This is the cutting tool used to machine Caterpillar C-15 blocks to install brass water repair inserts. 
This process can be done in chassis or in the shop by using a magnetic drill. I’ve done well over 100 blocks with great success.
Set the depth on your mag drill, the cutter will pilot off the original water hole. Plunge down into the block and the inserts are then press fit into the block. 
Custom size depth and O.D brass inserts are available if needed.
The cutting tool will do quite a few blocks ( if used properly ) before needing to be re-sharpened. 
$125.00 charge to re-sharpen 
Brass water repair inserts sold separately