Simple square model, to measure line width, wall a little to thick and weird gcode, changing direction at every layer, why ?

[sibianul 0]

Hello everyone, I'm a newbie in this 3D printing world,  I wanted to build one a few years ago, in this winter break I decided to actually build it, and started drawing the Lautr3k model in Fusion360, the dimension was given by the leadscrews I initially purchased, quite long (480mm), but didn't want to cut them.

 

So Now a week ago I did my first print, in the mean time I also printed a few more parts that are actually ok (I don't like the surface of all my prints, that is bellow, even with support underneath, but this will be a different thread), but now I want to talk about a very simple model I made , a 20 mm square with a thin wall. I first modeled the square with a 0.6mm wall (same as my nozzle), and tried printing it, the wall was actually thicker (~0.75mm), but on one side is not perfectly solid, and this is the part where the gcode is weird IMO, I don't know why it's not going in the same direction, in a continous move from layer, after it makes a full square it travels back one  side, and than it starts again on the oposite direction, is there a setting to make it move in a more logical way ? The red lines are travel moves, yellow arrows are showing the direction, I don't know why this wall is printed very bed, probably there is something not properly calibrated on my printer, but if there is a way to generate the toolpath in a continuous way, same direction, this test cube would be much more prettier 🙂 I attached the Gcode, speed was set to 

 

 

 

Any help is appreciated, I really want to tune my printer, so it will print better parts (so far I don't like bridges, see the 3Dbenchy model I attached, also I don't like the areas that are printed above support, the quality is quite bad, but adding a roof on the support helped, but weird on a symetric model, the right side above support was perfect, and the left sidewas not, the material didn't stick to support bellow but instead was to far up, will talk later about this, one problem at a time, I purchased PVA filament and now I'm milling an aluminum part to use 2 extruders, 2 nozzels).

 

Thank you.

cube straight corners 0.6mm line.gcode

cube 0.6mm wall - straight corners.stl

cube 0.9mm wall - straight corners.stl

[smartavionics 288]

Hello @sibianul, I'm just going to answer your first query about the nozzle movement when printing the thin walled square. Cura treats that model as a solid object that has a hole in the middle. OK, so the hole is nearly as big as the outline but that makes no difference, it's still a solid with a hole as far as Cura is concerned. So Cura prints one wall which is the outline of the model and then another wall for the hole (the inside of the square). Because the hole is almost as large as the outline, the two walls are very close together. So close that they overlap. There is a Cura setting called something like Wall Overlap Compensation and when you enable that it reduces the amount of plastic that is extruded when printing a wall that is so close to an existing wall that they overlap. If the outline wall and the hole wall are really close together, the overlap compensation will reduce the flow for the second wall to almost nothing and so it ends up as little blobs which looks crap. There is another setting called something like Minimum Wall Flow that is a min percentage of flow that any wall will have. Walls that have a lower percentage flow than that value will simply be omitted. So.... to get a nicer print, make sure you have the wall overlap compensation enabled and set the minimum flow to something like 20 and your rectangle should print nicely. Hope this helps!

[tinkergnome 691]

2 hours ago, smartavionics said:

So.... to get a nicer print, make sure you have the wall overlap compensation enabled and set the minimum flow to something like 20 and your rectangle should print nicely.

 

....or perhaps: model a solid rectangle (without holes), in Cura choose a wall line count of 1, zero top layers and zero infill.

Should also print nicely.

[smartavionics 288]

1 minute ago, tinkergnome said:

 

....or perhaps: model a solid rectangle (without holes), in Cura choose a wall line count of 1, zero top layers and zero infill.

Should also print nicely.

 

Of course, but that then rather limits what other features the model could have apart from some thin(ish) walls.

[tinkergnome 691]

True of course.

But personally i would kindly ask my favorite Cura contributor if he is willing to implement a "Allow single extrusion for thin walls" feature into the CuraEngine... 😛

[smartavionics 288]

8 hours ago, tinkergnome said:

True of course.

But personally i would kindly ask my favorite Cura contributor if he is willing to implement a "Allow single extrusion for thin walls" feature into the CuraEngine... 😛

 

No need, that's already been done. There's an option called "Print thin walls" that does exactly that. It's been in Cura for some time. However, the current implementation as supplied in Ultimaker's version of Cura is badly flawed. I am working on a new implementation that is currently producing much nicer results for thin walls and also for filling the gaps between walls. Here's an example of its output...

 

 

It's still a work in progress and I cannot say when (or ever) it will be incorporated into the standard release. If you wish to try it out install one of my recent releases which can be found at https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0

[tinkergnome 691]

1 hour ago, smartavionics said:

There's an option called "Print thin walls" that does exactly that.

 

Thanks - good to know.
The tooltip says it will print walls that are thinner than the nozzle diameter. That's a different feature (in my understanding), that's why i have not tried it yet.

[smartavionics 288]

4 hours ago, tinkergnome said:

The tooltip says it will print walls that are thinner than the nozzle diameter. That's a different feature (in my understanding), that's why i have not tried it yet.

 

I do not know how they can claim that. Maybe it does, maybe not.

[sibianul 0]

Thank you guys, I will try just a little later that plugin, but maybe I didn't made the correct model to test my line width, I tried to make that thin wall model just to see if I can tune anything to have the parts I print, as close to the original model, but none of the real models have thin walls, for example the model bellow was made to fit that zip in it, but the channelcame out a little to tight, The zip is 5.9mm wide, the chanel I modeled was 6.1mm wide, but the chanel that came out after printing the part with 0.6mm nozzle, is 5.5mm wide, as you could see in the photos above also , I have also a small problem on the corners, it seems there is to much material extruded in the corner, maybe this is the issue on that channel that came out not wide enough, I'm actually sure this is the issue.

 

Any help regarding ways to fix this would be helpfull. Also if I have to print some tests, just let me know, I will start printing right away.

 

Bellow I copied a few settings I initially set in Marlin config file, and which I think are related to the corners issue:

 

#define DEFAULT_MAX_ACCELERATION      { 1600, 1600, 100, 10000 }
#define DEFAULT_ACCELERATION          1600    // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION  2000    // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION   2000    // X, Y, Z acceleration for travel (non printing) moves

#define DEFAULT_XJERK                 10.0
#define DEFAULT_YJERK                 10.0
#define DEFAULT_ZJERK                  0.3
#define DEFAULT_EJERK                  5.0

//#define S_CURVE_ACCELERATION // this is commented out, will it help to enable it?

 

Test canal fermoar vertical.stl