Re: bridgeport series 1 retrofit

I am also contemplating the sample conversion, with a series II rather
than a series I, for lighter weight work than the machines are
designed for. I can not forsee me EVER having a workpiece over 100#,
as I would be making things like gunparts and ATV parts. I am also
planning on a dividing head/4th axis for making octagon barrels and/or
other neat things.

I thought that the series II probably has servo motors.

I am a complete neophyte on this stuff, so feel free to correct me.

my tenative plan is
1: reuse bp servo motors (if they are servos)
if not, please suggest motors and encoders

2: use the BP Powersupply for running the motors, and use the gecko's
for controlling the servos (right? or am I totally missing external vs
internal to gecko drives)

3: use existing leadscrews on the BP and have the software correct for
backlash. the 1600 bucks for ball screws is just too much.


4: use something like EMC or ramsoft for the PC software.

what do you think? Am I totally off base?

Since the BP II's are going for ~1000-1500 on ebay, if i don't buy
motors (500 each plus mounting hassles) and don't buy leadscrews
(1600) I think this can be done, including rotary phase convertor, for
1500 over the cost of the BP, or less

jeffe

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Robin Szemeti <list@r...>
wrote:

> 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 ..
>
> --
> Redpoint Consulting Limited
>
> Real Solutions for a Virtual World
> http://www.redpoint.org.uk