considerations so far: there is plenty of meat in the old (cast iron)
pulley; the keyway will be reduced to 1/16" deep, but that should be
enough (?).

Well ... you can always use a keyseat broach to re-cut the
keyseat to proper depth (and possibly to a wider keyseat as well,
depending on what is standard for the size of the final bore.)

Good Luck,
DoN.

--
Email: | 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 ---

"DoN. Nichols" wrote in message
...
On 2008-01-26, Bob Engelhardt wrote:
I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Well -- the first question is what will you use to do the
boring? I would want to do it on a lathe, taking the time to truly
center it in a 4-jaw chuck. (And I might use an old belt to fill the
outer V-groove so the chuck jaws are less likely to damage the pulley.

Soft jaws were made for a job like this. They support the pulley
adequately, and automatically align it in both planes. Best of all, they
won't mar the pulley, which will be delicate due to the narrow edges of the
groove.

Harold

On Sun, 27 Jan 2008 06:11:23 GMT, "Harold and Susan Vordos"
wrote:


"DoN. Nichols" wrote in message
...
On 2008-01-26, Bob Engelhardt wrote:
I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Well -- the first question is what will you use to do the
boring? I would want to do it on a lathe, taking the time to truly
center it in a 4-jaw chuck. (And I might use an old belt to fill the
outer V-groove so the chuck jaws are less likely to damage the pulley.

Soft jaws were made for a job like this. They support the pulley
adequately, and automatically align it in both planes.

I assume that your soft jaws engage the V groove and not the flanges?
Flanges on even some pretty good cast pulleys can be somewhat wonky
on the periphery of the flanges.

If the pulley ran OK before, e.g. pitch diameters perpendicular to and
concentric with bore axis, I would consider using a faceplate and
shims or blocks until the bore indicates tits both axially and
radially, then bore. Getting that set up would be a bit fussy, but
it might be quicker than making and mounting soft jaws with the
desired precision to get axial alignment. It needs to be dialled in
radially in either case.

On Sun, 27 Jan 2008 03:15:32 -0600, Don Foreman
wrote:

On Sun, 27 Jan 2008 06:11:23 GMT, "Harold and Susan Vordos"
wrote:


"DoN. Nichols" wrote in message
...
On 2008-01-26, Bob Engelhardt wrote:
I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Well -- the first question is what will you use to do the
boring? I would want to do it on a lathe, taking the time to truly
center it in a 4-jaw chuck. (And I might use an old belt to fill the
outer V-groove so the chuck jaws are less likely to damage the pulley.

Soft jaws were made for a job like this. They support the pulley
adequately, and automatically align it in both planes.

I assume that your soft jaws engage the V groove and not the flanges?
Flanges on even some pretty good cast pulleys can be somewhat wonky
on the periphery of the flanges.

If the pulley ran OK before, e.g. pitch diameters perpendicular to and
concentric with bore axis, I would consider using a faceplate and
shims or blocks until the bore indicates tits both axially and
radially, then bore. Getting that set up would be a bit fussy, but
it might be quicker than making and mounting soft jaws with the
desired precision to get axial alignment. It needs to be dialled in
radially in either case.


I stick em on an arbor, turn the OD true, give it a bit of a face
turn, then grab them by the OD in a 4 jaw, pot collet etc etc. Most
times, after the OD has been trued on an arbor, any decent 3 jaw is
accurate enough to turn the ID. A .003 runout isnt **** for most belt
applications.

Zinc, aluminum, and steel pulleys dont need to be clamped down with a
cheater pipe, to simply turn the ID.

And frankly..you really dont need the key, unless its a really really
strongly loaded pulley. Simply use a longer set screw and run it into
the keyway in the motor shaft.

If you were doing a surface grinder or tool post grinder, it would
need a bit more finess..but this is simply a drive pully.

