Est. 1998 — 27 years of woodworking knowledge
Sharpening Yankee bits
Neal in San Jose
>Picked up a very nice Yankee drill on the 'bay (thanks Mrsdeadhorse) but when I tried it out, I get a kind of burnished shallow dent rather than a hole. The bits are the straight ones, and seem pretty dull - not like the cutting edge of a "regular" bit or an auger. Are they supposed to be sharp, and if so, how do you sharpen them? Just grind the end slightly, maintaining the factory angles, etc.? Or is this a matter of technique?
Thanks
Neal
Re: Sharpening Yankee bits
Kevin French
>Neal
'The bits are the straight ones'
As in 'fluted'?
Re: Sharpening Yankee bits
Neal in San Jose
>Yes, they are fluted.
Re: Sharpening Yankee bits
Jim Crammond in Monroe, Mi
>Neal,
They should be sharp, and the good news is that it is fairly easy to do. Take a close look at a sharp twist bit, and try to reproduce the angles on your fluted bit. They should be soft enough to sharpen with a smooth cut file, if not us a fairly fine stone. The important thing to do is to make sure there is some relief on the back side of the cutting edge.
Jim
Ah, Ha
Neal in San Jose
>Thanks, Jim. I looked at them last night under 10x magnification, and there wasn't ANY back angle that I could see. The bits looked to be in great shape, so I was assuming they had never been sharpened. I guess I was wrong. I'll try some back angle tonight and report my results.
Re: Ah, Ha
Neal White (San Jose)
>That worked great. I now have 8 bits that all work well. Thanks for the info. Neal
A related question
Bill Houghton, back from Yosemite, Sebastopol, CA
>I've picked up a set of Yankee push drill bits that have been sharpened with an extremely steep point - I haven't tried them yet, but wonder why someone would have done this?
Re: A related question
thomd
>Probably thought it would improve their ability to be positioned, and to drill straight. The reverse can be true. While the pointy part is not a bad deal for placing it in contact with the work, the result is that the bevel now faces more towards the sides of the hole, and can result in a bit that wanders all over the place. Some bits for drilling out pen cores are sharpened this way. The ones I have while they cut extremely agessively are difficult to stop wandering or blowing out sides in narrow stock, not what one would imagine was the objective in designing them. There is a reason whay a 2 flute router bit designed to cut on the side has the bevels outward and the gunbore type bit has it across the end. Everything else is on a continueum in the middle somewhere.