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A project log for Stubby the (Teaching) Hexapod

100% open source robot platform with accessability and affordability in mind: teaching children of all ages about robots & programming

the-big-oneThe Big One 04/10/2014 at 02:560 Comments

I picked up a digital kitchen scale today (for a Pinewood Derby car I am making with my daughter)... out of interest, I weighed Stubby.  It is currently 401g (including batteries and radio).  The batteries + holders alone take up about 120g (batteries are 26g each, and the holders are a few more).  The servos are nominally 9g (although I think that is without wires), which makes for another 110g or so (Edit: the servo plus wires are 10g each, for a total of 120g or 180g if I get 18 on there).  I think that the best I can do to trim weight is to look at the chassis and leg joints... even though the chassis is hollowed out to reduce weight, it is still probably larger than it could be.  I need to look at alternate designs or materials.

The coxa leg brackets are probably the next largest source of unnecessary weight.  They are cut from 3/4" MDF, and for structural reasons are chunkier than they need to be.  I am thinking I could replace them with a thin aluminum L-bracket.

Why does this matter?  Well, if I can reduce the weight by 100g or so, I may be able to add another servo to each leg, making it a full 3 DOF per leg, and allowing for more accurate movements.

If anyone has experience with ultra-light, full 2 or 3 DOF hexapods, I would appreciate any comments on how to best design and manufacture the legs.  (I do not have any fancy toys like a 3D printer or CNC machine, but I do have a dremel and steady hands...)

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