TI OnStep V5 Controller mount for Bresser EXOS‑2 (38 mm)

What

Mount for the Terrans Industry OnStep V5 controller on a metal tripod leg of the Bresser EXOS‑2. Designed for Ø38 mm legs. It may fit other mounts with similar diameters.

Why

Minimal design that uses the two rear mounting holes on the controller. A zip tie sets the clamping force. Leaving a little play helps avoiding collisions and preventing damage, i.e. when using a longer optical train.

Variants

onstep_exos2_mount – rigid, solid clip. Tighter fit, harder to put on or remove.

onstep_exos2_mount_elastic – more compliant clip. Easier to handle. This is the recommended daily driver.

Tested the second over a dozen imaging nights without issues.

Hardware

Zip tie up to 4.8 mm wide. Narrower also works.

Controller screws are M4 × 8 mm. Check depth before use. Longer screws can touch internal parts of the controller (PCB board, etc.).

Printing

Orientation: print as provided to preserve flex and strength.

Material: ASA preferred for sun and heat. PETG should also work, although might crack during freezing nights. PLA not advised outdoors.

Perimeters: I prefer 7–8 walls for everything and that's what I've used.

Infill: about 40 percent. With 7–8 walls infill has little impact on such a small parts.

Layer height: 0.20 mm works fine.

Supports: Optional. Brim optional.

Assembly

Bolt the mount to the controller with two M4 screws.

Place it on the 38 mm leg.

Thread the zip tie and set the tension. Leave slight slack if needed to protect against collisions.

Verify cable clearance and slew limits before the first run.

Notes

Designed for 38 mm round legs. Might work for other diameters with a shim or some hammer persuasion.

Also please note that screws heads need to be quite flat to fit; button heads work nice.

Changelog

19.01.2026 - added STEP files