Question Lathe "Boring bars"

No need to get fancy with alloy steel or hardness for homemade boring bars, the grade of steel or hardness makes no difference in rigidity, this goes to the modulus of elasticity, which varies only a tiny amount for different steel alloys and hardness.
 
I made up many of these bars made of Tungsten , and steel filled with lead shot . It helped with chatter . We were developing a munition and the original design was damn near unobtainable . I suggested to thread the Tungsten penetrators and the Sabots for an exact fit . They bought it , and we did it . Once they saw how easy it was to set the distance they needed where the 2 met , it was a nice production job for me on the CNC Makino . I did get a very small amount of money from them for the suggestion but not much . :grin: I used Tungsten bars for the job with no issues and the Sabots were approx. 6" long .

Someone on here bought some of unfinished penetrators and machined them into darts . I guess it worked out .
 
Rubber bands is strategic locations also help eliminate vibrations.


Cutting oil is my blood.
 
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Looking for a set of files

I have a project, a set of darts, that involves making scallop patterns. They will need to be in the range of 13mm on center. I think the best approach is to rough out on the lathe then use files to finish the profile. I have been looking at the pin files which may work but in the long run...
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A while back .
 
Guys one last question.....

If you were going to buy only one boring bar what diameter would it be??
 
@twhite - for those boring bars on the right: does the head screw into the shank? (it sounds like it does).

Mike8623 said:
If you were going to buy only one boring bar what diameter would it be??
Click to expand...
I'd think it would highly depend on what your type of work is. For me: I rarely need to hit oddball bores <0.500", would use taps at that size, and ream for hitting critical standard sized bores. So if only 1 boring bar it would be no smaller than that.
 
Mike8623 said:
Guys one last question.....

If you were going to buy only one boring bar what diameter would it be??
Click to expand...
1/2". Just a feeling that is a good compromise between moving up from drill bits, to having enough beef for a decent DOC in larger materials.

But, to the original question. . . a multi-purpose boring bar. With careful selection of inserts, combined with a willingness/ability to mill the pockets, a 3/4" bar would provide ample space for 2 or even 3 inserts on each end when located radially. The insert sticking out the side would provide clearance from the workpiece. Swapping the insert for cutting vs threading would be a PIA, but that would be offset by only needing one tool holder, and fewer pieces to keep track of.

You could even keep a cutting and a threading insert in the tool. Cut by moving the carriage toward you, and then push the carriage away to cut threads by turning the lathe in reverse. All without having to swap out tools.
 
K, thanks guys. I have some at 1 inch and one at 1/2 inch for threading only. I'm thinking maybe one everede at 3/4 inch and then grind my own inserts to either thread or bore/turn
 
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