Originally Posted by Darren Ok, more info:
The servo's are Litton Clifton Precision Model# JDH-2250-BX-1C they are 360 oz/in and the encoders are US Digital E2-250-25-G, they have Ground, Index, Ch.A, +5v, and Ch.B pins. |
Do you have a datasheet or any thing on the motors? Stall current, rated voltage, rated rpm, that sort of stuff?
This will be a serious hobby machine. I will be working with wood mostly but would like the ability to cut aluminum, speed on aluminum isn't terribly important as long as it isn't prohibitively slow. I'm looking forward to any advice you can provide. I'm quite capable as a woodworker, have been remodeling homes and building furniture for many years. I'm mechanically inclined but don't know much about CNC to start with. I work in computers for a living so I'm adept with computers/software. |
Hey, I'm like you-except for the capable, mechanically inclined part.
See, you've already go the upper hand! I'll fess up-I've yet to start building my machine-though I have nearly all the parts.
Here's a short blurb on power supplies, but my time is limited tonight. O.K, servos are going to give you more upper end power and speed than steppers, but to take advantage of it you need those specs (voltages, currents, etc.) to match them with the right power supply or supplies. You want a supply that has a voltage at or just below the motors rated voltage. You might see values for continuous torque and stall torque. Your 360 oz-in rating is one of those two. The continuous torque is what the motor can deliver all day long and not overheat. It will have a corresponding current that will produce that torque when supplied with the rated voltage. But a servo will try it's best to give you what you want: load it down and it will produce more and more torque. It will produce the most just as it stalls out from too much load. That value is your stall torque. You can't run that way too long, as you'll heat up quickly. But it gives you acceleration and the abiltiy to push hard (for a short time) when needed. But to get it your power supply needs to deliver a lot of current. How much? The value given by the stall current value.
Example: I've got some big servos that will continuously put out 300+ oz-in when powered by 60V and drawing a few amps. But they will deliver up to 1500 oz-in when fully loaded. My supply has to deliver a stall current of 45 amps though for me to get that. For one motor!
So, basically, you want to get enough current from a supply to meet the stall current rating. I could go on, but I need to get off line. Get a pencil and paper and rough out what one motor would require. Believe it or not, you don't need three times that for three motors-you are very unlikely to simultaneously stall all three. Three motors will need exactly the same voltage. How much more current hopefully someone else can tell you. I didn't go this route-I'm building with three separate supplies. Ugh! I really need to go. Maybe more later. Bye!
Lance