2nd Post - Understanding Supports in Cura

Discussion of Ultimaker's open-source Cura software
Tessmacher
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2nd Post - Understanding Supports in Cura

Post by Tessmacher »

This one's going to be rather vague, as I don't completely understand what I am asking.

I am having a great deal of trouble understanding the relationships between the "Support Z Distance" and "Support X/Y Distance" and how the model gets supported overall. I'm not entirely sure how to describe what I don't understand. What I do know from my background and education (I'm an architectural historian) is that in order for something to support something else, it has to be physically attached and structurally sound.

I have been fiddling with the settings in 4.1.1 and am rather at odds with the "Support Z Distance" and "Support X/Y Distance" settings. Whenever I set them to a value of "0" (so that they actually touch and are valid support) the model won't slice. They have to be at some fraction of the line width in order for the program to slice the model.

What I am stuck on is this: If I have a distance between the support and the model, then what's supporting the model on that distance? The whole concept doesn't make any sense to me. I've even checked out the Settings Guide, and separate research on the 'net. And I still don't get it. For a support to actually hold something up, it has to be touching it to hold it up!

I have attached a screenshot. The red arrows indicate the space to which I referred in my original post. These occur on Layer 51 of the model.

Also, note the orange arrow, as it is indicating a little "blip" or dot of material laid down in the previous layer. (Layer 50) I don't know what to make of this either.
cura-space00.png
Before the thread goes off in unwanted directions, let me say that I know A) supports exist because of overhangs. B) What's above the layers where the supports start is irrelevant, because the issue isn't at the top of the support, its at the bottom. Duh.

Could I please get some responses to explain these phenomena?

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GrueMaster
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Re: 2nd Post - Understanding Supports in Cura

Post by GrueMaster »

So, in most structural architecture, you want the support to touch to prevent sagging during construction and in most cases, those supports become part of the finished structure and are not removable. Where they are removed (say a temporary stud wall to hold up a ceiling while replacing a beam), they are usually cut out by cutting the support wall in half and folding it out of place.

In 3D printing, this is not the case. You want a gap, but you want it as thin as possible, usually less than a full layer. Then, when the model is printed in that area, the layer is supported, but not adhered to like the rest of the layers in the model. This will prevent noticable sagging in that area and make it much easier for the support to snap off once the print is finished.

In Cura, you have a lot of different settings for how supports are created that you control. The best thing to do is find a simple print that you can experiment with the different settings. Most of the prints I do these days I add custom tree supports using the custom supports plugin. It allows me to specify where on the model supports can attach.

I hope that helps.

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Roberts_Clif
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Re: 2nd Post - Understanding Supports in Cura

Post by Roberts_Clif »

In 3D Printing you have basic settings Overhang angle, Fill percentage, distance X/Y, distance Z
These numbers should come close to those listed below, even the Factory setting do a good job.

Under Support definitions
Overhang Angle 50-90 degrees : on my 3D Printers depending on Model, you may more or less.
______To determine the Angle print A overhang test model
Fill Percentage 20-30
distance X/Y .7
distance Z .15 : is a starting place depending on your layer thickness mine was .28mm.
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Tessmacher
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Re: 2nd Post - Understanding Supports in Cura

Post by Tessmacher »

It has occurred to me that I've inadvertently left out some fairly important information. My apologies.

I'm going to be using an 0.6 nozzle. The layer heights are all at 0.3, and the widths are all at 0.6

My overhangs range in angle from 12.1 degrees to a flat 90 degrees. In fact, some of them I don't think even need supports, but I don't know how this works well enough to be confident in that guess.

Anyhow, I'd like to continue the discussion until I understand this.

I like the idea of printing the overhang test model, but I have to acquire the printer first.

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Roberts_Clif
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Re: 2nd Post - Understanding Supports in Cura

Post by Roberts_Clif »

Using your Cura 4.1.1 download models from Thingiverse take this Luna in Armor as an example.
Slice the model and view layers you will see the model and the support structures.
Changing the given values will change the support structures in response to the these changes.

Though until you have a 3D Printer testing the changes is impossible as most 3D Printer have different levels of overhang they are capable of printing. Even the different Materials will yield a different degree of overhang angles you are capable of printing.
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LePaul
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Re: 2nd Post - Understanding Supports in Cura

Post by LePaul »

If @nallath isn't too busy maybe he can chime in?

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