3D pipe 90 degree bends causing a minor missing face 'bowtie effect'


#1

Hi All,

An oldie but I’m sure this used to work flawlessly. I’m creating some kee clamp style work and have discovered something whilst creating the models which include 90 degree bends. I am getting a bowtie style missing face(s) occuring on the tight inner bend when using the ‘follow me’ tool and cant seem to find a way of making SketchUP draw these in automatically. I am able to rework them but it just seems there is a flaw in the math or just the way im going about it.

Method;

Create an arc (origin to any distance) drag until 1/4 circle (any axis), add small extension lines to the ends of the arcs running off in the direction of that axis…
Create circle on one end of the arc
Select the path (triple click)
Select Follow me tool and click on face of circle.

Works great until you looks closely at the tightest turn (see picture) Sketchup does not create faces there, investigating inside the model you can see why it hasnt, because it seems to have overshot and created a diagonal cross inside the model. Leaving unhealed faces on the outside.

Input appreciated.

Red.


#2

It’s caused by SketchUp’s tolerance of 1/1000".
If you have very tiny edges in operations like FollowMe and Intersect you can find that they do not get created because SketchUp takes their two end points as coincident
Because faces rely on edges then related tiny facets do not get made either.
This is solvable.
Scale up the offending part x10 and redo the FollowMe operation - or over-draw the edges to make the required facets form.
Scale by x0.1 - the tiny geometry can exist, but it cannot be created initially.

Incidentally, the color of the surface suggests that it’s modeled inside-out.
The off-white front faces should be ‘outwards’, the blue-gray backsides should be inside.
Select one and context-menu Reverse…
Then use Orient to make all such faces have matching directions…


#3

In addition to what TIG says, you can sometimes get strange results if there are edge segments in the followme path that are too small compared to the profile you are extruding. Unlike what he described, this is because the profiles around the adjacent segments protrude through each other in ways that can’t be cleanly faired together at any scaling. The attached is a deliberately absurd example with some very tiny segments at the end of a straight run.


#4

Thankyou !

@TIG scaling X10 does the trick hadn’t realised that it had a tolerance but good to know !

and

@slbaumgartner cheers for the extra info, something to watch out for !

Red :o)