Custom quadruped questions

Lynxmotion Legged Robots
1

So I’m diving into making a custom quadruped with almost no electronics or engineering experience. I’ve spent a long time researching it but naturally I have a few questions I’d like to run by you all before I order anything :wink: .

  1. My robot will have similar dimensions to the one made by this guy: viewtopic.php?f=8&t=8429
    Given that he got away with HS-311 servos (at least in the tibia, don’t know what he used elsewhere), should I expect reasonable performance if I use HS-485HB servos everywhere (3DOF legs)? The kits lynxmotion sells seem to mostly use beefier servos like the 645, but 485s are quite a bit cheaper.

  2. In the description for part PSH-04 (lynxmotion.com/p-399-injecti … rd-hd.aspx), it’s mentioned that HS-485s are too tall to be used with this part and a standard C-bracket. But apparently it fits other “standard size” servos. Which is strange, seeing as according to servodatabase.com, there’s very little variation in the height of servos listed by lynxmotion as “standard size”:
    servodatabase.com/servo/hitec/hs-485hb 37.8mm tall
    servodatabase.com/servo/hitec/hs-5485hb also 37.8mm tall!

So if someone could confirm that 485s don’t fit in C-brackets when used with the injection moulded hinge and a ball bearing then that’d be great - because if it turns out they do fit, then I’ll be doing just that probably.

  1. Grommets. Do I need them for securing a servo to a sheet of PVC foam board, or can i just screw it straight on? Lynxmotion don’t seem to sell them so I’d have to get them somewhere else.

Thanks in advance. Sorry if these are dumb questions but like I said, no experience, and I’m not taking any chances when it comes to ordering the right stuff.

2

We tested the fit and measure the servo and a standard C bracket is indeed not tall enough. The horn on that servo seems to be slightly higher than on other servos.

3

Thanks Carlitos, I guess that horn thing explains the confusion.

Anyway, that rules out HS-485s for the hip servos. That means my current choice is HS-485HB for the thighs and tibias, and HS-5485HB for the hips - simply because they should fit the brackets while still offering decent torque and not being too much more expensive. Can someone tell me if that sounds reasonable?

4

645MG’s all around - they are proven to work and don’t cost much more than the 5485s.