If anyone has any questions about this catagory, feel free to ask. This is my best robot building “skill”. Of course if no one posts here that probably means that no one needs help.
Hmm, I bet YOU have never needed help before. Right?
I will…If I wanted to would I be able to get away with using standard Hitec servos? Like the HS-325HB? The benefit of digi’s is they hold their position better, right?
Usually, yes. I am 90 percent sure. The digi’s have a higher friction. I personaly enjoy the Hitec servos for there torque.
And if you break them, Hitec will repair them free of charge 
it is true!
Howdy…
The servo of choice depends on the distance between the axis. A 325 will work for a very small arm. We use 422’s for the L5 which is 3.75" between axis. There are tricks such as load balancing with springs or rubber bands to increase the strength of a servo based arm.
An analog servo updates the motor every 20mS (0.02 Seconds). So if it drifts off the commanded position it will take up to 20mS to send the motor another burst of voltage. So the motor isn’t used to it’s full capability. A digital servo updates the motor every 400uS (0.0004 Seconds). So the motor gets these bursts of voltage much faster. The more often a motor receives voltage, the more work it can do.
An analog servo can be off by as much as 15 degrees under a large load. A digital servo will not have this problem. Hope this helps, Jim
Thanks Jim,
I learned that digi servos held their position better than analog but I had no idea about exactly how they functioned differently.
Thanks again.
Wow, I didn’t know all of that! I guess that’s why they cost more 
!
(no offence)
Well, digital and analog servos are not that much different from one another.
Take for example the HS-645 and the HS-5645.
One is analog, and one is digital.
Here is what the two of them have in common:
Case
Gears
Potentiometer
Electric Motor
Wires
Output Spline
Servo Horns
Here is what is different between the two of them:
Position Control Electronics
The analog servos require the position signal to be updated every 20ms or so, or they will shut off.
The digital servos only need the signal sent to them once, and they will go there until told to go somewhere else.
The digital servos are faster and have higher torque. The reason for this is that the voltage drop for the motors is less than what is lost in the analog servos.
The digital servos are programmable. Speed, deadband, center position, and endpoints can be programmed into the servos.
All of this makes the digital servos very responsive to external loading, and position commanding.
Pete
Actually, they usually have a large price range.