Creative Woodworks & crafts 2000-04, страница 60

Creative Woodworks & Crafts

Four factors for Quality Cutting

Four main factors affcct the quality of cut you achieve on a scroll saw. They arc: size of the blade, speed of the saw, feed rate of the material, and blade tension. All interact to determine the type of cut you get. Let's tackle them one at a time, and then tie them all togeth er.

Blade size

The size of the blade aITecls Lhe speed with which you can follow intricate pattern lines. The larger the blade, the harder it will be to turn in very intricate, closely spaced pa Herns. Using a smaller blade will let you make turns faster, but will extend your cutting time in thicker or harder materials. The ideal size will let you cut as quickly as possible and still follow the pattern line. Experiment, and don't be afraid to switch to a larger or smaller size.

Saw speed

Blade size and saw speed go hand in hand. Too small a blade at too fast a speed may cause burning of the edges of the male-rial, especially in tight turns on intricate patterns. Slowing the speed slightly, or going lo a larger blade, will usually cure the problem. On the other hand, cutting too slowly can be counter • productive. Using too large a blade in thin material can cause the blade to grab the material and jump it up and down on the saw table (the dreaded scroll saw chatter).

Sheet plastic or Plexiglas is also harder to cut at slow speeds. It can result in "cold granulation," a line of lava-like waste left behind the blade. Practice on scrap

pieces of the material first to find the right combina tion of speed and blade size.

Feed rate

It should be obvious that forcing material through the saw can cause problems. Still, it's easy Lo get so caught up in the project that you wind up feeding the material too fast. Overrunning the blade will cause an erratic cut that can burn the edge, leave blade marks, overheat the blade, and cause premature failure.

The easiest way to keep on track is to think of the blade as "floating" through lhe material, lake it easy, even while turning corners, and let Lhe blade do the work. You'll get a smoother, more accurale cuL and have more fun in the

A scroll saw with an accurate tensioning system is key to getting sweet cuts.

process. You will also find it easier to stay on the pattern line if you feed the material slowly.

Blade tension

A scroll saw blade that sags or twists loo much can break easily. It's like bending a piece of wire back and forth. A loose blade will Ilex within the cut, which means it can grab

lhe malerial, making il difficult to hold the material down. It also produces a wider, more erratic that makes it harder to stay the pattern line. It' your scroll saw is not equipped with an accurate tensioning system, about the besl can do is to employ one of three methods. The first is to the blade and listen for a "C" note, which can be difficulL if you are nol musically inclined.

1'he second method involves cranking down the knob, or the tensioning lever on saws, until tight. You then crank down again, or loosen a little, depending on lhe saw man-ufac turer's recomm en d a lion. When you slop breaking blades, you have il righL!

The third method is even more inexact. Adjust the tension until you think it might be right, then press sideways on the blade. You have it right when the blade flexes no more lhan about a quarter of an inch. Remember, even the thickest blades arc relatively flexible, tighten the blade according to the Instructions and keep in mind lhal you cannot get too much tension on a scroll saw blade. The worsl lhal will happen is LhaL lhe blade may slip out of the blade holder. Simply put it back with slightly less tension.

To wrap it all up

The combination of the four faclors above will deLermine the ease and type of cut you achieve. There is no magic formula, since the type of material and pattern will affect any project. Awareness of the four faclors will give you a big head start. Practice with varying combinations to reach the ultimate goal, a smooth, clean cut that floats through the project.

Thomas and Jake Miller are Sales Reps, for RBIndustries scroll saws. They also own and operate Winter Oak Studio, in which they do custom scroll saw work and crafts. They wclcome any questions regarding scroll sawing and may be reached at (800) 440-SAWS.

by Thomas Miller