Auger Bit Sizes

Jul 12, 2006 2 Replies

I found that several of the auger bits (Jennings pattern) that I recently purchased are not accurately sized. Anybody know what the size tolerance should be for the diameter at the spur and of the auger itself?



Thanks



John


No, I don't know but I do know there are ANSI and ISO standards for twist drills and I presume there would be for other varieties as well. I'd start looking in those directions if it is really that significant. Of course, what a Standard says is of no benefit if the manufacturer isn't following it... :)

Just out of curiousity, what's the application that requires such precision and what kind of measurements are you getting?

I'm getting 1/32" of error in the spur diameter on some bits and up to 1/16" ( or more) on the auger. This is fairly critical in a 1/4" hole, and it isn't very good in 3/4" either.

The application is using doweled tenons and in general dowel joints. I've used brad point bits up to now but need to move to use of brace and bit. I have only one bit that is an antique, but picked up a set of bits that disappointed me in the variations in their dimensions.

I will seek out the ANSI standard, if it exists.

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