Which support patterns remove easily?

[ShopGeezer 2]

I am starting to use version 4.1 of Cura and it has been working well.  However some complex prints with lots of overhangs build a lot of support and in some cases the support is almost impossible to remove. The supports seem almost as strong as the print.  Fine details come off with the support material.  I downloaded the Settings Guide extension and looked at the support patterns entry.  The various support patterns are shown and the intro text mentions that some are meant to be stronger and some easier to remove.  But it doesn't say which is which.  Very useless.  I want to know the easiest to remove pattern.  The Settings guide shows Lines, Grid, Triangles, Concentric, Concentric 3D, Zig Zag, and Cross.  It doesn't mention Gyroid.  Is there an order to this left to right?  Which are the easiest patterns to remove?

[rburema 26]

If you want relatively easy to remove supports, you might want to try the (sadly still experimental) Tree-support: Disable normal support, and enable 'Tree Support' in the experimental tab (you might need 'show all settings' first). It'll take a longer time to slice (but not nescesarily print), but most of the time its worth it.

 

Other than that, it's a bit of a trade-off between what'll actually print well and your particular model.

[geert_2 557]

For special models and difficult to reach areas, you could model the supports in CAD in the design itself. Then you have full control and you can adjust it to your needs.

 

See these examples for my single nozzle UM2 printers (I have no experience with dual nozzle):

 

A few different support concepts I have used: some with extensions, so I can grab the support with pliers; some with holes to insert pins to pull the support out, some with layers that peel off easily, some with several tiny blocks instead of one big block so I can wiggle each tiny part loose, some with overhangs to improve the first real layer of the bridge, etc...

 

These pink and orange supports extend from the model, so I can grab them with pliers, because the model is too small to get in there with a knife. Also they have a custom brim (footplate) for better sticking to the glass due to their huge overhangs: I do not want them to be knocked off when the overhangs curl up and the nozzle bangs into them. The ribs on top reduce the contact area and make removal easier, and they reduce sagging (the blue tray has to slide in the yellow part).

 

These supports hang to the side-walls, so they don't reach all the way down. This is usefull if you want to reduce the amount of support material, or if you don't want the lower surfaces to be damaged by supports. The concept is based on an idea from another user (was that "smartavionics"?).

 

The bottom layers of the center support bridge will sag a lot, but that does not matter, as they are discarded anyway. The inverted staircase shape reduces curling-up of the overhanging edges of the supports.

 

[ghostkeeper 105]

In my experience, Lines and Zigzag are easiest to remove, followed by tree support and concentric. The rest of the patterns are all really tough which makes them hard to remove.

 

Overhangs that are really close to the build plate are always problematic regardless of the pattern. That is my most common use case for PVA support.

 

The Settings Guide doesn't mention Gyroid yet because it's really new. I'm working on an update for Cura 4.2 that includes Gyroid.

[ShopGeezer 2]

I have used tree support successfully especially if there is an overhang close to the top of the print.  But in making a small figure of the moon lander (lem) as a table ornament for July 20th celebrations tree support was a disaster. The tree was so intertwined into all the complex shapes of the Lem that I could not remove them.  Normal supports were not much better.  It was impossible to keep the fine details, they all came off with the support material. 

 

Geert_2 that is interesting, a lot of design for the supports though.  How do you design the support attachments so that they release easily?  You mention the overhangs curling up.  I have that problem on electronics enclosure lids.  The thin edge wants to curl up despite the supports underneath. .  Any solution to this? I used zig zag supports but they were not easy to remove.  They seemed to merge with the box lid itself. 

[geert_2 557]

Yes, sometimes designing the supports takes time. But if that makes the difference between a succesfull or a failed print, or between almost no post-processing or a post-processing nightmare, I think it is worth the effort. I like designing more than post-processing...  :-)

 

Concerning the exact dimensions and gaps I would say: design a test piece in which you incorporate several variations, and try which works best for you. For me, the ribs on top work best if ca. 0.5mm wide, with horizontal gaps between 0.5mm and 1mm. Vertical gaps of 0.2...0.4mm usually work well for me. Smaller gaps give better accuracy, but make removal more difficult and vice-versa. This is all for single nozzle printers like my UM2; I have no experience with dual nozzle (I guess then you could make the gaps far smaller?).

 

It also depends on materials, models, printing temperature (cooler is better), layer height, speed. So you need to find a balance that works for your models and materials. Takes some trial and error.

 

Below a new one from yesterday which also works well. Here the supports are totally free hanging, with very small gaps. It works due to the stringing and the sagging first layers of the support just sticking to the side walls. This support causes very little damage to the rest of the model and consumes only a very small amount of material.

 

 

 

Edit: to reduce overhangs curling up: thicker layers tend to curl up less than thin layers: a 0.2mm layer is *much better* than a 0.1mm. Also printing slow and with lots of cooling helps. Instead of an inverted triangle, an inverted staircase also curls up less (as in the support shown above). All these things help, but do not eliminate the problem.

 

Edited July 26, 2019 by geert_2

[ShopGeezer 2]

Your image shows watermarks on the vertical sections of the design.  I tried this on the enclosure lid but they turned out poorly. The letters did not fill completely.  I am not sure if the letters are solid from the cad program.  I created 3D text and added it to the box lid. The entire lid shows as a solid group. Everything else printed well except for the top right corner which curled. The text is .1 cm high.  I understand the text prints better vertically as in your design but that would be difficult with this part. 

 

I increased the bottom inset of the lid to .3 cm thick.  The overhang part is also .3 cm thick. Since I have more "meat" in the lid now I added countersinks for the attachment screws in each corner. Haven't had a chance to try a print with the updated cad file yet.  Vacations are getting in the way.