Motor pulley problems

A couple months ago the motor on my bandsaw went up in smoke. It seemed pretty simple to just trot down to the local farm supply and pick up a new motor. I couldn't get the exact base plate, but it will work.
Got it home and set out to remove the old motor pulley to put on the new motor. As soon as I put any pressure on the puller it just snapped. The old pulley was made out of some sort of pot metal with essentially zero strength. So it's back to the farm supply for a pulley, all they have are these strange stamped sheet metal things, but what the hey. When I tried to install it there was no way I could get it on the shaft, the fit was just too tight. I managed to work it partway before it jammed and then the puller reduced this new pulley to a rather interesting free-form metal sculpture when I tried to remove it.
Now I have in hand a proper cast iron pulley. The shaft and bore both are supposed to be 5/8", but I still can't get the pulley to go on. So what do I do next? I'm thinking that I could heat the pulley with my heat gun then slip it quickly in place, but I'm not sure that will really work. Otherwise I could buff a few thou. off the shaft - it seems to be a bit rough, so that might be a good idea anyway.
What do you all think? I'm already torqued at having to replace the motor on a saw that I'm going to upgrade out of in a few months, but the saw was free and I need it sometime between *now* and *real soon*, and I'm not going to have the long green for the new saw until at least into the new year... soooo........
Tim Douglass
http://www.DouglassClan.com
Definition of a teenager: God's punishment for enjoying sex.
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If you're going to resize anything, I'd be resizing the bore of the hole in the pulley, certainly not buffing down the motor shaft. There's potential for damaging one or the other. Which one do you really want to risk?
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Agree with Upscale that if you're going to mod anything, it should be the pulley arbor and not the motor shaft.
Do you have access to a good dial caliper, to measure the OD of the shaft and the ID of the arbor? You may have a 16mm motor shaft (0.6299") instead of 5/8".
If they're close (within a couple thousandths) you can pop the pulley on by heating it -- but probably not with a heat gun. Think torch, and heavy leather gloves.
If they're not close... what you do next depends on what you measured with the caliper. If the motor shaft is really supposed to be 5/8 (0.625) and it's actually 16mm, either you take it back to the point of purchase, or you get a 16mm pulley. If the pulley is undersize, you could ream or bore it out.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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wrote:

And if you don't have a set of calipers, you can always haul the motor down to the bearing supply house and plunk it up on the counter. I have seen this done before. In one case, there was an odd diameter shaft. The bearing guys fixed him right up too.
Just a comment about bearing supply houses. They have saved my ass again and again. And I have only been to them about 20 times in my life. I have friends who have been to those places literally hundreds of times. Of course, they work on engines, tools and old machinery much more than I do.
Sooooo......, bearing supply houses are GOOOOOOD!!
Damn, I feel philosophical today. :-)
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"Lee Michaels" wrote in message

Am I recalling correctly, or did you not post some picture on abpw on a project you did with some pretty good size timber and a helluva lot of joints?
If so, did you ever post the finished results? I might have missed it.
Inquiring minds ... and all that.
--
www.e-woodshop.net
Last update: 8/8/07
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"Swingman" wrote in message

No, that wasn't me. I don't have a digital camera.
In fact, I am getting together batteries, film, etc. to do some pictures that need to be posted locally. Hopefully I will no longer be a JPEG net virgin by next week.
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On Tue, 04 Sep 2007 23:04:00 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

I went after them with my better dial calipers (the ones I use for reloading rather then the shop ones) I got .625 for the pulley and .627 for the shaft. That is probably within tolerance for the low-budget-no-name Chinese motor maker. The shaft is pretty rough - like it wasn't final ground after the lathe or something.

That's what I wondered, just how hot I would need to get things.

I don't have the equipment to bore out the pulley that precisely, but wouldn't be hard to take the shaft down those couple thou. with some silicon carbide paper and a metal backing block against the spinning shaft. I'll think about it a bit and see what other suggestions crop up on here.
Thanks all.
Tim Douglass
http://www.DouglassClan.com
Warning: Spelling errors in this message are the product of a poor school system. Pay teachures more than athletes.
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Tim Douglass wrote: ...

