Indexable insert holding system ?

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jcfx
Posts: 713
Joined: Sun Aug 09, 2009 1:24 pm
Location: NY

Indexable insert holding system ?

Post by jcfx »

I'm looking to get 3/8" shank indexable boring bar for my lathe, I've noticed that most of them use a torx screw thru the center of the insert to
hold it to the shank, some have a finger clamp system to do the same. Which one would be the best in terms of rigidity ?
John Evans
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Location: Phoenix ,AZ

Re: Indexable insert holding system ?

Post by John Evans »

If you are buying a 3/8 shank bar to do smaller holes I think you will find the top clamp style will have a fair bit larger minimum bore size . Which means you might as well start with a larger bar.
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jcfx
Posts: 713
Joined: Sun Aug 09, 2009 1:24 pm
Location: NY

Re: Indexable insert holding system ?

Post by jcfx »

I've anticipated that a top clamp style would make the minimum bore size larger, what I'm more concerned about is rigidity of the insert to the shank.
John Evans
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Joined: Tue Jan 20, 2009 9:33 pm
Location: Phoenix ,AZ

Re: Indexable insert holding system ?

Post by John Evans »

At last count I have 20+ insert style boring bars and as I recall none under 1/2 have clamps. I will say that one bar I have with screw only I have to keep a eye on the tightness of the screw,don't seen to have problem with any of the others. It is important to use the correct insert/screw set as you can use the wrong combination and still put things together. I have to watch that issue as I have a real dog's lunch of bars and insert types.
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RMinMN
Posts: 102
Joined: Tue Jan 02, 2018 8:50 am

Re: Indexable insert holding system ?

Post by RMinMN »

jcfx wrote: Fri Sep 21, 2018 4:20 pm I'm looking to get 3/8" shank indexable boring bar for my lathe, I've noticed that most of them use a torx screw thru the center of the insert to
hold it to the shank, some have a finger clamp system to do the same. Which one would be the best in terms of rigidity ?
The rigidity is not from the holding method but the supporting steel right under the tip of the insert. You're overthinking this.
Richard_W
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Joined: Fri Jan 10, 2003 1:00 am
Location: Molalla, Oregon

Re: Indexable insert holding system ?

Post by Richard_W »

The torx screw is the way to go. I would dearly love to switch all my TPG/TPU insert boring bars to that. On such a small bar you should go to a solid carbide boring bar for best results. I have a 1/4" solid carbide boring bar and it works really well. I have 3/8, 1/2, 5/8, 3/4 and 1" diameter boring bars that take the torx screw. (CCMT series inserts) It allows for better chip removal because of the less interference of a clamp and with a screw system.


Edit The CCMT are steel boring bars with the addition of a 1/2" and 1" heavy metal boring bars.
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