New Motor for Standard-Modern Series 2000 Question

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13 Jan 2024 16:27 - 13 Jan 2024 16:28 #290565 by mooser
Not really a LinuxCNC question but I figure it's as good a place to ask anyway.I've got a Standard-Modern Series 2000 11" lathe running LinuxCNC and the VFD has been starting to kick out when the spindle is starting. Looks like it's an over-current situation even when I remove the drive belt and it's just the motor. If I increase the soft-start adjustment to close to it's maximum the motor will start ok but it's a really slow start now.Anyway, I figure it's time to look into a newer motor so I'm looking for any suggestionsCurrent motor is 1.5HP 3PH, data-plate image is attached
 
The Control is a minarik VFD05-D230-PCM (full specs attached as well)
  • 1-Phase Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*115/230 VAC
  • 1 or 3 -Phase Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230 VAC
  • Maximum Horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 HP
  • Maximum Continuous Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . † 5.0 AC
  • AC Amps In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 / 10 amps
  • AC Voltage Input Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115/230 VAC ± 10%
  • 50/60 Hz single phase 


    ANYWAYS.... any suggestions for things to look at? Not looking for specific motors but more for "farm duty" or "cont.duty" or something to avoid.

    Thanks in advance for any useful input
    Mooser
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Last edit: 13 Jan 2024 16:28 by mooser.

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13 Jan 2024 19:17 #290575 by spumco
If you're running CSS using the VFD and LCNC to adjust speed you'll probably want an 'inverter-duty' motor.  I believe the insulation is better and can handle the heating that VFD's can cause.

Look for TEFC or TENV (totally enclosed fan-cooled or non-vented) to keep chips out of the internals.

"CT" or "Turndown" ratio is how low you can spin the motor without overheating.  Farm-duty or standard duty can be around 10:1, and better inverter-duty can be 1000:1.  If a motor specification doesn't identify turndown or CT, I'd avoid it.

Check the max motor RPM.  Better quality motors can be run >5000rpm - again, useful for CSS if your spindle can handle it.

I'm partial to Marathon Black Max and Leeson motors.  Pretty good CT ratios.  Washdown series motors tend to be very high quality but are a bit higher priced than standard.

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13 Jan 2024 20:06 #290582 by mooser
something new every day (been out of industry for 20 years now... a lot of things I've forgotten.. other's I've never known)
I'll have to check out "inverter duty" to see what's available or not. I'm still running the 6 speed (3H and 3L) gearbox but only the odd time I need the really low speeds for tapping (still use the tap in the sliding tailstock method) or knurling the odd time so I've often though about bypassing the gears and driving the spindle directly using a large DC treadmill motor or something and then I stop thinking about it and keep using what I've got that's working.
The spindle was rated for 1500rpm and I limit the drive to 1800rpm for some small aluminum parts the odd time, even then that's only with collets instead of the 6" chuck.

Thanks again for the advice, I'll check into those

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14 Jan 2024 20:01 #290698 by andypugh
Does the motor spin freely with the belt off? It's just about possible
that the bearings have gone. (and bearings on a 3-phase motor are
easy)

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14 Jan 2024 20:46 #290702 by mooser
Seems to.
Looked at some of the new inverter-duty motors and they are out of my budget for the time being so I was going to pull this one and give it the "once over" which really is just bearings and maybe a cleaning. Not much else in there.
The motor has been in there since the first conversion back in 2009 and the latest version in 2019 but it's a hobby machine with the odd small production run so total hours = not much. I have no idea what it's life before me was though.

The control is from my Tormach 1100 mill and it seems to use the same error light for both an over-current and an under-voltage state so although I don't think there's a voltage problem (can't test it that fast) during startup it's possible I guess. There is an auto-reset jumper for the voltage so I might switch that over just to see if it resets or not.

Just a pain since it of course happens when I need to do some dinky little job and it might be ok all day and then start acting up or it might act up first thing. I was thinking it was when it hadn't run in awhile so I'd get it running in a really slow speed and just let the spindle run for several minutes before actually doing anything and that seems to prevent it (or it wasn't going to happen anyway)

This last time it was after running for an hour or so and I just needed to polish the OD on a couple of pins and it wouldn't go. I quit for the night thinking maybe everything was hot from drilling 4" deep 1/2" dia holes in steel pins but it wouldn't get going in the morning either. Eventually had to play with that soft start but it's on max setting now.

ANYWAY, I'll try the voltage setting and if it still happens I'll pull the motor apart and replace the bearings.

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20 Jan 2024 23:35 #291226 by mooser
Checked the current on all 3 phases and while running (no load, just the gears and chuck spinning) they are all around 3.3-3.5 or so. but during starting they each pop above 5.2 - 5.4 for a second or two and that must be where it's tripping the vfd.
It's rated at 5amp continuous so I thought it would take the initial startup overload a little better but it doesn't seem to anymore....
Still going to check the bearings cause well... why not

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