Bandsaw techniques need some help please

[Aaron Rosenthal]

I have a King (Delta 14" Taiwanese clone) bandsaw with the 6" riser, 3/4" 3TPI blade. It's adjusted, coplanar and usually does good job on smaller things like cutting dutchmen, cutting tenons etc. I adjust the blade tension until it's at the 3/4" mark on the "gauge", then check with finger pressure for the tension.
Last week I built a jig to hold some ~10" diam. logs steady while I sliced them into planks for a few projects. The wood is Red Alder, 23" long, and dried for the last year in my heated basement.
I sawed one face, turned it 90 deg, sawed a piece, and with those 2 flatish, began my slicing career.
No matter how slowly I think I'm feeding the wood, keeping pressure on the outside face of the wood, the blade seems to wander anywhere up to 1/8" within the cut.
I can hand-plane one side of the board flat (too big for the jointer), then run it through the planer, but I feel I'm doing something wrong.
This is my first try at sawing logs on the bandsaw, and I know almost everyone has more experience than me.
Can you suggest a wayto make straighter cuts, or is this a practice, practice thing?
Thanks

[Brice Rogers]

Following. I have the same problem...

[Steve Fish]

I have almost no experience with resawing logs but I do know that once you install a riser, the tension “gauge” is not going to be as close to correct as it was before. I would try a little more tension and consider making a sled or jig to hold the work piece steady. If it’s rolling at all, you are going to have problems.
I believe this kind of resawing is pretty common with guys that do a lot of turning, hopefully some of them will find this thread and give some more solid advice. Best of luck

[Derek Cohen]

Hi Aaron
re
There are three issues. The first is set up - I have doubts about the blade tension you can achieve with your bandsaw, and especially with the riser kit. I used to have a similar bandsaw, and could not use wider than a 3 tpi 1/2” blade to achieve enough downforce, and even then did not resaw wider than about 7”. You may obtain a better result from a narrower blade. Also, fewer teeth are going to load up less. 3 tpi is about as many as I would go to for resawing. My 1” blade is 1.2 tpi.

The second factor is technique. The main culprit here is the speed at which you enter to wood. If you push the wood too fast, the gullets load up faster and do not release the waste. This then pushes the wood away from the fence. The answer is to slow down the feed rate.

The third factor is the wood, itself. You release tensions when you saw, and the kerf may open, with one side pushing the other away from the fence. The result is an uneven cut. My simple solution is a split fence, which I have posted pictures of previously ...



From the rear ...



Posted on a train to Vienna

Derek

[Lee Schierer]

Most 14" bandsaw are not capable of properly tensioning a 3/4" blade. A riser kit makes them less capable of tensioning a 3/4" blade. I have a 3/4" blade that I use on my 14" delta blade that is only 0.022" thick and my Delta saw without a riser can barely tension it properly. I can successfully resaw boards up to 5" , but with your 10" logs you have far too much pressure against the face of the blade for it to remain straight. You might have better luck with a 1/2" blade with 3 tpi.

[Grant Wilkinson]

All of the above, plus a note on technique. Make a jig that allows you to get rid of the fence. Here is one idea

https://www.woodmagazine.com/woodwor...-and-technique

There is a commercially-made one out there, but I can't find the link just now. The idea of all these is the the cut off can move without moving the "host" piece away from the blade.

[Mark Daily]

+1 that a 3/4” blade can’t be properly tensioned on a 14” saw. (Mine can’t) A 1/2” blade may solve your problem.

[John K Jordan]

I agree about the tension. I've seen this many times, both on my own saws before I knew any better and sometimes from others. On my 14" saw I found I could not use a blade larger than 12" and even then it required full tensioning according to the indicators on the saw. These indicators are notoriously useless.

Even on my 18" Rikon I have to set the tension mark on the saw to almost 1" to properly tension my 1/2" blades. This is not guessing - I use a Starrett tension gauge to set the tension and that's what it takes. Any less and I get all kinds of problems with thick wood. (The primary use of my bandsaws is cutting green and dry wood up to 12" thick to prepare turning blanks.)

Another thing which can cause terrible problems is a dull blade. I periodically stop and sharpen the blade or switch to a new one. I almost exclusively use Lenon 1/2"x3tpi blades, sometimes 4tpi, and sometimes 3tpi carbide blades.

If I do a lot of "skimming cuts" to true up blanks, one side of the blade will invariably get dull before the other. This can cause problems that resharpening fixes immediately.

