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Author Topic: Stepper freezes during jogging  (Read 744 times)

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Stepper freezes during jogging
« on: June 01, 2020, 01:37:28 AM »
Hi all,
So I have finally finished up my custom made machine and running into one irritating issue that maybe you can help with.
To start of I'm using the PoKeys57CNC together with postep60-256(for XYZ) and I'm controlling it via Mach4 and the USB-interface between computer and PoKeys57.

My issue is when doing manual jogging in Mach4 with the continued options the axis behaves abit weird:
The acceleration is smooth, the full speed is going smooth but as soon as I release the jog button the stepper motor stops for ~0.1 seconds before starting with the de-acceleration.
This of course is making me loose steps since the stepper is going from 100% speed to 0% instantly and then "pausing" for 0.1 seconds and then starting the deacceleration from 100% -> 0%.

If I jog with increments in Mach I do not get this issue.
What is more "weird" is that if I use the pulse engine from Pokeys57CNC own software the steppers do not behave like this, as soon as I release the jog button the transition to deacceleration is smooth and no "freezes".
This of course makes me think that the problem is Mach related.

If I run a g-code program I have no problems with this either.

It's maybe not the end of the world since I can manually jog with increments or the MDI but it is nice to jog a great distance with just holding the key down.

I will try to make a video later on so you can see/hear the issue for yourself.

Thanks in advance!
Re: Stepper freezes during jogging
« Reply #1 on: June 04, 2020, 02:51:22 PM »
Hi again,
so I have uploaded 2 videos on youtube where you can hear the differences running in Mach4 and Pokeys own software with pulse generator.
In both videos all the settings are the same. However in the pokey software I can go alot faster and higher acceleration without problem but if I try this in Mach the stepper stalls(as it does in the video).
Listen to the sound in the videos and compare.


Link when running with pokeys(smooth run): https://youtu.be/PLEAEEbw0J0
Link when running in Mach4(not smooth): https://youtu.be/Oe7QVKDOwhE


But as I said in previous post, when running with G-codes or MDI I do not experience this. It is only when doing manual jogging.
Thanks again :)

Offline Tweakie.CNC

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Re: Stepper freezes during jogging
« Reply #2 on: June 05, 2020, 01:10:30 AM »
If you do not have your machine tuned correctly then the results obtained are unlikely to be satisfactory.

In both videos it is evident that your Acceleration value is far too low.
In the second video your axis is stalling indicating that your Velocity setting is too high.

I think you need to set-up your Motor Tuning for optimum Velocity and Acceleration for each axis. Page 13 of the Mach4 manual gives more details.

Tweakie.
KEEP SAFE !
Re: Stepper freezes during jogging
« Reply #3 on: June 05, 2020, 06:39:17 AM »
Thank you for answer.
I have not tuned any of my axis yet due to the issue I have.

What is weird is that the stepper motor is stalling in the second video(when running through Mach4) but not stalling when using the pokey software.
In the videos the velocity is set to 2000mm/minute and that seems to be maximum value with Mach4, however if I run the steppers through the pokey pulsegenerator I can achieve speeds at 4000mm/minute.
The same goes with acceleration, I can double my value in Pokeys software compared to Mach4 software without stalling.

I have no clue how Mach communicates with my controller board and what data is sent between them but it  feels  like the eventual "over head cost" of using Mach is way to big compared to use the pokeys57cnc's internal motion controller directly.

I have seen that Polab have updated the plugin for Mach so I'm gonna try to see if those updates will solve anything.
Re: Stepper freezes during jogging
« Reply #4 on: June 05, 2020, 09:00:34 AM »
Alright so I'm an idiot...
As I mentioned in previous post Polabs have released new updates for the USB drivers and the chipset firmware.
I installed those on my computer and on pokeys57CNC and guess what, it worked!

I'm gonna check out the manual now that you refered to and tune my stepper motors.

Offline Tweakie.CNC

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Re: Stepper freezes during jogging
« Reply #5 on: June 06, 2020, 01:16:21 AM »
I don't think you have done anything different to what we all did to start with  ;)
You will get there but the Mach learning process all takes time.

Tweakie.
KEEP SAFE !