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What is Your Go To Insert/Angle when Boring

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If you were going to grab an indexable boring bar, to bore into say, a 2" piece of 12L14 cold rolled steel, what insert and angle would come to mind?
It has a 7/8 hole in the center already. (IN THE LATHE)
Style?
Shank size? (I have CXA)
I mean there is only about 1,000 to choose from.
I see plenty of zero to negative 5-degree lead angle bars/inserts.

I have had good success boring with the brazed carbon inserts that I touched up when I had a diamond wheel on my tool room grinder.
I am retooling and don't want to buy anything I won't use.
Thanks.
 
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I mostly use TPG inserts for most boring with zero lead angle on the bar. Also, I use HSS made by Bokum, they make both lead angle, flat bottom and threading style tools in both integral shank and screw on a separate bar styles, they are form relief ground and sharpened (only) on top, so they last a long time. I am going to bring you some at the meeting on Saturday.
 
All carbide inserts do is speed up production and maybe allow lazy learners to avoid learning tool grinding skills, same could be said for HSS! Carbon steel worked for many years too, machinists had much more sit down time in the past.
 
You did not mention how deep the bore is or if it is blind, this makes a great deal of difference in tool choice.

If less then 3 diameters deep a negative rake insert with a largish nose radius will work fine using a 3/4" or so diameter bar, the chips will likely not be an issue in that material. If a longer depth in a blind hole a positive rake tool with a smaller nose radius would likely be required, on the good side chips from 12L14 are rarely an issue.
 
2 inches in, not blind
How many parts and how much time do you have to do the job?
This is also a very large determining factor when choosing tooling, if only a few dozen and no time constraint then use what you have at hand, if several thousand in a fixed period of time it may be beneficial to invest in tooling that will do the job.

As is often the case not enough information to make a recommendation for tooling for the work.
 
Mr. Waller, I am a hobby guy.
I agree, if making a quantity for a project or a customer, adding the tooling to the job cost is a common business practice.
My question was an effort to simplify or clarify the most basic tooling this group would go to for this theoretical operation.
Let’s say, I will make a pair of bushings.
2.5” OD, 1.680” ID. And 2” long.
Depth of the blind hole is 1.5”
I have eliminated the material question
I believe I have given adequate dimensions
We now have the count to be produced.
What say you? What are you going to grab out of your basket/tool tray to bore to depth?
I find the whole insert world to be a confusing endeavor.
Thank you.
 
If it were me not in a production environment I would choose a 1” bar with a tpg or tcmt insert. Even a ccmt works good.
From what I know a negative insert takes more hp to work. Being negative the insert will be able to be flipped doubling cutting edges. Positive inserts are usually ground sharp easy cutting. You cannot flip positive inserts so cutting edge cost more. Having a larger lathe negative inserts might be more cost effective.
 
If only 2 parts that have shallow bores I would choose a CCMT insert bar 1" in diameter because this is the one that I use the most for that size work and is always set up, just change the inserts depending on the material.
12L14 is very forgiving so most any insert will do.
 
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.
 
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
Love the set up. Here is my small bars, I made special tool blocks for each bar.



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



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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.
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.
 
Nice work jded...
It looks like the 2nd one from the right has a story
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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