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.
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.
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.
![Wood slot car track router bit Wood slot car track router bit](https://thumbs.worthpoint.com/zoom/images1/1/0509/07/24-32-ho-slot-car-track-recess-router_1_df2846666c7e746cc326656274988914.jpg)
![Slot Car Track Router Bit Slot Car Track Router Bit](http://www.slotcarracing.org.uk/trackbuild/figI.gif)
The center pin rides in the track slot which keeps the router bit perfectly centered - the result is both 'gains' are the same width around the entire layout (even in the corners). In contrast, using a router base with a 2 pin setup and a standard router bit will result in gains with different widths in the corners (one will be a little too narrow, the other a little too wide).