Bandsaw blade tracking

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George wrote:

Don't bet your last dime.

Not only do we have the train off the tracks but it's careening down the embankment, towards the combo orphanage/old folks home/puppy and kitty adoption agency.
A band saw, a "properly" designed band saw, has a wheel. Into this wheel fits a shaft. This shaft and wheel fit into a bearing directly behind the wheel. This wheel, shaft and bearing fit into a cast iron housing where the bearing is seated. At the other end of the cast iron housing the shaft protrudes but before it protrudes we have another bearing also seated into the housing.
What we have here is a cantilever, or, more appropriately for this point and for this argument, a fulcrum and lever (a see-saw Dave). The first bearing, right behind the wheel, is the fulcrum. The wheel shaft acts as the lever.
Still with me? If not then grab your saw manual and take a gander at the es'ploaded parts drawing.
OK, as I've already confessed I'm no injineer but what I do know from experience and that is, any force being applied down onto the top of the wheel by the band is transferred and exerted onto the shaft which in turns puts a great deal (tremendous actually) of downward force onto the first bearing (the fulcrum).
The back bearing, it's got it's hand full with the upward force being exerted by the lever (shaft).
Now, with all of this going on inside your poor band saw, do you really want to peddle the myth of co-planar and bearing wear?

So, co-planar will allow me to buy and use the crappiest blades? Can anyone recommend a good crappy blade?

Ummm, the wheels, they don't give a rat's rosy red rectum about co-planar. They already have their hands full with the job they were designed to do.
Co-Planar Angled Table Saw Fences PVC Causing Dust Collector Fires The Lumber Car
How many more of these myths do we have floating around?
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10,000 nuns and orphans ...... They were all eaten by rats.

The leg bone's connected to the ankle bone The ankle bone's connected to the foot bone
(Sorry)
I just don't get all the "Oh my god, think of the poor bearing!" wailing and beating of breasts. For a given blade, there's only one "alignment" of the wheels which is correct: the one where the blade tracks properly. My bearings will just have to suffer with whatever that means.

You explode your band saw parts? Hmmm... I'm starting to side more with the bearing.

This comes up every week on the wreck. DAGS, lazy bones.

Aren't those rats supposed to be rancid? Doug, where are you?

I don't know about myths, per se, but the electrical threads often contain some real thigh slappers/side splitters.
How about "real woodworkers never stain cherry"?
--
Jeff Thunder
The From: header above is wrong on porpoise
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Jeff Thunder wrote:

Yes I believe you are correct but I think it was Charlie Self who first spoke the line.
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You may not be an engineer, but I are.
If the wheels aren't coplanar, the crowns of the wheels don't line up. The blade isn't going to ride on the centre of the crowns by itself. If it's centred on one crown, it's riding the edge of another and it will tend to wander off. Only if the crowns are aligned will the blade run on both crowns with minimal strain.
Once coplanar, you tension the blade and the force on the wheels tends to pull them out of plane. You adjust the top wheel to bring them back more-or-less into line. That's the tracking adjustment.
If you start with non-coplanar, you'll likely have problems with tracking unless you start torquing everything around to make up for it.
Lining it up coplanar is an easier way to start out. YMMV.
Mike
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Michael Daly

Finally, someone who admits to being one.

OK, we know this to be true.

OK, we know this to be true.

In theory this is true but as I have said, my wheels aren't co-planar and the band(s) ride(s) as true as anything I've seen.
OK, "maybe" someone could check it with some snot, boogers and a stick (or a TS Aligner Jr.) and find it out by half a thou but so far this gross alignment isn't an issue.

OK, I think I've found the crux of the biscuit. Define what you mean by minimal? Are you saying there's always strain no matter the alignment? Even in a perfect world? Sorry, I know the answer to this. I'm baiting you. OK, there, I admit it.

OK, we know this to be true. And we should add, that the given make-up of every blade is different and therefore each and every blade will have a different effect on the wheels?

OK, we know this to be true.

But, but...

But, but, my wheels aren't co-planar and my band(s) ride(s) right down true and center on the wheels. I'd be happy to open up my shop to any wreckreite who would like to ponder this problem (or stand in awe as they gaze upon it) with me or who doesn't believe me or who would like to further their studies on the subject. But in the mean time, I still say you're all blowing smoke up a rat's rosy red (and rancid) rectum to say it's worth any more time than to note it, i.e., don't get your undies inna bunch over it.
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wrote:

After snipping lots of wind, I add:
How about angled wheels? When ya adjust so the blade will ride in the center, you adjust the tilt of the top wheel from the vertical plane (trying to SOUND) like an engineer here).
Wottehell, this will have some effect, too. Real effect, not speculation
James snipped-for-privacy@rochester.rr.com\
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You tension the blade and the wheels tilt in. You tilt the top wheel out to realign. This makes them parallel again at the expense of a slight change away from coplanar. As I said in another message, you can get away with a _slight_ misalignment.
I once tried adjusting the saw so that it's coplanar even under tension. This is an iterative approach that means adjust, tension, check, detension, readjust, tension, check, detension, readjust, tension, check... until the alignment is "perfect" under tension. It didn't work significantly better than the conventional alignment but was a _lot_ more work and the adjustments were different for each blade. The reason is that all that fiddling doesn't make a lot of change in the actual alignment.
Coplanar - the easy way to get good alignment. Non-coplanar - maybe it'll work if you're lucky and/or you don't care much about the resulting cutting quality.
Mike
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In article <slQWb.36507$TPZ.12451
snipped-for-privacy@rogers.notthis.com says...

