56mm to 55mm step-down ring

thingiverse

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 will allow you to use 55mm filters with these binoculars when you otherwise would not be able to. Since I found it so hard to get the threads started when screwing it on, once I got the filter in place, I tend to just leave it in place and not take things on and off.