support/model contact points

Yes, now I can see the pictures. Thanks for re-posting them.

Your photos give a good view of the support interface, which almost looks like perforated paper points of contact, right? I saw that support interface in one of my earliest prints using supports and just jumped to the false conclusion that Cura prescribes where exactly the interface layer will touch the model. But then I did another print (baby Yoda’s black eyes in my other post) where the print failed over and over again. I was confused by the fact that eyes only actually touched the support in one tiny area and I couldn’t get it to touch anywhere else. I kept fiddling with settings, but couldn’t find a way to get Cura to make the supports touch the bottom of the eyes and the prints kept failing because the eyes would detach from the support structure before the print finished.

For some reason, here is how Cura initially places the eyes:

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“medium”,“data-attachmentid”:5492}[/ATTACH]

I would then rotate the eyes like this:

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“medium”,“data-attachmentid”:5495}[/ATTACH]

With the default support setting of 51 degrees, not much gets supported. I changed it to 20 to get lots of support that looks like this in the preview:

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“medium”,“data-attachmentid”:5494}[/ATTACH]

You see the gaps? They actually go all the way around under the eyes. Here’s another angle that shows more of the gap:

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“medium”,“data-attachmentid”:5493}[/ATTACH]

And the problem is that my printer kept trying to print them just like Cura was previewing them. They only touched the support at the very bottom of the V shape and kept breaking off.

It finally occurred to me to rotate the eyes around the red axis like this:

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“medium”,“data-attachmentid”:5496}[/ATTACH]

That orientation finally worked for me.

I kept trying to find a way to get the supports to touch the print more densely in my original orientation, but I couldn’t find a way. I tweaked lots of the support settings in Cura, but I never touched the ones that were really causing my problems: Support X/Y Distance and Support Distance Priority. I might have gotten the original orientation to work if I had changed those settings.

By the way, that Support X/Y Distance is seen nicely in your print–that large vertical gap between the support and the model as you mentioned. While you clearly don’t need vertical support in your model, in my model with the V shape, it was the X/Y setting that was causing the large gap between the eyes and the model.

So anyway, what I learned out of all of this, in addition to the importance of the Support X/Y Distance, is that Cura doesn’t actually prescribe where the supports actually touch the print. In your print, the first layer of the model above the horizontal supports were completely horizontal and not even a bridge, so clearly that first layer of model sagged down the 0.16 mm Support Z Distance and came to rest on the support. It probably actually touched on many of those “perforation-looking” pieces in the interface layer. But if you look at the preview in Cura and zoom in on the top of the horizontal support surface, you’ll see that 0.16 mm gap.

Anyway, your supports worked well and it looks like you got a nice print out of it.

Screen Shot 2020-11-01 at 12.12.04 AM.png

Screen Shot 2020-11-01 at 12.18.42 AM.png

Except that print just failed under slight pressure when trying to clamp it to 1 of my printer’s 2040 bars. My fault. I didn’t orient the layers correctly. What I should have done is lay the clamp on its side, so it would print around the perimeter of the clamp (along the top, down the back, then along the bottom; orienting it so the forces are distributed along the length of the layers instead of across the layers. This is a concept I had to learn pretty early on (even if I forget it now and then).