STUB DRILL BITS
There are 3 stub drill bit sizes:
The 5/16″ and 11/32″ stub drill bits have a 1 3/4″ flute length and the total length is 3 1/16″. The standard wood bit is longer and tends to “wander” if it hits a tight wood grain. The 5/16″ is the most common drill size for threading a 3/8″ x 16tpi hole. The 11/32″ makes it easier for threading resin, acrylic and dense hardwood. *Tip: if you’re using spalted or very soft wood, either stabilize the threads with glue or use the threaded inserts.
You may also like to buy the Bottoming Tap which cuts threads to the flat bottom. This is recommended for the hard exotic wood.
The 7/16″ stub bit is used for the Threaded Inserts Some wood or especially acrylic and resins do not hold threads well and the inserts (either brass or stainless steel) make it a lot easier.
Lathes Specifications: here is a list of lathe spindle sizes and Morse taper if you are not sure.
These drill bits are made in America