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Bandsaw Blade broke / Found another problem

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Blog entry by Karson posted 01-16-2010 11:39 PM 1884 reads 0 times favorited 19 comments Add to Favorites Watch

The other day I was cutting up some pen blanks on the bandsaw and the blade broke. It was a 3/4” Timberwolf blade that I had welded up and it had been running noisy and had a wave movement toward the front as it went around. I had figured that it has a crack in the blade at the weld and was going to fail, but I had kept using it.

So it broke. I took the covers off and removed the blade. It broke about 1/4” away from the weld. So I coiled it up figuring I’ll clean it up and reweld it again the next time I need some more blades. The blade is sharp and was cutting great, it was probably just a little shift in the jig as I was welding it the first time.

So I was cleaning up the wheels in preparation of putting on a new blade.

When I went to spin the top wheel it seemed a little slow in it’s spin. I looked at the bearing and it looked ok, but I tool off the top nut from the spindle and removed the upper wheel.

The outside bearing spun freely, but the inside bearing couldn’t be turned by my fingers. I put the upper wheel over an open vise and tapped the bearing out with a dowel. It popped out easily. The bearing looks good, the shaft on the bandsaw looks good, but, the bearing doesn’t turn. I measured the shaft – 15MM and the outer Bearing surface 35MM.

I went to my favorite bearing supplier, eBay and looked up the bearing number 6202Z. The bearings were 4.95, 7.95 or 13.59 for a quantity 10. So I bought the quantity 10. I needed 2 and possible the lower shaft on the drive wheel may use the same bearing. I’ll check that out when I put the upper together and reassemble. I’ll turn the motor on with no blade and listen for any bearing noise.

I put a long screwdriver on the bearing race and the handle by my ears and the sound is amplified so you can tell if everything is OK.

The fun of woodworking tools.

Little clue when you change blades, spin the wheels and also the bearing on your blade guides if you have bearings there and make sure that everything spins OK.

Another interesting point. I don’t think I’ve ever seen a bearing number with two different measurements before. But, on eBay I found the bearing number with two different sizes. One with 16MM bore and 1 with 15MM bore they were labeled as 6202ZZ on both. The ones that I bought also had a label of 6202Z.

When ordering bearings check your measurements. I took the bearing out of the wheel so I could check the outside measurement. The shaft measurement is a little under the 15MM by 0.01MM so it slips on and is not a press fit on the shaft. Also make sure that the bearings have dust shields. Some bearings are open and they will get packed with dust inside. Others have a dust shield on only one side. So make sure you get what you want and need.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †



19 comments so far

View Edward E Nock II's profile

Edward E Nock II

96 posts in 2898 days


#1 posted 01-16-2010 11:48 PM

VERRRRRYY INTERESTING!!

ED

-- ED NOCK

View Richard Williams's profile

Richard Williams

162 posts in 2546 days


#2 posted 01-17-2010 12:02 AM

I like the screwdriver trick. I used to listen to motor bearings the same way. :) Glad you found the problem.

-- Rich, Nevada,

View jack1's profile

jack1

1953 posts in 2781 days


#3 posted 01-17-2010 12:09 AM

The blade may have broken the first time and second time if the metal had crystalized in the original factory welding. You may have a blade that just won’t stay together because of this.

-- jack -- ...measure once, curse twice!

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 3053 days


#4 posted 01-17-2010 12:11 AM

I have an old Montgomery Wards circular saw, & the bearings used to wear out real fast, but at the

time I couldn’t find shielded bearings. You couldn’t find American made in that size.

The last time I bought bearings for it, I finally found some shielded ones.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

View blackcherry's profile

blackcherry

3209 posts in 2577 days


#5 posted 01-17-2010 01:13 AM

Great information Karson thanks for posting…Blkcherry

View jockmike2's profile

jockmike2

10635 posts in 3000 days


#6 posted 01-17-2010 02:53 AM

Thanks Karson good info. My craftsman is getting noisey maybe thats my trouble.

-- (You just have to please the man in the Mirror) Mike from Michigan -

View Karson's profile

Karson

34916 posts in 3154 days


#7 posted 01-17-2010 03:44 AM

I never seem to leave things untouched. When ever I have a bearing that I take out of a machine I always take the dust covers off it and see what’s inside.

