Robust VFD Question

[Clay Fails]

Hello all,
I am turning with a Robust American Beauty with the 3 HP motor. It is fitted with a Toshiba VF-S15 VFD.

After turning hundreds of bowls in the past 4 years, recently the drive has begun cutting out under load. I don't mean belt slippage, I mean complete electrical cutout.

Has anyone else had this issue, and if so, what parameter on the VFD did you adjust? I'm guessing it has to do with amp draw, but have not yet dived into the parameter list.

Please don't suggest I contact Robust, because I did and the response was maybe I should learn how to turn. I would have given that some thought had I not already successfully turned a cajillion bowls and this is a new phenomenon.

thanks in advance,

Clay

[Jeffrey J Smith]

Clay - I’ve got the same configuration but, with a lot of use over 6+ years, have experienced no problems so far with the Toshiba VFD. Surprised to hear of the response from Robust, they’ve always bent over backwards to be helpful on the few occasions I’ve asked.
Have you tried letting the VFD reset - power completely off, unplug, cycle all switches, let it sit for 15 minutes before powering up again? Checked your 220 circuit to make sure its not fluctuating?

[allen thunem]

call brent at robust

[Clay Fails]

Jeff, thanks for the response. Yes, I've tried all the re-setting, turning off, etc. Not sure how to check my 220 V circuit though. I have found the issue to be sort of random, but usually occurs when cutting hard wood like say maple burl. I'm using sharp tools and same technique as for all bowls. Once the issue starts, it seems to linger for a period of time. In other words, VFD trips out. I restart, trip out, etc. Then I might for several bowls and days with no issue. Then it's back again.

[Clay Fails]

Allen, thanks for the response. I tried that, and while he was cordial, he was more interested in getting me to take lessons from a mentor than discussing why the VFD is tripping out. I have to believe the 3 HP motor on this lathe can handle way more torque than the VFD is allowing. I have some experience adjusting VFD's on water pump motors, and in my experience it can just be a parameter needs adjusted. I'll figure it out on my own. I was just hoping maybe someone else has had this issue.

[Roger Chandler]

Brent is a stand up guy, and stands behind his product. Are you regularly using extra heavy cuts on your roughouts? I have stalled a 3 hp American Beauty, on more than one occasion, but unless you are really hogging off wood with heavy cuts I wonder about things. Just from an experience standpoint, I have a lot of it, with a number of different lathe units. Maybe you could fill in more details on how you are working on the lathe, so we might have some ideas on how to help you.

[Clay Fails]

415533415534415535415536415533Roger, thanks for the reply. I have attached images of the maple burl that tripped the VFD today, along with some of the tools I use and my grinding wheels. I have 6 CBN wheels and the Tormek system, and gouges from Thompson, D-Way, Carter, Mahoney, etc. i know how to sharpen a tool so that is not an issue. On this particular maple burl I first mounted the piece between centers and turned a tenon on one side. I roughed the outside at that time, then reversed and put the tenon in a Vicmark 4 jaw chuck. The piece then sat on the lathe for 3 or 4 days until today when i finally had time to work the inside part. That's when the VFD started kicking out. Again, I'm not talking about stalling the motor with a heavy cut or squealing the belts. I'm talking about an electrical cutout, which to my mind, has to be the VFD trying to protect the motor based on overload of some input (e.g. amp draw). Once this failure mode starts, it cuts out on just about every cut. I might turn the lathe off, unplug it, switch the breaker, etc. and maybe it will be good for a day or two. Then BAM, back again. This typically only happens with fairly hard woods, like the burl in the photos, not green wood. I still have to believe the motor is capable of significantly more load than the VFD is allowing to transfer to it. Maybe there's more to this issue, and if so I'm all ears.

[John K Jordan]

Allen, thanks for the response. I tried that, and while he was cordial, he was more interested in getting me to take lessons from a mentor than discussing why the VFD is tripping out. ...

Perhaps a simple way to test the VFD: Take your piece in the chuck to another turner with a known healthy lathe and see if the problem goes away.

