56mm to 55mm step-down ring

The purpose of this 56mm to 55mm step-down ring
is to allow the usage of 55mm filters on the
Orion 2x54 Ultra Wide Angle Binoculars.

These binoculars have 56mm filter threads which is a
non-standard size. 55mm, though, is a standard filter
size for camera so I wanted a way to use 55mm filters on
these binoculars.

Included here is the openSCAD script used to design the step-down
ring if anyone wants to tweak the design. All that is needed is
the openSCAD program and adding the threads.scad module to the
library path. You can find the threads.scad module with an
internet search.

If you just want to print out the stepdown-ring without tweaking
the design, just use the STL file.

I found I needed to sand the ring a bit to clear it up after printing.
I just printed it in PLA (since that is all I had) and since PLA is
fairly soft, it is easy to cross-thread when screwing it on. This
is in no way a equivalent substitute to a metal step-down ring but it
wi