How do I use (adapt) a quick change boring bar holder?

[zippyslug31]

when you swap out the bars they'd have to be oriented correctly

Just a thought, make each adaptor for one bar, put a tiny set screw in the adaptor so the bar and adaptor maintain position, then put a notch in each holder in the same place (on the back end?) so that when it is inserted in the quick change holder they will all orient in the same position.

Sounds like you're onto something... but I don't quite have the mental image yet.
"each adapter for one bar"?
"put a notch in each"?

Each of my boring bars have two flat, opposing surfaces along their lengths. I figured my grub screws would land on these surfaces to hold them into the adapters without spinning... are you talking about these surfaces?


EDIT: I re-read your post several times. You're saying notch the actual tool holder body so that a set screw (on my adapter) would register into this notch?

 

[Illinoyance]

I have several split sleeves to adapt smaller bars to my tool holder. For the smallest bars I use the boring/turning holder. It is like a turning holder but has a V groove in the bottom of the slot.

 

[WobblyHand]

I just made a bunch of sleeves one for each boring bar. Then I slit the sleeves all the way. My 3/4" bore AXA holder will hold 3/4, 1/2 and 6mm boring bars. If I need other size, I will make it. It doesn't take very long to make one. I used 3/4" 12L14 for stock, drilled and reamed to fit the bar. Then they were slit with a slitting saw. They are a perfect fit and clamp down very well.

 

[mksj]

The collar insert is for a specific size boring bar size. If you have a metric size bar, then the provided insert will not work. On boring bars in the range of 3/8" through 5/8" you typically would sue a #2 QCTP (BXA) holder which has a V notch on the bottom. If a boring bar has a flat on the top it helps set the orientation/position of the tip so you can retract or extend the bar and it should keep the same cutting tip height, but normally placing it through bushing/collar this is lost. I use an insert collar for my 1" boring bar, I drilled and tapped two holes on the top for flat head Allen screws that line up with the center of the boring bar, these keep the rotation alignment of the boring bar and add additional clamping.

 

[T Bredehoft]

EDIT: I re-read your post several times.

Bingo. Use a dog-point set screw, slot to be a good fit. so that once set each bar would be in the correct orientation. You might even make the slot on the other side (front-back) so you could use the same set up of reverse turning on the back of the work.

 

[Nutfarmer]

Are your bars metric and your holder inch sizes? Just make split bushing to fit the od. of the holder and the id to match the boring bar.

 

[Nutfarmer]

Another way to do it is to use a tool holder what has a v in the bottom

 

[WobblyHand]

This is what I was attempting to describe. 1/2", 3/8", and 6mm boring bar bushings. AXA holder has 3/4" bore. Bonus home made internal threading bar.

 

[zippyslug31]

This is what I was attempting to describe. 1/2", 3/8", and 6mm boring bar bushings. AXA holder has 3/4" bore. Bonus home made internal threading bar.
View attachment 432893

Nice! Yeah, I'm definitely going this route.

What's kind of amazing to me is the thickness of these bushings... especially the one on the far right. Crazy to think such thick steel has much "flex", but I know it does. I'm sure that additional slit all the way thru to the other side, helps the flex since you're technically only flexing, what, maybe a quarter inch. Neat visual trick.

Ninja edit: What are my options for slitting if I don't own a slitting saw or mill? I'll probably try tossing the bushing in a vise and running my porta-band down the length. Might not be super accurate tho. Hmmm.....

 

[zippyslug31]

Another way to do it is to use a tool holder what has a v in the bottom

You're not wrong and I am currently doing this, but read my previous posts... just looking for a creative way to utilize the boring bar holder that I also own, that's all. Otherwise, yes, the v-groove holder works a treat with my bars.