Stacking/Overlaying parts

Stacking parts in Preform (Form2)

I haven’t printed in a little while. I loaded up 4 files and decided to click “One Click Print” to see how it would orient them. Has stacking or overlaping parts like this always valid? On the second screenshot you can see supports stemming, not from the platform but from the underlying piece.

I am not going to print like this…but I was curious if this was something new or I could print like this all along. (BTW this is with Tough v4)


I suspect if you moved each individual item around, you would see that the supports are coming from the base.

What I don’t know, and have never seen a response from Formlabs, is that if you have overlapping parts is the overlapping volume double exposed? I am guessing that they will tell you stacking parts just won’t work right.

I guess if you don’t mind wasting some resin and print time it might be worth a shot to see what happens.

Well I saved the .form file to test in the future. right now I have a time sensitive print.

I’m pretty sure overlapping bases do get overexposed, so I would imagine the same would hold true for any overlapping areas…not 100% sure tho. I have successfully printed parts within parts, but I have never seen (or noticed) supports stemming from one part to another part (one file to another file). What I do see regularly is supports stemming from the same part such as this:


I guess it is no different.

Curiosity got the best of me and you are correct in saying the supports are coming thru the item from the base. So I guess the cylindrical area of the supports and part beneath would get double exposed?


In addition to being more difficult to cleanly remove, yes.

1 Like

Parts are exposed in layers, so how can these be double exposed?

The laser traces them separately. If you stack parts like this and then use the layer preview you will see two sets of tool paths, one for the model (blue) and one for the supports (orange).

The end result is that you are wasting a bit of time retracing the supports inside the model and the areas that are double exposed will be a bit more brittle in some resins. The base layers are compressed and double exposed to ensure they stick to the build surface, if you have ever noticed that your base and supports/model have different mechanical properties this is likely why.

Hope that makes sense.

If you have separate objects within an single file that you’ve imported (like detail parts that are intersecting a surface) then they will be treated as a single object and will not double expose. But if you have an object in Preform and you overlap it with another object then they will double expose the area that intersects.

In my case I imported 4 parts, 4 different STL files. My initial shock was I thought new support structures were stemming from parts underneath. My mind started going wild with ideas of stacking many many parts like the Fuse 1:

Alas @themedulla was correct in saying the supports were coming from the base all along, just intersecting the overlaying parts. So my original thoughts are moot, however I find the opinion of overlaying parts and single/double exposure very interesting.

If you wanted to try something like that you would have to layout your parts in your 3D application and export it in a single file to Preform and then enable the Interior Supports option, then it could build supports off other parts without a support going through an entire part.

But–with an SLA type printer it’s going to turn out very badly, SLS is OK since it doesn’t have support structures touching the surface but it’d be a nightmare to try and clean up parts that are printed like that in SLA.


Yep, yep, understood. I had just been out of the 3d printing game for about 3 months. I updated Preform and thought something had changed!

Intersecting parts of a model are double exposed and we’re working on improving detection for intersecting geometry. In some cases, users will intentionally intersect parts to fit more on a build platform such that the support structures from one model intersect through the body of another. This is doable but the supports are more challenging to remove and tend to need to be cut rather than pulled away.

1 Like