View Full Version : [Discussion] Indirect drive for joints

04-07-2008, 07:51 AM
The SES (servo erector set) series of brackets is excellent for RC servos, and shows quite a bit of ingenuity in design. These brackets have only one drawback:

The servo shaft bears lateral loads, not just rotational loads.

In other words, the servo axis IS the rotational axis of the joint.

There are a few examples on this site of indirect drive, like where the servo shaft has a toothed gear attached, which in turn meshes with a gear mounted on the rotational hinge joint. The advantages of this are twofold.

First, the servo is now only called upon to bear rotational loads (what it was designed for!) and second, it is now possible to use gears for mechanical advantage (or disadvantage!)

The SES has apparently been selling well. I think an ID SES (Indirect Drive SES) is the next natural evolutionary variant. Yes, I see the pieces as being slightly more expensive due to extra pieces ie. gears etc. but should still be reasonably priced.

Perhaps one of the bigger advantages is that of standardization. If your bot somehow bends/warps/breaks a part, there is an exact replacement available. Custom one-off parts will always be there, but the more you use modular components the easier it will be for maintenance or upgrades.

So where's the hue and cry for better brackets?

I dunno 'bout you, but with some of those new digital servos... some brackets... lasers... I'm ready to take over the world. :D

04-07-2008, 11:11 AM
The indirect drives LM sells are actually quite versatile, you could fit them in just about any SES joint config. Unfortunately they are spendy- I believe about $20 a pop. Were you looking at designing/building your own?