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.

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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.

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.

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I am pleased with the drill bit, it is just what I was looking for. The rapid delivery was very much appreciated, Ruth said 2 to 3 days and I thought, “yeah right, I’ll see it in a week or so.” Two days later it was in my mail box. Thank you. Great system.

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The stubby bit results in virtually no deflection of the bit when drilling the hole in a bottle stopper. Accordingly, the result is a well centered hole into which to mount the blank to the bottle stopper mandrel.

I had a stud drill bit that was lost during a recient move of home and shop. Like it so much that I am ordering replacement.