Do you use steppers or servos ?????

[nattyone960]

Originally Posted by Les the Luthier I worked with Dan Mauch at Camtronics. He setup the servo motors and changed the encoders. I realized that I wasn't that saavy on Servos, so I got some help. In looking around there seems to be a third option. Some places are selling stepper motors with encoders. Although I haven't gotten to see any of those in action, I like the idea that we have more choices! As far as connectors go the best course is to decide what connectors you like and then make up new cables to match those connectors. And of course you rewire the servos to match. One of the issues that caused me to change the encoders was that the old encoders drew too much current for the Servo Controller that I purchased from Camtronics. I had a very informative conversation with an engineer at Geco. He took the time to explain a lot of the issues that I was dealing with. So I'd give Geco and Camtronics both a big two thumbs up!

Good words I really should have stuck to Geckos but I wanted to go Brushless. That led me down all kinds of paths. I will re-tackle the whole over the X-Mas break and see if I can finally break through the glass wall.

[Cruiser]

I'm using a complete IH system, thats servos, with the largest power supply Aaron had available and i'll say its an awsome system with plenty of power in "x"&"y" being that i loaded an end mill with aluminum and pushed my part out from under three heavy clamps ! I do wish i had more umpf with the "z" tho as it works hard trying to do some drilling without a pilot hole, in steel.

[Mr.Chips]

Originally Posted by JRoque Hello. Steppers here, 150oz. They are cheap, reliable and less complex than servos. On the flip side, most are slower and can lose steps if they are not in closed loop. JR

What is a "Closed Loop"

Thanks
Hager

[JRoque]

Hey Hager,

Closed loop is a term used to describe a feedback method telling the controller and/or computer where the motor is. To close loop a motor, you could add an optical encoder to the shaft and connect it to your controller, if supported. Servos need this because they would otherwise spin uncontrolled not knowing when to stop. Steppers get by without one because you control the number of steps they take.

I used to work on IBM mainframes many moons ago. Those big boxes came with big ol' printers. These used servos to feed the paper and spin the character "chain" (long story). When the optical encoder went bad, the paper feed would spin top speed and feed the entire box of paper in a matter of seconds rolling it up in a tight pack under the printer hood. Those were the days.

JR

[TOSNUCGUY]

Servos are preferred by hobbyists due to cost and secondly simplicity. I don't believe anyone sells a non hobyist metal cutting machine with steppers. I only deal with larger equipment.If you're going to put encoders on stepper motors, use servos. Try comparing the torque curves between a servo and a stepper. (stepper bad, servo good) I suppose steppers are O.K. for smaller machines.

[JRoque]

Hey Tos,

Servos are preferred by hobbyists due to cost and secondly simplicity.

Did you mean steppers? Steppers are certainly preferred by hobbyists because they are, in fact, cheaper than servos and simpler in nature. A stepper motor can operate in an open loop arrangement while a servo must have a feedback mechanism to tell it's position. That, in turn, raises it's initial cost in addition to requiring a more expensive controller than can read the closed loop circuit.

Try comparing the torque curves between a servo and a stepper. (stepper bad, servo good)

True, but it might not matter depending on your application. For example, my open loop, stepper based machine can do about 150 IPM rapids and at that speed, there's hardly any torque in the motors. However, I don't cut at 150 IPM - I cut a 60 IPM at most and it so happens that my steppers have great torque at those speeds. For even slower feeds - like used when cutting steel, steppers output a very nice torque too.

Regards,
JR

[ALBERTO JIMENEZ]

IMO Servos might be better in many ways, but if it wasn't for the simplicity of the Steppers I would be otherwise completely discouraged to build anything CNC'd

[br1]

What motors would be best for 3/4-6 acme rod, I don't need speed but torque is what I am after. I am only moving 24 inches X and Y, Would I be better off with servo or stepper?

[Kelinginc]

Originally Posted by br1 What motors would be best for 3/4-6 acme rod, I don't need speed but torque is what I am after. I am only moving 24 inches X and Y, Would I be better off with servo or stepper?

I guess the stepper system is ok for your 24 x 24 machine
http://www.kelinginc.net/CNCNEMA23Package.html
Servo system costs more
http://www.kelinginc.net/CNC23ServoMotorPackage.html

[cncjunky]

I have both stepper and servo cnc's. I can't really say anything bad about the steppers in my experience they are pretty great, but I do like the servos more. They do a nicer cut, they are'nt loud and don't make that sound that the steppers do. I can't say much about the simplicity of setting them up to a machine because I never had too, but in the future do plan too. The steppers are more of a choppier movement I guess you'd say in comparison to the servos. The servos put out a smooth continuous motion, which leaves you a really beautiful cut.

[GeeksGoneBad]

Yep I have both too -but mainly use steppers