Saturday, May 27, 2017

Creating a TAP

Hello, I needed to take a break from laying out so many little tiny gears on my dads Cocoa Table Project, and I did need to redo one of my brass pens.  In order to do that, I had to create a tap to cut some internal threads (15/64" 18 threads per inch).  I had a chunk of 1/2" tool steel from building a tramming tool in Calibrating a Drill Press, so I decided to use that.  It was a matter of chucking it up, turn down a section of that to 0.24" (15/64 is 0.235", but I wanted some space after the threads were cut).  Then, throw on the gears for threading, and cut some 18-TPI threads.

At that point, all you have is a screw or bolt.  For a tap to work, you need to cut some relief to allow the material somewhere to go.  I used a Dremel with a cutoff wheel to put in a leading cutting edge, then some stones to put some good relief in there.  I also cut two sides parallel so I could use a wrench to get a grip on it, then heated it up and gave it a good dunking to get it hard.  Worked great!

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