My supports need supports!

[mitchfx]

My prints often have lots of overhangs that are above other parts of the model. For example ears, chins and hairlines that overhang the chest, neck and shoulders of a bust. What I usually end up with are bases of support towers that overhang because they do not rest on a flat surface, which sometimes causes them to collapse. Even if I use a 2mm support resolution I still cannot get around this problem since S3D doesn't "contour" or boolean the bottom surfaces of the supports to wrap around the model like it does on the tops. What this means is that I usually end up having to manually place dozens or hundreds of little 1mm supports in these area one at a time to solve the puzzle and prevent a failed print. Using any extra inflation on the supports actually exacerbates the problem since it causes the overhangs at the base of the supports to stick out even farther.

It would be great if S3D would have an option to contour the bottoms of supports to the model. Another helpful feature would be user defined "freestanding" supports that don't intersect with the model on top. That way you could place some extra supports on the outer perimeter to reinforce the problematic ones. Make sense?

[DarthRevan]

Could you post a picture of the results you're describing? I'm not sure I completely understand what you're experiencing.

[BaudR8]

I use supports on top of model surfaces all the time like you're describing without issue. I actually did a test printing a model on top of another model using supports and it turned out great for me:

[mitchfx]

I will post a picture showing what I'm talking about tonight. The reason your test worked fine is because you have mostly horizontal surface area on your lower model. Imagine you have a model of a person's bust and the supports holding up the chin happen to rest on his chest below. However the angle of the surface of the chest is pretty steep, thus more than half of each support hangs out over the edge. This often leads to collapse since the nozzle is depositing material in mid-air for those sections, with only a small portion of the support base attaching to the model.

If there was an option to have the bottoms of any support tower that do not meet the platform actually contour to conform to the model instead of being flat planes. This would be similar to how the tops are booleaned out fit the shape of the model above. Otherwise you needs tons of tiny supports with little or no extra inflation to make the volume of them "wrap" to the surface below.

I hope this is a little clearer.

[mitchfx]

Here is a mockup that illustrates what I am talking about. I'm not at the computer with S3D installed so I can't do screengrab right now, but I think this gets the idea across.

[DarthRevan]

I haven't completely dialed in my dual extrusion print settings yet but I did this in two colors to really show how the supports do contour to the models surface at the top of the support structure and at the bottom.

I can see how you'd think the supports need support but in fact they do not. see attached photos.

Manual Supports

Previewer

Printed

[mitchfx]

Actually they only appear to if you have enough SMALL supports and a shallow enough base surface for them to rest on. Your Yoda example has much flatter area than a lot of my busts' chest and necks that the ear, chin and other supports rest on. The resulting path layers on the bottoms of the supports are only contoured if the support towers that make them up are small enough to "antialias" that curve.

To test this theory try your yoda again with supports that are twice the mm size and run prepare to print again. You will see what I mean. Or put your octopus model on top of a very steep pyramid model and check that out.

[KC_703]

A bit unorthodox, by try rotating the bust upside down. The beard with all the intricacy would print much better.

Another orientation could be the back of the head on the bed...

[mitchfx]

Yeah, either of those approaches would cause even more issues than I am trying to solve I guess I will keep working with my "hundreds 0.5mm supports" method for now.

A great feature addition would be to add a "divide current supports" function. You lay out all your supports in 2mm for example, but then Simplify could then convert those to four 0.5mm supports each.

[DarthRevan]

Actually they only appear to if you have enough SMALL supports and a shallow enough base surface for them to rest on. Your Yoda example has much flatter area than a lot of my busts' chest and necks that the ear, chin and other supports rest on. The resulting path layers on the bottoms of the supports are only contoured if the support towers that make them up are small enough to "antialias" that curve.

To test this theory try your yoda again with supports that are twice the mm size and run prepare to print again. You will see what I mean. Or put your octopus model on top of a very steep pyramid model and check that out.

If you look closely at the images I posted from the software, you can see on the shoulders there are overhangs like you're describing. But the overhang results in the printed material dropping to just barely rest upon the model surface. Creating a contouring effect that is also barely attached and easy to remove.