I once ruined a good Forest 10 inch circular saw blade on my radial saw when the blade guard slide out of position. The guard touched the moving teeth and little chips of carbide flew against the wall. I also ruined a large router bit when it hit the tip of a drywall screw. The screw was part of a hold-down fixture and although I thought I was safe in its placement, it had strayed out of alignment into harms way. Again a chunk of carbide flew across the room luckily not in my direction. I try to learn from all of my mistakes and the learning curve seems to be never ending. Here is the question: If carbide is tough enough to be used in metal cutting blades how is it too brittle to survive the mistakes I just mentioned?
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Replies
There's different grades of carbide and for metal cutting much lower rpms and lower feed speeds are used or the same thing will shatter a carbide endmill just as easily.
Rich,
The carbide in your Forrest is a very fine grained tungsten carbide verses the larger grained titanium carbide typically used in metal cutting operations. This fine grain allows the teeth to have great wear resistance and also hold a keen edge, but at the same time it is quite brittle - as you have discovered. The teeth also have much more aggressive cutting angles than you will find in metal cutting, further reducing the tips resistance to shattering.
Richb, Carbide is almost as hard as a diamond (Which is the hardest mineral in the world)
It is so hard, that it is very brittle. All carbide tools should be handled with care so they don't bump into other tools and chip.
Once there's a chip, it will fail pretty quickly. Carbide cutting tools remain sharp ten times longer than high speed steel but is not as tough.
If you're going to cut any wood that may contain nails/ pebbles,use a high speed tool to save your good carbide and your money too. Stein.
Are the properties of the carbide as different as the properties of a carving tool versus a shovel e.g. hardness, toughness etc. ? What about the rpms of a metal chop saw versus wood chop saw?
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