Tool holder/boring bar question.

[Daver]

I have an HF 12X36 that I am still learning how to use, so bear with me.

I got a QCTP and just got the T-nut machined down to fit the other night. I am trying to use some of the tooling I have from my HF-mini lathe as I can so I can buy the bigger stuff slowly as I go!

Anyway, down to the question. The boring bar tool holder for the QCTP has a split tube in the center for holding the bar. Can I make a thicker walled one to hold the smaller 3/8" boring bars from my 7X10? Will aluminum be ok in this application? I was thinking of turning it down to the diameter of the hole in the tool holder (-0.002?) and then bore it to 3/8". then slit it down the side. Does this sound kosher?

 

[8ntsane]

Aluminum may work, but I would go with a steel sleeve if it were me. You certainly could try it out, no harm done if it doesn't last. If you intend on using this sleeve over the long haul, go steel. Just my thoughts.

 

[mikey]

I agree that steel is a better material; 12L14 will work. I made some to fit some small bars and they works fine:



My suggestion is to turn the OD to a close slip fit into your tool holder, then drill, then bore, then ream it to size. Go for the finest finish you can get inside the sleeve. Then you can cut a compression slit. Mine has a shallow expansion groove opposite the slit to prevent cracking of the sleeve. It also has a flat for the set screws to bear on so that any burrs won't prevent removal of the sleeve. It works great and the bar is held solidly with very little clamping pressure.

Hope that helps.

 

[David Kirtley]

12L14 is still pretty malleable. Mine (0XA import) is kind of odd and I would be afraid if it mushrooming and getting stuck. There is not that much room to make flats for the set screws if the holder is bored for 1/2" bars. If it bears straight down like Mikey's, it would be fine.