Hi,
I have been looking at my prints closely lately…especially with shiny PLA I am noticing a ripple pattern when the light hits it the right way.
It is not deep, and can barely be felt when you run your fingers across it. I’ve looked over my TAZ 5, checked belts, tightened any loose bolts, cleaned rods, etc…
Is this just a normal thing with this machine?
J
There are a couple of causes of that, some you can deal with, some that are more difficult to deal with. To understand what is going on, you have to think about what is happening when you lay down a layer. When you start a new layer, your printer goes to a new point, starts extruding which usually results in a bit of excess flow depending on your settings, then it starts to move to the next point at a constant acceleration, getting fastest at the midpoint, and slowing down until it makes the transition to the next turn or curve or or corner, etc. But you have multiple acceleration pieces in place here. With a Taz, the nozzle itself moves in X and Y, and is moving whenever you have a flat section in the X direction, but is stationary whenever you are doing a flat section in Y. What you will sometimes see with 3d printers, and what you are seeing in this case, is that after a transition From X to Y, or after a stop and restart of motion in X or Y, you will sometimes get a bit of excess extrusion from the sudden start of acceleration. You can see a much exaggerated version of that happen when a top fuel dragster or a funny car does a high speed pass. The front wheels come up off the track due to the intense acceleration, and then usually bounce a couple of times before smoothing out, even though the car is still going faster.
With a 3d printer, it’s a bit of the same thing. You can minimize it by cleaning any excess fuzz off the bearings, making sure you have no excess play on the bearings themselves, going with harder rods, making sure your belts are super tight, etc. The phenomenon is often known as “ringing” because in bad cases, it often shows up as an after image ring of a hole. A little bit of it is normal, and you will never be able to get rid of it entirely unless you decide to go print out in space, but you can improve it to where it isn’t noticeable anymore.
Hi,
I very much appreciate you taking the time to reply!
-One thing to note, the ripples continue down the entire length of the sides, at regular intervals. They are sometimes more pronounced in areas where acceleration/deceleration takes place, but they are in areas of constant speed as well.
-My system is very tight. Nothing loose or shaky, and the belts are good and tight. Everything is clean.
-I think the problem MAY be more related to resonance caused by harmonics or ‘springiness’ in the steppers. I found a good resource on it here:
http://wiki.arcol.hu/blog:printing-reasonance
Basically, the main thing he found that helped was adding vibration damping everywhere possible (also slowing down, and lowering temps to increase flow viscosity).
Do you have any other thoughts? Has anyone else been able to deal with this sucessfully?
Best,
J
I’ve been battling this off and on and find it odd. It mainly occurs on the first layer, which then transfers to subsequent layers.
After doing the perfect perimeters and then starts to do the solid infill at 45 degree angle, my first several lines will be perfect. Nice, flat, totally straight. Sometimes I’ll get 5 awesome lines. Sometimes 20. Sometimes all of them. BUT, all the sudden, when it happens, one comes out wavy for no rhyme or reason. Nothing drastic has happened. No sudden changes…just printing 45 deg line after 45 deg line after…until…boom. A wavy line. Since that line is wavy, all other lines touching that line horizontally is wavy because there isn’t anywhere else for it to go. It basically mirrors the first wavy line, except gets amplified slightly so they grow larger. Then the same thing happens vertically, because the layer below is wavy and not perfectly flat. Then you have the hotend dragging through those and grinding also because it’s not level.
I’ve been messing with initial layer line width and also flow % with some limited success, but it seems so inconsistent its hard to really dial it in. At least for me so far.
