Hubble Optics Dobsonian Accessories

This is a variety of accessories that clip onto a Hubble Optics brand Dobsonian. I designed it for the 16" which uses 40mm wide angle iron - other sizes may or may not use the same size angle iron. If they don't, let me know the measurements and I can adjust the clip size.

All clip-shaped parts print on their side for strength. Print with PETG or other tough filament, not PLA.
All parts print without support.

The clips with alligator teeth point upward and hold 5mm EVA foam as a light shield. Print several copies.

The Telrad holder prints in three pieces (for orientation strength without supports). They screw together with 4 mm x 10mm cap-head screws.
The tower prints on its back (dove tail facing up). The Telrad is held in place with a pair of M4 nuts and thumb screws.

The finder shoe holder has holes for mounting a finder scope shoe. It's sized for a ZWO synta/vixen shoe but I think other brands use the same hole pattern.
https://agenaastro.com/zwo-synta-vixen-style-dovetail-mounting-base-finder-shoe-red-zw-fs-ii.html?srsltid=AfmBOoqWPpv_3dlJvh9-2r5lxmDA7jNtLLec6GC1lptf75MvLIdAGdkH
The shoe can be used to mount a finder scope. The photo shows it with a Celestron StarSense (which I highly recommend!). The printed adapter for that is listed here: https://www.thingiverse.com/thing:7166832

The fishing reel holder pairs with this fishing reel. OriGlam Fly Fishing Reel Fishing Wheel. https://www.amazon.com/dp/B094QLMQ2N?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1
At $9, I'm sure it's a crummy reel, but as a ratchet with a friction clutch, it does just fine.

It gets mounted on the bottom of the mirror frame. I wrap the reel with 3/8 elastic cord that runs between the mirror box and the ground box. This takes the place of counterweights, without adding weight to the system. I set the reel tension to maximum. The elastic in the tension supports the weight, but at some angles the cord needs to be longer or shorter - tipping the scope down overcomes the reel friction clutch and pulls out more cord. The cord is strong enough to support the scope when tipped all the way down even with a 2" eyepiece or planetary camera. I haven't tried a DSLR. When tilting the scope up, the slack is reeled in.

There are two versions of the holder, one oriented to mount the reel horizontally on the upper tube assembly, one to mount the reel vertically at the mirror box. The photos show the second version.

To smooth out the motion, there is a pulley on the rocker box that is held on by the "pulley clip." The pulley it is designed for is this: HARKEN Premium Sailing 22mm Boat Blocks (the upright version). https://www.amazon.com/dp/B006LYJ974?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

The easiest to mount version is the one where the end of the bungee has a knotted loop that goes over the truss knob. However this puts all the force on one corner of the frame and I was worried it would mess with the collimation. Putting the pulley clip near the center requires sliding it into place from the side and that requires removing one bolt and a stack of four washers, then getting them all back into place and aligned.

The end of the bungee could be tied to the frame, but I wanted to avoid knots in order to make the reel removable so that the system could go into a transport box more easily. The "bungee hitch" is a secure way to attach the bungee while still being easily removable. The routing path is: up through the center hole, around the post, tuck it under itself, in to the top hole from the back, and tuck it under itself.

Revisions:
On the hitch, moved the hold that traps the loose end of the cord to create better clearance for a mirror cover.