Threading Insert Tool Holder

Project:
Building a threading insert tool holder / boring bar to allow me to cut internal 1mm metric thread for the Ejector Nut for my Emco Maximat V10 Mill

Difficulty Level (Easy, Medium, Hard, Insane):
Medium

Process:
The process in itself was fairly easy, but because I had never built one of these it took a little fiddling around. Also, I learned that a sharp end mill makes all the difference in cutting O1 tool steel. Duh...

I was getting ready to build the ejector nut for removing the end mill holder of my mill, but had not yet had a need for a small (under 5/8" diameter) internal thread so the first thing I had to do is build a tool holder for one of my threading carbide inserts I had scored on kijij a few months back.

I took some 1/2" O1 tool steel that I had bought at Metals R Us in Dartmouth, NS a while back, cut off a 5" piece and milled a triangle out at the end to hold my insert. After matching up the tilt-angle of the insert with another boring bar, I milled off about 60 thou at the top and about 80 thou at the bottom, then drilled and tapped a hole for the screw that holds down the insert.

After it was all milled to size, I hardened it by heating it with my oxy/acetylene torch to a bright cherry red and quenching it in motor oil. After it had cooled down I sanded the surface to reveal the shiny metal and tempered it to a slight straw color.

After letting it cool down slowly I was ready to re-install the threading insert and cut the internal thread for the ejector nut.

Pictures:

Using some Dykem layout fluid to mark the line to mill

Milling the top flat

Marking the height of the threading insert

The milled, drilled, tapped and installed threading insert

A side view

Top view

Dialing in the shank to mill

The finished threading insert tool holder

Threading the internal 1mm metric thread

The finished ejector nut

Tools:
Lathe and accessories
Angle grinder
Oxy/Acetylene torch
Tap & die set
Metal scribe

Materials:
Dykem layout fluid
6" of 1/2" O1 tool steel
Internal threading insert
Old motor oil

Cost:
$10.00

Time:
3hrs

Savings:
Probably at least $100 bucks if not more

Conclusion:
It worked pretty good. I ended up having to grind off some off the side of the bar but after that it worked great.