Dynomotion Forum

Hi Tom.

I still have some jerk motion in my g-codes.

Before I had some play in the X axis, but solved it with a preload in the ballscrew.
I still find some jerk in the axis movement and can't find the source of the problem.

I captured some motion with the CaptureXYZPosDestToFile example, but don't know what to do with the data.

Do you have a tutorial or can give me a help to solve this ?
Also, how can I generate the path with the data from the capture?

I can supply you with all the data you need, just request it please.

There are 3 example with different g-codes in the KFLOPdata files attached.

Thanks Tom!

Hi Gabriel,

Do you know Microsoft Excel?

Attached is an Excel Spreadsheet to import the data.

Here is a plot of the XY Path



Here is the X Velocity of the Trajectory vs time:


Here is the Following Error vs time:

Hi Tom.

That was exactly what I needed.

I tried but wasn't reaching that final result.

It seems that the profile and the following error are good, do you agree?
For woodworking at least.
30~ counts following error, 17000 counts / inch, total: 0.0017" or 0.05mm

So it must be coming from mechanical backslash?

Attached some photos of the "steps" in the final parts.
Theses steps are a little bit small, there are some other that I run with double speed that are concerning big. i think around 0.2mm.
The ones on the photos may be 0.1mm.

The data collected was at a high speed, around 8000mm/min.
The cutting that you see in the photos was done around 2000mm/min
The ones that had big steps were done at 4000mm/min

Thanks!

Hi Gabriel,

Sort of hard to say. The following errors are +/-0.05mm. Then you say the errors in the part are 0.1mm. But then you say those are at a lower speed?

Hi tom.

Will cut another piece with fast speed and take some photos.

Also will capture data with the same data for us to compare.

Thanks

Hi Tom.

Can you take a look at these captured motions ?

I analyzed them and found just the acceleration looks strange. It looks like accelerate and decelerate very fast.

They give a lot of jerk when the helix end and the radial motion starts.

the 3 data captured are from the same g-code, but with increasing speed and then increasing acceleration.

KFLOPdata7000 is captured with 7000mm/min and so on.

Thanks

Hi Gabriel,

The acceleration goes to ~53 inches/s^2 which is under 60 inches/s^2 so I believe that is correct.

Hi Tom.

The jerk seems to be where the helix end and the radial motion starts. (flat, not with Z movement).

Raising the Tau from 0.01 to 0.02 seems to do a lot better.

Now the machine is simple stopping in random places in linear one axis movement. (G1)

Without outputing a console error. photo attached.

Thanks.

Hi Gabriel,

It seems something is disabling the Axes. You might have checked the Axis Screen to verify.

Do you have any code running that disables axes?

Hi Tom. I have a code that disable axis all axis if one axis is disabled due to following error.

I had the Y axis following error set to 10.000, lowering it to 100 solved the problem. (my system is tuned for around 50 counts).

The Y axis seems to be doing very fine, but the X axis, at ~4000mm/min gives some marks on the finish, if you hold your hand in the axis, you can feel that it runs with some bumps. (even without load)

At 6000mm/min this can't be seem.

I'm starting to tune X axis again. Can you give me a help with filters?

Check the attached photo. i need to lower the Gain to raise D. what can i use? is ok to use for example a low-pass filter of 300 ?

Thanks.