# Insert boring bar information



## Investigator (May 20, 2021)

I have  decent set of boring bars and lathe tools that all use the CCMT style/shape of insert.  I have a 'need' to get a left hand boring bar, to cut outside profiles on aluminum, titanium, and stainless.  I am unsure which other 'shapes' of inserts are meant for rough cutting as well as finish work.  I don't really want to add too many styles or shapes of inserts to keep in inventory. However, I don't mind adding another for this specific thing.

What I want is:

 bars/inserts with clearance to get into tight places
Inserts capable of taking cuts on my 12" Logan
Inserts that are 'readily available' (not a problem ordering and waiting, just not unobtanium)
Inserts that are 'affordable' (I don't mind paying for decent tools, but I'm not paying $50 per insert)
Basically outside profiles such as this:


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## mikey (May 20, 2021)

HSS.


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## macardoso (May 20, 2021)

In this case if you want inserts, I'd recommend a VCMT insert in an SVJCR holder. The VCMT110304 is a good all purpose steel cutting insert while the VCGT110302-AK is a great insert for non ferrous material, or fine finishing in steel and stainless. The SVJCR1212 and SVJCL1212 holders are 12mm shank (1/2") and are the right and left handed flavors of the same tool. 

These are all available on AliExpress and eBay very cheap ($10 per pack of 10 inserts).

This is a fine profiling tool with great access due to the narrow insert profile. It is not, however, a strong insert and should not be used for roughing. 

I use these a ton. I think I bought 50 of the VCGT110302-AK inserts on my last order.

As an added benefit, the narrow included angle decreases cutting pressure and increases accuracy on precision turned surfaces compared to a different insert. Great for bearing fits.


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## JimDawson (May 20, 2021)

You might look at VCMT inserts and holders.  These are a 35 degree diamond.


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## macardoso (May 20, 2021)

JimDawson said:


> You might look at VCMT inserts and holders.  These are a 35 degree diamond.


Beat you to it


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## Investigator (May 20, 2021)

mikey said:


> HSS.



Mikey, 
I probably should be, but I haven't become a fan of HSS.  Not because of how it works, but because it is so much easier to pick a tool and change an insert as needed.


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## mikey (May 20, 2021)

Investigator said:


> Mikey,
> I probably should be, but I haven't become a fan of HSS.  Not because of how it works, but because it is so much easier to pick a tool and change an insert as needed.



I get it but you are missing out on a powerful tooling option on a lathe that was not built for carbide.


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## Investigator (May 20, 2021)

Agreed.  it is something I would like to be able to do. It just seems there is always something else to work on first


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## Larry$ (May 20, 2021)

" I have a 'need' to get a left hand boring bar, to cut outside profiles"
Why a boring bar? Your photo shows a right hand tool, are you needing to turn a square edge on the outboard inside end of the work?


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## Investigator (May 20, 2021)

Larry$ said:


> " I have a 'need' to get a left hand boring bar, to cut outside profiles"
> Why a boring bar? Your photo shows a right hand tool, are you needing to turn a square edge on the outboard inside end of the work?



At this point, I wouldn't make a hair on an apprentice's....head.  Terms and names still vex me.


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## macardoso (May 20, 2021)

Investigator said:


> At this point, I wouldn't make a hair on an apprentice's....head.  Terms and names still vex me.




Typically outside features will be cut with a turning tool and inside features with a boring bar.

Obviously it gets more complicated but that is a simplification.


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## Larry$ (May 20, 2021)

Don't feel a lone about the terms used sometimes being confusing. All the the letters and #'s used for various inserts can strain the memory. 
As for HSS I think people are turned off from using it because all the information about what angles, finishes and the like that are on an IDEAL tool seem to make it complex to do for the guy with just a bench grinder. Truth be known, you can get OK results with less than ideal grinds. One thing that helps is to use the proper grinding wheel. Softer wheels are better for HSS than the crappy wheels that come with a bench grinder.


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## mikey (May 20, 2021)

Actually, for complex external shapes, the ideal tool is a graver. If you have to make multiples of the same thing then a form tool is what you need. Inserts will work on a CNC lathe but freehand is much harder with inserts.


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## NC Rick (May 20, 2021)

mikey said:


> Actually, for complex external shapes, the ideal tool is a graver. If you have to make multiples of the same thing then a form tool is what you need. Inserts will work on a CNC lathe but freehand is much harder with inserts.