Gunner

On Jan 27, 4:38*am, Gunner wrote:
I stick em on an arbor, turn the OD true, give it a bit of a face
turn, then grab them by the OD in a 4 jaw, pot collet etc etc. Most
times, after the OD has been trued on an arbor, any decent 3 jaw is
accurate enough to turn the ID. A .003 runout isnt **** for most belt
applications....
And frankly..you really dont need the key, unless its a really really
strongly loaded pulley. Simply use a longer set screw and run it into
the keyway in the motor shaft....
Gunner

I'd turn down the threads at the end so they don't tear up the sides
of the shaft keyway but otherwise that works pretty well. The rim can
wobble quite a bit side-to-side without hurting anything.

Not saying a key isn't needed; my last two projects run around 5HP
through single 1/2" vee belts and use splines or press-fit keys. Stuff
I've fixed was assembled with only the setscrew and it held up OK. The
pulley stays on better if the screw threads bite into the shaft but
you'll have to clean up the slot with a file to install a key.

Jim Wilkins

DoN. Nichols wrote:
Well -- the first question is what will you use to do the
boring? I would want to do it on a lathe, ...

Yes

So -- I hope that you have another lathe to use for the boring,
or a creative way to drive the exiting lathe while its pulley is not on
the motor. :-) ...

Not another lathe, nor all that creative - just a big box of saved
pulleys, one of which will do in place of the one to be bored.

Bob

Gunner wrote:
I stick em on an arbor, turn the OD true, give it a bit of a face
turn, then grab them by the OD in a 4 jaw, pot collet etc etc. Most
times, after the OD has been trued on an arbor, any decent 3 jaw is
accurate enough to turn the ID. A .003 runout isnt **** for most belt
applications. ...

Ah - the voice of experience! And I just happen to have a set of arbors
that I've never used, but bought 'cause if I waited until I needed them
it would be too late.

I suspected that the runout wouldn't be too important, good to have that
validated. Actually, my Bison 3-jaw does hold pretty good - close to
..001, IIRC.

And frankly..you really dont need the key, unless its a really really
strongly loaded pulley. Simply use a longer set screw and run it into
the keyway in the motor shaft. ...

Good! I wasn't keen on using the lathe as a shaper. I know it works
and that it's a useful skill to have, but I'd rather just get on with
the conversion. I was planning on cutting down a key, to get some
keyed-ness. 1/2 a key is better than none.

Bob

On Sun, 27 Jan 2008 01:38:34 -0800, Gunner
wrote:

On Sun, 27 Jan 2008 03:15:32 -0600, Don Foreman
wrote:

On Sun, 27 Jan 2008 06:11:23 GMT, "Harold and Susan Vordos"
wrote:


"DoN. Nichols" wrote in message
...
On 2008-01-26, Bob Engelhardt wrote:
I'm putting a new motor on my lathe that has a bigger shaft than the old
pulley. I'm planning on boring out the old pulley (another 1/8"), but
I want to make sure that this is not a Bad Idea before I do. Is it OK?

Well -- the first question is what will you use to do the
boring? I would want to do it on a lathe, taking the time to truly
center it in a 4-jaw chuck. (And I might use an old belt to fill the
outer V-groove so the chuck jaws are less likely to damage the pulley.

Soft jaws were made for a job like this. They support the pulley
adequately, and automatically align it in both planes.

I assume that your soft jaws engage the V groove and not the flanges?
Flanges on even some pretty good cast pulleys can be somewhat wonky
on the periphery of the flanges.

If the pulley ran OK before, e.g. pitch diameters perpendicular to and
concentric with bore axis, I would consider using a faceplate and
shims or blocks until the bore indicates tits both axially and
radially, then bore. Getting that set up would be a bit fussy, but
it might be quicker than making and mounting soft jaws with the
desired precision to get axial alignment. It needs to be dialled in
radially in either case.


I stick em on an arbor, turn the OD true, give it a bit of a face
turn, then grab them by the OD in a 4 jaw, pot collet etc etc. Most
times, after the OD has been trued on an arbor, any decent 3 jaw is
accurate enough to turn the ID. A .003 runout isnt **** for most belt
applications.

That's how I'd do it too, if I'd thought of it. G