Blade Basics 

Buying a new table saw blade can be a daunting experience. There are dozens of manufacturers offering a wide selection of blades. On top of this, there are a host of factors that affect the performance of a blade: quality of the steel used in manufacturing the plate, the hardness and flatness of the plate, plate tension and balance, arbour hole concentricity and accuracy, tooth geometry and carbide quality.

Better quality saw blades are laser cut rather than hydraulically stamped (or die cut). Laser cutting puts less stress on the plate, particularly at the edge, and allows greater cutting accuracy. Additionally, laser cut arbor holes reduce harmonic vibration. Blades are subsequently heat treated and tempered to toughen the steel, usually in an oil bath. Before the teeth are attached the plates are run through a grinder for flattening and then hand tensioned to prevent them from vibrating at high speeds. Even with flattening and tensioning there will likely be some run out (wobble) in blades; up to .004” is considered acceptable.

Vibration and heat build-up are the bane of saw blade manufacturers. Most cut anti-vibration and expansion slots in their plates; a few fill these slots with a resin. The slots reduce vibration and noise, and help dissipate heat. Most blades use an anti-kickback design. Typically a chip limiter precedes each tooth, restricting tooth bite to a pre-determined safe amount.

The business end of a saw blade are its teeth. Tooth geometry, quality of the carbide used, thickness of the carbide and the quality of the brazing that attaches the teeth to the plate are all critical components. Crosscutting teeth are cut ‘alternate top bevel’ (ATB), and slice across the grain like knives. Two important tooth angles are the angle at which teeth cut into stock (hook angle), and the angle the top of the tooth makes from side to side (top bevel). Greater hook angles cut faster and more aggressively but can result in splintering the underside of stock, particularly in sheet goods. (Raising the blade about 1/4” above the stock helps to reduce splintering.) Increasingly, companies are using ‘super micrograin’ carbide in the manufacture of teeth, which means they use smaller grains of carbide powder with titanium added to the binder. This makes for a tooth that can hold an edge longer between sharpening. Teeth can be brazed onto the plate with a low melt alloy like silver alloy or with Tri-Metal Brazing, which sandwiches layers of copper between a layer of silver alloy, reducing stress and giving better impact resistance. In general, thicker teeth will allow you to sharpen the blade more often – expect to get at least 10 sharpenings per blade.

Is the choice of a saw blade that important? If you are looking to get the best cuts possible from your table saw, and the maximum value from your saw blade investment, then you want to choose the best blade you can afford. Its a good idea to have at a minimum 3 blades: a top quality combination and rip blade, and an a contractor quality combination blade. It only takes a few minutes to switch blades. Use the lower quality blade for cutting

Schumacher Blades
Upon close inspection it becomes evident that these German made blades are exceptionally well manufactured, featuring all the characteristics that you want in a top quality blade: laser-cut plates, expansion slots and arbour holes, carefully ground plates, and thick micro grain carbide teeth, which are well brazed onto the plate. According to the manufacturer, the secret to reduced noise levels in their blades is the varied spacing and pitch of the teeth - hence the VP designation in the blade moniker. This reduces vibration and dampens the resonance created by the spinning blade. These blades are also hand tensioned, which further ensures that the blade will remain rigid and straight when it reaches operating speed. As a testimony of the confidence that the company has in these blades it backs them up with a lifetime warranty against manufacturing defects. To avoid damage in shipping and storage the blades come in a protective (and re-usable) plastic case.

Performance
I carefully checked each of these blades for flatness - both plates showed virtually no measurable run out. The teeth were all well brazed onto the plate. These are large teeth. On the combination blade they measure 3.1mm wide, 7.66mm high and 2.9mm thick. The face of the each tooth is nicely polished. The blades fit perfectly over the saw arbour - when seated on the arbour there is no slop around the arbour hole.

Prior to beginning the tests I checked the alignment on my mitre gauge, rip fence and arbour shaft on the table saw. As the manufacturer didn't recommend a blade stiffener, I didn't use one. For the combo blade I made rip and crosscuts in plywood, MDF, soft maple and ash. For cuts in softwood and sheet stock I raised the blade 1/4” above the stock, while for hardwood I raised the blade 1” and fed at a faster rate. With the crosscut blade I made crosscuts in 2" and 3/4" soft maple and ash.

I was very impressed with the quality of the cuts. The combination blade produced as good a crosscut and rip cut as any blade I have used to date. The crosscut blade produced what I would have to describe as outstanding cuts - the finish was ultra smooth. Competition being what it is among saw blade manufacturers I did expect these blades to perform as well as other leading brands. However, what did set these blades apart was the veracity of the manufacturer's 'low noise' claim. I measured the db rating with an Extech Instruments sound level meter. The db level from the Schumacher combination blade was 90.2 (105.7 under load) when crosscutting, and slightly higher when ripping. The crosscut blade was quieter at 87.4db (96 under load). This is a good 2 to 5 db lower than the other blades that I have. The surprise is that they 'sound' quieter than the recorded db level would suggest. Apparently this is because the design of the Schumacher blades reduces the high pitched whining nose common to most saw blades.

At $80US for a combination blade ($88US for the crosscut blade) these are well priced. If you are looking for a premium blade that will give you excellent cuts and at a lower noise level than most other blades on the market, give the Schumacher a try. I don't think you will be disappointed.