Easy/best way to merge shapes for FDM?

  • 3D Printer Model: Prusa Mini
  • Slicer: Prusa Slicer
  • Hardware Setup: stock
  • Problem description: printing “nested”/embedded items, the “inserted” items easily pulls out
  • What I tried: This is my first attempt to create a 3d print which wasn’t just download/scale/print.

But let me simplify… imagine creating a “wheel” (ie. a disc) 10mm diameter (x,y), 2mm thick (z)… now insert an “axle” (cylinder) to the wheel… centered… call it 2mm diameter, 4 mm tall (z)… have both of them start at the same bottom layer (z == 0), and as such the “axle” will extend from the bottom and protrude 2mm above the rest of the wheel.

What I’m finding is that if I were to “sketch” that in Fusion 360… then “extrude” the outer wheel to 2mm, and the axle to 4mm, export to STL and print (prusaSlicer), the axle doesn’t seem to be “connected” to the wheel and easily gets pushed out.

Now I see in Fusion 360 that I can Solid → Modify → Merge … is that the correct approach to solve this? And if there are a much larger number of items (ie. a text phrase) is there any easy way (or other tool) to accomplish this vs. individually selecting each “embedded” item and merging it to the “base” ?

Appreciate suggestions.


Yes, using the “Merge” command in Fusion 360 would be the correct approach to solve the issue you described. This command will join the separate bodies together into one single solid object, ensuring that the axle is properly connected to the wheel.

To use the Merge command in Fusion 360, select the bodies you want to merge, right-click, and choose “Merge” from the contextual menu.

Regarding your second question, if you have a large number of separate bodies that you want to merge, you can select all of them at once and use the “Combine” command instead of Merge. This will allow you to join multiple bodies into one single solid object.

To use the Combine command in Fusion 360, select the bodies you want to combine, right-click, and choose “Combine” from the contextual menu. This will open the Combine dialogue box where you can specify the operation you want to perform (e.g., join, cut, intersect, etc.) and select the target body. Once you have made your selections, click OK to complete the operation… i hope this helps boss