Tooth and Slot Crank Design

Fri, 31 Mar 2017

The tooth and slot gear from the previous project works really nicely. The motion is smooth and positive and in contract to the mesh gears the tooth and slot gears are lined up on the same plane. Time to make a project with a practical application.

I’ve decided to make a geared down crank slider which could be used as the starting point for a character based paper automata. Here’s the first draft. Things are looking pretty good. The movement is smooth and the crank part works nicely. There is a 3:1 speed reduction which I am sure will be useful for future designs. Perhaps a model featuring a tortoise or a sloth.
As you would expect with a first draft there are a few modifications which I will need to make.


Firstly, I had flat bases to the teeth and really these serve no purpose. Making completely ‘V’ shaped teeth makes cutting the part out loads easier.


When I put the parts together the teethed wheel is over to one side in the slot. I’ll change some dimensions to centre it out.


Oops! I’ll make the box slightly taller or move the gear up a little so that the teeth don’t catch on the box front.


Over all though, I like the way it has turned out. Next step, final prototype…