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CNC Dimension Details _


indent While few home workshops have a CNC router, there are a number of Makers groups and Tool Libraries with CNC Spindle Routers. 2D files (.dwg) have been created for most of the module layouts described on this website - as well as Cut2D files that should be checked and edited before use. 3D models for visualization (vrml) have also been built. Available by request, these are intended for personal, organizational or classroom use. No commercial use is permitted without express, written approval.

2D Models redline

indent Models were constructed using Rhino 5.0 in a Top worldview at z=0. A rectangle defining the module outline and points for the track ends at the module boundary (inset 2.0") were the starting point.

indent Centerlines (white) were then established to define the path of the tracks maintaining minimum radii common with commercially available track (4-3/16".) This centerline was offset to establish the outline of the track (blue, 0.812" offset, 1.624" track width.) The centerline of the rail is offset from the centerline (red, 0.500" offset, 1.000" rail spacing.) Rail outlines for visualizing turnout and crossing geometry are roughly 0.2" at the base (sepia, 0.100" offset from the rail centerline.) Lastly, slots representing track ties (green) are spaced every half inch - these are optional, but complement the detailing of the layout.

indent Track geometry is segmented into discrete pieces to facilitate nesting for cutting and to reduce material waste. Consideration for grain direction and limited widths for half-inch maple stock influence break locations - maple widths over 7" are less common locally... Using the defined breaks, rail and ties are segmented. Rail lines (red) need to be extended by a quarter inch for complete cutting.

3D Models redline

indent Solid representations of the track were created by extruding the track outline (blue) by a half inch and subtracting the extruded rail outlines (sepia) and tie slots (green).

Cut2D Models redline

indent Milling the track requires at least two cutters - a specialty rail bit (e.g. Rockler), and a bit to cut the track periphery (1/8" cutter with a 1/4" shank is recommended). If cutting the tie slots, a small diameter bit (1/16") is needed. Due to variation in stock thickness in half-inch lumber, a large diameter bit is suggested to 'face' the track face (~3/4") for consistent results. The Cut2D files also have tabs defined to stabilize the track during the final cutting operation. Tabs are easily removed with a medium-coarse hand file.