JKJ

[david privett]

If you think you are trying to pull to many amps thru the vfd ,do you have or know someone who has a inductive amp meter (they can be had a harbor freight and not pricy ) you will have to make a short extension with just a single layer of wire insulation to go between the plug and the reciepticle . Then just clip on the probe on the hot side and turn away and kinda watch the meter . You will have to test both hot legs. That should tell you exactly what is going on amp wise.

[Clay Fails]

David that is a good idea. I do have a clamp style amp meter but would need to construct a line splitter for 240v ac. I may give that a try. The other way would be to set the vfd to display amps and have someone view the LCD display while I turn.

[Eugene Dixon]

or use a GoPro/cellphone video to record amps?

[Reed Gray]

Um, are you on high speed range or low speed range. I have one of the early Beauties, and it has 3 speed ranges, which I prefer. I use the middle range almost exclusively. Enough torque for heavy roughing and coring, and speed up to 2200 for smaller bowls. Brent helped me tweak the converter, which is a Toshiba. I wanted lower speeds on the low range for sanding. I do get a bit more belt squeal when turning. I am guessing that the belt is getting a bit worn after 10 years.

robo hippy

[David C. Roseman]

Clay - I have no experience with that VFD, but isn't it throwing an error code when it trips under load?

Is this the drive that you have: https://www.toshibadrivesandmotors.com/product/vfs15s-2022pl-w1/

If so, I'm also assuming you've already downloaded the user manual for it. But here's the direct link:

https://www.toshibadrivesandmotors.com/wp-content/uploads/2017/02/S15-IO-Manual.pdf
(https://www.toshibadrivesandmotors.com/wp-content/uploads/2017/02/S15-IO-Manual.pdf)
See pp. 344-352 in the pdf for troubleshooting of a trip.

Also, this might be helpful: http://www.manualsdir.com/manuals/212570/toshiba-tosvert-vf-s15-series-option-unit-function-e6581830.html?page=31





(http://www.manualsdir.com/manuals/212570/toshiba-tosvert-vf-s15-series-option-unit-function-e6581830.html?page=31)

[Clay Fails]

Reed, mine is the two-pulley setup and I'm on the "low speed/high torque" setup.

[Clay Fails]

David, thanks for the links. Yes that is the drive in question. I hope to find time this weekend to troubleshoot the issue and will report back on my findings.

Thanks again to all for your input.

[Jason Edwards]

If your drive is kicking out, you should be getting an error code. If you have the error code, maybe Robust could provide you more insight on any changes needed. If you're not getting an error code, you probably don't have a VFD problem, but may have some other intermittent electrical problem, like a funky switch. That may also explain why your problem seems to be intermittent.

[Brice Rogers]

If your drive is kicking out, you should be getting an error code. If you have the error code, maybe Robust could provide you more insight on any changes needed. If you're not getting an error code, you probably don't have a VFD problem, but may have some other intermittent electrical problem, like a funky switch. That may also explain why your problem seems to be intermittent.
Jason, you may be correct on this. In addition to a funky switch, some motors have a thermal cutout switch buried in the windings. Some are self resetting.

I look forward to seeing what Clay discovers when he has time to trouble shoot this some more.

[Bert Delisle]

Hello all,
I am turning with a Robust American Beauty with the 3 HP motor. It is fitted with a Toshiba VF-S15 VFD.

After turning hundreds of bowls in the past 4 years, recently the drive has begun cutting out under load. I don't mean belt slippage, I mean complete electrical cutout.

Has anyone else had this issue, and if so, what parameter on the VFD did you adjust? I'm guessing it has to do with amp draw, but have not yet dived into the parameter list.

Please don't suggest I contact Robust, because I did and the response was maybe I should learn how to turn. I would have given that some thought had I not already successfully turned a cajillion bowls and this is a new phenomenon.

thanks in advance,

Clay
Just a thought, after reading all the thread comments and rereading the original post it appears to me that one thing that could contribute to the issue described is a loose connection. When turning hard woods there may be a high frequency vibration that doesn't occur with green wood. Because this issue seems to have surfaced after several years of use and appears to be intermittent that leads me to think loose connection not fall out loose but just enough to cause the smarts in the VFD to recognize. In industry we used to do a PLC IO board tighten /check every couple of years, amazing how many points were found slightly loose.