Way _too_ hot to make it the way to proceed...I'd do the latter -- although I'd probably just go for the carbide cloth-backed "tape" emery cloth as the easier way. As you say, a couple thou is pretty easy that way unless the shaft is really, really hard (which you'll find out quite quickly)...
--
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Tim Douglass wrote:

Heat the pully with a propane torch and quickly measure it. Is it up to, like, 0.630?
If so, you know what to do.
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You'd have to get the pulley glowing slightly (adding about 800 degrees) to get it that big, then it would cool enough to bind on the shaft before getting to the correct point.
Pete Stanaitis -------------------
HeyBub wrote:

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wrote:

Yeah, that's what I found when I played with it a bit. There isn't enough expansion for a sweated fit. I'm going to get back to work on it this next week and take the shaft down a bit more. At this point I only need to go another thou.
Oh, in case anyone is still wondering, that shaft is *hard*. I didn't expect that on a cheap Chinese motor.
-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
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The method we used to put bearings on 3 and 4 inch shafts was to put the bearing in a bucket of oil. We would heat the oil as hot as possible then pace the bearing on the shaft. This method heated the bearing without damage. You have to be very careful handling the part to prevent getting burned. Once you start the bearing on the shaft you have to work fast. The only way we could remove the bearing was with a cutting torch.
Virgle
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HeyBub wrote:

;-)
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"Tim Douglass" wrote

Clean up the shaft with a little emery paper, then take motor an sheave to the nearest machine shop and have them use an adjustable reamer to clean up the sheave bore.
It will take longer to do the set up than the task.
Lew
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On Tue, 04 Sep 2007 18:11:21 -0700, Tim Douglass

First, run up the motor and touch the shaft with a strip of emery for a few seconds while it is running. That will knock off the burrs, nibs, and even out the natural machining lobes to make it more "round" . It won't hurt it, but it won't remove much material if it is at the correct hardness. Then make sure the pulley is chamfered on the end of the bore, if not do so. if it still won't go on, gentle heat to the pulley.
Frank

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Tim, BEFORE you start mucking about with the shaft . . . does it have a keyway? Does the pulley have a keyway? If neither have a keyway, how is the pulley locked to the shaft?
The point is IF the SHAFT has a keyway, almost everything else can be easily {relatively ?} solved. The shaft is the problem . . . hardened material and relatively inaccessible to hand tools. A decent machine shop - or better yet - a motor repair shop - can cut a keyway. {I wouldn't necessarily have them turn the shaft - unless it was an *non-standard* size. Will you 'junk' the saw when you 'up-grade' & keep useful parts? Or sell it off? }
Pulleys are available with keyways already cut, or you could cut them yourself - by hand. Then you don't need an 'interference fit', or a 'set-screw on a flat'. Either a true 'Woodruff Key' ?} or a bit of square stock. Isolation from any slight imbalance could be taken care of with one of those 'sectional-adjustable drive belts'.
Just my 'engineers mind' given free-reign . . .
Regards & Good luck, Ron Magen Backyard Boatshop {Everybody seems to have one of those convenient 'Farm Stores' near-by. I even see the 'Tractor Supply Store' commercials on the local channels . . . where's mine? }
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wrote:

No keyway on the shaft, just a flat. The pulley has a setscrew.

The saw is maybe worth $100 with a working motor. I'll probably pull the motor to build something else and give the saw away. It's an old 10" Rockwell with plastic wheels (and I suspect a rubber frame).
I really want to stay out of a machine shop just because I could easily drop more getting the pulley on the shaft than the entire saw is worth.
Since I don't have the motor mounted yet the shaft is very easy to work on. I'm leaning toward the polish down a bit and see how it works. Can't get to it until Friday probably, so I'll let everyone know then.

I am surrounded by a thousand "hobby farms" of about 5 acres each with one horse and a small tractor. The farm supply does a big business selling to the wannabe farmers. Me, I just shop there because they happen to stock some of this stuff and it's darn hard to find otherwise. Well, that and the fact they have the lowest price around on Wranglers.
Tim Douglass
http://www.DouglassClan.com
Definition of a teenager: God's punishment for enjoying sex.
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Tim,
I'm still of the advice to work on the pulley.
If you insist on taking down the shaft . . . 'fire up' the motor and start with a medium mill file, then Crocus cloth, etc. Less work & get 'there' quicker.
Regards & Good Luck, Ron

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Ron Magen wrote:

The flat instead of the key slot makes that a lot more problematical to keep it round, though...
Despite my earlier suggestion during which I was assuming there would be a key, I'm leaning towards the "pulley is better" camp now, too... :)
--
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I'll add one more vote for the torch on the pulley. If needed you can put the motor in the freezer for an hour also. This method also makes easy work of putting your pistons on the rods.
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