Southwest Industries Prototrak DPM conversion

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CRM
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System Serial Number: A900171

Re: Southwest Industries Prototrak DPM conversion

Post by CRM » Sat Feb 04, 2017 6:03 pm

While working thru section 5.10 (wiring spindle) of the ALLIN1DC manual, I came across a conflict. According to the cover on the ALLIN1DC and the manual, input 12 should be assigned to the Hi/Low gear switch to work with the default PLC program. So I wired it that way. When I bring up the real time I/O screen and cycle the switch, it does change the state of input 12, but I noticed that according to the CNC11 software that the input is labeled "zerospeed" and input 13 is labeled "spin low range".
QUESTION: What is the preferred way to configure the spindle low range switch? Move the switch to input 13, or change the PLC to look for the switch at input 12? At some point in the future I intend to add a spindle encoder and the rigid tapping option, if that factors into the decision. Moving the wire to input 13 would take all of 30 seconds, but would be in conflict with the silkscreen labeling and the documentation I've been following.
Dean Jahnz
Cannon River Machine

cncsnw
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Re: Southwest Industries Prototrak DPM conversion

Post by cncsnw » Sun Feb 05, 2017 4:38 pm

Toss a coin. The I/O assignments are not cast in stone, in spite of the silkscreen on the cover plate.

I have been leaning towards INP13, because on some machines (Bridgeport V2XT for example) the spindle high/low range detector is a PNP proximity sensor, which then needs to be wired to a current-sinking input bank. Moving it up to INP13 allows that bank to be configured current-sinking, without affecting INP9, INP10 and INP11 (which by typical convention are current-sourcing).

Rigid tapping does not require any additional I/O devices or PLC logic; only a spindle encoder and CNC11 software parameter settings.

If you don't have any other reason to modify the PLC program logic, then I would advise moving the wire to INP13. If you are going to have a customized PLC program anyway, and you would prefer that the silk-screen labels be accurate, then you may as well redefine the SpinLowRange input as well.

CRM
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System Serial Number: A900171

Re: Southwest Industries Prototrak DPM conversion

Post by CRM » Sun Feb 05, 2017 10:26 pm

After hair-pulling frustration yesterday, I'm all smiles today. Yesterday was to be the big milestone of putting power to the servos. All checks passed with flying colors up to that point. But after pulling the motors off the machine and trying to jog them under power for the first time, both the X and Z servos would spin violently for a second and throw a SV_Stall alarm. :( The Y axis would jog fine. (See, this is why they tell you to physically uncouple the servos from the machine until you successfully jog them!) I looked thru all the parameters trying to find a difference between the settings for X and Y that would explain the problem, but everything was set exactly the same. While laying sleepless in bed that night mulling over the problem, it occurred to me I never noticed which way the X and Z motors spun before faulting out. So today I checked and sure enough, while the Y axis rotated in a controlled manner CCW when jogging Y+, Both the X and Z motors spun violently CW when jogging to the positive direction. (at this point ALL axes were set to "N" for motor reversal in the motor setup page of CNC11). So, duh, the position encoder was saying out of position, but the ALLIN1DC was trying to correct it by moving even more out of position. The servos are DC so, on a hunch, I decided to swap the power leads to the X servo at the ALLIN1DC board (because that was the easiest spot) to invert the direction the motor would spin from the commands given by the ALLIN1DC. I powered up the control, tried again to jog, and VIOLA!, no more alarms and runaway servo. Not only that, but the shaft was turning the correct direction and the DRO was counting the correct direction. The same fix worked for the Z axis also.
Apparently, when I sent my servos to Scott 6 years ago to have him outfit them with new encoders (the old ones had too low of resolution to work with the ALLIN1DC) and pre-wire them for the retrofit, two out of the 3 servos were mis-wired (Black and Red leads coming from the motor windings were switched) To fix, I removed the pins from the Molex connector on the servo side, and slid colored heat shrink tubing over the leads as far back as I could to change the wire color, then reinstalled the pins in the opposite locations of the plug. So, in the future if ever the servos need maintenance, nobody is scratching their head wondering why Black was mated to Red, and vice versa. And, obviously, I moved the power leads back to the correct spots at the ALLIN1DC.
Because I had to reverse the X and Z axes motor rotation due to the physical mounting of the servos to the machine (not because of the incorrect color coding of the motor wire leads) I had to change the limit switch assignments in CNC11, and then their actual input assignments into the ALLIN1DC. The changes in the CNC11 software are pretty well explained in the manual, but there was no mention of having to swap the switches in regard to the limit switch inputs to the ALLIN1 board. I remember reading about having to do this somewhere -- maybe a technical bulletin? -- so when the I couldn't move off the limit switch after tripping it, I had a good idea of what the problem was. Just wish it would have been explained a little better in the manual. (And now I know why the inputs are labeled Axis1 CW & CCW instead of Axis1 + & -) I made sure to change how I labeled the wires also. :)

