Tool holder size question.

[chuckwrench]

Getting ready to purchase a AXA QCTP for my Atlas 10F. What size tool bits should I get? Looks like most handle anywhere from 3/16-1/2 bits.
Is bigger always better from a rigidity standpoint? Is 1/2 going to limit me in any way?

 

[pacifica]

If you need overhang of the bit the 1/2" would be better. Usually more of an issue with parting tools.

 

[mikey]

In my view, 1/4 would be adequate, 5/16 would be better, 3/8 would be optimal and 1/2 would be overkill, may not even get to center height and totally not necessary. This is for HSS.

For carbide, definitely stick with 3/8". You do not have the power or rigidity to use a 1/2" tool. In fact, I would avoid carbide altogether unless there is a special need.

 

[Firebrick43]

I have gotten a few 1"+ tool holders(with small inserts such as CCMT 21.52 or TPMT 21.52 and the Small 1 size top notch from kennemetal) You can get these somewhat cheap on ebay as they are thought to big for hobbyist and the use of manual machines in industry is becoming more and more uncommon.

Mill a dovetail directly into the large shank to fit snug on the axa tool post. Also have to drill/tap for a set screw to adjust the height.

 

[chuckwrench]

In my view, 1/4 would be adequate, 5/16 would be better, 3/8 would be optimal and 1/2 would be overkill, may not even get to center height and totally not necessary. This is for HSS.

For carbide, definitely stick with 3/8". You do not have the power or rigidity to use a 1/2" tool. In fact, I would avoid carbide altogether unless there is a special need.

That's the guidance I was looking for. It is interesting that you say to stick with HSS......currently frustrated with the learning curve to grind my own. I was hoping to use carbide bits for simplicity and hopefully a good consistent finish as well. 3/8 sounds like the way to go for my needs.

 

[Firebrick43]

That's the guidance I was looking for. It is interesting that you say to stick with HSS......currently frustrated with the learning curve to grind my own. I was hoping to use carbide bits for simplicity and hopefully a good consistent finish as well. 3/8 sounds like the way to go for my needs.

HSS will normally give you a better finish with lathe the size of an atlas(or I should say as flexible as an atlas). I have some GCMT 2152 inserts for aluminum that have a high positive angle and a very sharp edge that provide a good finish. They fit the common sclcr turning tool holder/boring bars that are designed for ccmt 21.51/52 inserts. They even work on 303 stainless and cast iron for a beautiful finish. They work on mild steel but life is short.


Aluminum inserts.

Have you considered a tangential hss tool holder such as the diamond tool holder from eccentric engineering? Even though I have enough ccmt/tpmt inserts for the rest of my life from an auction score, I rough with the tangential tool. The loads are low and super easy to grind with their little fixture they include. I am really good at grinding hss but I don't have the time to do so and hate the mess. With the tangential I can grind half a dozen in a few mins and my finger don't get burned because of the fixture.

 

[mmcmdl]

Mill a dovetail directly into the large shank to fit snug on the axa tool post. Also have to drill/tap for a set screw to adjust the height.

Better yet , just mill the bottom of the shank down to 1/2" or whatever floats your boat . Too much effort goes into the dovetail .

 

[Firebrick43]

Better yet , just mill the bottom of the shank down to 1/2" or whatever floats your boat . Too much effort goes into the dovetail .

The point is to get rid of the overhang and get it as close to the tool post as possible. The stiffness of the compound on atlas lathes is pretty lacking. You can eliminate half of the overhang by doing a dovetail directly

 

[mmcmdl]

I've owned Atlas lathes as well as too many other lathes . They won't take a deep enough cut to worry about overhang of the tool . And I did own a 10F . Check below in the sold site .

 

[Firebrick43]

I've owned Atlas lathes as well as too many other lathes . They won't take a deep enough cut to worry about overhang of the tool . And I did own a 10F . Check below in the sold site .

I can assure you, it make a significant difference on mine

Even the industrial machines at work(hardinge super precsion) it made a difference.

In fact while I use an AXA post, I recommend people use a slightly smaller and therefore less overhang Metal Lathe Accessories tool post. Problem is you have to make one, cant purchase it.