Re: [CAD_CAM_EDM_DRO] PWM input Servo Amp / Universal Stepper Controller

I wish I new it earlier - I would never get involved with steppers...
Alex

Jon Elson wrote:

>jess@... wrote:
>
>
>
>>Ok I have a question.
>>
>>Someone posted a link to US Digital on another topic so I surfed over and
>>found heaps of stuff about Encoders ie that can be fitted to various shafts
>>for motion data.
>>
>>Here is my question.
>>
>>Considering the cost of servo motors with encoders is quite astronomical,
>>what about a stepper motor say in the hi torque 34 42 NEMA size with encoder
>>
>>
>>from US Digital to over come the problem when a stepper loses steps.
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>Having an encoder will prevent an undetected loss of position. But, it
>won't help a stepper to not LOSE the steps in the first place. When the
>stepper
>skips a step, it often stalls violently. When a servo gets behind, it just
>keeps trying.
>
>Astronomical? I got 2 servo motors with 1000 cycle/rev encoders on eBay
>for $27.50, and another one that needed to have a better encoder put on it
>for $9.99! My new PWM servo amplifiers will be selling for $100 per
>axis. (I may have to come out with a cheaper, lower power servo amp for
>the lighter machines.) Note that the torque on stepper motors drops
>severely at higher speeds, while the torque on a servo is maintained to the
>maximum speed. People use 600 - 1100 Oz-In stepper motors to get
>250 Oz-In at rapid traverse speed. A 250 oz-In servo motor will outperform
>the 1100 Oz-In stepper in many cases!
>
>
>
>>But which controllers and drivers are compatible to accept encoder
>>feedbackloop while driving a stepper?
>>
>>
>>
>>
>EMC, using the Dan Mauch encoder card, or my Universal Stepper Controller
>are the only way I know of driving steppers with encoder feedback.
>
>Jon
>
>
>
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