# Purchasing right boring bar holder for existing lathe tool post



## Omni-impotent (Jun 3, 2020)

Hello all! First time poster here.

I want to be able to hold a 1/2" diameter shank boring bar on my existing lathe tool post but don't know how to make sure the holder fits.

The Tool Post we have is a Phase II 250-111 (see attached image). 
"Phase II
9 to 12 Inch Lathe Swing, Wedge Type Quick Change Tool Post
3-7/8 Inch Tool Post Height, Series 100, 4-11/16 Inch Overall Height"

The boring bars have 1/2" shank diameter. I'm hoping to get a different brand for the tool holder because it is cheaper. 
There are two I'm considering:
 (1) Value Collection - Tool Post Holders Series: AXA Tool Post Holder Number: 4
(Tool Post Holders; Series: AXA ; Tool Post Holder Number: 4 ; Tool Post Holder Type: Boring, Turning & Facing Holder ; Lathe Swing (Inch): 12 & Under ; Through Coolant: No)

(2) Value Collection - Tool Post Holders Series: BXA Tool Post Holder Number: 2
 (Tool Post Holders; Series: BXA ; Tool Post Holder Number: 2 ; Tool Post Holder Type: Boring, Turning & Facing Holder; Lathe Swing (Inch): 10 to 15 ; Through Coolant: No)

How do I know which one will fit? I'm confused by the OXA or AXA as I don't see that specified in the description of the Tool Post.

Thanks in advance


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## MrWhoopee (Jun 3, 2020)

250-xxx is the AXA series. A 250-102 is a standard tool holder with a groove in the bottom. I can be used for turning tools and a boring bar.




250-104 is strictly a boring bar holder, it comes with 19mm/3/4 in. bore and a sleeve that reduces to 16mm/5/8 in. You would have to buy or make a 1/2 in. sleeve.




HTH


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## darkzero (Jun 3, 2020)

Specifically you need 250-1xx series holders which are AXA size. 250-2xx is BXA.


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## MrWhoopee (Jun 3, 2020)

darkzero said:


> Specifically you need 250-1xx series holders which are AXA size. 250-2xx is BXA.


Thanks for clarifying this.


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## Omni-impotent (Jun 3, 2020)

Thank you! What an invaluable piece of information. While I'm at it, I actually have one more question.

The boring bars I have are in the attached pic. I want to use them on a lathe. Someone told me that these are for boring heads for a mill but "they'll work".

What's the difference between the two?


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## darkzero (Jun 3, 2020)

Omni-impotent said:


> I'm confused by the OXA or AXA as I don't see that specified in the description of the Tool Post



In case you wanted to know....

The letter designations were created by Aloris except 0XA which is not an Aloris standard. IIRC 0XA size was created by LittleMachineShop & Tormach which is smaller than AXA. Imports copied the sizes & use the 250-XXX designations.

For the tool posts:

Wedge Type:
AXA = 250-111
BXA = 250-222
CXA = 250-333
CA = 250-444
DA = 250-555

Piston Type:
AX = 250-100
BX = 250-200
CX = 250-300
C = 250-400


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## MrWhoopee (Jun 3, 2020)

Those boring bars will work for either a lathe or mill. They will probably require significant grinding to work properly in a boring head on a mill.


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## darkzero (Jun 3, 2020)

Omni-impotent said:


> Thank you! What an invaluable piece of information. While I'm at it, I actually have one more question.
> 
> The boring bars I have are in the attached pic. I want to use them on a lathe. Someone told me that these are for boring heads for a mill but "they'll work".
> 
> What's the difference between the two?



The boring bar sets for use in boring heads will usually have all the same size diameter & length shanks for the set. 1/2" dia being the most common. Yes you can use them. Lathe boring bars typically have shanks that are the same diameter for the full length of the bar. This allows you shorten up or extend the length when mounted.

Often those economy brazed carbide sets aren't ground well from the factory (geometry). So if you find that they are not performing well you'll need to regrind the geometry & most likely put a nose radius on them. They tend to come with too sharp of a nose radius & won't last long cutting like that.


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## darkzero (Jun 3, 2020)

Omni-impotent said:


> Hello all! First time poster here.



