work related question I am designing an oversize stud repair. Due to the boss thickness there really is only room to go one size over. there will not be full cleanup of the old internal thread when going to the next size. just curious how often do people do this, that is, leave some non cleanup of the old thread in the holes?
So, you're enlarging a tapped hole from, for instance, 3/8-16 to 7/16? If the pitch diameter of the new bigger threads is the same or larger than the major diameter of the old threads, you should be good. This should give you ~50% thread depth, which will not sacrifice too much strength. Go deeper to compensate if you can.
Typical tap drills give about 60% to 75% thread depth. If you wind up with a tap drill larger than 50% thread depth, you're on your own.
