Re: [CAD_CAM_EDM_DRO] bridgeport series 1 retrofit

On Thursday 08 January 2004 22:19, Bob Japundza wrote:

> 1. Stupid question: how can I determine if my motors are capable of
> microstepping? This will obviously determine my choice of drives
> between the G201 or the G210.

umm not really ... the G201 and G210 both produce a microstepped output, the
G210 simply has a 'pulse multiplier' on the step pin. Your motors will be
fine with either. If I was intending to run on EMC I wuold chose the 210's
myself, especially if running on a older PC. they give you a little more
flexibility in pulse rates that may help in certian circumstances.

there are lots of 'bridgeport specific' bits in EMC, it will work a treat.

> 2. Would a 77vdc power supply with some large caps on the output
> sufficiently filter out ripple and not damage the Gecko's? I'm
> concerned that my power supply may be a wee bit too close to the 80v
> rating for the Gecko's.

I'd drop that to half voltage by fiddling the tappings if you can... 40V is
more than sufficient in general .. there seems to be a 'as many volts as
possible' theory that comes from somewhere, that leads to nothing other than
hot drives and hot motors .. 80V is pushing it a bit I think ... esp. onhte
day when the mains goes a bit high ....

> 2. Is it possible to use EMC (or any other cnc package for the
> matter) to drive steppers with a DRO serving as a closed-loop
> system?

EMC at one stage in time had support for the mauch/kaluga DRO card. its still
there in the codebase AFAIK

> Some of the DRO's I've looked at have a RS-232 output, and
> am wondering if there's a 'standard' for DRO outputs so they could
> be integrated in a closed-loop system. I'm thinking of building one
> of Scott Shumate's DRO-350's.

it is extremely unlikely that you could use a serial DRO system in a servo
control loop ... the main problem is the inevitable delays of the serial link
reducing the phase margin of the loop. Oscillation is almost guarenteed I
would imagine.

However ... you'll find the leadscrew and backlash compensation in EMC can
map the leadcrews of a bridgeport every inch or so, and differently in both
directions to take account of wear so it should come out pretty much spot on.
The DRO's are very helpful in setting this up.

> Any help would be greatly appreciated.

call in on the EMC users list on Sourceforge or on IRC:

server: irc.freenode.net
channel: #emc

always some people on ..

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