[Tim Tucker]

Have not seen anyone ask this....so - Are you using a dedicated or shared electrical circuit? If shared...what else is on that circuit...could that create enough of a temporary load to create the non-errorcode stalls?
Hope that helps...
T

[terry mccammon]

Second the switch suggestion. I can and do stall or at least slow my AB when running at slower speeds and taking a big bite. That is a mechanical stall, I have never tripped the drive. However, from time to time, both the start/direction switch and the stop button get gunked up. This results in a refusal to start if it is the switch or a sudden stop if the issue is the stop button. Blowing out the switch fixes the issue. The root cause is dripping wet, green wood leaving the lathe, the control box, and me pretty wet.

Also second Brent English as a stand up, genuinely decent guy.

[Eugene Dixon]

Does your pendant stop switch have a boot (cover) or is it just the a bare push button? My AB had intermittent issues of not starting and then it wouldn't start. Brent correctly/quickly diagnosed it as the switch and talked me through the trouble shooting (had to remove the spindle lock switch and verify it was working properly). Brent sent a replacement switch since I was under warranty. Obviously not the same as your problem. but you might consider opening the pendant and seeing if it is 'dusty' in there. And maybe blow out the head stock?

[John Hart]

I know nothing of your VFD circuitry....but the behavior you describe is like that of a bi-metal thermal protector....which I do know a bit about. They are designed to cut out when high currents are sustained. They have a little heater that heats up the bi-metal disc....and then the disc snaps. After cooling down, it snaps back into place. If you apply high current again, it is already heated up and will snap quicker.
Either way....your circuitry is experiencing a high current condition.
Measuring the current is the best start

[Clay Fails]

Well, again I thank you all for the thoughtful input.
After several days of turning with no issues at all, again today the motor started tripping out on a fairly hard maple burl. When this happens the Toshiba VFD LED displays 0.0, which I believe is the default status when the motor is not running. From reading the Toshiba literature it looks to me like if in fact the drive trips out, the error code would automatically display (i.e. i would not have to scroll through the menu to find the error code).

so if all that is true, maybe the drive is not in fact tripping out at all. Could this be a motor internal thermal protection circuit that is cutting out? John Hart's comments have me wondering because once this issue appears, it tends to continue indefinitely until I walk away and come back later. That might indicate some thermal issue of some kind.

So any ideas on how I should proceed? If the Toshiba is tripping the error codes must be saved somewhere but I haven't yet figured out how to retrieve them.

[Clay Fails]

Just a thought, after reading all the thread comments and rereading the original post it appears to me that one thing that could contribute to the issue described is a loose connection. When turning hard woods there may be a high frequency vibration that doesn't occur with green wood. Because this issue seems to have surfaced after several years of use and appears to be intermittent that leads me to think loose connection not fall out loose but just enough to cause the smarts in the VFD to recognize. In industry we used to do a PLC IO board tighten /check every couple of years, amazing how many points were found slightly loose.

Bert, thanks for the idea. Do you know which connections I would check for looseness? Are we talking about the leads at the motor, or at the VFD, the on/off switch or all of the above?

[Clay Fails]

Have not seen anyone ask this....so - Are you using a dedicated or shared electrical circuit? If shared...what else is on that circuit...could that create enough of a temporary load to create the non-errorcode stalls?
Hope that helps...
T

Tim, it's a dedicated circuit. The only other 230/240V machine that runs while I'm turning is my dust collector, but that's on a separate circuit.

[Clay Fails]

Does your pendant stop switch have a boot (cover) or is it just the a bare push button? My AB had intermittent issues of not starting and then it wouldn't start. Brent correctly/quickly diagnosed it as the switch and talked me through the trouble shooting (had to remove the spindle lock switch and verify it was working properly). Brent sent a replacement switch since I was under warranty. Obviously not the same as your problem. but you might consider opening the pendant and seeing if it is 'dusty' in there. And maybe blow out the head stock?

