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Posted by Jim Wilkins on January 25, 2008, 9:36 pm
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> Grant Erwin wrote:
> > Bob Engelhardt wrote:
>
> >> I'm putting a new motor on my lathe that has a bigger shaft than the
> >> old =A0pulley. =A0I'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. =A0Is 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
>
> =A0 =A0Really . I use a boring bar set on center , with a cutter ground
> square on the end . Tedious ...
> --
> =A0 =A0Snag
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
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Posted by Grant Erwin on January 25, 2008, 10:44 pm
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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
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Posted by DoN. Nichols on January 25, 2008, 11:09 pm
Please log in for more thread options > 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.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Posted by Harold and Susan Vordos on January 27, 2008, 1:11 am
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>> 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
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Posted by Jim Wilkins on January 27, 2008, 9:34 am
Please log in for more thread options > 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 shit 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
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