Festool MFS Fence System Instruction Manual page 31

base and the template (as in most
through cut applications), then the
bearing needs to be mounted on the
cutter end of the router bit (the left most
bit in the photo on the previous page).
In either case, if the bearing is larger
than the router bit, it will act like the
guide bushing in our examples above,
and the same relationships will exist.
The work piece will be machined to be
smaller than the inside of the template
by one half of the difference in diameter
between the router bit and the bearing.
If, on the other hand, the bearing is
smaller than the router bit, as is the bit
pictured in the center of the photo on
the previous page, then the work piece
will be machined to be larger than the in-
side of the template, again by one half of
1010 guide bushing and ring set in metric
sizes designed around 4mm, 6mm and
8mm bits. 8mm carbide insert bit shown
the difference in diameter between the bit
and the bearing. Doing this will be un-
dercutting the template so use a thin
scrap between the template and work
piece to avoid scarring the template.
31
1400 guide bushings and rings in inch sizes mounted
on a 1400 "universal" guide bushing adapter
There is still a third way of establishing
the offset between the inside of the tem-
plate and the line of cut and that is
through the use of what are
called "snap on guide
rings." This is a two piece
guide bushing set. The
guide bushing itself is one
diameter and a machined
ring is fashioned which has
a hole in it the same di-
ameter as the guide bush-
ing but with a larger outside
diameter.
For any given router bit,
the difference in the di-
ameter of the guide bush-
ing and guide ring re-
quired to make a male
and female cut from the
same template fit to-
gether is twice the diame-
ter of the router bit.
So, whether working in inch size bits,
bushings, and rings, or with metric
size bits, bushings, and rings, you