As the device is inherently accurate,
using the jig as a mini-pivot, allows
holes and roundels of various
diameters to be cut with the same
cutters. It is also a simple matter to
make routed rings and fit them into
matching grooves, separately or in an
inter-linked fashion.
For small work, the grooves are
machined from scraps of timber to fit
into the recesses accurately (some
preliminary experimentation will be
necessary). For this, each piece must
be mounted at the exact centre of
the circular disc template leaving a
small wafer of timber at the base to
retain them, the wafer being removed
by sanding later. The rings are then
replaced in the recesses to machine
the joints required for inter-linking, an
important point to note since the
joint faces need to be accurately
curved.
By using the jig as a ski system, planing
operations avoiding the dangers and
difficulties of working short, thin or twisted
material can be performed. In addition,
‘flatting’ operations on fairly large pieces of
stock and any form of guided work against
a template are simple to execute. For edge
moulding operations, the jig can be set-up
as one-legged ski or support system,
ensuring that the router remains level
throughout the operation.
Finally, it is possible to adapt the pivot
frame jig to machine ellipses.
Maximum dimensions are limited by
the size of the circular disc template
but within this constraint any axis
ratio (ie. combination of major and
minor axis) can be achieved. Details
on cutting ellipses and other pivot
frame jig projects can be found in my
book Decorative Routing - Jigs and
Techniques. IP
By using longer guide rods (500mm)
together with the circular disc
template the mini-pivot is capable of
forming radii up to 175mm.
The Pivot Frame Jig can also be used in
conjunction with the Clamp Guide, to
maintain contact between the router and
straight edge throughout the routing
operation. With the guide clamped to a
flat worktop or workpiece and the jig bars
set either side of the guide, any deviation
from the cut line is eliminated allowing the
cutter to be fed into the wood in either
direction. This method can be easily used
for machining parallel channels and edges
and for accurately machined halved/scribed
joints and precise mitres.
INProfile
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