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Unread 12-07-2006, 19:21
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DonRotolo DonRotolo is offline
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Re: Bandsaw Troubles

Although a small amount of twist can be expected under certain circumstances, 30 to 45 is far too much. (That doesn't mean I haven't experienced it - it's just that it's not good).

I believe the solution lies in the adjustments to the blade and path. The blade has some influence as well. Properly adjusting the saw will definitely minimize twist for a given blade.

First, the blade: For Lexan, a not-too-coarse blade - say 10 to 14 teeth per inch - would be appropriate. Too fine and you end up melting the plastic from friction. Too coarse and you end up with only one tooth on the material at a time, particularly with thin materials like sheets of plastic. Conventional wisdom dictates not less than three teeth in the material at all times. Also, a wider blade (front to back, not thicker) will twist less, but the radius of curves cut is greater. If you make mostly straight cuts, or gentle curves, buy a 3/8" or 1/2" blade.

Next, the adjustments. There are the following:

Blade tension: If this is off, lots of bad things happen. If you don't know how, read the manual. Very important.

Blade guides: There three points of guidance on a bandsaw blade: Left, Right and Behind. Left and Right are blocks of steel which are held in place with setscrews. The blade needs to ride almost completely within these blocks while cutting, with only the teeth sticking out forward. They not only need to be touching the blade with a slight force, but they need to be adjusted side-to-side to hold the blade in its neutral position.

Behind should be what looks like a ball bearing. It is adjusted front to back, and held in place with another set screw. This should be adjusted so the blade rides about 1/16" in front of the bearing with no load. As soon as you start cutting, the blade will move back and ride on the bearing.

These exact same adjustments are both below the table, and on the adjustable guide above the table.

Lastly, adjust the guide so it rides just a little bit - 1/4" maybe - above the workpiece. If you have it adjusted so 6" of blade is showing, the blade can wander all over. Not only does having the guide improve stability, it greatly decreases opportunity for blade contact. Trust me, it hurts. A lot. For a While.

Delta is a big company. If you don't have the book buy one. If you do, read and practice the adjustments.

Although the issue may not be related to this, I have found that when my saw is carefully adjusted - it takes me about 20 to 40 minutes to change a blade - the cuts are great. Let me know if you need more explanation of any of the above. Or, if you know all this and it still cuts sideways.

Good luck,
Don
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