Wall thicker on curved sections

[Bad_Mechanic 0]

While doing some tests and calibrations on my printer, I realized the wall thickness is thicker on curved sections of the wall, while the wall thickness is as expected on straight sections. This poses a particular issue when printing something with a hole in it, as the hole ends up being smaller than designed. It's not much, only about 0.15mm, but it's enough to sometimes be an issue.

 

Any thoughts on why I might be seeing that?

[burtoogle 513]

16 hours ago, Bad_Mechanic said:

While doing some tests and calibrations on my printer, I realized the wall thickness is thicker on curved sections of the wall, while the wall thickness is as expected on straight sections. This poses a particular issue when printing something with a hole in it, as the hole ends up being smaller than designed. It's not much, only about 0.15mm, but it's enough to sometimes be an issue.

 

Any thoughts on why I might be seeing that? 

 

Here's a couple of possibilities...

 

Obviously, when you print a curve, the distance along the inside edge of the curve will be shorter than on the centre line or outside edge of the curve and so the extruded filament will tend to expand in the inwards direction.

 

Another effect will be the (printer firmware and settings dependent) momentary slow down of the nozzle as it changes direction at each vertex in the curve which will tend to thicken the line.

[yellowshark 153]

With reference to the hole rather than the wall thickness... 3D printers do not print circles, they print straight lines. Lol end of really. The line cuts across the arc so the radius is smaller. No way around that really apart from compensating in your design if dimensional accuracy is important and you have a tight tolerance.