i m making a hexapod using 18 motors (3 motors for each leg). could u please suggest the best and the most economical motors available in the market
Are you building your hexapod from scratch or using a kit? Do you have an idea of the leg dimensions and the overall weight?
I’m a big fan of Hitec brand servos for a good balance of cost and quality, but 18 servo motors are going to set you back a bit. Keep in mind though that you don’t need to get all one kind of servo. The vertical axis servos in your legs won’t be working against the weight of the robot, so you can get cheaper, weaker servos for these.
Off the top of my head I would consider going with HS-322HD servos for the vertical axes, and HS-475HB servos for the horizontal axes. Both have Karbonite resin gear trains (stronger than nylon, cheaper than metal) which will keep gear teeth from sheering off if your robot gets treated a little roughly, and both are available with quantity discount from Tower Hobbies.
Of course, do some torque calculations to make sure these guys can handle the load (who knows, you may be able to get away with all HS-322HD’s). And be gentile with the servos at first. Remember, if you’re disappointed with the performance:
P.S. I haven’t seen this from Tower yet, but some retailers have started closing the tops of servo boxes with stickers to see if you’ve opened them (and thus made them not new). In totally unrelated news, the bottoms of boxes open too.