2 objects assembled, play between the parts

I’m working on a 3D print which uses dovetails to join two parts.
It’s easy to make the positive and negative forms. However, I think I should plan to reduce the positive form to be sure it will fit to the negative, 1mm smaller seems to be fair.
Other than reducing the form with the scale tool, would there be an other solution more handy?
Here is below two screenshots of the assemblage.
Many thanks for your answer.

I wouldn’t use the scale tool because it’s likely to change the dovetail angle. Instead, I would probably use Offset and Push/Pull to create the clearance.

Do you know that a 1 mm gap with give you the clearance you need? How smooth does the sliding action need to be? It might make more sense to make the parts without the clearance and then clean them up to fit together.


So simple, using the offset tool. I was unaware of that tool! Shame on me. Many thanks Dave!

I find it works fairly well to reduce the inside shape, or increase the outside one, by about the diameter of the nozzle in FDM (extruded filament) printing. On my printer that’s only 0.5mm. Or split this distance between inside (half the nozzle diameter smaller) and outside (half the nozzle diameter bigger). Some printers have even smaller nozzles.

My printer and slicer seem to track the nozzle centre along the edge of the piece, so it prints about half a nozzle diameter on either side of the modelled shape.

Don’t know how it works on a laser fusion printer. Probably less offset even than that.

Do a small sample piece as a test, and adjust the offset up or down by 0.1mm increments to get the tightness of fit you want. You might even need to use smaller increments - I sometimes find that even 0.02mm is enough to make the difference between an easy push fit and a tight one. It can also depend a little on the material.

On my fdm printer I use .4mm for an easy slide, and less if it needs to be tight.

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