Tip #47
Resawing Techniques (continued)
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Back to the Basics

To understand how the part of your bandsaw work together-and what could go wrong when they don't-we need to review a few basics. Let's start with a definition: The bandsaw is a thin, continuous blade, running under tension between two or more wheels. A frame supports the wheels and the blade, while a table supports the work and keeps it at the proper angle to the blade.

Since the blade is thin, it can be distorted or deflected easily. Feed the work too quickly or turn it too abruptly, and the blade will bend or twist. To keep the blade running true, most bandsaws have two sets of blade guides and thrust bearings, above and below the table. These support the blade from three directions. The bearings back up the blade and keep it from bending when you feed the stock. The guides rub against the guides and keep it from twisting.

Figure 1. Before you resaw, check that the "Cutting length" -- the porition of the blade between the guides -- is perfectly square to the bandsaw table.

If any of these parts are poorly aligned or adjusted, the quality of the cut will suffer. The thicker the stock, the greater the effect of the misalignment or maladjustment. When cutting thin stock, you may be able to live with a bandsaw that's seriously out of whack-the problems may not even be discernible. But they will become all too apparent when you try to resaw. So, before beginning a resawing operation, take the time to check your saw. If necessary, realign or readjust the blade tracking, blade tension, angle of the table to the blade (It must be precisely square. See Figure 1.), relationship of the upper and lower blade guides (they must be in line), position of the thrust bearings, and the position of the blade guides.

All of these things should be discussed in-depth in your owner's manual. There's no sense in giving them more than a mention here. But there is one common problem that you won't find in your manual-vibration. No manufacturer likes to admit that their machine vibrates, but they all do. And this vibration can affect the quality of the cut as much or more than anything else on the checklist.

Figure 2. Here's an example of what a little vibration can do to the quality of your cut. The motor pulley that came with my bandsaw had a bad wobble that caused the blade to vibrate. I resawed the left half of this board using the wobbly pulley, and the right half using a better pulley that I bought as a replacement.

Vibration is the cumulative effect of all the tiny problems with all the moving parts on the bandsaw. It starts at the motor and travels up the pulleys, belt, and the wheels to the blade itself. The blade picks up the vibrations of the machine and slaps back and forth in the kerf, the teeth scraping one face of the cut and then the other. If the vibration is too great, this will produce a “washboard” effect-the cut will be rough the uneven. (See Figure 2.)

Many things add to the problem of vibration. Motors are sometimes out of balance, pulleys wobble, belts may not be out of round. If you suspect one or more of these may be causing your bandsaw to vibrate excessively, track down the problem and fix it.

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