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gkman11
11-25-2004, 09:16 PM
http://img.photobucket.com/albums/v494/gkman/bandsawwheel.jpg

Am tring to get the wobble (1/8" or 3/16") out of the lower wheel of my Dayton Horz/Vert Bandsaw. Has always had it since I got it used but decided to bite the bullet today and try to fix it. Assumed the 1/2" shaft was bent (1/2" looks small anyway). Made a new one, spent a couple of hours at the parts washer, re-assembled and just as Murphy's law would predict - still had the same wobble.

The wheel must be bored crooked. Need help in boring/bushing back straight. Looks like a good place to turn a holding fixture on the faceplate bored to the od of the wheel to center it. Someone on this boad mentioned MDF (medium density fiberbord) to do this? I could drill a couple of holes in the wheel to bolt it onto the faceplate. Should I bore the center hole about 7/8", braze in a short piece of 7/8" shaft and rebore to 1/2"? The wheel is cast iron. Don't have a way to broach the keyway, could I pin it on some way?

Thanks for the great forum.

ibewgypsie
11-25-2004, 09:23 PM
Has to be trued to the "true running" part.

On a mill table feeler guage setup till it is square to the table , find true center, check tram on machine, bore and bush.

On a huge lathe, chuck in on true outer, check runout adjust, bore center and bush.

If you don't have either, farm it out.

I have a new milwaukee portaband that does the pulley wobble, even though it has never been dropped or misused. As long as it cuts It is going to cut. Loaned out right now. Perhaps he will lose it and replace it w_new.

Perhaps? blade spun on pulley doing it's own machining?

ibewgypsie
11-25-2004, 09:31 PM
OR? make a dummy shaft, clamp pulley making center true, true outer edge on lathe to match inner true shaft. *if your machine can take a reduction in outer size.. Remember Light cuts.

I cut a Vee belt slot into a air compressor pulley a while back.. talk about a slow cut.. the diameter made it high surface speed. Took about a hour.

Don Young
11-26-2004, 01:20 AM
You could try aligning it on the faceplate with bolts and shims, boring it only enough to true up, and making another shaft with an oversize stub to fit. You could probably use the existing keyway, maybe filing the key a bit.

roninB4
11-26-2004, 06:17 AM
If you cannot broach the wheel you could always key it across the axis of the shaft. Granted it won't be much of a key but it is done on large machinery when it's difficult to key in the standard method and a weak link is used to prevent breaking more expensive components. It's better to use a key than a pin (taper would be better than straight for easy assembly) but if you have nothing else then key across the axis. If it's a saw then there will not be much of an issue with shearing the cross key.

[This message has been edited by roninB4 (edited 11-26-2004).]

tattoomike68
11-26-2004, 06:56 AM
If the bore is tight machine the outside a little and true it up.(thats the part that wears on a drive)

I have machined parts on $25,000++ band saws, machined the outside and slugged the bore.(it cut 30,000 parts some days)

as far as key, 1/8 key in a 1/2 bore cost about $5 at my shop.

[This message has been edited by tattoomike68 (edited 11-26-2004).]

RobDee
11-26-2004, 11:40 PM
If it's to big to chuck then drill a couple of holes in the wheel and mount it to a faceplate. Dial in the outside hub that you need true.
Oversize the bore and run a plug in it and bore it to your machine shaft.
RobDee

J Tiers
11-27-2004, 10:41 PM
I have rebored spoked pulleys by clamping them to blocks I made to fit the slots in the faceplate. I shimmed or moved the blocks to get the pulley groove running true and concentric.

You don't have spokes, but if you clamped it down to your faceplate via some drilled holes, you would have the edge running true. If the edge isn't true, you would have to shim it to get some reference surface or line true. tapping to get the OD true would allow you to bore the ID.

Keyways can be filed, "shaped" using a boring bar and proper size cutter, and reciprocating via carriage feed. I would use the smallest key possible.....it takes a while.

BTW, is the wheel OD not true as-is? Meaning, is the OD surface not a true cylinder parallel to the shaft? If that is the case, the blade should be wandering badly.

If the OD is OK but the edges are not true, it may LOOK like it wobbles, but it will work fine. If the blade runs right, the wheel probabl=y isn't messed up in reality.

Then if you "true" it you may generate a problem instead of fixing one.