Note that you do not need to use a Starrett tension gauge which is not priced through the ceiling. Ittura Design sells a much cheaper version, recently updated. There have been posts here showing how to measure the tension with a dial caliper and a simple jig. I saved the reference if you want it. Note also that you don't have to check the tension with a gauge each time - do it once for each type of blade and remember the settings on the saw.

There are those who believe in the usefulness of other tensioning methods such as flutter and deflection. I'm not one, based on my own experience and that of others.

Sorry, I didn't have time to read the whole thread...

JKJ

[Alan Schwabacher]

I agree with John Jordan that blade sharpness is a likely contributor to the problem: resawing benefits from a sharper blade than is needed for other cuts. Here's a quote from Matthias Wandel's "The physics of bandsaw resawing" after mentioning the problems caused by filling the gullets with sawdust:

"The solution, it would seem, is to cut slower. But as the blade gets slightly dull, the tip of each tooth becomes slightly rounded instead of a perfect point. When the tooth isn't pushed into the wood fast enough, that round causes the tooth to just rub on the edge of the cut instead of biting into the wood. So really slow feed rates only work when the blade is very sharp."

Fewer teeth let each take a larger bite at the same cut speed. Another reason to prefer a blade with few teeth per inch is that it is easier to resharpen. I am too cheap to use a carbide bandsaw blade, but a bimetal blade can be touched up with a diamond sharpening card pretty easily while on the saw.

[Paul F Mills]

How about a 3/4” blade on a Rikon 14” bandsaw? It came with a 1/2” I think, but the Woodcraft guy recommended a 3/4” for resawing. I only did one resaw with the 1/2” and it was great, and One with the 3/4 and it was ok (I was in a hurry which may have affect it too). But it was sycamore and walnut respectively, not sure how much that matters.

[Jacques Gagnon]

Aaron,

In addition to what has already been mentioned, one word of caution: make sure you do not get « too enthusiastic » with the tensioning of larger blades. You run the risk of either ruining the tensioning bolt or the cast aluminium cradle holding the spring and bolt. Sticking with smaller blases will reduce the risk of damaging the saw.

Regards,

J.

[Doug Garson]

All of the above, plus a note on technique. Make a jig that allows you to get rid of the fence. Here is one idea

https://www.woodmagazine.com/woodwor...-and-technique

There is a commercially-made one out there, but I can't find the link just now. The idea of all these is the the cut off can move without moving the "host" piece away from the blade.

Is this the Little Ripper the commercial one you were referring to?
https://www.youtube.com/watch?v=bWMM49qFgX4

[alan tasoff]

Most of the comments above reflect probably more expertise than I have, but I noticed that no one mentioned drift angle. I have a 16" Minimax (the subject of a different recent thread). I was recently resawing a cedar log using a 3/4 inch blade (Timberwolf, 3 tpi), and the blade was drifting terribly. (I hadn't had that problem after switching to Timberwolf blades from carbide tip). I changed the blade and the drift disappeared. With the carbide 3/4" blades, I was constantly fussing around with the drift angle of the fence. I have found the TW blades excellent (I have no financial incentive here) for eliminating that problem. Another thought would be to use a point fence(not sure if that's what it's called, but it's just a pivot point just in front of the blade). My blade tensioning is purely guesswork so I guess it's not critical on my saw.

[John K Jordan]

... as the blade gets slightly dull, the tip of each tooth becomes slightly rounded instead of a perfect point. When the tooth isn't pushed into the wood fast enough, that round causes the tooth to just rub on the edge of the cut instead of biting into the wood. So really slow feed rates only work when the blade is very sharp."

That's probably the reason I read years ago that there was an optimum pressure and speed for cutting - they said too slow would dull the teeth and too fast took excessive pressure and cut poorly. But I think the sweet spot depends on the blade, the sharpness and the wood. You can feel when it's right.

I sharpen using the face of a tooth with a little metal-cutting disk on a Dremel - get the angle right and a 1/2 second touch on the face of the tooth gets it sharp. Sometimes I'll angle the disk to match the tooth set pattern (left, right, center on the blades I use) but sometimes I just grind straight across. Straight across cuts well but angled might be better.

bandsaw_sharpen.jpg

There are 426 teeth on my 3tpi blades so it takes a while to sharpen. I usually sharpen two or three times before swapping blades. Eventually the tooth set gets small. The cut is not as smooth as the blade when new but for processing wood into turning blanks that doesn't matter.

I used to be bewildered when feeling the teeth for sharpness. Blades that were obviously dull still felt sharp to my fingers. Then one day I tried running the flat of my fingernail up the teeth instead of my finger. I can tell now when I need to sharpen rather than wonder if instead that wood I'm cutting is extra tough.

JKJ