Spherical worm gear design animation - GIF

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One thing bothers me and I have seen the results of this. The issue is that on some designs such as this, the force is basically put on one tooth. I have seen broken teeth due to this design. Others have at least 2 to three teeth engaged. Thus if one tooth is contacted then I would think the length of the gear would have to be longer. Thin gears, specially plastic ones that are way to common, are usually what break or strip. Drives me bonkers. And disgusts me because now I have to toss a perfectly good device.