STUB DRILL BITS

7/16″ is for stainless steel inserts
31/64 is for brass inserts

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.

The 31/64″ and 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.

You may also like to buy one of the taps: Bottoming Tap which cuts threads to the flat bottom or Spiral Tap which cuts cleaner threads.

These drill bits are made in America