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

I’ve wondered why they don’t copy some of the old analogue stuff.

I suppose the issue is probably the fact that most digital engineers hate
analogue work and so they keep clear, that little analogue I have seen on
digital cards is very poorly done.



Regs Mark



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Patrick J
Sent: 27 May 2007 12:27
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: Big servo motors drive recommendations

>>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.

Thats my general impression too. They are not quite made for these 'big'
machines.

>>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

Well, time is money and money is time. If converting is sucha a pita ill
hold on
to this machine a year longer bleeding $$$ for repairs and then buy a new or
fairly new instead of messing for countless hours to convert it into
something
slow and sensitive. Rapids in my machine are 12000mm/s, 10000mm/s and
7000mm/s. And I need to be able to cut in 400mm/s.

Loooking at my 20+ years old analouge servo drives they dont look that
complicated. Its a powerboard with few components and a signalboard with
more components, but not that many. Wonder why none of the DIY-guys just
dont copy these. I have all the schematics. Judging from the parts they are
soo
overpriced at $1500 for an exchange unit. Prolly not worth the effort if one
could get a few of those £250 Chinese analogue drives. If those could be
turned into a drop-in-replacement to mine...

I'd like to take a look at those, no URL ?





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