This one surprised me. The inside of the bearings was packed with sawdust. I’ve emptied all of the sawdust and the bearing is still not free to turn. The center rotates about 1/8 of an inch. (It did that in the beginning) and it hasn’t gotten any freer. One edge of the dust cover had a little depression and I assumed that I did that when I tapped it out with a 1/2” dowel. Maybe I did, maybe I didn’t That could be the only place that the dust could have entered that I saw.

I’ve used the bandsaw for maybe 8 years and I’ve done a lot of resawing and I usually have 3/4” or larger blades up to 1 1/2 so I’ve kept a lot of pressure on the bearings. I’ve never released the tension on the blade at any time. I don’t know if the bearing is/was the inside or outside one. But, it certainly is time for a replacement on this one.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View Karson's profile

Karson

34916 posts in 3154 days


#8 posted 01-17-2010 05:03 AM

Further looking at the saw shows that the bearing in question was the back bearing, and the drive bearings are all in great shape. No noise and no movement at the lower bandsaw wheel.

Now I wait for my parts.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View sandhill's profile

sandhill

2128 posts in 2677 days


#9 posted 01-17-2010 06:16 AM

You were right in getting the more expensive of the lot. You are replacing them as a pair right? Its been my experience that the cheep ones don’t hold up I have seen a 5:1 ratio meaning 5 cheepos to 1 not so cheep, I like your methods

View Jimi_C's profile

Jimi_C

507 posts in 1988 days


#10 posted 01-17-2010 03:51 PM

Nice. I’ve actually been trying to take the upper wheel off my PowerKing but I can’t seem to get it loose. I’d like to replace all of the bearings on it since I doubt they’ve been replaced in the 60+ years since it was made. I’ve sprayed it liberally with WD40 several times, but it won’t budge.

Any tips for getting the wheel off without damaging the wheel or anything else? The top assembly is only held on by two bolts, but I don’t really want to take that apart unless I absolutely have to.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View Karson's profile

Karson

34916 posts in 3154 days


#11 posted 01-17-2010 05:27 PM

JimiC: I took the nut off the end of the shaft (The nut was looser that I would think it should be) and then I pulled outward on the wheel with my hand and hit the end of the shaft with a chunk of wood (This might be a great place to use a hand made mallet)

The wheel slid off after some slight pounding and slight pulling. It wasn’t hard.

But, the end of the shaft had a small hole in it so that a gear puller could be used to pull the upper wheel off. I didn’t have to resort to that. You might have to.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View Jimi_C's profile

Jimi_C

507 posts in 1988 days


#12 posted 01-17-2010 05:57 PM

Interesting, I’ve been using a block of wood and a rubber mallet with no results, guess I’ll just have to keep banging on it. I was trying to get it off without damaging the bearing just in case I can’t find some in the exact size I need, probably not a valid fear.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View Karson's profile

Karson

34916 posts in 3154 days


#13 posted 01-17-2010 07:47 PM

Jimi_C yes bearing are usually easy to find. I pulled hard when I tapped. you might also try a taper board between the back of the wheel and the case. If you try that also try to get your pressure on a couple of different points. You don’t want all of the pressure on one side. Thats why gear pullers have 3 or 4 jaws

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View Joe Kimmell's profile

Joe Kimmell

32 posts in 1908 days


#14 posted 01-17-2010 08:58 PM

Good & informative thread, Karson. And also a good reminder about machine upkeep! I break blades pretty often on my old (1977) 10” Rockwell/Delta….Mainly because I try to do more with it than the machine was engineered to do.
At any rate, every time I change blades, I make sure to grease every zerk on the machine, and generally give the the entire machine a good once-over.
This maintenence program has made my saw so efficient that it cut off the tip of my middle finger a few days before Christmas ‘09….and I didn’t even have to ask it to! Hence my signature below!
Great posting, Karson…..and Thanks. ~Joe

-- Beer and Bandsaws just don't mix. Take my word for it!

View Grumpy's profile

Grumpy

19715 posts in 2605 days


#15 posted 01-17-2010 11:01 PM

Thanks for the heads up Karson.

-- Grumpy - "Always look on the bright side of life"- Monty Python

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