front of the buildplate "shakes"

[korneel 175]

All;

I'm wondering if i'm the only one facing this;

when printing large prints, for instance i'm printing a tower with a dimension of 200X200X200 MM, when the print-head reaches the front of the build plate the build plate seems to be "shaking". it's a couple of MM and it seems to be causing irregularities in my print..

did not check if any of my other printers do the same but did anyone experience something like this before?

thanks

 

[densohax 0]

I have the same issue. It would be nice to fix this!

 

[illuminarti 18]

I think its inevitable that you are going to get more movement at the front of the build plate, just due to the distance from the anchor points at the back of the bed.

That said, I would also make sure that all of your bed springs are reasonably well tensioned to begin with. The bed tends to droop slightly under its own weight, so that the springs at the front are less compressed than the one at the back, to begin with. Its easy to end up with them barely compressed at all - which will certainly cause the front of the bed to shake.

Make sure that you tighten down the back spring until the terminal block under the bed is almost touching the base plate, before you run the leveling wizard. This will make sure that all three springs are as tense as possible in normal use, and should minimize any vibrations at the front edge.

 

[korneel 175]

Thanks Illuminarti, i did not try that yet.

completely agree that the front will always be moving a bit.. but i'm really seeing shaking that is affecting the quality of the print :(

 

[leopop 0]

Hi Korneel and others,

Yes! I'm having similar problems. If the filling is being made, the head moves over a series of previously-laid strings and air. This, with certain speed, yields in an intermittent reaction force. This intermittent force causes the bed to vibrate, in one or more of its natural frequencies. If you play with the speed % button during the build, you can see and feel that your right within or right next to this natural frequency. Running faster or slower brings you out of the danger zone.

This is a general dynamical effect.

The two parameters that influence the natural frequency are stiffness and mass.

Of course you can make the be stiffer by adding beams or so, but tweaking with mass is easier.

My plan is to add substantial weight into the space between the bed plate and the heated bed (approx. 13mm left there), so to bring the natural frequency much down. Then, when building at reasonable speed, I end up pretty much higher frequent than this natural frequency (and hopefully not meeting the second natural response - twisting!).

I was just going to experiment with it, and then discuss it here, but then this thread came across.

Any better options? Post them!

Leo.

 

[emilio2 2]

I thought the back screw had to be as much tight as possible. Is it necessary to tight/lose that screw when calbrating bed?. I never touch it.

[jlud3d 0]

I have had this problem too, The bed violently vibrates especially when the printer prints the fill in structure. Instead of hanging weights (which I was worried might affect/bend the build plate/the build plate mechanics in the long run) I cut dampers out of 2 inch thick upholstery foam and placed a square under each of the feet, it has vastly reduced the vibration problem and the print quality is pretty much back to normal.