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mike-truly

Terrain Model Problem

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Not sure if this is best posted in Cura or not.

I have a need to create terrain models on the UM2. They will have to be created in sections and put together later. They are basically rectangular sections of terrain. Imagine mountainous terrain with high peaks and low valleys. The low valleys are thin and close to the print bed.

1. I created a terrain in MAX, saved an STL and brought it into Cura. When viewed in Cura, the low valleys are thin but they seem to be above the zero level of the print bed in the Cura viewer. Yet when I start printing the terrain, rather than the print head making a perfect rectangle, it leaves open areas like it thinks the low valley goes below the zero level of the bed. It does not display in the Cura viewer as open or below the print bed or in the MAX display that I can see. Not sure why it's not printing these low areas? Is the Cura display not accurate?

2. Ideally, I might want to create just the terrain surface but I think it must have support from underneath to work so I have basically made the model to go from the surface points all the way down to the zero bed level. I saw a checkbox for 'Print Support Structure' but did not check it when saving the gcode. Yet when I watch it print, on areas inside the terrain it seems to print a waffle like surface rather than solid. Is this the support structure? If not, if I had chosen the checkbox, could I have created a model with only the surface shell and would it have created proper support for the whole terrain (and been faster, using less PLA)?

Thanks!

 

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your model is probably not watertight. In 3dsMax make sure you dont leave any open edges.

In Cura always verify the result in layer view before printing. It will save you material and time...

In Cura you can also look at the model in XRay view. If you see red then you have open edges.

layer view issue 3

 

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If you want to make a model with just the surface you can use the shell modifier in 3dsMax to define the thickness you want. Make sure to check the "Straighten Corners" option at the bottom to prevent issues like this:

BAD SHELL

Again. Always check the result in layer view. Wait for the slicing to be done and the tool path to be loaded to see the result of the print

 

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The "waffle like" structure you are referring to is infill... it is defined as a percentage value in cura.

0% infill will slice and print your model as just a hollow shell, 100% infill will slice and print your model as one solid " filled" object.

Any value in between will give you this waffle pattern in varying size/resolution.

It is designed to save material and print time, while maintaining object strength and internal support.

The support options on the other hand, will generate similar patterns under any overhangs on your model (parts of the model hanging out in the air with nothing underneath them to hold them up)

regarding the open areas you are experiencing, check that you dont have a value set at the "cut off object bottom" setting...

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Thanks very much for the info! Greatly appreciated. I will look into these things.

Regarding the Shell modifier, I'm familiar with it but I'm having trouble visualizing how the model would be able to be printed in UM2. For example, if I would apply the Shell modifier in MAX to the surface... I would basically get a surface with some thickness, which is fine. But it would still be elevated in space above the print bed. Would I need to use the 'supports' checkbox to automatically have Cura generate supports underneath?

Obviously, I still have a lot to learn.

Thanks again.

 

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Ideally in cad you want an object with a flat bottom and walls.

When you slice I recommend unchecking 'bottom'. This will reduce warping of corners. Also I recommend 20 percent infill.

If you rotate 90 degrees you will get much higher resolution print but it might fall over. Do brim if you choose to do that.

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When viewed in Cura, the low valleys are thin but they seem to be above the zero level of the print bed in the Cura viewer. Yet when I start printing the terrain, rather than the print head making a perfect rectangle, it leaves open areas like it thinks the low valley goes below the zero level of the bed.

 

The first layer is not at 0.0 in your model, but at 0.3. So if the valleys are below the 0.3 point, it will leave those areas open.

The 3D view of Cura simply display the model as you modeled it. If you want to know exactly what will be printed, you can switch to the "layer view" in the top right corner.

 

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The default initial layer is 0.3mm so check you model in max to make sure its at least that.

If I'm not mistaking it should sample the model at the center of the layer meaning it should check at 0.15mm for the first layer and not on the top but I'm not sure.

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Great you sorted this out, I was about to suggest you checked the thickness in the low parts of the model as well :)

Now for printing, move away from the basic setting options and switch to full settings, you'll learn alot, and in the end get better results.

You don't need support enabled for a print like this since terrain is typically "flat" without overhangs... You do however need som internal structure in the model for the top surface to rest on... For this, you need to put a % value in the "infill" setting, somewhere around 20-25% should be sufficient

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