I've been making circular picture frames for wife.com and I'm trying to
perfect the technique.
I'm using various types of wood, primarily oak, walnut, and alder. These are
about 1" thick, 8" ID and 10" OD.
Basically I make a hollow octagon out of strips of 5/4 wood, gluing the end
grain together. These have the grain oriented such that it 'flows' around the
circle. I then resaw this ring and overlap the two pieces so that the glue
joints overlap 50%. Nice and strong without any joint failures, coolio!
The problem comes when I turn the octagon into a true circle. I made a jig
for my router table that is basically a 1/2" post on a flat board that can be
clamped to the table (think of a jig used on a bandsaw for the same purpose).
I then attach a piece of hardboard with a hole in the center that allows me
to pivot the unit on the post, making perfect circular cuts (and all the
grooves/dados required to hold the artwork).
Anyhoo, the problem comes up when I'm routing the inside and outside
surfaces. Given that the grain is alternating both 'uphill' and 'downhill',
routing in the usual direction (upcut) results in lots of chip out when the
bit decides to split out sections of wood.
Simple solution is to vary the feed (rotation) direction to avoid this. The
best solution that actually produces a perfect, split free surface is to do a
climb cut all the way around. Aside from the white knuckle grip I need to
avoid the setup going into 'self feeding' mode, I can live with it but would
prefer something safer.
What I want to try is instead of the grain flowing around the circle, I want
to cut the octagon sections so that the grain follows the radius of the
circle. What this changes is I end up with end grain exposed along the
inner/outer surfaces. Advantages would be I can eliminate (I hope) the need
to do the overlapping since the glue joints are (mostly) long grain against
long grain. I'm hoping that since I'll be routing end grain to turn the
octagon into a circle, I can revert back to routing in the normal feed
direction and avoid the climb cut scare factor.
I've routed miles of end grain, but never something that is entirely end
Any tips (i.e. depth of cut, bit type, speeds/feed rates)?
I want to avoid any grain pullout or other damage that would require
patching, excessive sanding, etc
I'm using a two flute spiral bit if that matters.