Losing Steps

Losing Steps

Postby JerryBurks » 09 Mar 2016, 16:10

Sorry, this should have been posted under "MK2".....

I am running an MK2 controller on my home built machine successfully for the last 4 years and had not much to complain. Lately I upgraded the firmware to the December '15 Beta and that worked fine so far (not sure if the upgrade is related to the problem below or if that would have happened with the old software as well).

The problem materialized, cutting a rather small high resolution pattern on the x-a-z indexer. At certain points I can hear the machine stall and find at the end the pattern is screwed up and the x-zero has shifted. I still need to try if it also happens when cutting the same pattern flat in x-y-z plane.

I can also observe that the buffer indicator bar that normally hovers around 240/250 sometime drops very low and I believe that is when the stall occurs. I reviewed the settings and modified a few according to the manual recommendations, with lower acceleration and increased lookahead angle but that made it only worse. For that matter, the latest software has now a few fields in the settings that are not explained in the 2014 manual.

I am attaching the offending .tap file, my original settings and the modified settings.

My questions are:
1. Can I do anything to the settings to make it work?
2. Or is the NC file just too complex and overwhelms the controller?
3. Would the MK3 controller work better?
4. Is the MK3 drop-in compatible with the Mk2? Or would I have to rewire the whole thing?

Thanks, JB
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Posts: 217
Joined: 10 Jan 2012, 20:26
Location: Pasadena, California
Controller: Mk2

Re: Losing Steps

Postby JerryBurks » 10 Mar 2016, 02:58

I did another air cut test tonight with the flat design x-y-z, no indexer but otherwise the same path. So far I could not observe skipped steps, the buffer bar stayed mostly at 240, sometimes dropping to 200 but never under 100 like with the indexer version. Overall I have the feeling that the motion is much smoother and continuous.

Looks like it has to do with the rotary axis calculations but what now?
Posts: 217
Joined: 10 Jan 2012, 20:26
Location: Pasadena, California
Controller: Mk2

Re: Losing Steps

Postby Zerspaner » 30 Apr 2016, 07:59

Hi Jerry,

please see my post to loosing steps - I've a similar problem.


Posts: 118
Joined: 13 Mar 2013, 06:01
Controller: Mk2/4

Re: Losing Steps

Postby Support » 05 May 2016, 09:38

What kind of stepper driver do you use?

The problems can be caused by short moves which can be very erratic if acceleration and speed values are high.

You can use lower speeds and accelerations and also please try re-configuring these settings(File/Settings/Lookahead):

Angle: 170
Radius: 0 ; Angle: 20
Speed Adjust -> enabled
Radial Acceleration value should usually be same as "Acceleration" value from "Axes" setup.
Path tolerance: Depends on your requirements
Path blend: Enabled
Path Range: 5-180

Also try changing machine type to RotaryABC
Please try your g-code programs with this settings configuration and post the results.
Posts: 2657
Joined: 07 Apr 2014, 17:39
Controller: Many controllers

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