Ringing

Hello,
I have been having a lot of problems with quality of my perimeters lately and I've just found out that when my printer prints perimeters (0.35 nozzle and 0.7 perimeter) it kind of tries to print infill between those two perimeters very fast which causes the bed to shake like crazy. It look like this [picture]. Black lines are perimeters, green ones are infill thats being printed well and red lines are infill which I dont want there. Any idea how to fix this in Cura?

Edited 2 time(s). Last edit at 06/16/2016 06:37AM by Basell.

You are trying to print a perimeter size not possible with the nozzle size you have, so it looks like Cura is separating the lines and fill the gap in between. Check your extrusion width and adjust your perimeter to the right size. Can't verify it right now but for a .35 nozzle the usual extrusion width is 0.42 which means your perimeter needs to be 0.84 for the printer to print two lines side by side.

Whoa, thanks. It really helped. I would have never guessed that. But now i get this like under extrusion (?) in the middle of a print when geometry suddenly changes (e.g. in the letters area as shown in the picture). So it is like perimeters are fine in the beginning then poor and then fine again. Any ideas what's the cause?

That effect happens a lot with FDM printing. When the shape of the object abruptly changes to something more or less complex or even just different in size (or even if the infill changes), the time it takes to print the layers changes. When the time changes, the next layer is deposited on a warmer (softer) or cooler (harder, more shrunken) previous layer. Very small details become little thermal islands that can soften when the extruder comes around to them, where larger continuous areas behave differently because they have cool, hard plastic surrounding and supporting them.

If you're printing PLA, use a cooling fan. Other than that, try diverting the extruder away from the part for several seconds between layers, such as printing another part elsewhere on the bed. Try printing two or three parts at a time and see how it changes. Sometimes printing multiples of the small part is not enough to give a good result because the time is still too short between the different parts and layers, so I print a sacrificial cylinder that guarantees extruder distraction for at least several seconds between layers.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks for such a detailed advice, I will work on that

If you are using Marlin firmware, change this values:

// The speed change that does not require acceleration (i.e. the software might assume it can be done instantaneously)
#define DEFAULT_XYJERK 20.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 5.0 // (mm/sec)

To:


// The speed change that does not require acceleration (i.e. the software might assume it can be done instantaneously)
#define DEFAULT_XYJERK 15.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 3.0 // (mm/sec)

And try it, if 3 is too much of a change do 4 instead.

New settings didnt help much, but I figured out that the ringing was partially because my printer apparently has too stiff "legs" (no idea what its called in english) and now its much better because it is standing on some pieces of sponge. Not perfect yet, but I just noticed that X Y bearings are loose (just a little bit) I hope thats the main problem (k8400 has no ball bearings on X and Y axis but it has some plastic bearings and the plastic may have worn off a bit which is weird - I have my printer for only about 2 months) I will print some new bearings and try them out. Not sure if I can install ball bearing there 'cause the bearings are mounted on the rods that also rotate like in ultimaker

Edited 1 time(s). Last edit at 06/20/2016 09:34AM by Basell.