Tuesday, March 1, 2011

Tailstock tap

I received a package on my front porch this afternoon.  I ordered a new 3/4"-10 tap from Enco late last week for my upcoming demo.  I now have all 3 of the most common sizes that I will need. 1" X 8 TPI, 1 1/4" X 8 TPI, and 3/4" X 10 TPI.  There are other thread sizes and pitches out there (3/4" X 16 TPI, 1 1/2" X 8 TPI, 33mm X 3.5) but these 3 should be all I need. 

This tap is used to tap small blanks to be used on my live center in the tailstock. The blanks are secured in my chuck, drilled, and then tapped with the thread that matches the thread on the nose of the live center.  The outside of the blank can then be turned to any shape needed. 

The trick for turning the outside is to lock the live center so that it doesn't turn.  A small screw inserted into the locking hole (which can be seen at the rear of the cylinder) and then secured with a couple of wraps of tape will prohibit the bearings from spinning, allowing you to shape the outside.  It's a right hand thread so it actually tightens as it spins. 

This one will be used to center the tailstock ends of peppermills.  Other shapes can be used to drive spheres, kalidescope blanks, and anything else that you don't want to mar the surface of.  It's also useful for preventing Turner's Elbow.

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