The wrong VFD settings can cause an overheat due to overcurrent. Were you running the spindle at lower RPMs? Router spindles generally don't like running at speeds less than 6000rpm, especially if the VFD settings aren’t right. The VFD needs to be set so that it reduces the voltage applied with reduced frequency. If this volt/hz reduction curve isn't right, either you can over current and overheat the motor at lower speeds, or if set too low you lose what little torque the spindle has. To know what these settings need to be set to you need to know the motor's rated speed and voltage at those speeds and current ratings. If the spindle manufacturer didn't supply a midrange voltage setting, you may need to find that setting experimentally.
That said, high speed spindle bearings can be failing and the spindle still spin mostly freely by hand, but the spindle will be loud at speed due to vibration and will overheat if run for extended periods of time at speed. A high speed spindle should be very quiet at speed (not sound like a conventional router motor.) Check for any slightest notchy-ness, when turning the spindle by hand. It is often more cost-effective to have a loud spindle rebuilt before it totally fails, than to run it till it won’t run anymore and then try to rebuilt it or have to replace it because damage to the spindle is too severe. What are your spindle motor’s rated speed, voltage and current? What do you have the VFD set up for minimum, maximum, base and mid-range voltages, and frequencies? Yes, those are 8 separate settings that most VFDs need to have configured to run a high speed spindle correctly. Unfortunately many times the spindle manufacture will only provide you with the spindle’s rated frequency and voltage (use this for the “Base” frequency and voltage in the VFD) and the maximum frequency and maybe voltage. If you are lucky and the spindle manufacture provided you with some numbers to use for the mid-range settings if so, use them. They may not be called that, it might just look like a low or minimum speed setting with a reduced voltage (might be 5-7k rpm). If you don’t have a recommendation from the spindle manufacture, experiment with different mid-range voltage settings to find one that keeps the VFD’s current output safely below the spindles rated continuous current. For example I was just working at replacing a VFD for an HSD spindle that had recommendations for 7k rpm @ 220v for the mid-range, but I also had to set the minimum frequency and voltage to 0.5Hz and 1.0v, to prevent the motor from occasionally stalling on acceleration when starting from stopped. When those settings were incorrect the drive would overcurrent and shut down. When they were close but not quite right the drive would run at high current and not always accelerate correctly (stalling). With them correct the drive accelerates the spindle quickly and only shows peak currents of about 15amps while doing it. PS I meant to send this last week, but forgot to click send, so it sat on my work computer till this morning. Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -----Original Message----- From: Leonardo Marsaglia <ldmarsag...@gmail.com> Sent: Wednesday, March 08, 2023 9:20 AM To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] OT: Air cooled router spindle problem [EXTERNAL EMAIL] Be sure links are safe. In fact, the day the rotor slipped, when the spindle cooled down a bit, it started to work ok until I had the problem again. What I'm mostly worried about is, if this was caused due to an overheat, why did that overheat occur in the first place? El mié, 8 mar 2023 a las 11:17, Leonardo Marsaglia (<ldmarsag...@gmail.com>) escribió: > Most high speed spindles (such as router spindles) are rather > particular >> about how the VFD is configured because of their low inductance. >> What are your settings for base frequency and voltage? You may need >> to adjust the settings for midrange frequency and voltage. What >> these settings will do is adjust the volts/hertz curve to help keep >> the motor from overcurrent when running at lower RPMs, and help >> prevent stalls/excessive slippage on acceleration. These settings >> usually need to be significantly different from most VFD's default >> setting (which are usually configured for a 60hz >> motor.) > > > Hi Todd, > > I'll take a look and attach my settings as soon as possible for you to > see. But this setup was working well until the extreme heat days started. > > Could it be that the ambient temperature (40ºC or more) could have > made the rotor slip effect worse? Maybe I was on the limit before and > the extreme heat conditions triggered the effect? > > Thank you! > > El mié, 8 mar 2023 a las 10:57, Todd Zuercher > (<to...@pgrahamdunn.com>) > escribió: > >> Most high speed spindles (such as router spindles) are rather >> particular about how the VFD is configured because of their low >> inductance. What are your settings for base frequency and voltage? >> You may need to adjust the settings for midrange frequency and >> voltage. What these settings will do is adjust the volts/hertz curve >> to help keep the motor from overcurrent when running at lower RPMs, >> and help prevent stalls/excessive slippage on acceleration. These >> settings usually need to be significantly different from most VFD's >> default setting (which are usually configured for a 60hz >> motor.) >> >> Todd Zuercher >> P. Graham Dunn Inc. >> 630 Henry Street >> Dalton, Ohio 44618 >> Phone: (330)828-2105ext. 2031 >> >> -----Original Message----- >> From: Leonardo Marsaglia <ldmarsag...@gmail.com> >> Sent: Tuesday, March 07, 2023 10:05 PM >> To: Enhanced Machine Controller (EMC) >> <emc-users@lists.sourceforge.net> >> Subject: Re: [Emc-users] OT: Air cooled router spindle problem >> >> [EXTERNAL EMAIL] Be sure links are safe. >> >> Well, I tested it for almost an hour with no load at 15000 RPM and >> the temperature settled at 55ºC in the bottom side where the bearings >> for the tool holder are, and almost 65º in the body part where the stator is. >> According to one of the Chinese suppliers of these spindles, 75ºC >> it's a pretty common working temperature. I'm still waiting for a >> detailed answer from the factory. This time, the VFD worked fine, no >> whining with no rotor spin. Now I need to cut some wood while >> monitoring the temperature during the process and hope the temperature >> doesn't go too high. >> >> Anyway, I'm looking for new VFD drives just in case. From what I can >> tell the problem could be the VFD as Gene and Jon pointed out. >> >> I'll let you know how it goes when cutting wood again. >> >> Thanks to all for your help! :) >> >> El dom, 5 mar 2023 a las 18:11, gene heskett (<ghesk...@shentel.net>) >> escribió: >> >> > 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. >> > >> >> > > >> > > _______________________________________________ >> > > Emc-users mailing list >> > > Emc-users@lists.sourceforge.net >> > > https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%252> >> > > Fli%2F&data=05%7C01%7Ctoddz%40pgrahamdunn.com%7Ca716ced2cd8b45443 >> > > b1208db1fe039ab%7C5758544c573f47cebee96c3e0806fb43%7C0%7C0%7C6381 >> > > 38820129481532%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIj >> > > oiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=rj >> > > 6R%2BZb94rpPdzr%2F32kOery9rQ%2Ft47LLFaSdSWYo5h4%3D&reserved=0 >> > > sts.sourceforge.net%2Flists%2Flistinfo%2Femc-users&data=05%7C01%7 >> > > Cto >> > > ddz%40pgrahamdunn.com%7C7c75dca8021a427b281508db1f821107%7C575854 >> > > 4c5 >> > > 73f47cebee96c3e0806fb43%7C0%7C0%7C638138415730530106%7CUnknown%7C >> > > TWF >> > > pbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJX >> > > VCI >> > > 6Mn0%3D%7C3000%7C%7C%7C&sdata=s1%2FMmGIe%2BOIgMMj1IgKv6OTsDFxMuEk >> > > 7ms >> > > t4mMsD%2FGE%3D&reserved=0 >> > >> > 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. 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