There are quite a few long reaches in the engine block that need special tools. We didn't want to wait for custom tools to be made...so, we made our own. Here we are relieving a 1/2" carbide end mill. We relieve (cut down) the shank of the end mill so it doesn't drag on the walls as the cutter goes deeper into the part. We are grinding the end mill with a CBN (Cubic Boron Nitride) grinding stone.
