Boring bar holder ineffective

[Winegrower]

Here's a mother of invention boring bar that I quicked up to bore out the inside of this stainless tube. I wanted to do the whole 12" interior in a single pass, i.e. no step from coming at it from both ends. I had a nice little carbide insert bar that always cut nicely but way too short, so I made a clamp to hold it to a 1.25"x0.75"x24" tool steel bar from the inventory pile, and setscrewed it into a standard CXA mount. The result was pretty solid...a dial indicator on the end of the bar only deflected about 3 thousandths with me pressing pretty hard on it. I thought there would be way more deflection due to the QCTP but surprisingly not. In any event this cleaned up the interior walls in one 0.020' DOC, 165 RPM, about .004/revolution feed with zero chatter. The picture is a bit deceiving...the bar is only about an inch more stickout than required.

 

[Batmanacw]

That is a very nice noodle, then! I guess what I mean is that the double all-beef patty tool holder is a lot of extra beef over a plain tool holder when holding a tool that sees plenty of deep bore deflection and head twist oscillation at rather low cutting forces compared to a 1/2" square profiling tool, so the beef is superfluous at a certain point. But everyone loves a well-supported tool.

The CXA boring holders are all 1" or 1.25" without the sleeve except a very expensive Aloris boring bar holder that is 3/4". I'm not going for beef. I just want to use my holder for all my boring bars because it will be at the correct height all the time.

Today I need to make a sleeve for 5/8".

Any bar smaller than 3/8" gets put in a er16 3/4" diameter collet chuck so no need for smaller sleeves.

 

[Batmanacw]

Finished up the sleeve for 5/8".
3/4, 5/8, 1/2, 3/8

Easy!

 

[RaisedByWolves]

That is a very nice noodle, then! I guess what I mean is that the double all-beef patty tool holder is a lot of extra beef over a plain tool holder when holding a tool that sees plenty of deep bore deflection and head twist oscillation at rather low cutting forces compared to a 1/2" square profiling tool, so the beef is superfluous at a certain point. But everyone loves a well-supported tool.

If your procedures are correct you shouldn't really be exceeding the stiffness of a small ~1/2" boring bar in the first place.

They're for finish work, that is why there are so many different sized drill bits.