Finishing the SFO Bravo lasercut

I finished up my lasercutting project, a model of SFO Bravo airspace. It’s a stack of 11 roughly circular objects, one every 1000′, that when stacked should be SFO bravo. It was a total pain finishing this out from the rough SVGs, but I think I’m there. It will be about 7in in diameter and 2in thick when assembled.

I ended up doing most of the finishing work in Inkscape. I never could get the SVG objects to scale correctly; the SVG viewpoint and scaling model is really confusing. And after calling ST_Union on the shapes I still had some interior lines I had to delete manually. But I got it close enough and could then paste all 11 objects into the Inkscape template, scale and style afterwards.

I got clever and cut a square hole in the middle of the airspace to insert a spindle. Hard to find that position, btw, it’s not really the center of any of the objects. It’s implied by the radii of the circles. Anyway I figured it out (it’s the VOR location, as expected) and added a rectangle to cut. I think I managed to make the holes 4.5mm wide, the width of the material I’m using, and even cut a 4.5mm long rod elsewhere on the sheet to use as the spindle. But it’s hard to get precise measurements out of Inkscape; it seems to be using the line width as part of the size of the object or something. And I’m in the habit of making the lines 1mm thick while editing so I can see them, then rescaling to 0.01mm for the final cut, which seems to throw off all the sizes. Oh well, if the spindle’s not perfect it’s OK.

It’ll cost of $37 + shipping in blue acrylic. Amazing how much cost depends on thickness. 4.5mm acrylic = $37, whereas 3.0mm is $20 and 5.6mm is $51. Most of that is laser time.