When I design parts that must fit in each other, I usually keep in mind that prints are 0.2-0.5 mm wider than expected (depending on material) and I size the parts accordingly.

However, sometimes I design the whole part and then I slice it with planes or lines. In these cases I need to push/pull afterwards each contact surface manually by the same amount (0.2-0.5 mm) and that is a time consuming task. Another option is to use a cutter to remove the outer surface layer (basically I remove the rigged surface, making it smooth again) but it's not safe and even more time consuming.

How can I quickly generate said controlled gaps on the contact surfaces between two objects, but not on the rest of the object? to make it everywhere I could use shells, I guess, but I don't need that on the whole object.

  • $\begingroup$ This isn't an answer exactly, but I'd suggest you skip 123d design and check out Fusion 360. It's easy to use, much more capable, and very well supported by tutorial videos. The way I normally handle tolerances is to add them as parameters that I use in my sketches. The sketches define the 3d geometry. If I decide I need more clearance later, I just change the tolerance parameter and it all updates automatically...that's the power of good parametric CAD. $\endgroup$ – Chris Thompson Oct 24 '16 at 17:25
  • $\begingroup$ I think fusion 360 is not free... Unless I lie and I say I'm a student. $\endgroup$ – FarO Oct 24 '16 at 21:45
  • 1
    $\begingroup$ No need to lie, use the free startup license. Autodesk has been offering this for a couple years now. This lets you legitimately use it for hobby, fun, or even business as long as you're not using it for a business that makes over $100,000 per year. See here and feel free to confirm with Autodesk. (I'm paying for my license just to maintain my access to Fusion 360 Ultimate, but really Ultimate doesn't offer much more yet.) $\endgroup$ – Chris Thompson Oct 25 '16 at 22:23

Unfortunately, 123D Design doesn't have such a feature.

You could select multiple surfaces and push/pull them all at the same time though.

Remember, your 3D Printer's slicer should have an option to undersize or oversize holes and walls, to help reduce/remove the effect you talk about. It's called size correction, I think? Simplify3D Has it, atleast. You might have to tweak this for every filament type, though.


AFAICT Push/Pull faces is the closest thing to what you're looking for. eg:

In OnShape there is an "offset face" command that allows applying such an offset to multiple faces at once: How to add tolerances/gaps in OnShape?

Unfortunately I'm not aware of a way to do exactly the same thing in 123D Design, but I'm far less proficient with that tool (as Alucard Pawpad noted, though, it is possible to just select multiple faces at the same time and manipulate them all together, which is somewhat similar)

  • $\begingroup$ So that's what I was already doing. In the meantime, I switched to Fusion, 123D is no more available. It works the same way, but with the history I can always change that amount later on, which is a bonus. $\endgroup$ – FarO Jun 23 at 7:52

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