... holes and making a boring bar that works with insert tooling. If you have a boring bar, most likely of Far-Eastern provenance, you will have encountered them - import boring bars, with their little (usually dull) carbide inserts soldered on. Now one can work with them rather well actually, with some rework on the bars with a diamond file to make the inserts resemble some sort of a cutting geometry and some very, very light cuts one can get some pretty good results with them. But with the task at hand of pushing what the 6x26-mill can take in terms of cutting and doing a lot of it, this quite literally won't cut it.
As this isn't quite my first rodeo, in the past I got a cheap boring bar and modified it as below. Unfortunately (for this boring bar), I no longer run TCMT16 inserts on my lathe and thus would have to buy inserts solely for this one bar. Not very economical, especially as I have a ton of CCMT09-inserts.
So this one started it's life as a 16mm, right handed boring bar for CCMT09 inserts. I shortened it to a reasonable length. (The shorter, the stiffer and more stiffness means less vibrations and that in turn means a better surface finish.) Then turned it down in the lathe to fit the boring head. In my case this meant going down to 12mm. Also this is where cheap boring bars shine as they are made from some butter-like alloy and turn beautifully on the lathe.
At this point, one could go ahead and just use it, but every time you install it, you'd have to clock it to get it right on center (or actually a bit below) again. So I put it in the mill and made a little flat spot to register against.
And there you have a boring bar where you can burn through inserts and not care much about it.
Oh and burn through inserts... I did not. For five holes, which resulted in enough swarf to fill up the whole vice and pile up left and right of it, I had to change inserts once, because it got a bit dull.
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