Woodworker's Journal 1992-16-6, страница 75

Photo 9: Finger-operated Quick ( lamp on Excaliber saws: available for Delta. Hegner, and RBI as aftermarket accessory from Seven Sales (see Sources).

I sec Sources!—also offers variations of these clamp sets as aftermarket retrofits for the Delta (which also fits the Shopsmilh). Hegner. and RBI saws (top clamp only). Hegner now offers a nearly identical version for their saws.

San Tensioning: l or the most part, adjusting the blade to the proper tension has always been a hit-nr-miss proposition: the ideal tension depends on the blade size and type of material you're cutting. However, once you have enough experience under your belt, the process becomes intuitive.

On most saws, you adjust the tension via a knob-operated tensioning rod at ihe back of ihe saw: on C-arm saws, the tensioning knob is located on the front of the top arm. The RBI saws haw a cam-type lever, rather than a knob. This feature provides a nearly foolproof method of tension adjustment: you finger-tighten the tensioning rod until the cam contacts the tensiOn-rod pivot block at the 11:00 position: you then flip the cam lever forw ard to lighten the blade to the correct lension. When changing blades, you simply flip the cam lever hack to loosen the tension (Photo 10). The RBI 220YS also has a quick tension-release lever mounted on the front of ihe saw arm. as does the Delta (Photo 11) and Excaliber. Once you achieve the proper tension, all you need do is flip the lever forward to release tension for blade-changing, ilien flip the lever back to return to the same tension setting on the saw. Because the lever on the Excaliber wasn't yet available at ihe time of this review, the model pictured doesn'l have one. As with the finger-release quick clamps, the front lension Niiveraber/Dctemhcr IW

Photo 10: C am-type lever on RHI saws enables quick tension release for changing blades.

release lever is .t real lime-saver, especial!) if \ou're silting on a stool in front of the saw. Even with this device, however, you usually have lo readjust the tension when you switch blade sizes.

In the final analysis. 1 found ihe Excalibci EX II had ihe best blade-changing system, followed by the RBI 220VS. Delta RBI 21ftVS. Hegner. and Shopsmilh. in that order

Motors

The si/e ami weight ol some of these machines approach that of a small stationary hand saw. but they don't require nearly is much power to run. (The motors range from 1.7 to 2.8 amps).

Why.' \ll you need do is look at the size of the blade the motor needs to power. I hi example, even if you're aggressively cutting thick hardwoods w ith a no, 12 blade, you're more likely lo bend or snap ih₍ ht.ide before you bog down the motor in any great degree. All of the saws tested hail more than enough [lower, in my opinion

Electronic Variable Speed (EVS)

As a rule, most scrolling jobs are done at the saw's maximum speed—1.400 to 2,000 strokes per minute iSPM)— because ihe high speed generally provides the fastest, smoothest cuis in a variety of wood and wood composite materials. However, the ability to change lo a lower blade speed becomes important when cutting plastics (which tend lo melt as higher speeds I and metals (which lend to heat up the blade). !l also helps to slow down the blade speed when you're first learning how to cut.

Photo II: Front-mounted tension release lever on Delta is also available on RBI 220VS and Fxcoliher EX II saws.

gelling acquainted with a new saw or trying out new patterns—especially if you find the blade making burn marks in ihe light curves. Even veteran users prefer lower speeds when making intricate cuts in thin stock, such as for marquetry or intarsia projects.

Before manufacturers added variable speed to their saws, speed changes were accomplished by means of a manually changed belt and a step pulley system, which provided two to five different fixed speeds. Now. all the major companies offer models with EVS, along with single-speed versions (several also offer step-pulley models). While EVS isn't exactly a must-have feature for most scrolling projects, it certainly adds to the saw's versatility and provides more precise control of ihe cut. Typically, ihis feature adds aboul $100 to SI50 to the price of the saw.

All EVS controls have an electronic feedback feature thai enables the motor to maintain a constant speed under varying loads. In my lesis. the Hegner and Delia were slightly better at maintaining smooth, consistent speeds throughout their range, although the speed controls on the rest worked perfectly well. The controls on most saws have an arbitrary I to 10 speed-control dial, the dial on the I legner reads in SPM increments. Wilh its I.F.Ddigital readout in actual strokes per minute. Ihe Delta control (Photo 12) is ihe most sophisticated. My 4-year-old daughter said she likes ihe Delta best "bccausc it has a little speedometer on it."

Accessibility of Controls—While some woodworkers might consider the Delia's LED readout a trifle gimmicky.

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