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Home
Track
Building
Jigs |
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| Jigs and Tools |
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In addition to common tools, a few
custom jigs were used. The jigs were
constructed after the layout and lane
spacing had been selected as they are
scaled for this track.
The jigs were built using 3/8"
plexi-glass or 1/2" to 3/4"
plywood.
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| Routing - curves,
long radius |
For routing the edge of the
curves with a radius between 2'
and 7', the following jig was
used. A slot down the center of
the jig provides a variable pivot
for different radius.
A 1/4" bolt serves as the
pivot, a nut in the recessed slot
secures the pivot bolt to the
wood. The bolt is about 2"
in length.
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| Routing - curves,
small radius |
For routing the inside edge
of the curves with a radius of
up to 18", the following
jig was used. A slot down the
center of the jig provides a variable
pivot for different radius.
A 1/4" bolt serves as the
pivot, a nut in the recessed slot
secures the pivot bolt to the
plexi-glass. The bolt is about
4" in length, a piece of
wood from a closet rod serves
as a handle. The two outside slots
are for attaching a rip fence;
the same jig may also be used
to cut a straight edge.
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| Routing - curve
center guide |
For routing curves for which
the center point is on the edge
of the panel, the following jig
was used to provide a solid pivot
hole.
Two pieces of 1/2" plywood,
the first 3" x 8", the
second 1 1/2" by 8",
were screwed together. A 1/4"
hole was drilled on the center
line thu both pieces.
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- The jig is screwed to the
edge of the MDF panel from
the bottom, aligning the center
of the jig to the centerline
of the curve (4 screws not
visible in second photo).
- The curve's pivot hole in
the MDF is dilled using the
hole in the jig as a drill
guide, from the bottom of
the jig..
- The MDF panel then has a
"half hole" on the
edge of the panel at the curve's
center, with the jig serving
as the pivot guide rather
than a hole in the MDF.
- The router jig's 1/4"
pivot bolt is then inserted
thru both the MDF panel and
the curve center guide.
- The result is a 180 degree
curve, with the straight edges
of the section being the uncut
edge of the MDF panel.
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| Drilling - cross members
and legs |
For drilling the cross members used
to join the track sections as well as
the upper half of the legs, the following
jig was used.
Each cross member and leg required 3
holes. To ensure the pieces aligned,
the jig was clamped to the drill press
and not removed until all the pieces
were drilled.
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- The work piece is placed with
the top left edge in the left corner
of the jig, the right hole is drilled.
- The work piece is then moved to
the right in the jig, with the hole
just drilled being place on the
dowel (located about 9" to
the right of the drill bit), the
middle hole is drilled.
- The work piece is moved to the
right again, with the middle hole
being placed on the dowel, the left
hole is drilled.
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| Routing - slot
trammel guide |
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For routing the initial slot,
a trammel was used. The reasons
for this were to provide an
eliptical entry and exit to
the turns and increase the width
of the outside gutter in the
curves.
When routing a straight, the
slot is offset from the edge
of the track by the distance
from the router bit to the edge
of the bearings. When routing
a curve, the slot becomes eliptical
as one bearing rides on the
curve and the other on the adjacent
straight. By varying the distance
between the bearings, the eliptical
effect and the gutter offset
in the curves is determined.
One of the track building sites
provided a formula for calculating
the distance between the bearings
for different radius curves,
and the resulting gutter distance
in the curve.
Using the formula provided,
the holes for the bearings were
drilled so the distance from
the center of the router bit
to the edge of the bearing was
5", this is the offset
from the edge of the track when
routing a slot on a straight
section. The multiple holes
provide for gutter offets of
6" for the different radius
curves.
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- The two bearings (not shown
in photo but would go under
the wing nuts) provide the
pivot guide and are held against
the outside edge of the track
surface.
- Only the outside lane of
each curve and the same lane
on the adjacent sections are
routed with the trammel.
- The two bearings must be
repositioned for the different
radius curves to provide the
same gutter offset in all
of the curves.
- The bearings used were from
the wheel of a "Razor
Scooter". You must have
the bearings before drilling
the holes in the jig to ensure
the offset is correct.
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| Routing - slot
pin guide |
For routing seconday slots,
a pin guide jig was used.
Two 1/8" bolts serve as the
guide, the bolts are attached
to the jig via a recessed nut
on the bottom. Once the bolts
were in place, the threads were
filled with solder to provide
a smoother guide pin.
The center of the guide bolts
are 4 1/2" from the center
of the router bit.
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- After the trammel jig was
used to route the slot of
the outside lane, this jig
was used to route the inner
slots.
- The 2 guide pins are placed
in the previously routed slot
of the adjacent lane.
- The jig is currently set
for 4 1/2", the extra
set of holes is for 4"
lane spacing.
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