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View Full Version : Al_The_Man> please check this thread



flybynight
01-30-2004, 06:36 PM
Hi, Al_The_Man. Thanks for checking this thread. You answered my question about AC stepper motors about 17 or 18 posts below this one. I was wandering if you might could help a little more. I have found out by contacting "Vexta" tech dept that these motors are NOT stepper motors as the seller advertised them to be on Ebay. They are low rpm "continuous" motors, the samr as you described them. The gentleman at Gecko also said they will not work as steppers due to their high "inductance". My question is would it be practical or even possible to add an encoder and run them as a servo instead?? They are really nice motors and are , I think, "nema 34" size which is what i need. Thanks to you and to anyone that cares to comment. Thanks, Tom in Ga.

Al_The_Man
01-30-2004, 08:14 PM
Tom, I do not think you will have much luck running them as servo's, they are designed primarily as synchronous motors which mean they faithfully follow the frequency of the supply, even if you could feed them with a 120v variable frequency or a large step and direction signal, you would not get much in the way of rpm. I would put them back on ebay and try and pick up some nice DC or AC servo's that come up regularly on ebay.
It might save you a lot of grief rather than trying to get the Vexta's working as servo's.
Look for DC servo's made by Aerotech, EG&G, Reliance, Electro-craft. You can pick up amplifiers like Advanced Motion Controls (AMC), Copley Controls. Aerotech, to name a few.
Hope this helps.
Al

flybynight
01-30-2004, 08:45 PM
Thanks for your advice and replying to my question. I agree its not worth the risk. I can't get the seller to return any emails. He clearly advertised them as "stepper motors". I probably think he did not do it on purpose. He probably just didn't know. But he could at least talk with me about it. Anyway, again Thanks. Tom in Ga.