I cannot get my head wrapped around Slicer (subtractive) function in Edit Support mode

I am very likely missing something here, but for the life of me…

I am in edit support mode, in an attempt to add some extra supports to some minima/islands. When in this mode, I see that the slicer functions in a subtractive mode when slid from bottom to top. Where as in normal mode, the slicer is additive, effectively simulating the printing process.

This seems counter-intuitive when trying to find the islands that might need a bit of extra support.

Can someone steer me in the right direction? I’m confident there is a rationale, but for the life of me can’t see it.


You should no have to find the islands by slicing through the parts, as those are highlighted when present. The highlight feature is a bit finicky to work with at the moment but it is reliable.

Hi - By highlight feature, do you mean the red shading that indicates unsupported minima?

I had a failed print yesterday where two islands fell from the supports, despite no unsupported minima indication. That said, I also wonder it was too cold in my studio, as I was lucky if the room was 65 F.

You need to use the slicer with the supports visible. This way you can see when the supports taper and where islands start without a support in place.

Using it in support edit mode means that the island become invisible. I suspect this is a bug.

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The reverse layer slice view in support edit mode makes sense to me. It allows you to edit internal supports that would otherwise be completely inaccessible.

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Can’t the internal supports be viewed in the standard mode (additive), just as readily?

Not the ones that are inside the object.
Think about it - imagine the object as it is oriented in Formlabs.

In “normal” mode, you hide the layers above a certain point.
Imagine a hollow sphere, with supports inside it, at the top.
How will you visualize the support points if you’re either showing the whole of the object below (obscuring the top of the inside surface), or you’ve cut away the top, and the support points with it?

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Eureka! Thank you, very much. Synapses formed.