Why does this happen? [Display not accurate]

The edges of my polysurface don’t coincide with the fill edges…

Why does this happen? Is it Rhino? Is it tolerance? Is it units? It is zooming? Is it my graphic card?

It only happens across this edge.

Not displaying correctly.3dm (107.2 KB)

Hello- the edges are off by a bit - less than tolerance but enough to see if you look at the overall object as the thing is quite small.
After RebuildEdges:


Hello Pascal, thanks for taking a look.
Weird, all I did was a boolean difference and that happened.
Its fixed now, I exploded the piece > deleted all faces except one > dup border> planar srf > extrude again. Tried the boolean difference again and no error this time, maybe I did something wrong the first time.

Is there a faster way to fix this though? I am sorry if you were hinting into RebuildEdges, I don’t use the command often, tried it but the error persisted.

Hello - RebuildEdges is not a fix here, it just lets us see what the problem is - that gap/overlap/extra is .0005 wide - not much, except that it is proportionally large compared to that face. The overall part is .6 units long, that small face .017 units. What this all suggests is that the part is modeled in the ‘wrong’ units. cm or mm would make more sense to me, at .01 or .001 tolerance.


Okay, that’s what I thought.

Yeah, I agree, thing is this is part of a bigger whole. So… stay in Meters but maybe increase tolerance up to 0.0001 instead of 0.001? Is there a big disadvantage in using a very high tolerance? I am often reluctant to keep adding zeros to that number…

Hello- I guess it depends upon the use you’ll make of the model - pictures, 2d drawings, machining… etc.

Rhino is happiest between .01 > .000001 tolerance, and in general you want the smallest feature to be at least 10x tolerance. You’re there, with this file, just barely, but also keep in mind you are looking at very small (in terms of units) details on a small object, very close up, to see that anomaly.


1 Like