MIMF

I'm drilling in canary wood and I'm having a problem with tear-out. Even without fretslots to make the situation complicated, a new 1/4" drill bit often causes a little tear-out on a piece of scrap. I only see forstner bits down to 1/4 and some of the postion markers are about 5/32". On a slotted mandolin fretboard, this is causing problems in the upper frets.

Suggestions?

Place a thin, scrap piece of hardwood on top. In practice, drill through the scrap first and leave it on your drill bit but move it up a bit. Then place your drill bit on the fretboard where you want the hole. Now push the scrap wood down flush with the fretboard and hold it down tight while you drill the hole. After you get the hole started you can remove the scrap piece and drill to the depth you need.

Try running the drill in reverse. I've had luck preventing chip-out that way. It takes a bit of downward pressure.

Are you using brad point bits? if so try sharpening the spurs with a file.

https://www.toolstoday.com/g-22-the-bra ... boring-bit

Yes brad point bits are much better.

It's possible to sharpen any drill bit to a brad point, although getting the point centered can be a trick, especially with the small ones.

Otherwise I'd just super glue a piece of something like maple onto the fretboard, and drill the hole. Be sure to get the depth right, of course. Once you've got the hole you can shave/scrape off the piece, and do the inlay.

One advantage to brad point bits in this application is that they can leave a flat bottomed hole, especially when you sharpen them yourself with no spur. The problem with a brad point bit is that it doesn't automatically center in a pre-drilled hole well. Once you learn how to sharpen them it's easy to modify any size bit you want to a brad point for this job, and saves a lot of aggravation.

I might be a tad late on this, but the best method I used was the very first. I had a small portable drill press and used a straight 1/4" router bit. The holes were flat and clean.