[Photograph of Neil Fraser]

Neil Fraser

For the past decade I've been a software engineer at Google in California.  In my spare time I've created a mélange of open-source software.  I've also built some rather unusual hardware.  On rare occasions I've even been known to write something interesting.

Wooden Pylons Tuesday, 20 November 2018

A year ago I made a wooden train crossing for Beverly. However, the resulting carnage has proved the need for proper grade-separation. Time to build some pylons that allow one track to pass over another.

The straightforward approach to cutting out the pylons from a 2x4 is to just stack them end to end, lengthways. However, the orientation of the wood grain would mean that the smallest pylons (the 1 cm and 2 cm tall ones) would certainly split into pieces. A better orientation is to rotate the pylons by 90°. One side benefit is that this orientation happens to be a more efficient packing solution, allowing a second 7 cm pylon to be extracted from the same block of wood.

[Marked 2x4]

The actual cuts weren't exactly as laid out in pencil above, since the saw-blade has a non-zero thickness. So the cuts were adjusted such that each pair of blocks would not be short-changed by a few millimeters. Rounding off the top edges using a belt sander helps the track sit better, since the track would be angled either up or down.

[Cut wooden blocks]

Each block is marked with its height using a laser engraver. The 1-7 pattern was created in SVG using Inkscape. Stacking the blocks allows the top surfaces to be at a constant height so that the laser can focus.

[Laser engraving numbers on wood]

The laser cut was much cleaner than I expected; I'd actually been hoping for more visible charing of the wood. So I painted the engraved areas black. The tolerances were too tight for the smallest brush I had, so I used a wire instead.

[Painting numbers with a wire]

Painting numbers on all 16 pylons was rather tedious. Sierra offered to help and was really good at it.

[Painting the pylons]

The last step was to add some guide posts so that the rails wouldn't slide off the pylons when in use. I bought one foot of plastic fuel line, cut it into 32 small lengths, then screwed them into the tops of each pylon.

[Completed pylons]

The pylons were popular with Beverly, she kept exclaiming "Over!" and "Under!" as she pushed trains around the layout.

[Beverly playing with trains]

As always, I'm thankful to be able to use Google's workshops for personal projects. Though everyone in the workshops who saw me building wooden train accessories assumed I had a son, not a daughter.


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