KBAC 27D - saga goes on !

Rashid, I make this comment in utter ignorance about VFDs and motors:

is there by any chance a multi-lugged connector that the manufacturer would be plugging into a test rack to do the troubleshooting instead of actually connecting a motor to the same terminals you would use for a motor? A "test point", so to speak, for "electronic loading" with slightly different pathways than what you are using with the motor. I'm sure you see what I am suggesting.
 
Rashid, I feel for you bro. I've been where you are. I fought with my tools for a long time. Like you, I tried building my own grinder. I knew I couldn't live with a Craftsman 2x42 anymore but couldn't really justify the cost of a real knife grinder. I tried the "engineer it myself" variable drive system and got a big shock (not literally) when the NEMA 1 VFD I'd used blew up with a big flash and a loud bang! Like you, I even had a Jet 9x20 lathe that I quickly discovered wasn't rigid enough to do anything serious with unless I was willing to REALLY work at it and mod the machine.

Eventually I came to the conclusion that if I didn't want to spend all my time working on my tools instead of making knives, I had to invest in some stuff that someone else had already mostly debugged or was designed right to begin with. It cost a bit more, but made my shop life so much better :)

Both my KBAC-27D VFDs run Leeson motors as smooth as you could hope for. They're both hooked up to Beaumont Metalworks KMG-10 grinders that work flawlessly. This speaks to your comments about buying from a place that will give you support. I paid a bit more thant the lowest price around and bought my drives from Rob Frink partly because I had bartered for, or been given Leeson motors which is what Rob sells with the KBE drives, and partly because I was willing to pay a little more for the security of knowing Rob Frink would help me and take care of me if there was a problem. As you've seen in this thread, he's willing to go a long ways to help a guy, even if he's not a customer (yet). That kind of support is priceless and guys like Rob need to pay a mortgage and provide for their families too.

I've got a Minarik Bluechip II DC drive and 1hp motor on my Hardinge (Chinese 9x20 replacement). Unlike the KBE/Leeson drives on my grinders, I didn't install this system. It came on the lathe when I bought it. If you need, I can disassemble and see that parts are used the way it's wired now. It uses one single throw switch for main power, then a seperate dual throw, center off switch for forward and reverse with a rotary pot for speed control. 100% reliable in the two years I've owned it.

From your posts, it sounds like you're really passionate about your craft. I hope you can get pas this tool related frustration soon and get busy making what you want to.
 
JCaswell said:
Hmmm, getting past tool-related frustration ... what a nice thought.
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For tool users or junkies, there's never an end. My Bridgeport needs a DRO and power feed for the table and my surface grinder isn't a hydraulic drive automatic machine :(
 
The way the box is designed, I don't think there's an EZ way to attach a test harness to it. I am pretty sure I got the right wires connected to the right terminals.

The 9x20 will require some love. I have already converted it to Varispeed.
Today, will turn a beefed up topslide mount, add tumbler reverse AND may
be, just may be :), will beef up the cross slide to have 7/16x20 leadscrew.

Gonna be a BZ day ! Having the darn On-off-On switch blow on me don't help
at all, but I feel all warm and cozy knowing that Minarik is SOLID :) . Had to be to survive the accident. I aint buying another one from RatShack, will prolly drive down to my McMaster branch and get proper stuff

If I were an FTKM or in machinist trade, I'd prolly spring for other tools, but
I just enjoy making my own too much ! I constantly get distracted like that !


For cross-slide mount, I cut out 3.6 ~round out of 5/8 HRS (.625) and
then ground it (to better circle) on the HMG "NJ". Sure wuz fun as it ATE the metal at simply ridiculuos rate, running a $3 generic Norton belt from McMaster
 
Rashid, I wasn't trying to imply you connected it wrong. I was asking if there was a possibilty of a test point the manufacturer plugged into that then had a "wire crossed" by the time the circuit got to the terminals you plugged in to. A manufacturing glitch that isn't obvious because of a design flaw. It "appears" to test right on the test bench when there is actually a flaw downstream of the test point. It wouldn't be the first time.

I only mentioned it because you seem at wit's end to figure this out. It seemed to be a good time to consider the "fringe" possibilities. I ran into a problem as I describe in the lab with a $10K liquid pump. It didn't work right, out of the box. I sent the board back. The manufacturer said it tested right. Unfortunately, their "test point" was poorly designed and where they plugged into turned out to be a little too early in the circuit. They redesigned their diagnostic plugin point because of that, and revised their QC protocol. They tested the controller board electronically but never actually plugged the damned thing into the stepper motor connector.

Sorry for the intrusion. Good luck with your controller problem.
 
The guys that design the control schemes for the VFD's where I am working now and at the last place I worked say that it is only neccessary to tune the VFD's PID controller for motors over 5-10hp. Both of these places design and manufacture general purpose VFD's that are sold as a commodity, not "matched" to a particular motor. For a simple application like a grinder, it is not necessary to use a tacho or encoder on the motor to get the needed results.

I have looked in the KBAC manual and it does not have all the programmablility of the newer, digitally controlled VFD's. It also does not sound right to me that the KBAC VFD can be that "picky" about what motor it will work properly with. It is even less likely that both motors that Rashid has are types that the KBAC will not work properly with. KB does not look like they make really Micky-Mouse stuff.

