What is Your Go To Insert/Angle when Boring

for that size starting hole, a 1/2" SCLCR boring bar. In my lathe I would most likely use a CCGT (sharp ground) insert as that's what works well on my small lathe. You would be fine with a CCMT (molded not as sharp, but more robust) insert.

I settled on CCxT inserts as I use the same inserts for facing, turning and boring. means I only have to buy one lot instead of several.

for your size lathe I'd guess the 32.51 or 43.51 (-09 or -12 in metric land) insert size would work well.
 
I rarely run production jobs, I consider +2000 of the same part in one run to be production.
I do often run jobs that are 50, 100 or 250 parts, this is why I always ask about the number of parts.
You can often squeak out 2 or 20 parts in a reasonable time using less then ideal tooling, this often becomes problematic when 200> parts are required.

These are the boring tools that I use most often in a 15" X 40" lathe. There are another dozen internal tools for larger internal threads, internal grooving, internal back turning and internal knurling.
Different tools for different jobs. Use the positive rake triangle tools when you have to produce a deep bore, use the CNMT inserts when the bore is shallow and you can push the operation without the chance of chatter, use the solid carbide ground tools when the holes are small.

As an example I made one part this week that took roughly forever because of its geometry and we did not spend the mill time to do a one off lathe job., Used the small 3/16" boring bar pictured to produce a counterbore .380" deep X 2.375" diameter then a second concentric counterbore .118:" deep by 4.437" diameter starting from a .281" through hole, this took roughly 130 boring passes at .015" DOC each and one .005 DOC finish profile pass.

This is not fast
 
You have a lot of $$$$$$$ invested there.
Do you use the coolant through as equipped or a mister?
I notice Sandvik and Kennametal offer mostly coolant through boring bars. At least during my search.
 
P. Waller said:
I rarely run production jobs, I consider +2000 of the same part in one run to be production.
I do often run jobs that are 50, 100 or 250 parts, this is why I always ask about the number of parts.
You can often squeak out 2 or 20 parts in a reasonable time using less then ideal tooling, this often becomes problematic when 200> parts are required.

These are the boring tools that I use most often in a 15" X 40" lathe. There are another dozen internal tools for larger internal threads, internal grooving, internal back turning and internal knurling.
Different tools for different jobs. Use the positive rake triangle tools when you have to produce a deep bore, use the CNMT inserts when the bore is shallow and you can push the operation without the chance of chatter, use the solid carbide ground tools when the holes are small.

As an example I made one part this week that took roughly forever because of its geometry and we did not spend the mill time to do a one off lathe job., Used the small 3/16" boring bar pictured to produce a counterbore .380" deep X 2.375" diameter then a second concentric counterbore .118:" deep by 4.437" diameter starting from a .281" through hole, this took roughly 130 boring passes at .015" DOC each and one .005 DOC finish profile pass.

This is not fast
Click to expand...

Love the set up. Here is my small bars, I made special tool blocks for each bar.
1af60d96802e2e9ed5d88c5872aa50ed.jpg



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mattthemuppet2 said:
for that size starting hole, a 1/2" SCLCR boring bar. In my lathe I would most likely use a CCGT (sharp ground) insert as that's what works well on my small lathe. You would be fine with a CCMT (molded not as sharp, but more robust) insert.

I settled on CCxT inserts as I use the same inserts for facing, turning and boring. means I only have to buy one lot instead of several.

for your size lathe I'd guess the 32.51 or 43.51 (-09 or -12 in metric land) insert size would work well.
Click to expand...

I’m all over the map, I do use the same inserts in the small bars, but my turning tools are dovetailed full size ones
711dedaf17bde0ed039c3edf8544db1c.jpg



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Janderso said:
You have a lot of $$$$$$$ invested there.
Do you use the coolant through as equipped or a mister?
I notice Sandvik and Kennametal offer mostly coolant through boring bars. At least during my search.
Click to expand...
Coolant through if the tool has it.

Most belong to my employer, the tools that are thru coolant belong to me, he will however buy the tools that I ask for without question.
 
Janderso said:
Nice work jded...
It looks like the 2nd one from the right has a story
Click to expand...

You must mean the one that’s ground down, I actually purchased it off EBay like that, it comes in handy to rough things out, not rigid at all. I’d would have ground it shorter to increase rigidity but I didn’t do it. If I remember correctly the bar was inexpensive.


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I would use a 1/2" bar with a #2 size 80 degree insert that has a .005 radius to reduce chatter. 12L14 can be run dry and it should come out looking like a mirror. That particular insert has a 7 degree clearance angle and positive rake.
 
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