Material for bushing?

Hello all,
I decided to build a band mill and have acquired the
band wheels (24", aluminum), but need to have the center bushing made.
The OD of the bushing will be ~ 4" not including the shoulder and I'll
use a 1 15/16" keyed shaft to go through the center.
Before I walk into a machine shop, what are your opinions on the best
material for this bushing? I don't need the best as this will be a
hobby mill, but I don't want junk either.
Thanks for any opinions or suggestions.
Paul
Reply to
chisel
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I am assuming that this will be fixed to the shaft(seeing as you are keying it) Cheapest will be just a plain steel bush. Aluminum would be lighter but a 4-5" chunk will cost you. How do you plan to mount it into the wheel? Shrink fit, press in and bolt ??
chisel wrote:
Reply to
Machineman
FWIW, I don't think that either plain, unhardened steel or aluminum would handle the loads on a 24" bandsaw without being vulnerable to galling. Much better would be almost any kind of bearing bronze. Cast iron would be OK, too. It requires an extra thousandth or two clearance over bronze.
Specialty materials, like special bronzes, hardened steel, or babbitt, would each present their own problems (cost, fitting, the need for lubrication). But, if it were my project, I'd go for something at least medium-performance.
Ed Huntress
Reply to
Ed Huntress
Sorry if I wasn't clear. I planned to have a shoulder-type bushing made, bolt it to the wheel, run a keyed shaft through the center of the bushing, and mount the shaft on pillow-block bearings on either side of the wheel.
If you're interested, you can see a pic of the wheel here:
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Paul
Reply to
chisel
Oh. Then, you can make the bushing out of anything that's handy. If those are ball- or roller-type pillow blocks, you can make the shaft out of any steel you want.
If things are going to get warm or hot, remember that aluminum's coefficient of thermal expansion is 3 times that of steel. Either the bushing-to-wheel, or the bushing-to-shaft fit is going to be vulnerable to this, depending on which you make out of what.
But it shouldn't get hot, anyway, if you've designed right for the loads.
Ed Huntress
Reply to
Ed Huntress
On Fri, 11 Jun 2004 19:48:03 GMT, "Ed Huntress"
One more question: Obviously one wheel is the idle and one is the drive...
So even on the drive wheel I could use any material for the bushing? I was concerned about the key camming out the keyway in the bushing...
Thanks for your help!
Paul
Reply to
chisel
Another possibility would be to attach weld-on hubs for taper-lock bushings to your wheels. No worries about shaft and key fits with taper-lock, and not too expensive, probably less than custom hubs.
Otherwise, as long as the fit is proper and powered by a reasonable sizes motor, most any steel or aluminum should be fine. Make sure the key is a snug fit and put a set screw over it to make sure it doesn't move.
Ned Simmons
Reply to
Ned Simmons
Eh, no, I'd probably use steel there. But that's just playing it safe, not an engineering judgment.
The hard part looks like getting the bearing concentric and co-axial. A little bit off, and that thing probably will wobble or vibrate.
Ed Huntress
Reply to
Ed Huntress
Juct curious. How will you change blades?
Kevin Gallimore
Reply to
axolotl
Hi Kevin,
Imagine an tall "H." The wheels will enter from the top and bottom of the H and are parallel to the vertical lines in the H. "H" will be supported in the middle.
I'm thinking of making the saw head similar to the pic on the bottom of this page (It's a sideview of the H):
formatting link
So the blade will easily go around both wheels. Does that answer your question?
Paul
Reply to
chisel
Hey Chisel,
I can't tell, from what you wrote, what "sizes" you may have at hand. But if the aluminum wheel has a large enough hub, have you considered an "H" bushing as is commonly used on electric motors and pumps shafts to adapt any given pulley to any given shaft size (all within limits of course)? You would have to make a tapered hole in the hub, and two or three tapped holes. They work great.
Take care.
Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXXXXXX
Reply to
Brian Lawson
Thanks Brian. I'll see what I can find re the "H" bushings.
Paul
Reply to
chisel
H is just one size - S and SH are others, I don't recall the full range or ever knowing a rationale for the labelling of the sizing. They are tapered split bushings which fit into tapered holes in the pulley, an result in a clamp onto the shaft that's almost as good as a shrink fit, with a lot less fuss and bother. Typically have 3 bolts and six holes - 3 holes to put the bolts into to draw the bushing into place, 3 holes to put the bolts into to pull the bushing out.
MSC sells them, so I'd guess that McMaster and Enco do, too.
Reply to
Ecnerwal
I found the H and larger bushings, but the band wheels I have must only take a "Dake" bushing (the maker of the band wheels) since I didn't find anything to fit it. The center hole is approx. 4 1/8" and has 4 holes surrounding it for the shoulder of the bushing.
Thanks for your suggestion.
Reply to
chisel

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