It is hypothetically possible that the manufacturer is using instead of the output terminals, as Fitzo has suggested. If they really did this, the test points would be visible on the circuit board. However, it is difficult to justify doing this due to the cost of the extra parts and that it is really bad practice to not test at the actual output terminals. I have never seen this done in a manufacturing environment.

A last suggestion is to try new wires between the VFD and the motor. There may be a bad wire. Do this after checking the output of the VFD like I had described in my last post. It is not that hard to verify that small VFD's are working correctly.

Phil
 
pso said:
...

It is hypothetically possible that the manufacturer is using instead of the output terminals, as Fitzo has suggested. If they really did this, the test points would be visible on the circuit board. However, it is difficult to justify doing this due to the cost of the extra parts and that it is really bad practice to not test at the actual output terminals. I have never seen this done in a manufacturing environment.
......

Phil
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That's interesting, Phil. The pumps I'm speaking of were extremely accurate high-pressure (200-5000PSI), low flow (0.2-5.0mL/min), with several feedback controls from lab instruments called High Performance Liquid Chromatographs. I had them from several manufacturers and all had one or more terminal blocks that the field guys would come in, set up their little interface box, hook it to their laptop, and measure all sorts of stuff for diagnostic work. Seemed common on any number of high dollar instruments, now I think about it. I just even had a visual memory flash thru the old head of one of my first HPLCs with one of those early Compaqs-in-the-carrycase being used by Norm the field engineer with the 50's Brylcreem hairdo....LOL

Perhaps it's just more specific to overpriced lab equipment?

Apologies for the OT. 'Luck with your controller, Rashid.
 
Fitzo

It sounds like the test points that you are talking about are the low-level speed, current, voltage feedback points that the technician was hooking up to. The encoders and tachometer feedback signals are really only needed for applications where extreme accuracy or where synchronization of multiple motors is required. It sounds like the equipment that you had in your lab qualified as such.

Whenever I have heard of a drive being optimized for a particular motor in a particular application, especially ones under 10hp, the optimization was really for the characteristics of the load placed on the motor, not the motor itself. The motor was probably also optimized for the load too. The main objective of all this optimization is to keep the cost down; ie. take out functions or excess capacity that is not needed for that particular load.

Phil
 
Phil, I'm sure you're correct. My "electronics skillset" is limited to removing the case, disconnecting the terminals, removing board and sending to the guy who knows what he's doing. If the field tech's there, he can do all that. :) With the directions in hand I was able to wire in two VS DC setups for grinders and adjust trimpots; that's about my limit. Fortunately, it was relatively problem free except for adjustments. :o I had a situation where one would start up, then sort of cut out and slow slightly, then restart with a "thunk" constantly. The problem was resolved by adjusting one of the pots, and I've tried to remember which without success. It has struck me that if it happened with rapid frequency it would have made the motor shake like heck.

I really had no business in this discussion but felt bad for Rashid that this was so aggravating for him and thus offered a remote possibility to inspire creative thinking outside the box. I hope he finds the problem. It's great to have the help of those of you who know what they're doing.

Have a good day, folks! :thumbup:
 
I wish I had seen your request earlier. I would be glad to help anyone with a KB drive issue. With vibrations caused by the drive you must turn the COMP pot down. Expecially with Premium effient motors.
 
electricmotortech said:
I wish I had seen your request earlier. I would be glad to help anyone with a KB drive issue. With vibrations caused by the drive you must turn the COMP pot down. Expecially with Premium effient motors.
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I understand you are searching for VFD related posts, but have a look at the date to that last post in the left of the blue bar.
October 2006.

5 years ago.

Either he's got it figured out, or given up.
 
Actually, ironically, I read this post yesterday or the day before, and when I went out and hooked my VFD back to my grinder after using it to test some scrap yard motors, I had the exact same described issue. =\


So I think this popped up for a reason. I was pretty sure I somehow fried my VFD, but now I think something in the software has been modified. I had to turn the COMP pot all the way down, from the default which is supposed to be 160%, and then I had to crank the CL pot all the way up. Without doing that, the motor would run very erratically, which I guess was slippage, and would bounce around like crazy.

I'm still a bit concerned that it's not running ideally, although I did some grinding last night and it worked fine. Reading through the manual, it talks about clearing any error (one of the motors I tested didn't work properly, and would cause the VFD to shut down), before re-starting it, but I can't figure out how.
 
Did you check your ground? I read the whole post since I also have a KBAC VFD. I do some electronic diagnosing/troubleshooting in my job and it sure seemed more like the OP had a ground issue to me in my limited knowledge. Especially since it checked out when he sent it back and also found the problem occurring with a different motor.
Grounding issues cause lots of problems that can be hard to diagnose.
 
Brian Ayres said:
I also have a KBAC VFD.
it sure seemed more like the OP had a ground issue to me in my limited knowledge.

Especially since it checked out when he sent it back and also found the problem occurring with a different motor.
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I had the same issue on a motor and KBAC-27D
When running on the bench with default settings & bare motor shaft it would jerk and stutter.
Once I put a drive wheel on it, it smoothed right out.
 
This one was running the good motors fine even on the bench, but after the bad motor, it started shaking them all hard, that's including my motor mounted on my grinder, with or without a belt on it. You could watch the fan increase and decrease in speed.

As far as the grounding issue, I think that's fine, and like I said, adjusting the CL and COMP pots got it back into working order, so who knows. I will probably get on the phone and try to get some support on it, since it's under warranty. I will check the ground again, it's possible there's a break in the cord somewhere, but it's definitely still grounded in the VFD.
 
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