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Problem with pulley on bandsaw

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Forum topic by abehil posted 12-02-2015 12:29 AM 505 views 0 times favorited 19 replies Add to Favorites Watch
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abehil

104 posts in 805 days


12-02-2015 12:29 AM

The pulley is knocking on every rotation because it’s wobbling a little. I’ve looked really closely and I can see the set screw is smaller than the keyway slot and that allows it to move a little.

I know nothing about pulleys. Should there be square key in the slot so that the pulley won’t wobble. This is a used BS and it’s the first time I have seen a loose pulley. Advice is very appreciated.


19 replies so far

View MrUnix's profile (online now)

MrUnix

4237 posts in 1665 days


#1 posted 12-02-2015 12:39 AM

Yup, you are missing the key… standard hardware store item. Pull the pulley, measure the width of the keyway with some calipers and run down to the local hardware store. You can get them individually, in packs of 3 or 5, or in long lengths that you can cut to any desired length needed.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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MrUnix

4237 posts in 1665 days


#2 posted 12-02-2015 12:40 AM

Also, if you can’t measure it, just take the pulley with you so you can match it up..

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Kazooman

628 posts in 1419 days


#3 posted 12-02-2015 12:43 AM

Yikes! You are missing the key that fits in the slot in the pulley and shaft. The set screw just holds the key in place. Take the pulley to a good local hardware store and they should be able to give you a key that will fit the connection. It will slide into the key way made by the pulley and shaft and the set screw holds it in place.

By now your set screw might just be a little beat up. I would recommend getting a new one at the hardware store. If all else fails, they should be able to provide you with a new pulley that fits on the drive shaf and has an appropriate width slot for the key. Either way, this is a cheap fix and you should be on your way again.

Geez….. Once again I actually know the answer and Brad beats me to the punch. Oh well, he knows more of the answers than I do.

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MrUnix

4237 posts in 1665 days


#4 posted 12-02-2015 12:52 AM

Geez….. Once again I actually know the answer and Brad beats me to the punch.

The next one is all yours… promise :)

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Kazooman

628 posts in 1419 days


#5 posted 12-02-2015 01:04 AM



Geez….. Once again I actually know the answer and Brad beats me to the punch.

The next one is all yours… promise :)

Cheers,
Brad

- MrUnix

Damn!!!

FOUR minutes! How is a poor minor leaguer supposed to have a fighting chance?

Great call on the problem, MrUnix. Just needs the key and we are good to go.

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distrbd

2227 posts in 1913 days


#6 posted 12-02-2015 01:16 AM

Post quickly then edit later,lol.

-- Ken from Ontario, Canada

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BurlyBob

3695 posts in 1732 days


#7 posted 12-02-2015 03:14 AM

Once again, I saw the problem and knew the answer right off. Had it happen to me a couple of weeks ago and I’m late to the party.

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Slemi

103 posts in 1007 days


#8 posted 12-02-2015 06:40 AM

Actually is is not the key that is the problem it is the shaft and pulley. They shoud fit snug enough to have no free play without the key. Key only prevents the pulley rotating on shaft, so does the screw that is in its place. You would be better to takre the pulley an shaft to some local machinist to make You a piece to fit between pulley and shaft, he will have to remove a little of material from pulley to do that. Then You will have no wobble anymore and no knocking. Just fitting some tight fit key into there is like putting a wedge in loose mortise and tennon joint.

View Tennessee's profile

Tennessee

2410 posts in 1981 days


#9 posted 12-02-2015 12:42 PM

Of course, you have to actually be online and signed in AND watching your computer, instead of working in your woodshop!

Let me guess, Brad keeps a computer in his woodshop tuned to LJ!

-- Paul, Tennessee, http://www.tsunamiguitars.com

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MrUnix

4237 posts in 1665 days


#10 posted 12-02-2015 02:30 PM

Gee.. Didn’t mean to ruffle feathers… just trying to help ;-)

Actually is is not the key that is the problem it is the shaft and pulley.

That can’t really be stated as fact… Without the key, and with a set screw that is smaller than the keyway, the pulley can slip back and forth on the shaft. I’ve seen that condition before, and you will get some unusual noise from the pulley because of it. It can cause damage though, particularly if left in that condition long enough… not only can the keyway get buggered up (although that can usually be cleaned up with a needle file), but it can cause excessive wear on the pulley bore and shaft. Something that needs to be determined when the pulley is removed.

Cheers,
Brad

PS: I’m on the computer most of the day as part of my work (my screen name should give you a hint!)... and my browser automatically opens multiple tabs (and automatically logs into LJ) when opened. Most of what I wind up doing is just monitoring systems across the globe, and waiting for glue or polyurethane to dry gives me plenty of time to do ‘other stuff’ :)

-- Brad in FL - To be old and wise, you must first be young and stupid

View abehil's profile

abehil

104 posts in 805 days


#11 posted 12-02-2015 09:57 PM

I measured the key slot with my caliper and it is 3/16”. I then took a closer picture and enlarged it enough to get a better idea of the problem.
It looks like the pulley is not a perfect fit on the armature. The set screw has been driven in so as to push against the shaft maybe hoping any looseness would be slight enough to not matter. Pushed over like that it looks like the pulley is about 1/32 or maybe 3/64 or so larger than the shaft but I’m just doing a visual estimate.

I’m wondering if the pulley was a replacement and it was the closest in diameter so it just got fudged on, or possibly the wheel shaft was replaced and it was the closest in matching diameter and had to be used.

Based on the rings on the pulley I don’t think the hole is elongated yet. The shaft doesn’t look out of round at least from this image. Maybe caught it in time before it did any real damage.

But, how to remove the pulley is now got me scratching my head a bit. I went and got a socket wrench but I can’t reach behind it. It’s enclosed in a metal box too tight for any hand. The lower box where the motor is doesn’t look like it’s been opened in forever with two slotted screws without any scratches on them so I’m only half guessing that is how I’m going to have to get to it.

The lower pulley in the picture is actually the the middle one of three.

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MrUnix

4237 posts in 1665 days


#12 posted 12-02-2015 10:13 PM

Come on guys… here is your chance… I’m going out to the garage to rip some oak so I can make picture frames for a couple of scroll saw portraits I made as xmas presents :)

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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rwe2156

2198 posts in 947 days


#13 posted 12-02-2015 10:22 PM

Looks like you’ll need a new pulley.

;-)

-- Everything is a prototype thats why its one of a kind!!

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abehil

104 posts in 805 days


#14 posted 12-02-2015 10:57 PM

I got the upper box off, not easy. Caliper says the shaft is 3/4” and the id of both sides of the pulley measures 3/4”. I’m going to try just a key and see if it still has any movement. The set screw was way down in there but of course it’s not a wide as a key so maybe that’s enough to make it knock.

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conifur

955 posts in 618 days


#15 posted 12-02-2015 11:29 PM

For pulleys that size the key is usually a 1/4”square.

-- Knowledge and experience equals Wisdom, Michael Frankowski

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