Drifting Away........

Stuart Ablett

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Tokyo Japan
You know my resaw bandsaw, Big Blue, the one with the 2 1/4" W-I-D-E blade................????

Well would you believe that even with a blade THAT wide, I still have to set the "Drift" on it.........?

Well I do.............

big_blue_drift1.jpg
Brand new blade, out of the box, and this is the drift, compared to the old blade that is going out for sharpening.......


big_blue_drift2.jpg
Not a ton, but WAY to much to slice nice thin veneer.

big_blue_drift3.jpg
A slight adjustment, and all is good!

Yep, even Big Blue drifts a bit ;) :D

Cheers!
 
You'd have to adjust for drift ESPECIALLY with a blade that wide. Your set angle is probably less than one degree, right? So the blade won't crab at all. It might be easier, long term, to; 1, align the wheels parallel to the frame and 2, align the wheels to each other (co-planar) and then 3, square the table to the frame. Any fine adjustments from there could be accomplished by squaring the guide blocks , if you use them.
 
hi bill! what`s goin` on with your reground blade? i`m curious as to how that`s working out......i`ve been sawing some 16" mahogany 14ft long and wishing for a better way:eek: ......tod
 
OK, I am confused. I thought if you had the teeth overhanging the wheels you really didn't have to worry about drift.

You have to adjust for drift regardless of blade size?

How do you cross cut if this is the case?
 
Hi Tod, I'm not talking re-grinding, I'm re-setting for more set angle. But yes, it's coming along. My machinist is still working on the prototype for the re-setter and in the meanwhile I'm still building a replacement for the resaw I was using. (I hate selling these saws because every time I do , I have to build another one before I can experiment again.) It'll probably be a month or more before I get the re-setter working but I still plan to shoot the "resaw sans guide rollers" video soon as I finish this saw. I'll hand set this one with a hammer and punch. I'm wondering if anybody out there has yet taken a minute to calculate the set angle of the blades they're using, and tried to relate them to the results they're getting with their saws. It wouldn't appear they are so far,-but I'm determined to prove my point and inspire the manufacturers to get us some better blades in a wider range of choices. There's a lot of band saw capacity going to waste out there and I mean to fix that. One way or another.
 
travis, the teeth overhanging the wheel will have no effect on drift....drift occurs from uneven tooth load if one side is set .0000000004 greater than the other it`ll cause the blade to pull or drift somewhat to that side...of course there are other factors involved here too but most blade drift is due to minute differences in the tooth protrusion.
bill, i knew that you where planning to regrind the gullets to get more set:eek: ..i was just wonderin` how far you`d gotten..tod
 
Hey Tod, Not very-I'm still building the saw. If you have a "suicide area" on this forum I might post a picture of the tool I use to grind gullets free-hand.

no suicide area bill:eek: ......just post it in general woodworkin`.....part of sharpening afterall.....is it similar to my ol` foley set-up?
stu, sorry for hijackin` your drifter thread:eek:
tod
 
Travis: fear not-we're still on your quesion but side-tracking. I'm going to challenge Tod's assertion that drift is caused *primarily* by uneven tooth set. I believe drift is caused by a blade's inability to crab in response to deflectional forces beyond earthlings' understanding or control. If Tod is correct I can up-set only one side of a blade that already cuts flat and cause it to drift consistently to one side. If I'm right the blade will continue to cut flat, but with a slightly wider kerf and a rougher finish. A dull blade just cuts slower, heats more, and tends to bow in either or both directions. (Bearing in mind that you can over-feed the best of blades.) I'm busy with the "guideless rip" movie project right now now so Tod will have to try the one-sided re-set trick for himself til I get the time. I'll cut that as a movie, too, if anyone's interested. It would be a cool movie to show on my website.
 
If you set up your bandsaw properly, there shouldn't be any drift. I admit that correcting the fence is a lot easier and faster than truing up your machine, but in the end you will be a lot farther ahead by doing so. A lot of people just assume drift is part of woodworking with a bandsaw. Its not, its just people have lived so long with it, they do not know it is a totally curable problem.
 
