Torsion Garage Door Switch to prevent Over Travel by gustafson_cj

Last crawled date: 2 years, 11 months ago

I needed a way to detect when my garage door was fully raised, so that I could switch off power to the lifting motor.
This 3D print includes 7 printed pieces that can be installed on an existing torsion garage door. There are 2 brackets that can be bolted onto the torsion bar while it is in place with 5mm screws. The brackets include races for 6mm steel bearings allowing low friction between the bracket and torsion bar. Lube the races with bearing grease first so the ball bearings are held in place while assembling the brackets onto the torsion bar.
A connecting bar joins the brackets together with 5mm screws, and has 6mm recesses for threaded brass inserts that can be heat staked in place. The connecting bar contains a cut-out for 3mm steel cable that lifts the garage door. The cut-out is profiled to match the drum roller surface as the diameter steps down. A microswitch is installed in the connecting bar that detects when the door has been fully raised.
A hinged gate with matching cut-out is attached to the connecting bar and presses against the microswitch to close the switch when the garage door is fully lifted. A 5mm screw and threaded insert are installed to reduce the angular stroke of the hinged gate and prevent excessive rubbing against the 3mm steel cable.
Finally, a cable clamp is installed around the 3mm cable and can be slid into the correct position in relation to the door and switch, so that it presses against the hinged door to close the microswitch when the door is fully raised.
Printing:

Prusa i3 MK3S
0.4mm nozzle
0.2mm layers
20% infill
PETG filament