Deep Throat Optical Filter Wrench

thingiverse

I created this project because I desperately needed a way to securely mount a 2" filter inside the 48mm adapter of my RedCat telescope. The side of the filter with 48mm threads fits perfectly onto the adapter, but this added length affects the optical train's backfocus. By mounting it inside the adapter, I ensured that the backfocus remained unaffected. With bare fingers alone, I struggled to properly grasp the filter and maneuver it into the throat of the adapter. Once there, rotating the filter to engage the internal threads proved impossible. The situation was made worse when I misread the instructions and removed the scope's entire rotator assembly, making it even more challenging to reach the internal threads. There is very little clearance between the outside of the filter ring and the inside wall of the adapter. This wrench fits snugly inside the metal ring of the filter and securely grasps it from there. Its design allows it to hold the filter in place while encouraging a few turns onto the threads of the adapter. To remove the filter, simply rock the wrench back-and-forth to loosen its grip on the filter, then withdraw it. It is essential not to overtighten the filter into the adapter, as temperature changes can cause it to become stuck. The wrench cannot exert enough force to free a tightly secured filter. I fabricated this wrench from PLA, but a softer material might be more effective. Regardless of the material used, it does not come into contact with the glass. This project works well and keeps my fingers away from the filter glass. Now that I understand the correct method for changing filters, the wrench is slightly longer than necessary, but it still reaches into my filter wheel.