According to George :
Hi Don,
It's running again.
Great!
I could not wait till tomorrow. There were a
number of things wrong, the main one being the "dead" phase being on
the wrong wire. I changed it once and the light over the chuck would
not come on and when I changed it again, although the pre-op motor was
still jamming, I tried the "inch" button, while the pre-op was running
and even though it did not start the main motor - there was a hefty
click as it tried. Next I went back to the chuck speed selector knob
and button and, working on the theory that, as it had freed up once, it
was a simple jam caused by non use and / or damp, I tapped the external
controls lightly with a small hammer for a while. The next time I
tried it, the jam was overcome and although the main motor was trying,
it was not able to start up due to insufficient current from the
converter. The converter has various switch positions which you are
suppose to adjust for lowest current when the 3 phase device is
running.
O.K. That is a bit better than some versions, as it offers a
way to tune out the "imaginary" current.
I tried a few other positions and got a quicker trip out of
the pre-op motor but a more healthy attempt by the main motor (3 / 7.5
Hp.) to start. I tried this a few times and finally I got the main
motor turning before the pre-op tripped and everything got dramatically
better after this. With a proper load on it the converter gives quite a
good 3 phase supply.
Actually -- what is probably giving you a three-phase supply is
your spindle motor,acting as an idler once it is started. "static"
converters, such as yours appears to be, simply observe the third phase,
and as long as it is below a certain value, keep a starter capacitor
switched into the circuit. This will work properly only on a fairly
narrow range of motor horsepowers. If your pre-op motor was starting,
this makes me suspect that it is a single-phase motor, not really a
three-phase one.
As long as the spindle motor is running, it generates the third
phase for anything else which might need it. However, if you want three
phase good enough so the whole system works normally, what I would
suggest is that you get an old three phase motor, perhaps around 10 HP,
and use the static converter to start it. When it is running, it will
be generating the third phase for you, and your lathe should be fully
happy -- even if the pre-op motor *is* three phase. Just mount it
somewhere out of the way, use the static converter to start it, and you
now have a rotary converter in your shop -- ready to feed three phase to
any tool of the 7.5 HP or lower range. (This presumes that you have
enough current to start the 10HP motor in the first place.) You
probably should make some kind of housing around the shaft so nothing
gets fouled in it while it is turning.
It must have all been very stiff and when it started the oil gradually
got back in the works. I left it running and went up and down the
gearbox several times and everything was fine. There do seem to be
several oil filling caps around the machine, but I am reluctant to pour
anything in until someone can tell me what sort of oil I should be
using. When it had been running for a minute or so it sounded very
smooth and no vibration, so there is not much wrong with it. I got on
with some painting and left it running light for about an hour. It got
nicely warm and I am sure that I will not have any problems in that
area.
Thanks to you, I am back in business.
Great!
Best of luck,
DoN.
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