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Router bit for F hole?

Atlantamm
March 7th, 2011, 07:00 PM
What router bit are you guys using for the F hole? Mine will be done with Flamed maple so a little concerned about tear out. Pics always help too!

Thanks

guitarbuilder
March 7th, 2011, 07:19 PM
A new Freud .25 dia straight bit is what I'd use and have used in the past.

Nick JD
March 7th, 2011, 07:38 PM
Run it at full speed and don't go uphill against the grain if you can help it. Use the shank as a "bearing".

hackworth1
March 7th, 2011, 08:35 PM
I used a snug fitting brass sleeve as a bearing on a dremel spiral cutting bit.

Apparently, there is no ready-made bearing-guided pattern bit available that has a diameter that is sufficiently small enough to cut f-holes.

Atlantamm
March 7th, 2011, 08:37 PM
Any burning of the wood due to the friction on the shank?

adirondak5
March 7th, 2011, 08:52 PM
Here;s what I used , a freud 1/4" x 3/4" cut length spiral downcut bit , cut figured maple like butter , used a 1/2" mdf template and just let the shaft of the bit up where the flutes end/taper off ride the template , worked great , no template damage either.

http://i832.photobucket.com/albums/zz246/adirondak50/p90%20build/p90build152.jpg?t=1299545196

http://i832.photobucket.com/albums/zz246/adirondak50/p90%20build/p90build146.jpg?t=1299545397

http://i832.photobucket.com/albums/zz246/adirondak50/p90%20build/p90build148.jpg?t=1299545429

http://i832.photobucket.com/albums/zz246/adirondak50/p90%20build/p90build154.jpg?t=1299545476

hackworth1
March 7th, 2011, 08:56 PM
The shank rides on the edge of the pattern (template). The cutting part of the bit rides in the guitar top's f-hole to be. Burning of the pattern (template)is minimal and no distortion of the template should occur.

As always, it is critical to be sure that the router bit is secure and the shank rides exactly where it needs to be. And the cutting portion does not cut the template.

Careful checking and testing on scrap is required.

spook777
March 7th, 2011, 09:47 PM
I picked up a 1/4" diameter bit with bearing on the end (opposite side of router) from Rockler. The cutting surface is the same diameter as the 1/4" shank. Its small enough to get in there and run off a template...assuming you haven't already glued the top down. As for burn out, I took off at most 1/32nd at a time so the final pass was a clean cut, no burn out. For the little I did get I sanded it out.

This is what I do to get the f-holes cut
1. Resaw top
2. thickness sand
3. join edges
4. glue up
5. trace shape + f-hole location, and rough cut
6. drill ref points from template (neck bolt locations + bridge screw locations)
7. I bore out the excess wood using a forestner bit
8. route the f hole
9. glue it on the core body
10. clean up the top material with band saw then either router or oscilating sander (I use a drill press and robosander).

If you already have it glued down, you'll need a straight bit. Otherwise you don't drill the f-hole and think of those ones as "chambered". ;)