Yaskawa Motors WORK!!!

Jon,Matt et al

Well I finally got some time to work on the mill. It it sad to say i've done nothing on it for 2 Months
( with holidays, and my Singapore trip ... it's a wonder I get anything done).

So I started to clean up the Yaskawa motors. I reported earlier that they were hard to turn. I spent
all day yesterday painting one. I then decided why paint it if the bearings are bad? So I decided to
take one appart (usually a bad idea) But I said I would NOT get into the motor, Just check the
bearings for rust. Well these thing are built like tanks (48lbs) and I figured how to remove the
encoder (very high rsolution... will check that next) and the tach (buried in a can I can't open). So I
got one end cover off and found that it had nothing more than a seal. Behind it was a pristine bearing
no rust anywhere. AH it must be the Rear bearing by the encoder that is rusty!!! So I began to get to
it but was thwarted by a Flex coupling that has small set screws tha will NOT come out. Instead of
buggering it up I decided to go to bed. (damn locktite!!!)

Some time early this morning I woke up and it hit me!!! The motors came from a ROBOT. What
will happen if power drops out? The load would fall!!! SO they put BRAKE in the motor that keeps
the load from dropping in case of power failures.

Eureka!!! This also explained the extra two wires with 38 ohms between them that came out of
the motor. These release the brake. !!! ANd the extra "space" between the motor and the
encoder houses a brake (which I can't see because the flex coupling is stuck forever!!).

So I decided to try my theory. I figured 12V would be a reasonble voltage to use on the brake. I
applied 12V to the 2 unknown wires and heard a click!! then the motor spun like glass!!!! I connected the motor wires and it spun
at about 50 rpm at 12vdc drawing less than 1 amp!!!

So the motors work!!!! Even after being out in the weather for 1-2 years, the industrial
explosion proof motors kept out the elements. Now to check the tachs and the encoders and
see if they work. They look really clean inside, no corrosion at all.

Now to find out what the Rated voltage for the brake is. I can try going from 1V up until I hear
it click in. Then add a few volts. I just don't want to burn out the coil since it is on all the time!!!
I might even wire these to the ESTOP so the machine stops quicker!!!

Moral of the story. Don't let a bad motor get you down!!!!!

P.S. Check out your local scrap yard for broken painting robots. They have great motors!!!
( altough a little large!!!!!) There are smaller ones in the arms, but they are tough to get at!!!!

I'll try to post pictures next week..... Time to paint the second one!!!!!!

dave