On 9/25/22 11:20, dave engvall wrote:
On 9/24/22 11:18 AM, gene heskett wrote:
On 9/24/22 11:34, Jon Elson wrote:
On 9/23/22 17:24, gene heskett wrote:
Each brand of vfd seems to have its own setup. But that lf boost is
a tricky one. I don't know
if that invertor shows you the amperage being delivered but it
seems it would be an odd one
if it didn't. What you normally do is read the motors nameplate for
the FLA, Full Load Amperage.
Then set the lf boost to not exceed that.
Yes, I have found that the default current limit is 3 A, my 2 HP
motor is rated at 6 A, so that was the reason for the trips.
If you intend to use it in both directions, quickly as in rigid
tapping operations, the accel/decel
registers are generally set rediculously conservative. Those can be
sped up to almost instant,
but lcnc can still confuse the vfd into tripping.
I have a lowpass filter on the spindle speed value in the HAL file.
This has worked great on my old mill. I did have to turn off the
motor overheat integrator in the old VFD, as the Bridgeport motors
can handle plug reversing. I do 4-40 rigid tapping at 1000 RPM. I
will have to figure out how to do that on the new VFD.
Thanks,
Jon
I've not seen a register so named in any of the vfd's I've played
with. They've all been 1.5 hp rated, driving 1hp rated motors. I'd
never consider a vfd as "plug" reversable, as that puts it all in the
time lag to trip the'
service breakers. Delaying the reverse signal until the motor is
stopped, shifts all those surges into the
filters in the drive., and uses little or no mains power to effect
the reversal. My mill draws around 5 amps
wide open, and an analog amprobe says it drops to around 2 amps
during the reversal. Loaded and throwing
swarf all over the place it might peak at about 15-16, but the only
indication I have that its working too hard, is when your driver goes
into current limit at about 17.5 amps of DC into the motor. With a
pid-p at 25 or so
there is no slowdown as the current goes up, until I hear the squeak
from the motor iron as your driver limits.:)
Those gears in the go704 head are nylon, and I'm still amazed I
haven't broken them. Among other things
in controlling it, I used a mux4 for the speed change vs tach scale
and such, so there's 4 inputs to control
speeds. Two inputs from tally switches watching a notch in the rim of
the gear shift knob control what gets
fed to the limiter in front of the pid_S input. When neither switch
is true, a speed of about 25 rpms is
fed to the motor. By this means, it can be doing 3000 at the
spindle, I can grab the knob and the tally
goes false in maybe 2 degrees, leaving the motor turning very slow
while I'm changing gears, those
gears all have square sided teeth, the slow turning engages the gears
with no hesitation I can feel, and
the tally does not go true until 98% engaged. So I can reach up and
change gears on the fly at any rpm.
Before, I had to stop the spindle, then grab the spindle and turn it
by hand in order to engage the new
gear. Then restart the spindle. Now I just turn the knob.
Picky little stuff, Jon, but its safer too.
I bough me a circular square to use to make the post square to the
bed, its leaning about 2 degrees,
but have been occupied with the 6040 as I teach it how to make a BIG,
LONG, hard maple workbench
vise screw. And trying to get a 2nd 3d printer to work with PETG in
various flavors to make the buttress
thread nut and such.
Some pix of it are on my web page in the sig. John K. won't let me
post them.
Take care and stay well now.
Cheers, Gene Heskett.
The controller for the spindle motor on the Mazak changes field
current relative to spindle speed. I don't suppose there are any hooks
to do the same for the XSY inverter. Just a random thought.
Dave
That is a pretty ancient tech. Because the speed is regulated by the
back emf from the
armature, it takes a lot of current to run slow. Reduce the field
current and it has to run
faster to generate the balancing back emf. With motors wound for that
sort of control,
it works fairly well, But it also has a huge gotcha,
If the field supply fails, the motor runs faster and faster if it can,
until the armature parts
exit the frame in pieces big enough to make quite effective bullets.
I take it that Mazak is considered to be pretty long in the tooth? At
least 40 yo to have
that sort of a controller
In any event, I would schedule the next major fix after you get it
working, to be finding
a suitable 3 phase motor and a vfd big enough to run it. In the
meantime, I'd put a circuit
breaker in the armature circuit rated not more than the FLA + 20% to
protect the stuff should
that field supply decide to take a vacation.
Good luck. Take care & stay well.
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Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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