Stepper Encoder/Closed Loop

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Re: Stepper Encoder/Closed Loop

Postby Gary Campbell » Fri Jul 27, 2018 1:53 am

"I am actually using rack and pinion with a 3:1 gear reduction on the X&Y axes. Those are the axes I am most concerned about at the moment. Knock on wood, I don't seem to have an issue with my Z axis. My Z is using 1/2-10 leadscrew, so if I am understanding correctly, I am already pretty close to the 10mm pitch right?"

Not even close by my calcs. a 1/2-10 leadscrew has 10 turns per inch and a 10mm pitch ballscrew has 2.54 turns per inch.

I assume you are using the 3:1 reduction and integral pinion and if that pinion has 20 teeth and a 1" pitch diameter, at least that what my calcs show. Based on those number you have .954 revs per inch. That motor should be reliable to 600 rpm on 48V. That should yield 500ipm rapids on the XY. Personally I would jump up a couple teeth on the pinion and run them on 60 volts as the drives are rated for 80, I think. Good even if they are rated for 70. You will be lucky to ever get near a hundred on the Z if its 1:1 with the screw.

Here is what you need to know about reading between the lines on the provided motor torque chart. Even tho is doesn't say this, assume those numbers are at full step settings. If set at 1/8 m/stepping assume 20% of that number to be accurate, ~40% if using 1/4. Way less than either if using 1/10th.

https://www.micromo.com/media/wysiwyg/T ... g%20WP.pdf
Gary Campbell
CNC Technology & Training
Control & ATC Retrofits
gcnc411(at)gmail.com
https://www.youtube.com/user/Islaww1/videos
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Re: Stepper Encoder/Closed Loop

Postby drxlcarfreak » Thu Aug 02, 2018 3:23 am

Whoops, I seem to have missed this post! Ahh I apparently messed something up converting units!

Are you referring to the Clearpath motor or the Chinese stepper I am having issues with? I am using the 3:1 reduction currently. Do you have a source for pinions of different quantity teeth? I had assumed that they were custom made. I don't necessarily need 500ipm rapids, but would like reliable cutting and to be able to turn my cutting speeds up quite a bit from where I am now.

Hmm.... that is a good point for the microstepping. I was at 8x and seemed to be doing okay, but switched it back to 10x just because that is what seemed the norm. I will switch it back for now to see if it helps. Heck even 4x seems like I would have okay resolution.

I am really looking into these clearpath motors. They seem like the bee's knees. I am partial to the 3421S, though it requires me to upgrade my rack to nema 34. It seems to have a great torque curve compared to the CNCRP stepper.
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Re: Stepper Encoder/Closed Loop

Postby Haik » Mon Aug 06, 2018 5:06 pm

I'm using both Leadshine and JSS-Motor closed loop stepper drivers. These drivers are truly great especially if mechanical error (backlash, etc.) is not a problem.

Here's my Amazon reviews with PICs (having mostly duplicate info), I also use these with my existing (premium) motors and external encoders...

-Leadshine DSP Closed-Loop Stepper Driver HBS86H 8A 30-100VDC
https://www.amazon.com/dp/B015QQFGS8/?coliid=IISMUBUBNPTB6&colid=1471GKU1HUWL7&psc=0&ref_=lv_ov_lig_dp_it#customerReviews

-JSS-Motor (aka- Changzhou Jinsanshi Mechatronics Co. Ltd.) HSS86 Hybrid Servo Drive
https://www.amazon.com/dp/B075HBXF9W/?coliid=I1BL06ARAQBOCW&colid=1471GKU1HUWL7&psc=0&ref_=lv_ov_lig_dp_it#customerReviews

Also, I use the above JSS-Motor HSS86 w/motor to drive the Geneva mechanism within my 16 slot ATC. Previously my ATC had an AC motor with a brake which was okay, but now my ATC is much smoother and I can customize the motion and the code/logic to include the new sensors and features that I've added.
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Re: Stepper Encoder/Closed Loop

Postby drxlcarfreak » Sat Aug 11, 2018 12:42 pm

I haven't really looked into the knockoff style motors/drives since I got burned the first go around. These seems pretty decent based on your reviews. Were you able to dig up a torque curve for these motor/drivers?

I am really interested in seeing the machine you have that you are planning to run what was it, 11 motors based on your reviews?!
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Re: Stepper Encoder/Closed Loop

Postby Haik » Tue Aug 14, 2018 10:44 am

Here's the info that's available for the HSS86 w/86HSE4N-BC38 motor that I bought at Amazon...
http://www.jss-motor.com/product/nema-34-closed-loop-stepper-motor-and-driver.html

I've put the above, motor included, to work powering my ATC carousel. Loaded that carousel rotor weighs only around 200lbs.

No, not 11 motors... for motion just 5. :)
My machine is Thermwood (gantry) Router that has 5 axis motors (2 Y, 1 X, 1 Z, 1 A) on 0.5 inch pitch (zero lash) ball screws.
I'm using new Pacific Scientific (PacSci) nema 42 (4000oz/in or 28.23Nm) motors (80vdc/8amps) with AutomationDirect TRD-SH1000 encoders to support Leadshine HBS86H (DSP Closed-Loop) drives.
Previously, my old Gecko 203v drives (2000 microstep) are sturdy but even the new Gecko gm215 (w/morphing) won't do what either the HSS86 or HBS86H drives can do.
I'm also nearly done moving to UC300eth/UB1/UD1-U on this machine. I'll do a followup with pics, laser tool measurement and all, when it's done.
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Re: Stepper Encoder/Closed Loop

Postby Haik » Tue Aug 14, 2018 6:48 pm

Update:
I did find the torque data you asked about. Check out this link, notice that closed loop performance is better than open loop...
http://www.sah.co.rs/media/sah/techdocs/86hse_manual.pdf
torqueInfo.png
Torque info


For interest sake I've included the (open loop) toque data for the PacSci 42's also.
PacSciK42HLLNchart.JPG
PacSci42
PacSciK42HLLNchart.JPG (26.74 KiB) Viewed 917 times
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Re: Stepper Encoder/Closed Loop

Postby drxlcarfreak » Thu Oct 18, 2018 5:31 pm

Oh man, I totally missed these responses as I was out of the country those dates! Wish I would have looked here prior to buying my new setup. I literally pulled the trigger yesterday on a set of Teknic Clearpath SDSK-3421S servos. It was a pretty penny to get everything required. I will have to try those closed loop steppers on my next project and hopefully save some coin!

I do have a related question about setting up these servo motors with UCCNC. These motors have a High Level Feedback Output with a few options on what/how it outputs. I am guessing the only one UCCNC could use is a trigger if a servo faults? What is the best way to trigger UCCNC to stop motion if one of the motors fault?
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