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Tune-Up of Bandsaws

Bandsaws that are properly tuned cut true, do not drift, and work effectively in straight and curved cuts. It will not require the addition of hundreds of dollars in accessories, either; just help to make the machine run more efficiently.

Simple adjustments will help to keep the saw cutting true, and the order of adjustment is designed for either a new machine or one that could really use a good tune-up.

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Blade selection —  may be the most important section of all. The correct blade is critical to optimum performance. A wide, coarse blade is for re-sawing; a fine, narrower blade is for thin stock. Too fine may produce smoother cuts but cause drift when sawdust build-up in the teeth pushes the blade out of alignment. The wrong blade could cause breakage in excess heat situations.

Drive Belt & Motor — the drive belt should be adjusted for proper tightness and alignment with the pulley of the lower drive wheel. Use a straight edge to align the pulleys and adjust the motor position to adjust belt tension. Replace any belt with cracks or evidence of wear. Any belt that has sat in one position for a long time may need replacement to eliminate vibration induced by flat spots on the belt.

Wheel Alignment — wheels must rotate in the same physical plane (coplanar). The straight edge must touch the top of the top wheel, bottom of top wheel, top of bottom wheel, and bottom of bottom wheel —  all at the same time. Non parallel wheels mean turning the tracking knob behind the saw to tilt the upper wheel forward or backward. Once the wheels are parallel, determine whether or not they are coplanar.

Tires — need inspecting, and when in doubt, replace them. Old tires will have flat spots or lumps which inhibit the blade from proper tracking. Tires need to be free of lumps, flat spots, sawdust build up, cracks, or loose sections. If the saw blade appears to jump around as it rotates, the cause is likely to be worn tires.

Blade Installation — the first thing to consider is tension and then applying enough in order to keep the blade secure. Adjust for minimum tension required to keep the blade on the wheel. Rotate the wheels by hand several rotations. Make sure the blade is free wheeling and does not strike any guides or guards. Inspect blade carefully for imperfections like kinks or bad welds. Imperfect saw blades will produce poor quality cuts and are also dangerous. The inspection should be done with minimum tension on the blade so that kinks and any blade variation are easier to detect.

Tracking — the single most important factor in saw performance. Correct tracking means the blade is running along the center of the wheel. If this isn’t the case, adjust the tracking by tilting the top wheel in relation to the bottom wheels. A knob behind the upper wheel housing controls this adjustment. Drift occurs with improper tracking. Use of the wrong blade, blade replacement, or improper tracking are to blame for drift.

Tension — blades and bandsaws can handle increased tension, but it isn’t a good idea to apply too much. This will cause premature wear to both the blade and machine. High tension blades are generally made of carbon steel and require more tension since steel is less flexible around the wheels. Low tension blades are made with higher silicon content which is more flexible than steel. Lower tension blades are also thinner (.025”) and will work on smaller two-wheel saws and large models.

Guide Adjustment — the rear bearings should be set first, both top and bottom. Move them forward until they almost touch the blade. Leave about a 1/32” gap between the blade and the bearing, then set the guide blocks on the side bearings. Once all bearings are in place, lock them.

Upper Blade Guides — in order to avoid blade twist, and to maintain proper tracking under load.

Lower Blade Guides — serves to support the blade and maintain proper tracking under heavy cutting load.

Table Alignment — should be set at 90° to the side of the blade, also square to the back of the blade for advanced joinery techniques such as cutting tenons or dovetails. It will also help to square the guidepost. Most saws have a stop that adjusts the horizontal stop of the table (tilt stop). Set the table square to the blade by placing a square against the blade and setting the table at 90° to the blade. Adjust the stop. Most saws have an adjustable angle gauge, set when the saw is at a 90° angle. These gauges are typically not very accurate, so a square is needed if accurate angles are needed.

Fence Alignment — not critical on a well tuned bandsaw, doesn’t need to be perfectly square to the blade since the tooth set allows straight cuts even when the fence isn’t perfectly aligned. Close enough is fine.

A properly tuned bandsaw should produce minimal vibration, noise, and chatter. A high-pitch sound suggests there is a chip generation issue; usually caused by too high a speed/feed rate or improper blade pitch. A low-pitch humming could suggest the guides are set too far apart, blade tension is too low, or the pitch is incorrect. A clicking sound indicates blade issues; possibly tooth damage or a cracked blade.

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