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August 21, 2017, 07:27:46 am


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Author Topic: To those who are familiar with Servo Motors.  (Read 942 times)
Dragonfly
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« Reply #15 on: May 27, 2017, 22:36:11 pm »

Yet you do not say a word about the indicator lights on the drivers. If there is no servo tracking error the problem may be somewhere else, not in the driver-motor group.
Saying this I also take into account that the Z-axis is moving correctly. Also wrong encoder ppr will produce larger errors in positioning and they will grow dynamically while moving.
« Last Edit: May 27, 2017, 22:39:44 pm by Dragonfly » Logged

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Bubba
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« Reply #16 on: June 18, 2017, 14:17:21 pm »

Yet you do not say a word about the indicator lights on the drivers. If there is no servo tracking error the problem may be somewhere else, not in the driver-motor group.
Saying this I also take into account that the Z-axis is moving correctly. Also wrong encoder ppr will produce larger errors in positioning and they will grow dynamically while moving.

Finally got to the machine..

So, after making a test cut and measuring the test piece the results was pathetic (0.015" oversize), then checking setting of the encodes, turn out they were set to 256 PPR (way low). Not what I thought and posted in previous post (sorry), Changed the setting of the encoders to 500 PPR and the drivers to default settings as Dave suggested. After making another test cut the final dimensions were 0.004" oversize, so it is obvious thats where the problem lays.. Because it was so hot in the shop and the day was coming to a end, we called a day with understanding those encoder setting should be set to 1024 PPR which should be the final setting for it. Those servo motors are very quiet and responsive, no fault LED's coming on.

The machine (Bridgeport Boss 10 ?) mechanically is very solid, no backlash at all to speak of, so the 1024 PPR encoder setting should be it.

Fly,

To answer your question about the LED indicators, before there was no way to see it because the drives were jumped for test purposes for continuous enable state (5v and ERR terminals connected with jumper wire) Now, those drivers are connected for normal running condition, and the drives will fault when something goes wrong. During the last test cut only green LED's were lit with no errors present..

Final report coming when the project completed. Ti'll then, Thanks to all who helped with answers/suggestions. 
 Cheesy
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dave benson
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« Reply #17 on: June 18, 2017, 14:29:24 pm »

HI Bubba
Glad to here your getting somewhere, remember to set Mach3 (on the motor tuning page) as well.


* motor setup Capture.PNG (70.7 KB, 686x422 - viewed 22 times.)
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Bubba
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« Reply #18 on: June 18, 2017, 21:27:22 pm »

Oh, yes.. And this as well  Grin Grin


* Steps.JPG (39.72 KB, 551x409 - viewed 20 times.)
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Dragonfly
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« Reply #19 on: June 18, 2017, 22:36:25 pm »

If there are no servo errors then you may want to pay attention to the driving screw pitch related to encoder PPR. So that Mach3 will not accumulate errors due to rounding. But 1024 PPR will bring the theoretical resolution in the thousandth of an inch if the pitch is 1 IPR.
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Bubba
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« Reply #20 on: June 19, 2017, 02:34:04 am »

 But 1024 PPR will bring the theoretical resolution in the thousandth of an inch if the pitch is 1 IPR.
******************
I believe , but I'm not 100 % positive, those lead screws are 10 thread per inch so one revolution will move the table 0.100"  Cheesy
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Dragonfly
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« Reply #21 on: June 19, 2017, 08:42:25 am »

Smiley
When I write about inches I am in a mess.  I try to convert the values to metric in the back of my head.
In this case the pulses per unit value is 10 times the PPR and IMHO even 500 should be enough.
BTW, are you sure it's 500 and not 512? Because 256 and 1024 are multiple to 8. (My math English is not good)
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Bubba
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« Reply #22 on: June 19, 2017, 13:23:59 pm »

Yes, it is set at 500 right now,  based on max rpm. The motor Max rpm at full voltage and amperage is 4000.
Here in the attachment is table for this encoder.. Cheesy


* settings.JPG (120.72 KB, 1505x809 - viewed 22 times.)
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Dragonfly
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« Reply #23 on: June 19, 2017, 17:53:08 pm »

Either inside there are two sets of encoder wheel and pickup or ... I don't know Smiley
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