The Miracle of 3D Printing!

Completed 3D print of Ritchey Chretien RC-6/8″ Adapter Bracket for ZWO EAF autofocuser from Thingiverse design by MikeinWI

ZWO EAF Autofocuser Needed a Ritchey-Chretien Friendly Bracket…

After listening to Nico Carver talk about his autofocuser during a recent Patreon Sunday Chat, I decided I needed one! The (actually two – one for Big Bertha/Big Zeus and one for the Southern Cross) ZWO EAF Autofocuser(s) arrived about a month ago. Paul and I began installation by attempting to attach the EAF to Big Bertha with the ZWO-supplied bracket. We decided to start there knowing that was going to be the more challenging installation. It was! The ZWO-supplied L-shaped bracket on the RC’s curved focusing knob housing was absolutely NOT going to work. Especially not as ZWO described in their instructions by simply using the RC’s tensioning screw to attach the bracket. Not only was the screw not long enough to reach through the bracket, that screw is needed to provide tension on the focusing tube so that it moves when the knobs do! (Lesson learned from the first night out when the focusing curve was a straight line, not a hyperbola!). Further, the L-shaped bracket wasn’t long enought span the RC focusing knob housing’s full curve, so is a bit like a diving board flapping in the wind. Paul did end up coming up with a solution – not elegant, but functional. (Not sure what people without engineering degrees and mechanical prowess do in these situations…) On the second night of using the EAF with Paul’s attachment solution (after discovering the purpose of the tensioning and lock screws on the focusing tube), it worked fine.

Fast forward a couple of weeks to my attending the CSASTRO Holiday Party and having a chance to talk with Ann Chavtur. She mentioned that she’d also gotten a ZWO EAF for her 6″ R-C and 3-D printed a bracket for it. Really? Where did you print it and where did you get the design? The conversation then turned into my being educated about the 3-D printers our Pikes Peak Library District (PPLD) offers and the website, Thingiverse, where you can most likely find a design for just about anything that you might need to print. To say I was intrigued and excited is an understatement! The next morning, I went on the PPLD website and got “badged” (took the training and quiz to be able to reserve and use the 3D printers), made a reservation for The TAZ Workhorse 3D printer, and found MikeinWI’s Ritchey Chretien RC6 ZWO EAF Adapter Bracket design on Thingiverse (

Wednesday, I went to the library and printed the bracket (pictured above sitting on the TAZ Workhorse 3D printer warming plate). What an amazing process!

A HUGE thanks to Ann Chavtur for turning me on to this fantastic technology offered through our PPLD and to MikeinWI for his elegant design solution! BTW – in case you’re wondering… The design was free and the library charges $0.05 per gram of material used, with the first 20 grams (i.e., $1.00) for free. The bracket weighed a whopping 54 grams, minus 20, came to a grand total of $1.70! AND MikeinWI is working on the design of an RC-10″ adapter for Big Zeus! Triple bonus!!

The production…

PPLD TAZ Workhorse 3D printer laying down the initial layers of the Ritchey Chretien RC6 ZWO EAF Adapter Bracket

Inner webbing of the bracket’s collar

TAZ Workhorse laying on the bracket’s ledge

Installation on Big Bertha…

Big Bertha with Ritchey Chretien RC6 ZWO EAF Adapter Bracket installed – Zeus approves!

Ritchey Chretien RC6 ZWO EAF Adapter Bracket installed on Big Bertha with the ASI2400 attached and ready to be focused (actually fresh off it’s first night of imaging…)