Peaks on sharp edges

[Kastenbrot 0]

Hey!

 

I am fairly new to all of this. However, I created a 3D-Model and am seeing some peaks on top of sharp edges on the upper layers of my model.

The  peaks do not exist on the actual model. I am sure that there is something I am getting wrong.

 

To add some additional background, I am using Cura 4.6.2, which should be the latest version. 

I also added a slight chamfer (0.2mm) to the vertical edges, from which the peaks seem to extend. It did not fix the issue though.

 

I attached a screenshot of both, the model and the sliced layers. I also tossed the project file into there. 

 

Any help is greatly appreciated!

 

Thank you

CE3_LongDiamondFixedSet v3.3mf

[Labern 774]

Hey. Welcome to the forum.

 

What you are seeing here is what it will actually print. 

This is determined by your nozzle size and as those corners of the model are actually bigger in area then the straight lines then it will print them. Where as the straight lines are to thin at that point. 

 

Are those thin walls tapered? Fatter at the bottom and get thinner as they go up?

Sorry I'm not able to view your file right now so can't check myself.

[Kastenbrot 0]

Thank you for the quick reply, Labern!

 

To answer your question: Yes, these walls are all tapered. It's supposed to be a cookie cutter. So the thin edges are thought of as cutting edges. 

 

Between the lines I read that my taper might be to steep? Is there a setting within Cura to adjust how tapered edges are to be treated, or should I adjust my model?

 

Thank you!

Edited July 30, 2020 by Kastenbrot

[Labern 774]

So for something like this I would design the thinnest part of the edge a little bit bigger then 2 x the nozzle size. So 0.81 if printing with 0.4 nozzle. 

Alternatively you could reduce the line width in cura a bit smaller. It will currently be 0.38 or something. You could make this 0.3 but this can effect you print quality. You could just try it and look at the model in layer view just to see how the nozzle size effects how it will print your model. 

[Kastenbrot 0]

Thank you very much!

 

This absolutely makes sense and after playing around with nozzle size, I see what happened here. 

I will invest some time into learning how all the parameters affect layers and consequently G-Code creation.

 

If I was to run the print as described on my original post, but deleted the G-Code for the overshot layers, do you think things will still work out? Or will I likely have pockets on the inner side of the angles? Just asking out of curiosity - this doesn't really go towards my initial problem. I might as well just give it a try and learn from a print.

 

Again, thank you for the quick help and explanation!

 

Best regards

 

[Labern 774]

It will depend on the top thickness set in cura if you will get pockets or not. 

But you can check this in layer view by sliding the bar on the right side and looking at the point of where you will delete the gcode lines to make sure that layer is complete. 

But normally I find a quick edit to a design or swapping out nozzles to a smaller one faster then editing gcode. 

[geert_2 557]

If the cookies or dough are soft enough, and if the cutter is open at the back so you can push them out, maybe you can get away with straight sidewalls, untapered? The constant width makes it easier to find optimal print settings.

 

And then as desired go for single walled or double walled sides? A single wall has the advantage of easier cleaning, and no internal openings in which bacteria might grow. But it's weaker obviously. Also print rather slow and in thin layers, for smooth and strong walls.

[Kastenbrot 0]

Thank you for the input! 

Actually, I am not really worried about food safety. As technically I won't be cutting cookies; my wife will use it for her arts and crafts. I do appreciate the input though! I will be experimenting around with a few different designs, such as single walled and non-tapered walls. I am intrigued to see how they will hold up.

 

To be quite honest, I do not even have a printer yet. It should be here next week. So I am just trying to get ahead of the game a little bit!

The input you all gave me will definitely help me, as I am learning more about the constraints of FDM! I can already see how this is a super fun hobby, though I am just getting started.

 

Thanks! 🙂

[geert_2 557]

If you are just beginning, I would say: start with small test pieces that complete quickly. Stay with the printer while they print, and carefully watch what happens. This is important to lear fast, and to react fast if things wouldn't go as expected.

 

Try different overhangs, wall thicknesses, infil percentages, bonding methods (stay with the printer!!!), speeds, layer thicknesses,... Begin with simple models with a couple of holes, curves, extrusions, slight overhangs, and see how they come out. Start from standard profiles, until you get bonding and general things good and routine. The standards are quite good. By beginning with dedicated small test models, and trying various things, you will learn the fastest.

 

Later on, you could try printing slower, cooler and in thinner layers for more accuracy if that would be what you desire.

 

Introducing 3D-printing in our lab in 2014, was one of the best decisions we made. I am still glad we did. It opened huge possibilities for prototyping and making small custom tools, and even clinical tools for use in the hospital. But 3D-editing and 3D-printing is a huge learning curve, just expect that it takes some time and effort.

 

[Kastenbrot 0]

Thanks for the input!

There really are a lot of parameters to try and fiddle around with - just on the software side. I am interested to see how it all plays out once 'the rubber meets the road'. I already have some familiarity with G-Code, post-processing, and numerically controlled machines from work, but I am yet to see how and if I can utilize it for home 3D-Printing.

 

I was also intending on trying different designs on a simpler part at first. I was just playing around trying to learn about 3D-Design and wondered why it sliced differently from my initial expectations. Which is why I came to post here in the first place.

 

I will be running a few pre-made prints from thingyverse, trying to get a feel for how the printer behaves with different settings, as you suggested. Once I start feeling comfortable with what I am seeing and know what the base line quality looks like, I might move on to my own files. Then at least I know what to expect and can troubleshoot a little easier - at least I hope.

 

In the end of the day I am sure this will end up in me changing a bunch of things all at once, ruining prints and wondering what went wrong. Just to go back and change a bunch of other things.. I am sure most people here are familiar with how that goes.