Boring out pulley
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 |
Boring out pulley
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. |
Boring out pulley
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 |
Boring out pulley
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 |
Boring out pulley
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 |
Boring out pulley
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 |
Boring out pulley
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 --- |
Boring out pulley
"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 |
Boring out pulley
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. |
Boring out pulley
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 |
Boring out pulley
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 |
Boring out pulley
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 |
Boring out pulley
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 |
Boring out pulley
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 |
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