Re: [CAD_CAM_EDM_DRO] Re: Big servo motors drive recommendations

On Sun, 27 May 2007 09:47:58 +0100, you wrote:

>That was my thoughts Patrick about 12 months ago. I looked at the old
>analogue servo cards covered in oil and crude and decided to look at digital
>cards, the cheap hobby ones. I believed all the BS I was told. There are
>some digital ones that are OK, ELMO do some, but they are £2500 each, Ouch.
>
>The biggest problem I have found with all the DIY ones is it seems the
>designers don’t understand how the requirements change as the motor gets
>bigger to keep some viable dynamic range, and if you mantion dynamic range
>they will say it’s OK the PID takes care of it. They all say it will be OK
>you just have to drop the acceleration and speed a bit. They design their
>cards so that the error signal gives a fixed ON time to the PWM signal.

That's the problem of expecting Ferrari performance from a Mini.

It seems to be becoming a trend these days for companies to expect that.

I've seen lots of examples over the groups lately from people knocking
"hobby" products because they demand "commercial" performance for a cut
down price.

Short of doing it yourself, or spending commercial money you'll continue
to be disappointed.


Steve Blackmore
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