This “Tapping Fixture” project is completed almost exclusively on the lathe, with only a few steps requiring the mill. This project is a bit more challenging than the Spring Center or the Soft Face Hammer because it requires single point cutting of internal threads, and boring of an internal thread relief.
Feel free to pick a more coarse thread than what’s called out in the plans (11/16-24 UNF is a bit fine, a coarser thread would be easier for a beginner to cut – especially when cutting the internal threads). Just remember, if you decide to change the thread pitch, remember to do so on BOTH parts!
The title of this post requires a bit of explanation. If you search the web for “T-Handle Tap Wrench” you’ll find these: If you search the web for “Tapping fixture” you’ll find something that much more closely resembles this project:
Oddly, the plans call this project a “Tap Handle”. So as you can see, there are several ways that people use to refer to this tapping tool. To take it one step further, it would be more appropriate to call this device a “Jig” since “Fixtures” typically hold onto the part in question. But I digress …
Here’s what you need to know. The tapping fixture that you’ll make from these plans consists of a T-Handle Tap Wrench that fits smoothly into a Tapping Fixture. The Fixture itself has has a flat base with a “V” cut in it. This base allows the user to tap a hole on a flat surface like this: Or the user can use the “V” in the base to help steady the Tapping Fixture and keep it perpendicular to a cylinder:
To complete the project you’ll need a ball detent like the one pictured below to hold the Tommy Bar in place.
I had a hard time figuring out how to cut the groves in the jaws. Eventually I held the jaws (one at a time) in a Toolmaker’s Vise, which was held in the vise bolted to the X/Y table on the mill. Then I tilted the head of the mill at a 45 degree angle and used a 1/2″ 4 flute end mill (not shown). Here’s a Picture of how I set that up:
Below is a link the plans in PDF format. Leave a comment if you have a question or get stuck.[download id=”12″] [ad]