Reduce vibrations

#1

I am wondering if anyone has improved the heatbed so that there are no vibrations from head movements anymore.
But even with a solid attachment of the heatbed to the triangular base, the whole base would still vibrate.
So it seems to me the printbed would maybe need some rails, so that up and downward movement is not hindered but left and right is completely stopped. But the head is in the way of simply attaching a rail left and right of the printbed.
How did you solve this problem?

To visualize vibrations:

#2

This is not caused from the bed, it’s caused by the heavy printhead: if you perform a change in direction the x or y belt is still (even if it’s fiber reinforced) a bit flexible, so the heavy printhead tries to follow its former direction and vibrates a bit causing this concentric rings.

I usually include small radius’s in my creations which help a bit but with such a heavy printhead you’ll never be able to solve this.
This is a benefit of a bowden-feeded hotend as you do have only a very light XY sled: absolutely no rings and artefacts but other problems with oozzing of the nozzle :confused:

You may get better results by changing the acceleration and deceleration settings in the firmware but this will need a lot of time… (did that once on a printer…)

#3

These big “waves” you can see in my prints are caused by a >90° direction change of the print head resulting in very visible movements of the print bed.
After noticing these I tried a very rigid attachment of the printbed to the triangular base. The improvement was visible in the printresult. But still heavy waves in the printresult.

So now I am constructing some rail in the front to make the printbed stay in place in X axxis.
At least this would reduce these very big waves.

#4

Ok, but I guess we’ll never be able to completely avoid those waves without tuning the acceleration.

Please post pictures of the rails as I also thought about doing that a while ago (I only get those vibrations at the first few layers as my first layer hight is too small resulting in a compressed printed area…)

#5

To backup what King Martin said, my understanding was that one cause of ringing like this is caused by jerk on abrupt angle changes with a heavy print head. Reducing maximum jerk is supposed to reduce the ringing, at the expense of print time. I haven’t noticed the print bed vibrating much on mine, but the printhead of my Zim has probably 3x the mass of my MakerGear M2. I do the same thing King Martin mentioned. I build fillets and curvature into hard edges in the model to prevent 90 degree angle changes where surfaces must be smooth. This is something the SmoothieBoard is supposed to handle better than Rambo/Marlin, but the Zeepro design of 2 steppers and big heatsink on the head is a big part of the problem that I’m not sure a SmoothieBoard could overcome. Take a look at this post for example.

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#6

I understand that it is impossible to completely remove vibrations.
But I needed to get rid of these really big and long waves in print results.
It was a mechanical problem for my print bed.

It seems my Zim has many problems no one else has.
But at least I was able to get rid of the major vibrations. The improvement is very big and now I only have three tiny waves.
Here is what I did. Its not pretty, but it works.
I will make some fixations next to get rid of the improvised attachments.

Pasted image519Ă—539 438 KB

And the result:

If anyone wants my specs or the design files, I can upload it. Just leave a message.

#7

Here are the files:

#8

Hi!
Nice solution for the Problem! The Z-axis of our prescious ZIM was designed to fulfill more the design concept than a good stability. The guides are deep inside the body, way too far away from where the print process takes place. Also the plastic arm with the springy magnet connectors can´t really suppress vibrations coming from the heavy head being stopped and accellerated quickly.
So, normally you might think that the Z-Axis should not be affected by any force in X or Y direction, because the Printhead should not touch the part. But that´s not true. sometimes, the nozzles (of the second extruder) scratch over the surface of the part because of overextrusion or bent up layers, what also makes the Z-carrier swing. Not speaking of the tolerances that the spring-loaded magnet connectors show!
Another point is, as you all said before, the fact that an abrupt direction change or stop of the massive head result in a shockwave going all through the body of the printer.
1: The most stable solution would be to add another guide, that 3DPrintEvangelist did. Although you destoy the smooth design.
2: Another way would be to reduce the intesity of the shocks by slowing down pinting (that most of us don´t want to…),
3: or change the resonance of the printbed itself by simply adding weight to it. Sounds strange, but it helps. But also, it wears down the Z-guide bushing if you add too much, so be careful!
4: Also, take a look at where your ZIM stands. If you placed it on some wiggly camping-table you´ll notice that the whole printer and the table shake while printing a 20% honeycomb fill with 60mm/sec! So if you want a stable print, you´ll have to take care of a stable base.

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#9

Attaching to this thread, as it’s related.

Have any of you tinkered with acceleration and jerk settings to reduce the vibrations that cause ghosting?

#10

No, I haven’t played around with the settings… but it might be interesting…