I broke a boring bar

Tonight a new member came through the machine shop and was trying to drill out a 1/2 bolt he had sheared off in a part to his Harley. I offered to help after he had drilled through the bolt with a 1/4 inch bit. We tried to get it out with the bolt extractor set but it wouldn’t budge. So I squared it up on the mill and drilled out a bigger hole. Then I used the boring head and one of the boring bars with the triangular inserts. I was going slow and steady but the inside of the hole had shrapnel from the bolt that was breaking off. Long story short, it grabbed and broke the insert but also bent the tip of the bar.

@TBJK Tim, do you know where we bought those bars. I’ll look into replacing it. It was the smallest of the 3. On a positive note, I did get the bolt out and have a nice little souvenir to boot…


It may be reparable,

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I’ve always found those bars to be very uninteresting, I prefer to use intriguing bars vs boring bars!


Thank you Paul for fixing that for me. It was actually the motor mount for my car and the bolt had broke somehow. What looked like a certain catastrophic failure turned into a learning experience. Thanks again.



Thanks for disclosing that. Likely some of the boring bars were purchased through MSC Direct, but some may have come in as donations. As a practical matter the necks on the small boring bars are very prone to bending; done myself more than once and watched others do it too. Really these are semi consummables due to that characteristic, much like end mills and drill bits. ( Yea, the fact that it takes an insert might suggest otherwise, but not really)

In my humble opinion, you should not worry about replacing that item at your cost. There are plenty of pieces still remaining in the set and when the day comes that is no longer true, the committee can order another whole set much more economically (per piece) than you can buy a single piece.

Further more, you were helping out another member when you broke it; so, thanks for being such an excellent member!