Ive got a question. what would be the best servos for the 3DOF arm servo erector set. I dont want to spend too much money but I need to lift about a pound or so. If I get my bot pattented, I will upgrade to the best possible. thx.
BTW, whats the difference between digital and standard servos? 
you may need some strong servos to lift a pound with an arm, but im not really very good with gauging
but i can help you with the servo question, ok, analog servos are usually less expensive and weaker, also they require a pulse to be sent to them every 20 ms or sumpin like that, and as soon as those pulses stop the servo will lose its position, digital servos on the other hand, will hold their position after you send a pulse for as long there is power to them
hope this helps
ok, so digital servos are better? If so, can I get these servos. There are the digital version og the standard servos that are recomended for the 3 DOF arm.
If I were you, I’d chose my servos based on the following, in the following order:
(1) Torque - Hands down, this should be the biggest reason for you to get a servo. Without enough torque, all you’ve got is a floppy rag doll.
(2) Size - Note the 300+ oz.in. 805BB.
That sucker is 1/4 scale (about 4x the size of a standard servo).
You get too big of a servo, and you’ll have the big hassle of making your own brackets for it.
But, if small servos don’t have enough torque for your needs, size takes a backseat.
(3) Stall Current Draw - I should probably include this with the size, since they tend to be tied together.
If your servo draws too much current, you’ll be forced to feed it higher-density batteries, which means much more weight.
Probably only a problem when you’ve got a hex or a biped and are using 18+ servos, though.
This spec is hard to come by, but if you ask around, people can give you an estimate.
The rule of thumb:
Stay with standard-sized Hitec servos and you’ll be fine.
Switch to off-brands or use a lot of big Hitecs and you might run into problems.
(4) Digital/Analog - If you’ve got two servos to pick from that are near the same price, and near the same torque, go with the digital for convenience’s sake.
That way, you can pose your bot in a position, turn on the power, and have it stay there without needing any SSC-32/ABB control.
(5) Speed - The speeds of each servo are so close to each other that the slight differences aren’t really noticeable.
At least with bipeds, I’ve never needed to go full-speed for any of my sequences.
Too fast walk and the bugger falls over.
If I try to punch too fast, the momentum carries it backwards, so I don’t even go full-speed then.
So, looking at the servos that you linked, I’d suggest paying $5 more and getting the 645MG’s.
You’re servos won’t hold position on their own, but that’s only a convenience, since the SSC-32 will take care of the 20ms repetitions that it needs.
For $5 more, you almost double the torque, which, in my opinion, is the highest priority.
If you’re planning to lift a pound with them, though, I don’t think it’s feesable.
Remember, the arm’s got to lift itself, first!