Re: gecko burned again ?oil dripping on the motor..

Oil dripping on stuff is not a problem per se. The problem is it
attracts other contaminants. It is sticky and any metal shavings will
collect in the residue.

I got a very nice series of pictures from an OEM that had a water
spray from a solenoid valve inside the control box. The drives
continued to function for a week (NEMA-42s, 72VDC supply) until they
died. What the pixs showed was a massive buildup of blue-green salt
crystals between the MOSFETs inside the drive. These salts were the
product of electrolytic action between the MOSFET drain tabs under
the influence of the drive supply potentials.

These conductive salt crystals grew until they overwhelmed the drive
and ultimatly shorted it out.

The pixs looked very pretty. A blue-green frosting of hydrophillic
copper-salt crystals covering the MOSFETs like moss on old oak trees
in the South. Deadly though because they were conductive.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "john labutski" <kd6wd@c...>
wrote:

> It depends on the type of oil. Coolants are hygroscopic and absorb

water.

> If its coolant odds are it has microscopic pieces of metal which

could get

> into the bearings of the motor if the mount has air gaps in it. You

may be

> able to check this with an ohmeter set for megohms. Just put some

of the oil

> from the motor on a plastic sheet and check for continuity with the

probes

> about 1/8 of an inch apart. If you get a reading on the meter, you

may have

> found your problem or a potential new problem.
>
> John
>
> ----- Original Message -----
> From: "Keith Clark" <mail@t...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Sunday, November 07, 2004 7:15 PM
> Subject: [CAD_CAM_EDM_DRO] Re: gecko burned again ?oil dripping on

the

> motor..
>
>
> >
> >
> > In the process of inspecting the problem on the y axis I noticed
> > that the y axis motor sits directly under the ball screw with oil
> > dripping down onto the wires and the motor. Is it possible that

the

> > oil could get inside the motor or down the wires onto the
> > connections and cause a short? If there is oil internally is the
> > motor possibly damaged?
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Keith Clark" <mail@t...>
> > wrote:
> > >
> > > I now have 3 separate 10 amp slow blow fuses, one leading to the
> > > power input on each drive. The motors are rated at 7 amps. Is
> > that
> > > the correct fuse to be using?
> > >
> > > Thanks,
> > > Keith
> > >
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "john labutski"
> > <kd6wd@c...>
> > > wrote:
> > > > Jon
> > > > You have an excellent point. Keith could probably test this

with

> > a
> > > new
> > > > Gecko. He should just add the correct amp fuses to the motor
> > > drive lines.
> > > > When one fuse pops he will probably find you are correct.
> > > >
> > > > Your comments also bring up another great point to consider .
> > > Fuses and
> > > > fuse holders are cheap compared to driver boards as well as
> > > computers. I've
> > > > been a ham radio operator for a long time and over the years
> > fuses
> > > have
> > > > saved me thousands of dollars worth of equipment when a power
> > > supply or a
> > > > transformer went south on me. Old "Buss" and me are great
> > buddies.
> > > >
> > > > John
> > > > ----- Original Message -----
> > > > From: "Jon Elson" <elson@p...>
> > > > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > > > Sent: Sunday, November 07, 2004 1:26 PM
> > > > Subject: Re: [CAD_CAM_EDM_DRO] gecko burned again
> > > >
> > > >
> > > > >
> > > > > Keith Clark wrote:
> > > > >
> > > > > >Well, the y axis gecko drive burned again this morning.

This

> > > time
> > > > > >there are no loose wires. I was doing very little with the
> > > machine
> > > > > >and had just turned it on when during a y axis G0 move, the
> > > drive
> > > > > >burned up. I assume this is an indication that the Gecko
> > cannot
> > > > > >handle the motor I am using. This is an old topic and I

have

> > > asked
> > > > > >for help with this problem before. The mill is a

Bridgeport

> > > Series
> > > > > >1 CNC originally controlled by Boss 6 but now using Anaheim
> > > Nema 42
> > > > > >high torque stepper motors and Mach2 software with a

Campbell

> > > > > >breakout board.
> > > > > >
> > > > > >At this point is seems reasonable to try another brand

drive?

> > > > > >
> > > > > >
> > > > > I think you need to retire that MOTOR. There is nothing

wrong

> > > with
> > > > > the Gecko drive, when used with good motors. But, one of

its

> > > weaknesses
> > > > > is that shorts to ground, or just plain internal shorts in

the

> > > motor
> > > > > windings
> > > > > will pop transistors in the Gecko drive. I think you'll

find

> > > the Rutex,
> > > > > Xylotex,
> > > > > etc. drives all have this same weakness. After blowing TWO
> > > Geckos on
> > > > > the SAME motor, doesn't that tell you something? Why didn't
> > the
> > > X or Z
> > > > > drivers blow? Why always the Y axis?
> > > > >
> > > > > Explanation: Your Y motor has an intermittent short. How
> > much
> > > you are
> > > > > doing with it doesn't make much difference. I assume the
> > motors
> > > heat
> > > > > up, even when idling. The heat probably causes the short to
> > > develop
> > > > > every once in a while, when the winding expands from the

heat.

> > > > >
> > > > > Jon
> > > > >
> > > > >
> > > > >
> > > > > Addresses:
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> > > > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
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wanliker@a...,

> timg@k...
> > Moderator: pentam@c... indigo_red@q... davemucha@j...
> [Moderators]
> > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> > OFF Topic POSTS: General Machining
> > If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com to

reach it if

> you have trouble.
> > http://www.metalworking.com/news_servers.html
> >
> > http://groups.yahoo.com/group/jobshophomeshop I consider this

to be a

> sister site to the CCED group, as many of the same members are

there, for OT

> subjects, that are not allowed on the CCED list.
> >
> > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY

POSTING THEM.

> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> > bill
> > List Mom
> > List Owner
> >
> >
> > Yahoo! Groups Links
> >
> >
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