What is Your Go To Insert/Angle when Boring

Janderso

Jeff Anderson
H-M Platinum Supporter
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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.
 
Oh thank the Gods.
I feel like I'm in pre-school with inserts.
HSS I get.
 
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.
 
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