The reason this is important if you are going to use it in a boring head is the loss of diameter range on the boring head. You have to move your boring head offset just to bring the tool on center. This can be as much as 3/16 of an inch if the boring tool has a .030" minimum bore and the shank is 1/8". You would effectively lose 1/2 of the adjusting range of the boring head in this example.
|1/4" Shank Carbide Tools Design for use in Boring Heads|
Because of this Criterion introduced a line of 1/8" shank and 1/4" shank solid carbide boring tools and adapter sleeve for use in our boring heads. Our tools are ground around the centerline of the tool shank so you minimum offset to bring the tool its smallest bore diameter. This gives you the maximum off-set possible with the boring head. Being able to take advantage of the offset means you need less boring tools in inventory.