Steppers running very rough

Hello,
I recently got hold of a CNC-Plasmacutter (for free).
The guy who gave it to me said it ran on LinuxCNC, but didn't have any of his old computers and config files at hand.
It currently runs from a IBM T43, LinuxCNC 2.8.4, 3.4-9-rtai-686-pae, directly via LPT-Port into a German so-called Triple Beast controller. Jitter is around 8000, I got rid of the spikes with SMIctrl.

The issue I have is very rough running of the steppers. I made a video of it which can be seen under the following link: uploadnow.io/f/KMd7Vrn

I am very new to LinuxCNC and relatively new to CNCs (build a MPCNC running on GRBL), so I have no clue what the issue in this case could be.

Mechanically, everything moves freely, I tensioned the belts, but the "roughness" seems to come directly from the stepper.

Does anybody have an idea where I should look to solve the issue?



(I made a similar thread in the German section of the forum, but not too many answers, hence I'm trying it here as well, hope that is ok.)

Double posting is never OK, but due to languages, i do not mind.
You could have at least added a link to the other topic.
And you could have provided more info, like most important stuff, are you using microstepping? What value?
If you are running full step, vibrations are not going away no matter what you do.
Stepper motors vibrate, mounting dampers help, microstepping helps, stealthchop helps but messes accuracy a little, etc etc.

I am very sorry, I did not think of that.

I was hoping it might be some stupid mistake I made, obvious to those with more knowledge of CNCs, but not to a rookie like me. 

The other post in the German section is here: forum.linuxcnc.org/42-deutsch/49286-linuxcnc-und-triple-beast

If I configured correctly, Microstepping should be 1/10th, but I might have configured it wrong, please see attached image of the stepconf wizard (in German, sorry).

The machine is agitated by 34H280-35-8A steppers on x- and y-axis, driving timing belts with 5mm pitch via a pulley with 20 teeth.

The z-axis has a lead screw with a much smaller stepper, which runs smooth.

Did I maybe mess something up with microstepping or my other settings?

 

Microstepping is set in the drives, not in PncConf, there it is used just for scaling.
You have a 20 tooth 5mm pulley directly on the motor shaft?
That is not good on many levels, vibration is huge, the distance moved for one rotation is 100mm so it is useless for ... well anything.
Use reduction.

Thanks again, Tommy.
Jep, 20 tooth 5mm pulley directly on the motor shaft. Similar as on my 3d printer, that's why I didn't think anything about it.

I will look for some kind of reduction gearbox.

What irritates me though, wouldn't the jerking get less as the machine moves at higher speeds? It gets worse the more I ramp the speed up.