Friday, September 16, 2011

V2.21 - Make a Straight Cutting Band Saw

Let’s go visit our old friend the bandsaw, this week. One of the most common problems with a bandsaw is getting it to cut straight. You start out with a nice straight line and start the cut and before you know it, the blade has decided that it wants to shoot off at an angle and destroy the part you did not want to cut. Some of the ‘old pros’ call this ‘blade drift’- I call it ‘don’t cut straight’.

Most often, here is what happens. Looking directly at the blade teeth, one notices that each tooth on the blade is bent out at a precise distance. This is called the ‘set’ of the blade. Having the teeth set outward provides clearance for the back of the blade to move through the work. It also provides some clearance for the blade to cut around a curve. However, if (for example) the teeth that are bent to the right stick out further than the teeth that are bent to the left, the blade will cut towards the right. The best solution to this problem is to purchase a high-quality blade, but I have even seen those drift sideways - right out of the box.

Another solution is to make the ‘set’ more equal - more balanced, if you will.
One way to do that would be to increase the bend of the teeth that are not sticking out as far; however, that is a very difficult thing to do. The more practical solution would be to slightly file the tips of the teeth that are sticking out too far- actually you would be ‘dulling’ them ever so little.
A method I have used is to hold a whetstone against the running blade and let the blade teeth lightly skim across the surface of the stone. A fine touch is a must, but with some practice, it isn’t hard to manage. Take your time and test the blade often by taking a test cut, so that you don’t dull them down too far.

Another thing that causes blade drift is when the number of blade teeth per inch is too high and the wood chips cannot escape from in between them. This typically shows up when doing resawing – sawing very thick wood – because the blade spends a lot of time inside the wood and can actually heat up and bow inside the wood, thereby causing a warped cut. The solution is simple: Use a blade with fewer teeth per inch.

Next week, we’ll talk a little about how to get your blade to track properly. It’s always a scary thing to be cutting along and POW! the blade pops off the wheels.

Send your questions or comments to: and we’ll see what we can do to help you.

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