Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Radio Equipment => Topic started by: Brian60 on November 20, 2018, 06:16:48 pm

Title: Servo's SG 90 generics
Post by: Brian60 on November 20, 2018, 06:16:48 pm

Is this really the smallest servo available? I need something half this size ideally, anyone got a clue please?

Title: Re: Servo's SG 90 generics
Post by: Allnightin on November 20, 2018, 06:48:29 pm

If I understand correctly, the SG90 weighs 9 grams

You would do much better if you look at component shop offerings:

https://www.componentshop.co.uk/servos.html

Title: Re: Servo's SG 90 generics
Post by: Brian60 on November 21, 2018, 12:37:12 pm

I've actually managed to locate one on the Hobbyking website, a nano size weighing just 2 grams, physical size along with weight were my considerations, but as they were only £2 each I ordered a couple of varying dimensions, I've a feeling the smallest will not have enough torque to move even the rudder which is only a 10mm by 10mm blade, but we will see.

Title: Re: Servo's SG 90 generics
Post by: Subculture on November 21, 2018, 04:43:41 pm

More than enough torque for a small rudder that size.

Title: Re: Servo's SG 90 generics
Post by: roycv on November 21, 2018, 08:22:20 pm

Hi all, there is a point to watch with these small sevos.  The first time I fitted one I involuntarily moved the rudder and it stripped the plastic gear in the servo.  So be careful.

regards
 Roy

Title: Re: Servo's SG 90 generics
Post by: Subculture on November 22, 2018, 03:31:27 am

If you’re concerned about that, putting a small hoop/ u-bend in the linkage can act as a basic servo saver.

Title: Re: Servo's SG 90 generics
Post by: roycv on November 22, 2018, 08:45:32 am

Take your point sub....  I have since bought metal geared servos this size.  I have a Billings Mary Ann which now has a 9 grm servo for the rudder, but there is not much room to allow for a relief system for the servo.   Bear in mind that the torque numbers was less than 1 kgrm.  I note Howes ones are twice this figure, which would suggest that the gears are more substantial.
regards

Roy
 

Title: Re: Servo's SG 90 generics
Post by: Subculture on November 22, 2018, 04:05:55 pm

You won't generally find metal geared servos below the 4-5 gram size, the whole point is weight saving more than size, and whacking lumps of metal in somewhat defeats the object of the exercise.

There are also the micro (1.5g) jackscrew type servos, which are inherently self-locking, although nothing is indestructible.