This is a beefed up version of the basic torque tester for the DC90 motor that was designed previously. It consists in a ~7cm (2.75") diameter drum that lifts a thin rope with weights attached. For background and principles see the aforementioned link.
It is compatible with the JCF63 motor type described below.
The Fusion360 CAD model (messy), STEP and 3MF files are on Github and MakerWorld
Feel free to copy, remix, whatever (non-commercially)
Happy torque maxxing to all !
The motor used has a 10mm shaft diameter with a 3mm large keyway: JCF63R DC 24V 80W 160RPM
There's a plethora of such motors out there as they are typically used to open / close garage and gate doors. Anywhere from 10 to 220RPM, 40 to 80W, left or right handed, etc. They usually go for $35 to $90 depending on specs.
Results
- lifted 50lbs (22Kg) with an 18V lithium battery. Same with 2 batts in parallel, so current wasn't a limiter
- lifted 55lbs (25Kg) with a 24V 20A power supply. Plateau'd at 15A at 23.5V, ie 350W peak electrical power
- No Load speed at 19.5V is ~140RPM
This resulted in a 22 x 0.4 = 8.8Nm (6.75ft.lb) max torque (see DC90 post for formula).
Still not the ideal 16Nm I've been looking for for a rope winch project, but getting closer.
Note that in the test the motor was only experiencing half of the attached 100lbs weight seen in the top picture as a ratchet pulley was used. See the DC90 post for details on pulley setup and types.
Print settings
- PLA, 0.4mm nozzle, 0.24mm layer height
- 4 walls, 8 top, 8 bottom (added an 8 walls modifier around the shaft to get a lot of plastic around the keyway, not needed for lighter loads)
- 20% Adaptive Cubic infill, combination ON
- no support needed
Assembly
1. Attach the hanging plate to the motor with M6 flat head screws
2. Apply CA glue (superglue) to the drum's grooves, rotate the drum cap 180 degrees if need be to align the shaft keyway grooves, then slide the drum cap into place
3. Add a wood screw (#6 or #8 can't remember) into the starred hole in the pic above. Leave the head out ~3/8" (8mm) to attach the end of the weighted rope to it
4. Slide the drum onto the shaft, forcing it tight around the keyway (if too tight try reprinting the drum with -10% filament Flow)
And remember: never leave a foot or your favorite hamster under the weight stack during a torque test. 40lbs freely falling will make quick work of any "squish bag" 😅
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