When making hex head screws in number, it was bit cumbersome to turn the tread part of hex rod to the size for each piece. I got information about “Rose Bits” from a club member and tried it. It had a hole of the read size at centre surrounded by four cutting edges. Hex rod would be cut simply push this tool by the tail stock.


Making the bit was not so hard. I drilled a hole at the centre of a piece of silver steel rod, made cutting edges by a file, and hardened it.


However it did not work well at all. Huge burs were produced. There might be some hide secrets. I gave this idea up.


So I moved to more secure way. That means “Box Tool” shown as above. I took a piece of 25X25mm black skin mild steel and cleaned it up, and then fixed on the four jaw chuck of the lathe.


I turned out the shank part and made M4 thread at the centre. I would put a long M4 screw in it and use it as a stopper.


I turned the work over and cut a hole for a bushing.


A hole for cutting bit and M4 tread for fine adjustment mechanism were made.


By cutting 12mm wide groove the body of the box tool was finished.



The tool bit was ground from a broken end mill. Escape angles were set at 8 degrees.


Bushing (yellow) and cutting bit (blue) were set. The bushing was hardened silver steel with proper size of hole, and interchangeable for different sizes of materials.


Finished box tool looked bit complicated than rose bits.


Fie adjustment mechanism of the cutter bit. It was almost impossible to set the bit at correct position without this. At first set the bit slightly further than desired location and push it toward the centre until you get proper diameter.


Fix the tool to the tail stock.

Apply a drop of oil to the bushing.

Push the tail stock against the material.

It worked well without producing excess burs. However adjusting the bit location was very cumbersome. It would be better to make dedicated tool for each diameter.




inserted by FC2 system