3D printing of curved object

How smooth are objects with many segments when 3D printed. I was wanting to model an object for my brother. But he is afraid that he will have to sand the final object down when he 3D prints it. If I model it will hundreds of segments will it print smooth?

Why not print a few small rings with various segments and see what is acceptable?

He is going to have to pay to have the things he needs printed.

Oh, sorry the “when he prints it” part tripped me up.

It would be worth checking with the service that is doing the printing to see what they need from the .stl files and what their printing resolution is. That’ll guide you in how many segments you need to use when modeling curves.

jimhami42 created a plugin that might be helpful. See:

Thanks. I will tell him

It also depends on the shape and the material.
Some shapes may lend themselves to SUbD or other smoothing options.
Some materials will be more coarse than others and some will always need finishing, some of the cost is in the finishing.

what do you mean some of the cost is in the finishing? Do some services offer smoothing of the surfaces.

The material and type of printing can require finishing, printing in metal needs professional finishing.

Ok, thanks. He is going to be printing in something like the resins he uses to make things by hand now.

Yes, for example the i.Materialize folks offer to print some materials in a raw form and in a processed form (as I recall).

Small holes 24 segments prints nice. Big objects i try to not go less than 48…prints perfect

What is small? And what is big?
It’s safe to say that the bigger the circle or curve, the higher you need your segment count to be…
For my printer I use a segment length of 1mm. Above that the segments will show.
Below that is a waste of time…

For screw holes like m4 to about m8,
24 segments will print good. Yes the bigger you go the more segments… m12 hole 48 should be fine. If you go bigger i go up to 96 aslong as you don’t see the edges in sketchup. Best for you would be to print a few at different segments untill you find the 1 perfect for you.