Believe me, you can get away with gross misalignment if you have a forgiving blade and a good crown on the tires.

While this might help you sleep better at night, you're spending way too much time on this. The bottom line is that if the blade tracks well while under tension and torsional loads, you got a winner.
It's kinda like tuning up a 65 Mustang. You throw out the book and go by feel.
And while Duginske is a good read, he puts too much emphasis on coplanar wheels. He should have spent time teaching the masses how to crown a tire.

Pretty broad brush there Mikey. Do you have scientific evidence to prove this? Seems to me my non coplanar saw cuts just fine, thank you. And, I *do* care about cutting quality and blade life.
Just remember - it's wood, not platinum.
--
Regards,

Rick

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Rick Chamberlain wrote:

Thanks Rick. I was this close to slitting my wrists onna 'count of I wasn't getting glue ready edges from my band saw.
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@wi.rr.com says...

Welcome. I know what you mean about those pesky bandsaurs - even the old arn ones. No matter how hard I try, no matter how much I spend on blades, no matter how much time I spend with my trusty TS-Aligner Jr (tmEB) and straightedge, I can't get those glue ready edges!
I go slow, no love. I speed up, no love. New bearings and tires, no love. I adjust the positioning of the saur relative to true magnetic north, still no love.
Surely, there is some book or infomercial that can save us!
I'm hoping that Mikey will be at the Mahwahkee WW show next week so he can show me (and the boys at Laguna) how to do it the right way.
Rick, willing to make 3 easy payments of $29.95 so I can get rid of my jointer, planer, and sandpaper...
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I'll ignore it.

For blades of different size - yes. For blades of the same size and make - negligible.

Either the alignment isn't bad (even though you haven't changed anything since you bought it) or the amount of crown + the tension + other stuff is forcing your blade into some stressful alignment.
I've done a bit of experimenting with the amount of alignment (easy, since the one I have came 1/4" out of coplanar!) and you can make it work while slightly out of alignment. But if properly aligned, you get good tracking and less blade vibration/wander/drift/etc.
Maybe you're not fussy about the quality of the cut.
Mike
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Michael Daly wrote:

What railroad?
--
Ed



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brought forth from the murky depths:

The problem is the movement of the force from the flat of the bearing area to the edges of the bearings. Auto engineers moved to tapered roller bearing pairs to overcome the longevity problem and angular loading. (I read all about that in wrenchin' school 30 yarn ago.)
Co-linearity is one of those items the engineers push for. It probably makes a difference only in long-term use in heavy production environments. But why NOT try to set it on your home machine? It can only make the beastie run better. Ditto link-belts. They made a helluva difference on my Griz. My neighbor lost a large branch off one his madrones in the wind a couple weeks ago and I'm going to see if I can get some lengths to resaw. I love the look of that wood.

Pre-Crapsman, eh?
--
Impeach 'em ALL!
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Larry Jaques wrote:

George? What have you done with Larry?
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brought forth from the murky depths:

Hey, hey, hey! We'll 'ave nun o' that here, lads.
Well, whaddya know? My G1012 has a pair of 6202ZZ bearings on each shaft.
OK, so you're a disbeliever. A famous man once said
        What me worry?
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brought forth from the murky depths:

Vertically? Always. Browse Duginske's "Band Saw Handbook" for "coplanar", Keets.
--
REMEMBER: First you pillage, then you burn.
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I don't buy the "coplanar" argument. The goal is to have the blade track correctly. My common-as-dirt Delta 14" tracks correctly when the wheels are not coplanar. There's even an adjustment to change the plane of the upper wheel in order to correct any problems with the blade not tracking right.
--
Jeff Thunder
Dept. of Mathematical Sciences
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I was at a Scott Phillips demo a few months back. He said the same thing. You have to get the blade tracking on the top of the wheel just right. He is a fan of high tension for resawing in spite of what Timberwolf says. Ed snipped-for-privacy@snet.net http://pages.cthome.net/edhome
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On Mon, 09 Feb 2004 18:16:02 GMT, Larry Jaques

Keith is down on Duginske, judging by some recent snide comments. Care to explain why, Keith? Please. Inquiring minds want to know.
Luigi Replace "nonet" with "yukonomics" for real email address
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Luigi Zanasi wrote:

I dunno. I suppose I just like to poke my goad at the Gods.
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