UM5S: calculating clearances

[aag 6]

Is there a reliable way to calculate the minimal clearance of slots and plugs for UM5S prints, as a function of printhead, layer height and layer width? As an example, take the following pic, where a metal bar is inserted into a ToughPLA slot. I typically give 0.4mm clearance on all sides but I could go a bit lower. It also seems to me that vertical and horizontal miminal clearances differ. I know that I could find out all this by trial-and-error but maybe there is a mathematical option that would save me from reinventing the wheel...

[Carla_Birch 116]

Best way to get better clearance is to dial in your flow rate and speed more, but you have to keep in mind you dealing with plastic that shrinks when cools and each type/brand might shrink more than another. But i do find personally myself that 0.4-0.5 is the normal clearance needed for pla.

[aag 6]

400 µm isotropic clearance is perfect for ToughPLA on ToughPLA, where both the male and the female parts will shrink a bit. In the case depicted above, a metal male part pairs with a female ToughPLA scaffold. I am currently trying 300 µm isotropic, but for a flush fit I suspect that the minimal vertical clearance is going to be smaller than the horizontal one.