Sure feels good to be able to power up the machine and hit cycle start to successfully home the machine! :D
Dean Jahnz
Cannon River Machine

Centroid_Tech
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Re: Southwest Industries Prototrak DPM conversion

Post by Centroid_Tech » Mon Feb 06, 2017 12:44 pm

If an axis takes off on you when you either energize that axis or try to move that axis, then it most likely means that the motor power wiring is not correct. What is happening, which you have explained, is that the control is trying to move that axis in one direction but it sees the encoder feedback going in the opposite direction so it keeps trying to compensate for it until eventually it gets into a fault state, typically Position Error. This will NOT be resolved by setting the Direction Reversal field. The easiest way to resolve this will be to do what you did and swap the motor power wires. Once you get the motor to move in a "controlled" fashion then if the values in the DRO for that axis are moving in the incorrect direction, then that is when the Direction Reversal field will be used which is described in the attached tech bulletin.
Attachments
137 Setting Direction Reversal.pdf
(27.3 KiB) Downloaded 8 times

CRM
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System Serial Number: A900171

Re: Southwest Industries Prototrak DPM conversion

Post by CRM » Mon Feb 06, 2017 11:31 pm

Good progress so far, but I have a question: Years ago when I first worked with Scott to identify my SWI mystery servos, he told me I needed to step down the AC with a transformer, which I bought as part of the kit. The original specifications for the machine said it had a Max federate of 150 IPM. I have finally gotten to the point where I could run autotune to set the max federate, but it comes up with only 95 IPM...doesn't seem right since the servos and machine iron haven't changed. The servo load bar never peaks above halfway when jogging at max federate override from a dead stop, so it would seem I still have some headroom.
I noticed a label on the servos which had previously been covered by the Drive that was originally attached to each motor. (See picture)
20170206_184554.jpg
servo motor label
It would seem to me that the servo has a max RPM of 2200 and max voltage of 160. Because of the transformer, I am feeding the capboard 83vac, which is only giving me about 120 vdc. Is that the reason I can't attain the 150 IPM federate? Line voltage is approx. 120-121 vac, so my motors are rated too low to do direct rectification, correct? (I would need 180 vdc rated servos, right?)

Is there something else that might be limiting my max federate that I should check? I am at chapter 6.7 of the ALLIN1 manual (page 58) I'm guessing I don't want to start on the manual tuning of acceleration if I still need to improve the max federate values.
Dean Jahnz
Cannon River Machine

CRM
Posts: 40
Joined: Mon Jan 03, 2011 11:54 pm
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System Serial Number: A900171

Re: Southwest Industries Prototrak DPM conversion

Post by CRM » Sat Feb 11, 2017 2:03 am

20170210_175211.jpg
Not what I wanted to see when homing the machine this afternoon in preparation for some servo tuning. But since I'm no where close to running a job, I let it slide. During my attempt to tune servos (which is going miserably) I discovered WHY that error came up...
20170210_230303.jpg
Turns out, Southwest Industries uses a ballscrew timing belt pulley with a built in slip clutch. That's how they get away with allowing the machine to thump into the hard stops without causing damage. They get away with it since they were reading table position directly with "Trak" encoders--micro knurled wheels that roll along the box ways and table to measure movement. (a poor man's glass scale system)
Slip clutches are obviously unacceptable for a system that relies on servo motor encoder feedback for position, so I am going to have to machine a couple of hubs to mount the pulleys solidly to the ballscrew shafts for the X and Y axes. Fortunately, the Z axis DID rely on the servo encoder to track position, so that pulley is mounted solid to the ballscrew.
Sigh. More work.
Dean Jahnz
Cannon River Machine

cnckeith
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Re: Southwest Industries Prototrak DPM conversion

Post by cnckeith » Mon Feb 13, 2017 4:06 pm

CRM wrote:Good progress so far, but I have a question: Years ago when I first worked with Scott to identify my SWI mystery servos, he told me I needed to step down the AC with a transformer, which I bought as part of the kit. The original specifications for the machine said it had a Max federate of 150 IPM. I have finally gotten to the point where I could run autotune to set the max federate, but it comes up with only 95 IPM...doesn't seem right since the servos and machine iron haven't changed. The servo load bar never peaks above halfway when jogging at max federate override from a dead stop, so it would seem I still have some headroom.
I noticed a label on the servos which had previously been covered by the Drive that was originally attached to each motor. (See picture)
20170206_184554.jpg
It would seem to me that the servo has a max RPM of 2200 and max voltage of 160. Because of the transformer, I am feeding the capboard 83vac, which is only giving me about 120 vdc. Is that the reason I can't attain the 150 IPM federate? Line voltage is approx. 120-121 vac, so my motors are rated too low to do direct rectification, correct? (I would need 180 vdc rated servos, right?)