Well, I've done everything I can think of to set up Big Blue, the wheels are coplanar and everything runs as straight and true as I can seem to make it, but I still get a bit of drift on my blades, it is not a lot, but it is there.

Travis, if you can explain what more I can do, please do.

Tod and Bill, enjoying the conversation, please continue :thumb:
 
Stuart: Two questions: 1, what is the a, thickness of your blade? b, the Width of your blade? c, (using a spark plug gap gauge) the width of the kerf?

Question 2: What is the thickness and species of the wood you're drifting through?
 
Stuart, Travis: Here's another thought. I don't use guide blocks myself because soon as they start to wear they take on an angle that the blade can "lean" on. If your blade can't crab it will lean against one or the other side of these slanted blocks and give you a consistent drift. Giggling the wood sometimes just makes the blade lean against the other side again, where it will stay "pinned" until you release it again. Incorrect blades can be compensated for with various machine gymnastics (I call it "red-lining" the machine) but that doesn't really solve the underlying fault-the blade. In the present context, your guide blocks can act on your blade the same as your fence acts on the wood. If they are out of sync with each other, well...........

I use roller guides set so far apart that they only touch the blade when I'm twisting into a very, very tight radius cut. Now that my new saw is finished I'll be setting up to videotape a rip cut through 6" of manzanita without side rollers at all; just to make this point.
 
Onward! Into the fog!

I got the movie! Not edited yet but shows a three foot rip, perfectly flat, through 6" of______(Manzanita? That's still in question, but it's very, very hard wood) Look mom! No pinch rollers! Guides fully retracted with thrust support rollers 18" apart. I used a reset 1/2"-2TPI. The finish is rougher than I'd like so I'm going to try it again with less set (a lower set angle-this was over 6 degrees; I'll try the same trick with 4* set angle and shoot that also. If you want to see it send me an e-mail and I'll send you the edited-down-to-6Meg version. falbergsawco@bresnan.net
 

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Jerry rigged this, not me!

At 4500 RPM this a very exciting tool to cut aluminum with, but really excels at getting into tight spots for the quick removal of excess steel and cutting off bolts. Not recommended for normal folks. OSHA would not approve. My kids won't touch it.
 

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Stuart: Two questions: 1, what is the a, thickness of your blade? b, the Width of your blade? c, (using a spark plug gap gauge) the width of the kerf?

Question 2: What is the thickness and species of the wood you're drifting through?

The blade is 63mm wide, and 0.55 mm thick, the kerf is also about that, as there is next to no set in the teeth.

the wood was about 19mm thick, I think.

Cheers!
 
Bill, my "Guide Blocks" are not the same as usually seen on other bandsaws......

blade_guide.jpg

This is a stock guide block, a kind of hard plastic, this was the best of the four that came off the machine.

I used some UHMW plastic stuff to make some new ones...........(sorry for the crap pics)

bs_guides1.jpg


bs_guides2.jpg


bs_guides3.jpg

I run them about the thickness of a sheet of paper on each side of the blade, away, so they are not tight at all.

I think that the guides are not needed that much, as the rest of the saw is well tuned.

I also replaced the tension spring on the saw, the old one was almost collapsed.


Big Blue slicing <- video link

This was done with the stock, worn out guide blocks and the old dull blade, that I touched up, but it was missing some teeth too.

Big Blue cuts much better than this now.:thumb:

Cheers!
 
Stuart; Big Blue is obviously an alien artifact and has no place on this planet. It's mere presence could set off catastropic ripples in the time/space continuum. In your website video it acts like a vertical band mill, sans transport. What's it got "under the hood"? What's the shipping weight? Would my concrete floor hold up such a thing without buckling? Seriously, bandsaws in that size range are clear off the scale of my research and have rules of their own regarding set-up and operation; and blade dynamics. I use them as a reference point to the upper end of the scale however, as I do the benchtops in the 1/3 HP range. "Band Saw" takes in a wide, wide variety of machines and it's good to have info from both perspectives. Thanks.
 
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