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

Trouble is Steve we didn’t expect Ferrari performance out of a mini, but a
mini will still get you from A to B eventually in an acceptable time to most
people.

I would be happy to run with the machine derated a bit which is what I
expected, I was even more thrilled when some of it managed to start knocking
professional capabilities, almost got there with Rutex cards, but not quite.
Were it to be a mini then it keeps stalling.



Actually in practice I have found Mini’s far more reliable than Ferrari’s,
I’d still love a Ferrari of my own, nearly bought one two months ago but
decided to hang onto the money instead.



We do tend however to mislead the newcomers who quickly think some DIY
software and servo drives on a £2000 machine can be near as good as a
£100,000 machine.

In many cases this is nearly true and we have something commercially viable
at a fraction of the cost of a commercial machine and in a format we can
self maintain.

Then there are machines like mine, lots of Iron so you think nice rugged low
wear and tear, it’s just a tiny bit too big to pull off with DIY kit.



I suppose over the last few months we as a group have learnt a lot more
where these boundaries are likely to be. Sadly the servo suppliers haven’t
caught on where there can and cannot be success, it seems they’ll swear to
you it will work, sell it to you, take your money and that’s the last you
hear from them. (Not all so but fits one in particular)



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 Steve Blackmore
Sent: 27 May 2007 11:19
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: 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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