Let's Make Robots!

selecting servo's?

Hi,

I am about to build my first real robot, based on a partially gutted RAD robot.  The electronics are no problem to me, I have a good understanding of what is required there.  My problem is that I completely suck at anything mechanical.  I have been looking at servo's to move it's head, sensors, arms, etc but I cant figure out what the difference is between them, and how to select the ones best for my application.

Thanks in advance.

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Servos have 2 specifications you'll want to consider - speed and torque. The best for your application will depend on the purpose of the servo on your bot. If you need response, get the fastest servo you are willing to drop cash on. If you need strength and holding power, get a high torque servo. Most servo catalogues have wide ranges of speed, torque and cost. I have always had good luck with the Hitec servos. The ServoCity web site has a good selection and lots of information.

For most part you want to look at how strong they need to be (torque, you can find it in the specs if not listed). The stronger they are the more they can lift (and more expensive) they get.

Then there are some differences between analogue and digital servos. The latter is more precise (very). Show the ones here you want to buy and what for you want to use them. Plenty of good advisors here on this site (not me ;))

Seems hitec has good ones for robotics. I bought a whole bunch of http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8782&Product_Name=BMS-705MG_Low_Profile_High_Torque_Servo_(Metal_Gear)_6.0kg_/_.18sec_/_34g BMS servo's and had some problems with them (lots of noise). Probably because they are high torque and all metal gears. Now, I wouldn't save the few euro's on good ones anymore.