I’m going back to more HSS because of what you say and because with a manual lathe that won’t go over 2000 rpm, it’s hard to get to optimal speeds.  I like that I can make a “combination tool” with a suitable cutting edge and a built in chamfer tool.  The other day I wanted an 8mm radius and the HSS came to the rescue.  I “learned” on HSS with a little bench grinder and I continue to learn.  I can even drop them without wrecking them…
This s a 3.5” work piece.


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## mikey (May 20, 2021)

NC Rick said:


> I’m going back to more HSS because of what you say and because with a manual lathe that won’t go over 2000 rpm, it’s hard to get to optimal speeds.  I like that I can make a “combination tool” with a suitable cutting edge and a built in chamfer tool.  The other day I wanted an 8mm radius and the HSS came to the rescue.  I “learned” on HSS with a little bench grinder and I continue to learn.  I can even drop them without wrecking them…
> This s a 3.5” work piece.
> View attachment 366623



Hey Rick, I just noticed that your cross slide has slots running the full length of the slide. Have you considered making a rear mounted parting tool post or mounting a knurler back there? If you did, you would not regret it.


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## Watchwatch (May 20, 2021)

Investigator said:


> Agreed. it is something I would like to be able to do. It just seems there is always something else to work on first



Mikey knows what he is talking about. HSS is the answer for the low HP lathe in a hobby shop.

Plus it’s fun grinding the bits on a belt sander with ceramic belts.


Sent from my iPhone using Tapatalk


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## NC Rick (May 21, 2021)

mikey said:


> Hey Rick, I just noticed that your cross slide has slots running the full length of the slide. Have you considered making a rear mounted parting tool post or mounting a knurler back there? If you did, you would not regret it.


I’d love to hear more regarding that option.  I have been hanging on to an old Hardinge compound, thinking of how I might use it.  I never thought of a knurle back there.  parting tool I thought of for sure but that could be totally solid. i have never used the “T” slots for anything.  I think about a time when I may need to setup a line bore job with a boring bar between centers And that gives my nightmares.  I also have a funky old tool post grinder which might go on there but I hate the thought of using abrasive machining on my lathe.


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## mikey (May 21, 2021)

NC Rick said:


> I’d love to hear more regarding that option.  I have been hanging on to an old Hardinge compound, thinking of how I might use it.  I never thought of a knurle back there.  parting tool I thought of for sure but that could be totally solid. i have never used the “T” slots for anything.



My opinion is that rear mounting any tool confers greater rigidity than you can achieve any other way. Two key processes benefit from all the rigidity you can get - parting and knurling. Form tools would also benefit from rear mounting.

I own a little Sherline lathe and it doesn't like to part from the front; it chatters with even light work so you have to run the lathe at very low speeds. However, with a rear mounted parting tool that same lathe will part almost anything I throw on it at high speeds and without a hint of chatter. It is also very accurate, improves cooling/oil deliver and has made parting a routine affair. If you own a Sherline, you need to rear mount your parting tool. I haven't made one for my Emco lathe yet because it parts from the front without issues but I fully intend to make one when I find the time.

Rear mounting a knurler is simple. You just need to get the centerline of the tool fixed in a solid mount at the spindle centerline height. This not only improves rigidity; it also greatly improves visual access to the wheels so you can more easily dial in your depth of cut. I rear mounted the knurler for my Sherline lathe and it seriously improved the rigidity of the tool and greatly improved the quality of the knurls. I highly recommend that you give it a try.

You are very fortunate. Most lathes today do not have T-slots running the length of the cross slide. I would take advantage of that if I were you.


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## NC Rick (May 22, 2021)

mikey said:


> My opinion is that rear mounting any tool confers greater rigidity than you can achieve any other way. Two key processes benefit from all the rigidity you can get - parting and knurling. Form tools would also benefit from rear mounting.
> 
> I own a little Sherline lathe and it doesn't like to part from the front; it chatters with even light work so you have to run the lathe at very low speeds. However, with a rear mounted parting tool that same lathe will part almost anything I throw on it at high speeds and without a hint of chatter. It is also very accurate, improves cooling/oil deliver and has made parting a routine affair. If you own a Sherline, you need to rear mount your parting tool. I haven't made one for my Emco lathe yet because it parts from the front without issues but I fully intend to make one when I find the time.
> 
> ...


I assume turning the parting tool upside-down is the route to go?


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## mikey (May 22, 2021)

NC Rick said:


> I assume turning the parting tool upside-down is the route to go?



I am going to start a new thread on this so we can stop hijacking this one.


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