Eugene, thanks for that thought. A couple years ago Brent at Robust sent me the new pendant assembly because the original one was sticking as you note. Since then the switch has performed flawlessly. So I don't think that's my problem but at this point I"m not sure of anything.

[Chris A Lawrence]

Check all the high voltage connections that you can. Wire and connections heat up and cool down alot. This can cause expansion and contraction of mechanical connections causing them to loosen up. My other hobby is home brewing. I have an electric system that uses 220v elements. After 4 to 6 brew sessions i go in and tighten up all the screw down connections and check the spade connections. You would be surprised how much the screw down connections loosen up and there is no vibrations in my control panel.

[Bill Boehme]

Clay you insinuated that the inverter is holding back the motor from reaching it's full potential. Do you have any relevant data to substantiate that statement? I'm an electrical engineer with quite a bit of experience in various types of systems involving motor control. I've had a Robust AB for eight years so my model is the one that preceded yours, however, as far as I know the inverter is the same, but the motor is a different frame size to work with the new style headstock casting. I'll clear up one thing right away ... the inverter isn't limiting the performance of the motor. And, I would say that the inverter isn't failing because as a rule digital electronics either work right or they don't work at all. I'll offer a couple thoughts ... some might have already been discussed.


There is always a possibility of the motor failing. The probability is very low, but not zero. Mechanical devices eventually fail, but the Leeson and Baldor motors used by Robust are high quality. The most likely conditions for early failure are extended periods of heavy load at any speed, but especially minimum speed operation under heavy load which leads to the motor overheating.
The inverter might be cutting out when it's temperature gets too hot. There are numerous possible reasons:

Heavy load operation for extended periods of time
High ambient temperature
Dust and shavings blocking the airflow around the inverter
Inverter cooling fan not working or periodically stopping ... you should be able to hear the fan running
Try blowing all the dust out of the inverter as well as its electrical enclosure


The motor has a thermal cutout switch so it might not have anything at all to do with the inverter ... it might simply be the motor getting too hot
The display on the inverter is the frequency so 0.0 would be seen when the lathe is stopped or if the speed control pot is turned all the way down. Intermittently going to zero could be the result of an intermittent FWD/REV/STOP input or an intermittent open circuit from the speed control pot.


When I got my Robust I also got a full users manual on CD for my Toshiba inverter. I have spent quite a bit of time perusing it. I would strongly recommend that you don't go diddling with any of the settings unless you thoroughly know what you are doing. Changing one thing often has a ripple effect on other parameters. However, it won't hurt to read through some sections of the manual to at least have some familiarity with it. There are some settings that can be safely changed such as ramp up and down times.

As far as lessons are concerned, I don't know anybody who isn't a better turner as a result of taking lessons. I've been turning for nearly sixteen years and still jump on an opportunity to take lessons ... this year it was with Michael Hosaluk.

[Ted Baxter]

Clay is your lathe past the 7 year warrenty or does the warrenty not cover electrial issues?

[Jason Edwards]

I'm going to reiterate my note above, if you're not getting an error code, you probably have a switch problem. I suggest you call Robust and see if they can help you trouble shoot it.

[Clay Fails]

Update on this issue: Yesterday Brent from Robust graciously reached out to me and offered the following possibility:

Since you’ve confirmed the inverter is not tripping out, I suspect it’s the switch inside the headstock that determines if your spindle lock is all the way down. Sometimes with heavy cuts, the spindle lock will jiggle inside the headstock and tickle the switch enough to shut off the machine, but not enough to engage the spindle lock of course. When the headstock settles down, the spindle lock sets back down on the switch and the lathe can restart. If this is the problem, the solution can be found in your manual, the very first paragraph:

Failure to Start, try these six steps in order:
1) Push down on the spindle lock: it may have moved upward just enough to open the internal safety switch but not
enough to lock the spindle. If the problem happens frequently, try tightening up the screw that puts tension on the
spindle lock. You’ll find it in the threaded hole directly below the spindle lock knob

This explanation sounds plausible and may well be the issue I've been experiencing. Unfortunately I have flown the coup to southern climate, so it will be awhile before I'm back in my shop and able to test this theory.

Thanks again to all who have offered valuable input, and to Brent for his recent help.