Why you Should Only use Saw Blade the way they were intended
Saw Blades were designed to cut forward. Running them backwards can put you and others around you at risk.
The first problem with running a saw blade backwards is that saw blades are designed to cut forward and a great deal of the strength of the saw blade comes from the design. If you look at a carbide tipped saw blade you will see the carbide tips sit in a notch. The design of the saw blade is such that the cutting action forces the carbide tip deeper into the notch and against the steel. If the saw blade is run backwards the force of the cutting action is such that it wants to pry the carbide tip out of the notch.
I have been dealing with tungsten carbide saw tips since 1981. A big part of that has been pretinning saw tips where each saw tip is inspected by a person who then puts a bit of braze alloy on it and runs it through a brazing oven. In 30 years we have processed well over 100 million saw tips, each of which was individually inspected before it was pretinned and after it was pretinned. So, when I say, that tungsten carbide parts vary between batches and also within a batch I have experience to back it up.
One way tungsten carbide saw tips vary is in their ability to bond with the braze alloy. Tungsten carbide saw tips are mixed from a powder mixture of tungsten powder, carbon powder and cobalt powder. There are many other variations but this one is the most common. If you do not have enough carbon in the mix then you get tungsten carbide parts that are carbon deficient. This is called eta phase. If you have a wee, tiny, bit too much carbon powder all your tungsten carbide parts are good and the excess carbon deposits on the surface of the tungsten carbide parts. The problem with this is that this free carbon deposits as graphite which creates a surface that does not want to accept braze alloy.
Tungsten carbide parts are sintered in an atmosphere controlled oven. This is much like baking cookies or crackers and the parts nearest the heat source receive more heat than parts farther away from the heat source even in the best of ovens.
Theoretically tungsten carbide does not oxidize below 1,000 degrees Fahrenheit. (Other temperatures are given but this one seems to be the most common.) If you are familiar with chemical processes you will realize that they do not take place instantaneously at a given time or a given temperature. You have to stir your coffee for a while to get all the sugar to dissolve. When you put an ice cube tray into a freezer, no matter how cold the freezer is, you do not get ice cubes instantly and different parts of the tray freeze faster than others.
It costs a great deal of money to run a sintering oven so there is pressure to remove one batch and get the new batch in. Tungsten carbide parts are often removed at a temperature well above room temperature. Theoretically any temperature below 1000°F is safe as it will not form oxides. However there are a great number of possible oxides all of which form at different temperatures. So it is quite common to see some oxide formation on tungsten carbide.
Sintered and cooled tungsten carbide parts are typically sandblasted to clean them up. One theory is that sandblasting alone is enough to remove all the oxides, free carbon and other contaminants on the surface of the tungsten carbide. This is not always true.
60 years ago L.B. Toney was granted a patent for a method to treat tungsten carbide so that it brazed better. In 1981 I started my business with a Weyerhaeuser contract to figure out how to keep saw tips on the saw among other things.
The best manufacturers treat saw tips to make them braze better but not everyone does this. In addition there are variations in the process as with anything else and sometimes the process just doesn’t work right.
Some saw blade manufacturers do incoming inspection to make sure the parts they get are right. Some do not. Some manufacturers control the quality of their parts all the way through the process and do testing on their finished parts. Some do not.
The quality of the saw blade has almost nothing to do with the price you pay for it. Some of the best made saw blades in the world are the incredibly cheap little saw blades from Black & Decker. Our World’s Best custom saw blades and our All American saw blades really are better than any other saw blades in several measurable, quantifiable ways as well as in user reviews. This is in spite of the fact that they sell for less than other saw blades.
If you spend enough time in design and practice and buy the best equipment it is entirely possible that you will produce superior results with less effort than others. This is true whether we are talking about golf, fishing, or manufacturing.
Anyway, there are definitely good and bad saw blades. By bad saw blades I mean, in this case, saw blades where the saw tips are more likely to come off.
You cannot always rely brand name. The tool industry is full of examples where a high quality company was bought out by another company that immediately cheapened the product.
Even if the company doesn’t change ownership it may change management. There is a Wendy’s restaurant across from the bank branch I use. I finally figured out that the food is really good on days when the general manager is working there, pretty good most of the time, and pretty bad on Fridays when there is a substitute manager of some sort. The same thing is true in manufacturing. Some managers are just better than others. Some companies go through management changes at the top level. Quite often the new manager will do exactly the opposite of the old manager. The old manager was all about quality. The new manager comes in and decides to increase profits by cutting costs.
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