Is there something else that might be limiting my max federate that I should check? I am at chapter 6.7 of the ALLIN1 manual (page 58) I'm guessing I don't want to start on the manual tuning of acceleration if I still need to improve the max federate values.
if you retifiy 110 vac that yields around 155 vdc.. if the motors are rated for 160 vdc,, i would go for it.. voltage = speed higher voltage, higher max rpm the motor will spin.
try it.. and rerun autotune.
i've pumped 155 vdc into some SEM servos rated at a max of 140 vdc and they have been running for a few years now, they don't get hot.

also can you post a "report.txt" or report.zip from the control and i can take a look at your configuration settings.

CRM
Posts: 40
Joined: Mon Jan 03, 2011 11:54 pm
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System Serial Number: A900171

Re: Southwest Industries Prototrak DPM conversion

Post by CRM » Mon Feb 13, 2017 9:34 pm

Keith, Thanks for the reply. When checking my mains voltage, I'm getting 120 volts, not 110, I thought that would be too high. But I assume the Capboard is rated to handle direct rectification, so I am going to temporarily hook directly (bypass the transformer) and see what the actual DC output is. I do also still have the drive boards that were originally mounted directly to the servos. Not sure why SWI chose to do it that way, other than they could tune it at the factory and use a "plug and play" approach to unit repair? At any rate, it should be possible to take a peek inside and see what AC voltage they were using, right? In the original setup they were running AC to each independent drive board attached to it's associated servo.
Is temperature the only real limitation to going a little above rated voltage? If so, how "hot" is too hot? I don't have the formula in front of me, but if I remember right, 120vac yields about 177vdc. Do you think the engineers left a little headroom on their 160vdc rating? ;)
I will post up a report as you asked, but it will probably be a couple days before I can get back out to the shop. I've already messed with the tuning parameters manually, except for the Z axis; that one is still where autotune set it. However, all the servos are very "buzzy" when sitting idle holding position without load against them.
Also, as I indicated in the previous post, I have a little lathe work to do to get rid of some slip clutches that I believe are the culprit for the homing errors. I think I better tackle that first and get the servos reattached to the ballscrews.
Dean Jahnz
Cannon River Machine

CRM
Posts: 40
Joined: Mon Jan 03, 2011 11:54 pm
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CNC11: Yes
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System Serial Number: A900171

Re: Southwest Industries Prototrak DPM conversion

Post by CRM » Wed Feb 15, 2017 1:28 pm

Keith--
here is the report.
I have a problem though. I went to temporarily feed the capboard with 120vac line voltage (bypassing the transformer), but I kept the transformer powered on the primary side to provide the 24vac for the E-stop circuit. I did disconnect and tape off the green 83vac output from the transformer that fed the capboard. I made two short jumpers to feed the capboard from the terminal strip, stacking the leads on the terminals that feed the primary side of the transformer. When I applied power, it instantly tripped the 15a circuit breaker. Changing back to the original configuration, everything was fine. Is there something inherently wrong with that method for a temporary test? Is there too much inrush current feeding the capboard and the transformer directly? (If the test would have returned favorable results, I would have replaced the main transformer with a small one I have from a HVAC system to supply only the 24vac for the E-stop circuits.)

The information on the big blue cap is:
360A 85*C
12000uF 160v
11S13L 07
+ POSITIVE

and the Capboard has this silkscreened in one corner:
CAPBRDLO
030203

Looking for some help on how to proceed.
Thanks!
Attachments
report_0301110110_2017-02-15_10-50-21.zip
system report
(5.01 MiB) Downloaded 8 times
Dean Jahnz
Cannon River Machine

cnckeith
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Re: Southwest Industries Prototrak DPM conversion

Post by cnckeith » Fri Feb 24, 2017 10:22 am

Is temperature the only real limitation to going a little above rated voltage? If so, how "hot" is too hot? I don't have the formula in front of me, but if I remember right, 120vac yields about 177vdc. Do you think the engineers left a little headroom on their 160vdc rating? ;)

<<<voltage limits of dc motors are the winding insulation, winding design and the brush and commutator design, if you fry a motor and it shorts out it will fry the transistors on the in allin1dc. so be careful here. the safe thing to do is adjust the ac input voltage so the DC output voltage is lower than the maximum rating of the motor.>>>



I will post up a report as you asked, but it will probably be a couple days before I can get back out to the shop. I've already messed with the tuning parameters manually, except for the Z axis; that one is still where autotune set it. However, all the servos are very "buzzy" when sitting idle holding position without load against them. << tuning process... 1.) set base PID parameters to match motor , 2.) tune movement with the built in tuning scope in the centroid cnc software, watch the video or sign up for a teamviewer session and we will do it for you. 3.) then you can adjust Kd very carefully to calm down the motor when holding a position. typically the buzzing when holding occurs when the servo motor has a large mechanical advantage over the mechanical system that it is attached to. this commonly happens on knee mills belted 2:1 to the servo motor. Kd will add software damping. >>>

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