Which servo would be better?

There's two servos

  1. The larger sized HD-1235MG , torque : 40 kg-cm (7.4V), weight : 170 g.
  1. The standard size D950TW Servo (titanium gear) , torque : 35.0 kg.cm (7.4V), weight : 68g

The second nearly matches the first in torque, and seems really great since a smaller size is always a plus, let alone it's 3x lighter weight.

Would there be any disadvantages to the second option? Noise, Heat?

Thanks in advance

If both servos are in boxes setting on a shelf somewhere, they are both equal. Perhaps you can expand a bit on your project ideas.

Paul

I'm trying to find the best servo to rotate a 60cm long robotic arm which weighs about 0.6kg.
If I can reduce the amount of space and weight the servo occupies that would be a big plus.
I would like however to avoid the servo getting hot and/or making a lot of noise.

If you want to move the arm more than a couple of times, then both servos are not suited. The torque given is "absolute maximum for one time use", i.e. they wtill spit teeth when done repeatedly. That said, depending on your desired speed the acceleration and deceleration phase will introduce significantly more torque than the static case makes you believe. Go for something that has a dynamic rating written somewhere or use a servo with at least the 4-fold torque rating than what you calculated.

What is it that you are trying to do? Tell us more about your project.
Neither one of those servos are cheap, and the D950TW is quite expensive.

You might find less expensive servos with the the same specs at vendors such as hobbyking or towerpro. If you are a DIY type, you might check youtube for “windshield wiper servo”. If you really need some torque, you might get a cheap harbor freight winch and modify it into a servo.

kolleamm:
I'm trying to find the best servo to rotate a 60cm long robotic arm which weighs about 0.6kg.
If I can reduce the amount of space and weight the servo occupies that would be a big plus.
I would like however to avoid the servo getting hot and/or making a lot of noise.

Rotate about what point? Rotating a uniform 60cm of 600g about one end can take about 2Nm, about
its centre might need a tiny fraction of that.

To move it rapidly could take much more torque.

Try if possible to avoid loading a servo with high static torques, they will simply cook themselves.

Its a really good idea to balance all the rotating parts, even if it makes everything heavier.