Oh & Welcome to H-M!


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## mikey (Jun 3, 2020)

Yes, welcome to HM. 

I have an opinion on boring bar holders that differs somewhat from the typical tool holders like the 250-102 or the type that uses cotters to pin the bar. I think you will have a much better boring experience if you go and buy an Aloris AXA-4D. This holder surrounds, supports and solidly holds the boring bar shank better than almost any other tool holder. The boring bar holder is more important than the bar itself, at least in my opinion, and the 4D is worth the cost. The 4D has a 3/4" bore so you will need to make reducing sleeves to fit your 1/2" bars but that is not difficult to do.

The set you have is a HSS cobalt set. They work well in a boring head on the mill but can also be used on the lathe. Just keep in mind that the theoretical depth they can bore to is 4 times the diameter of the smallest part of the shank up near the head. Cobalt bars like yours will bore very well within their depth limits and will often finish better than most carbide tools. They can be easily sharpened by using a diamond hone to lightly flatten the end of the head and a very light dressing on the top flat.


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## benmychree (Jun 3, 2020)

I am a big proponent of HSS boring tools for lathe and mill, I particularly like Bokum tools, they have back rake, and so cut much more freely, they are made in 90 degree styles, lead angle styles and threading styles in various diameters, and are sharpened only on the top, as they are form relieved, and they will last for many years with careful sharpening.


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## Omni-impotent (Jun 3, 2020)

Thanks, everyone. I wish I knew about this forum earlier. It would have saved me a whole bunch of frustration over the years!



mikey said:


> Just keep in mind that the theoretical depth they can bore to is 4 times the diameter of the smallest part of the shank up near the head.


Didn't know about that. Is this the same for all boring tools? Because I see some are very long.

I actually have a Phase II 250-104 that came with the tool post. I'll try to get an adapter ring with a split made. I was worried if the ring was too thick it wouldn't compress and grip properly.


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## mikey (Jun 4, 2020)

Omni-impotent said:


> Didn't know about that. Is this the same for all boring tools? Because I see some are very long.



The 4:1 ratio holds true for all steel boring bars, while carbide shanked bars can usually go 8-10:1 depth to diameter ratios.

That type of holder uses two cotters (angled ramps) to put pressure on the boring bar in two places. It is NOT the same as having the entire holder clamp down on the bar like the 4D does. It might work so give it a try but if you get chatter in the bore, suspect the tool holder first.


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## benmychree (Jun 4, 2020)

A thick boring bar adapter can be made to compress easily by cutting a slit through one side and partially through the other side.


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## i_r_machinist (Jun 4, 2020)

Inserted boring bars are stupid cheap on ebay. I was hesitant to buy these but I have not had any problem with them.
i_r_









						Set of S20R-MWLNR08 20mm Lathe Turning Tool Holder + 10X WNMG0804 Carbide Insert  | eBay
					

Find many great new & used options and get the best deals for Set of S20R-MWLNR08 20mm Lathe Turning Tool Holder + 10X WNMG0804 Carbide Insert at the best online prices at eBay! Free shipping for many products!



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## Tozguy (Jun 4, 2020)

Omni-impotent said:


> Thank you! What an invaluable piece of information. While I'm at it, I actually have one more question.
> 
> The boring bars I have are in the attached pic. I want to use them on a lathe. Someone told me that these are for boring heads for a mill but "they'll work".
> 
> What's the difference between the two?



Those boring bars shown in the picture will work fine in your 250-102 holder. Choose the shortest and fattest that will work. If you are just starting your adventure into boring then it would be important first to make sure the bars are sharpened for the job at hand.
It is also important to minimize overhang in the compound/tool post setup. Lock any axis that is not used for the boring.
The tool has to be on center, horizontal, rigid and not rub in the bore no matter what type it is and how it is held.

The 104 holder is designed for larger boring bars than the 102 holder. The advantage to making a 1/2 sleeve for the 104 is marginal when the 102 holder can do the job.

Get amazed at what you can accomplish with your current boring bars and holders. After you get some boring experience of your own with what you have then it will be more clear in what direction to go for additional tooling.


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