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by TheAceOfHearts 336 days ago
Does anyone know what design considerations, if any, might've gone into deciding to have 4 fingers instead of 5? And what tradeoffs that entails?

I actually saw this posted a few days back on Twitter and had been wondering if there was any deeper consideration for the number of fingers. It seems like you save around $10 in parts by getting rid of a finger, based on the information in the BOM.
2 comments
michaelt 336 days ago
Ignore the fact the hand is as thick as a servo motor, for now, and just consider the palm width.

This 4-finger hand is just below 4 inches wide, across the knuckles. By the standards of gloves for humans, this is already "X-Large"

The SCS0009 servos are 1/2in wide and there are two for each finger. Adding two more servos would make it 5 inches wide, taking it into "XXX-Large" territory.

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p_d_r 336 days ago
It looks like the width of the servos driving each finger makes a certain finger spacing necessary, and I bet five made for an awkwardly wide hand.
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