# Dropped Carbide Bit/Blade Failure



## PittsburghTim (Jan 16, 2012)

Another forum topic has caused me to wonder about the failure mode of carbide router bits and blades. I have always been fearful of using any carbide bit or blade that has been dropped in the shop. I know that carbide is extremely hard and I assume that it is brittle as well. For the very few times that it has happened, I have never used them again. Throwing these out seems wasteful, but I cannot see risking a piece of carbide flying at me for the cost of a new bit or blade.

Does anyone have any authoritative info on this?


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## Nubsnstubs (Aug 30, 2013)

I think I would be more concerned about cutting through a knot than using a carbide blade that's been dropped. if carbide was to take flight, it would only be when the saw is first started. Once started and cutting, if you've raised your blade properly, you should have only a small amount of blade that would allow carbide to fly in your direction, plus, you should be standing out of the line of fire when cutting anyway…... Experience is from 30 years of owning and operating a custom cabinet shop…......... Jerry (in Tucson).


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## DKV (Jul 18, 2011)

Wear safety glasses and you should be ok.


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## bowedcurly (Aug 31, 2013)

If you don't want it I will take it, just kiddin, really I will, it should be fine, take a small brass hammer and ping the teeth from the back side, a clean sound you will hear and if you hear a different tone then you have a problem


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## bowedcurly (Aug 31, 2013)

or a brass rod this will be light taps, the sound will be the same unless you have a broken tooth or crack in the plate


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## knotscott (Feb 27, 2009)

I'd just send it to a well qualified sharpening service….tell them what happened, and ask them to go over it and correct any problems, as well as sharpening. Forrest, Ridge Carbide, Dynamic Saw, Scott Whiting, etc.


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## unbob (Mar 10, 2013)

This 12" rip blade lost a partial tooth. It hit the blade gaurd hard.
A quality blade that came with a saw, used, in a box loose with other blades. Most likely received a sharp blow, and cracked the carbide, only to let loose in use.
This saw spins the blade at 4000rpm, a tiny piece of carbide coming off is no joke..
There is no way I will place myself in front of any blade at anytime.
I had the blade repaired, nice rip blade.


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## NormG (Mar 5, 2010)

All great suggestions, anything that comes at you 4000 rpm or more is not to be taken lightly. Again though it is a personal choice if you do not feel safe better not use the tool


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## knotscott (Feb 27, 2009)

4000 rpms is child's play compared to a router bit spinning at 22k rpms! :-0 ;-)


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## unbob (Mar 10, 2013)

The actual cutters edge surface speed is close to the same on a router bit and a saw blade, even with the rpm difference.
I have never used a router bit extension, that would add to a fling factor, if a bit/extension should pull from a collet.
I am going to try bowedcurly's test much like testing grinding wheels, I have a lot of blades, I have not tried yet.


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