Worm Drive, Non-Throated
by syvwlch, published
Like all worm drives, the gear advances by one tooth for each revolution of the screw but with non-throated ones, there is only a single point of contact at any one time, and so torque and wear capabilities are limited.
As I pointed out in the comments, AFAIK a trapezoidal profile for the worm screw is all you need to match the worm gear's involute.
To make them mesh, all I did was to make sure that:
1. the pitch is the same (distance from crest to crest),
2. the pressure angle of the gear is equal to the angle of the sides of the screw profile,
3. the distance between screw and gear is equal to the gear's radial pitch plus the screw's mid-profile radius, and
4. the twist on the gear is equal to the gear's pitch radius divided by the screw's mid profile radius, with a sign depending on the screw's handedness.
Recent Commentsview all
Nah it's ok I've reverted back to 2010 version.
However printing the screw is now proving very problematic. Specially when using PLA. And switching on Support while also using PLA is a nightmare to clean up.
Time to invent a two headed Cupcake extruder :-D
Yeah, the one on Git I've been bashing on to try to get the throated worm gear to work, so I don't know if if works with this script anymore.
As for the bald gears, that's a bug in the later versions of OpenSCAD that breaks the MCAD involute gears library. That's been an issue for at least two versions of OpenSCAD and no-one is fixing it. I have a kludge/hack version of the involutegear library that sorta works, if you want.
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It is ready for animation, and I have added a GIF of the animation in the comments below.
This code is in the same repository as the library:
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