Woodworker's Journal 1994-18-3, страница 26

wheel to spin freely. If the w heel is off-balance. il will consistently stop with the heavy spot at the bottom when you spin it. For various solutions to an out-of-bal-ance wheel, be sure to read "Fine-Tuning the Band Saw" on page 12.

Heavier wheels provide more momentum to help keep the blade from bogging down. Large cast aluminum wheels are preferable to the lightweight ABS plastic wheels found on the cheaper benchtop models. (See chart on page 25). Cast-iron wheels are better yet. but none of the benchtop units have them. Surprisingly, the Reliant (one of the smallest saws tested), has relatively wide, heavy, cast aluminum wheels. These, along with a heavy-gauge, well-reinforced cast aluminum frame make it one of the smoothest running saws I tested, despite its bargain basement price of SI 19.95.

Check the upper guide assembly lo make sure il operates smoothly and locks firmly. The guideblocks and thrust bearing should remain in the same position relative lo the blade no matter what height you position the assembly above the table; otherwise you'll be constantly readjusting the blocks and thrust bearing. Grasp the guide assembly with your hand and try lo twist it—the assembly should be rigid. The stationary lower guideblocks should be located as close as possible to the bottom of the table to provide firm support for the blade.

Generally, the larger and heavier the machine, the less it will vibrate. The frame must be rigid enough to withstand the stress of a tensioned moving blade without flexing. You can test the frame for Ilex by grasping the edge of the table with one hand and firmly pushing against the top of the upper wheel housing with the other. All of the benchtop models I tested have rigid, ribbed cast-aluminum frames—sturdy enough for the size and weight of the saw.

Adjusting the Saw: How Easy?

More than any other woodworking machine. band saws require considerable fiddling with various adjustments to get them operating smoothly and accurately. With older saws especially, many woodworkers complain that they spend more time Fine-tuning and setting up the saw to make a cut than they do running the wood through it. Look for easily aeces-

Dremel, Kyobi (shown), and Skil have square, graphite-impregnated guide blocks, which provide more surface area and less friction than steel pins. Note deflector shield on table insert to direct sawdust away from lower wheel.

sible. smoothly operating controls. The mechanisms should hold their settings. On all of the saws I tested, the tracking, tensioning, guide assemblies and table tilt settings stayed put once they were set. However, it's a good idea to recheck all settings each time you use the saw.

Tensioning the Hlade On mosl band saws, you adjust blade tension by turning a knob on the top of the wheel housing. The knob should turn easily, tension the blade quickly, and the mechanism should hold the set tension once adjusted.

I liked the large, comfortable knob on the Ryobi. The Sears works a bit differently: You tension the blade by opening the cover and lifting up on a handle that

Check table tilt for smooth operation. On most saws, two locking knobs attach the trunnion to the frame (Reliant shown here).

fits into one of a series of slots machined into the inside of the saw frame: a knob on the oulsidc of the frame tightens the handle in place to hold the setting. While il may sound like a hassle, the process doesn't take any longer than tightening and loosening blade tension with a conventional twist knob.

The Dremel and Skil have a tensioning scale, like those found on larger saws. As you increase or decrease blade tension, an indicator arrow moves up or down an arbitrary scale from I to 5. While the owner's manuals for these two saws don'i tell you how io interprei the scale (such as recommending particular numbers for each blade size), you can keep notes and use the scale as a reference for optimum tension with different blade sizes and various types of wood.

However. 1 found that the tension scale, like those on most other band saws, is neither accurate nor especially helpful. Instead of a tensioning knob, the Delta two-wheel saw incorporates a unique tension lever device that provides the correct tension for Vs, 1/4. and -Vs in. blades. After installing the blade, you lift up on the lever and turn it clockwise until the tension spring begins to compress. You then turn the lever one additional turn for '/8 in. blades, two turns for 'A in. blades or three turns for -Vtt in. blades, then flip the lever down to lock in the tension.

Tracking the Hlade As mentioned, you keep the blade running on the center of the wheels by adjusting a wheel-tilt mechanism on the top wheel. The mechanism should operate smoothly and positively without excessive fiddling to get the blade centered. Once the blade is centered, it should stay there, rather than wandering from one side of the w heel to the other during operation.

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The Woodw orker's Journal