Dealing with Blade-Diving Waves

      More blade tension, better blade lubrication, and a sharpening modification may help keep bandsaw blades from wandering when cutting larger logs. December 1, 2005

Question
Every time I saw a large 30" or more log I get waves. I don’t get any waves with 18 or 20" and I have tried every thing. Woodmizer says it is dull bans, but it does it with a new ban also. Can anyone help?

Forum Responses
(Sawing and Drying Forum)
From contributor W:
Can you give more info? I have a Woodmizer and it will only cut 24" wide. I can cut a larger log than that but 24" is tops for width. Is it waving throughout the hole cut or at the beginning or end? What species and what blade are you using?



From contributor C:
I had the same problem with diving. Woodmizer said it was occurring because I was using belts made by someone else. It turned out to be tension.


From contributor B:
If you've checked everything else, check your main drive belt tension. It's got to be tight to not slip when making the heaviest cuts. Also, your choice of blade hook angle, set, and kerf may be too much for the power you have.


From contributor L:
I noticed the same wavering when I sawed a really big dry oak log for a customer on my Timberking 1220 bandsaw and I was able to correct the cut by increasing the lubricant quite a bit.


From contributor P:
The blade is probably not tight enough and you should use something to cool the blade. A water tank may work. Put a little dish soap in the water tank also. Friction is what makes the heat. When the blade warms up it expands. Check the height on your guides, and make sure that they are perfectly level with the blade and crank up the tension.


From contributor L:
I've experienced wavey cuts on my WoodMizer's in the past too. It's frustrating to say the least. Here's what I found would work every time to cure it.

Do you have your own blade sharpener and setter? If so try this:
1. Set the blade teeth out wide. If you're using Woodmizer's blades maybe go out to .030 if your setter will let you get there.

2. Then get a magnetic protractor (it can be bought at Lowe's or Home Depot usually in the tool department near the levels). Put it on the Sharpener housing of your Sharpener. If you're standing looking at the sharpener, put it on the right side of the grinding wheel cover. The magnet should make it stick to the side as you make an adjustment. Loosen the appropriate nut that allows the grinding wheel to rock left or right. Bringing it left should bring the needle on the protractor towards the 0 degree mark. Do that and then bring it back right until the needle is pointing at about 8 degrees. Now lock the nut down, leaving the protractor attached to the housing and re-check after tightening to make sure you haven't moved it away from 8 degrees.

3. Now take your push arm and set it to push the tooth extra far, so that the grinding wheel comes down ahead of the tooth. Cycle the blade around slowly, backing the push arm off until the grinding wheel just barely kisses the tooth - and I mean barely. It's better to take small bites so you don't burn the tips and crystallize them - they'll just wear off if you do that.

So kiss-sharpen that blade, concentrating at first on the face of the tooth to get the angle right.
If you put safety glasses on and watch closely as it grinds you'll be able to see the difference in the face angle as you're grinding. Cycle that blade several times until you have the entire height of the tooth ground to the new angle. Once this is accomplished grind the gullet to maintain a tooth height of about 3/16 - 1/4". Even though you started with a relatively wide set of .030 on each side, you'll see that after kiss-sharpening several times that set will have been decreased because you have removed material from the tooth. Do not re-set after you are done kiss-sharpening. That tooth has been sharpened to the angle (set) that it is going to cut at.

Make sure your log is relatively clean. It's your call as to whether you want to use water to cut or not. In my experience, if you have enough set you don't usually need water. Use it if you need it or want it though. Make sure to keep your feed speed slow, easing the blade through. If you don't have your own sharpener, maybe you can send the blade out with these specs to someone close by.



From contributor P:
I would go through and check my blade deflection and blade tilt – there should be something on it in your manual. That is the first thing I would check if I tried a new blade. I have had an LT 40 hd for twelve years and sold it and just bought an LT 70 and love it.



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