5.  Cutter Failure – Bad Surfaces And Too Much Heat

Several problems

1.       Sloppy brazing  - the braze alloy ran all over the steel

2.  Uneven heating.  The side in the right photo got a lot more heat than the side in the left photo.   Those nice, little round holes are caused by a metal (usually Zinc) boiling out of the alloy.  This is much too hot.   The left side has two holes at the very bottom.  This side also got too hot .   The location of the holes shows that the  joint was not heated evenly from top to bottom.        

The braze alloy wouldn’t stick to the carbide.  They kept heating it until it stuck some what.  I would guess that the braze alloy got liquid enough to form a purely mechanical bond using the roughness in the carbide.  This is not a rough piece of carbide so the bond was very weak.