On 3/5/23 12:59, Leonardo Marsaglia wrote:
By the way, one subtle thing I noticed too that leads me to the bearings as
a problem.
Normally when the spindle is off and the dust removal vacuum system is
working, the spindle tends to spin by itself because of the vacuum action
on the impeller I installed. This almost never happened yesterday. So, to
sum up: I was able to free turn the spindle by hand at all times, but the
vacuum was not always able to make it spin the impeller and if it did it
wasn't nearly as fast as days before. This is what makes me suspect about
the bearings. Also, almost all the problems I experienced yesterday were
with cutting forces involved, never with the spindle turning free. Could it
be that the extra heat and torque that's building up because of a damaged
bearing is what's making the VFD triggering for overcurrent?
What puzzles me still is when the spindle was too hot and with no load the
VFD only whined and couldn't make the spindle turn. This, as Jon pointed
out, recovered on its own a few minutes later.
I'll be there doing some tests in a few hours so I'll let you know if I can
note anything new.
Again a lot of thanks to you guys for being so kind and helpful! :)
El sáb, 4 mar 2023 a las 15:51, Leonardo Marsaglia (<ldmarsag...@gmail.com>)
escribió:
Hi guys.
Sorry for the OT but I'm having a strange behavior with my spindle and I'm
a little worried.
The problem I had today for the first time is the spindle was getting
really hot and started to slip (you could hear the frequency from the
inverter was on spot but the rotor sometimes wasn't even turning).After a
few seconds of slipping the VFD triggered the over current alarm and the
spindle was stopped. Once the the spindle cooled down it worked perfectly.
This never happened before but also I must clarify that today the ambient
temperature reached 40⁰C and I'm sure that under that roof where the router
is placed there were 45⁰C so I suspect this has something to do with the
problem.
The spindle is rated 11kw of max power output and is air cooled. It has a
built in fan motor so it doesn't rely on spindle speed for cooling. It
always gets warm (there are several labels on the spindle’s body for
caution because of the heat) but nothing like today.
Could this be normal because of the extremely hot days I'm having here?
Should I think about changing bearings or even rewind the motor? I've only
had the over current alarms when the spindle was too hot.
I will be really thankful if you can share your thoughts about this.
I think I'd want to look at the solder joints on the big capacitors in
the vfd, keeping in mind that they can hold quite a charge for quite a
while when turned off, and that is definitely a lethal voltage. When I
said look, I'm looking with an old camera lens for a magnifying glass,
checking for hairline cracks in the solder, particularly at the edge of
the solder puddle where the copper foil begins, that is a favorite place
for some seemingly crazy thermal effects. And you can't just scrape it
down to clean copper & bridge it with solder, you must bridge the crack
with a piece of suitable gauge copper wire when patching such. And for
future crack development protection, a 2% silver bearing solder is much
stronger than the usual eutectic mix.
Same inspection comments apply to the semi's soldered joints, heat sinks
can exert joint breaking forces as they heat. I have a couple of old
16mm projector lenses that get me up close and personal views. An rch
looks like a saw log to them.
Thanks for your help as always!
Leonardo.
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