Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: Redcap on April 07, 2011, 01:12:02 AM

Title: [Solved] Attaching Servo to pivot bracket
Post by: Redcap on April 07, 2011, 01:12:02 AM

Hi all,

I'm just starting to design a walking quadruped spider bot, but I'm having trouble finding a source to explain how best to attach the servos to a pivot bracket.

I'm wanting the longer side to attach to the chassis so the servo moves inside the bracket, not the bracket itself.

I know I have to attach a servo horn and the protruding servo gear shaft to the inside of one of the shorter sides.

(http://i1117.photobucket.com/albums/k598/Blue-LED/servo.gif)

But what do I do with the other shorter end of the bracket, the part that would touch (or come close to touching) the bottom of the servo?

Thanks in advance,
Red

Title: Re: Attaching Servo to pivot bracket
Post by: Soeren on April 07, 2011, 06:21:09 PM

Hi,

You could make a bracket that fits snugly (glued perhaps) over the servo end and have a short rod (welded or bolted on) coaxial with the center of the servo axle and a matching hole in the large bracket (if possible with a bushing of bronze, brass, nylon or PTFE).

Title: Re: Attaching Servo to pivot bracket
Post by: Redcap on April 08, 2011, 12:18:52 AM

Ah, cheers Soeren :)
Seems like an easy solution, thank you :)

Title: Re: Attaching Servo to pivot bracket
Post by: igor on July 13, 2011, 12:47:14 PM

Quote from: Soeren on April 07, 2011, 06:21:09 PM

You could make a bracket that fits snugly (glued perhaps) over the servo end and have a short rod (welded or bolted on) coaxial with the center of the servo axle and a matching hole in the large bracket (if possible with a bushing of bronze, brass, nylon or PTFE).

I've been thinking about the same problem during the last few days.

I somehow dislike glue and have no means to weld/brase.

My conclusion so far (wip and not yet implemented): create a C shaped piece from an aluminium foil (i've found 1.6 mm and seems good enough) so that it wraps itself on the side of the servo, the upper part screwed on the mounts, the lower part drilled and milled so that it can contain the head of a flat-head screw sticking out and holding in place a flanged ball bearing and the other side of the pivot bracket. The BB is kept in place by a nut and standard washer is inserted between the BB and the servo wrapping.
For improved stability, the "wrapping" can be drilled so that the 4 screws at the bottom of the servo are made to go through the wrapping as well.

The idea is an evolution of this product: http://www.lynxmotion.com/p-399-injection-molded-servo-hinge-for-ball-bearing-two-pack-standard-hd.aspx (http://www.lynxmotion.com/p-399-injection-molded-servo-hinge-for-ball-bearing-two-pack-standard-hd.aspx)
The BB can be found (at less than half the price) from hobbyking.

Nuts and screws from MCMaster.