Sunday, December 25, 2016
I made this box thing for a Christmas present. It is made from a square of heavy manilla paper. A thinner piece of paper would have been easier to work with.
I drafted the pattern directly onto the paper using the drafting machine and compass. While drawing the dozens of arcs, I discovered that my 70's(?) Alvin Speed Bow has slop in it! I had previously assumed it was moving due to operator error. You can see the resulting double lines in the image below.
A really good compass is hard to find, especially now. Ebay is ripe with vintage ones, but few look inspiring. The Starrett 92-6 looks nice with the exception of its threads. It might just be the sort of tool I have to make myself. I just want one that's quick to adjust and SOLID when set.
Maybe like this. I already want to re-draw it... the side view is ugly. Important parts are: Big ol' sharp knurled thumb nut to lock adjustment, mated with shoulder screw going through a tight slip fit in the arms. Greasy O-ring to provide some resistance when adjusting. Thoughtful clamps to lock the graphite and center point in place, maybe only one per side, but not with the standard pathetic 0-80 locking screw. While we're dreaming, the arms should be hardened tool steel with the sliding surfaces ground.
Sorry, I got distracted.
Wish I would have figured out how to make it hold itself closed, some sort of interlocking flaps. Maybe next Christmas.