Summary

This is a simple ±3° kinematic mount for 50mm filters. The two screws allow the mount to tilt downwards/upwards. Together with rotation on the post, there is enough freedom to align the face of the filter to be normal to the beam.

Instructions

I needed 50mm filter holders for the optical engineering lab. Obviously these should be printed in black, but for the prototypes I used white.

The basic idea is simple. The thin upright deforms more than the thick one does. The screw forces the filter to rest on the thin side. As the screw is turned, the filter tips slightly. The clever bit is pre-tilting the filter in one direction. This means that tightening the screws will always allow the filter to be positioned perpendicular to the beam.

All the holes are intended to be tapped with an 8-32 screw. I use plastic 8-32 screws to secure the filter (to avoid scratches) and an 8-32 stud/screw to mount to a 1/2" post.

I printed these with ABS at 235° and a 110° bed. 30-40% fill seems to work fine. In Slic3r, I got better results after slowing perimeter tracing from 60 to 50 mm/s.

There are three STL files. The first two print as a single piece and the second prints as two pieces that need to be glued. The two piece model is significantly stronger at the critical bend joint.

The first file (filter6.stl) uses 8-32 threaded studs and the second (filter9.stl) uses a simple pan-head 8-32 machine screw (which are cheaper and more readily available). I like the pan-head version because the head seats tightly in the recess, which ensures that the screw does not rotate when attaching a post.

The last file (filter13.stl) is printed as two parts which need to be assembled. I just coated one of the mating faces with acetone and clamped both pieces together.

One-Axis Kinematic 50mm Optical Filter Holder