I have attached an example I came across while modeling today. Sometimes I get failures on basic geometry that I've inspected and not sure why?

I proceeded to separate and manually build so that I could keep working but I'm curious if there is something I'm missing as to why these two solids won't join properly?
I wonder if there is a distance from 0,0,0 that can be at issue or units maybe? I have default units at inches and modeling in inches as I'm in the U.S.

Thanks!

Jason

P.S. I made the cylinder and back of plate to have tangency and no floating numbers so they mathematically should be coincident.

Hi Jason, the shapes are just not totally coincident.

This piece here is an exact circle which you can tell since it reports as having a radius value in the properties panel:




Note that this other piece does not report having a radius value, that means it is not an exact circular arc and is instead a generic spline curve that happens to be shaped pretty close to circular:




From the look of it I would guess that your non-circular one started out as a circle but then had its control points edited? When you edit a circle's control points it is replaced by a generic spline curve that will no longer be perfectly circular. It will deviate from a circle by some small amount. So you don't want to do that, instead you generally want to keep the circles perfect with no control point manipulation on them and make tangent lines coming off from those rather than trying to mush the circle to the line.

- Michael

Hi Jason,

re:
> I wonder if there is a distance from 0,0,0 that can be at issue or units maybe?

There can be an issue with things far from the origin but it's if you're something like 100,000 units away from the origin. There isn't any kind of issue with it for your case here.

Your case is just that one piece is an exact circle and the other piece isn't a circle.

- Michael

Thanks Michael. I may have concentrated on the cylinder too much in this instance and not the rounded base plate!

Hi Jason, I've attached a version here where I've replaced that piece of the base plate with an exact circle. I moved your other circle over there and trimmed it, your lines appear to be all set up well.

Is it possible on the other one that you turned on edit points, then moved a point somewhere then rather than undo you moved the point back? When you move a control point like that MoI assumes that you're trying to squish points around and replaces the exact circle with a general spline curve that is not an exact circle anymore. So for the particular case of a circle moving a point and then moving it back to its original spot will not result in the same exact starting curve.

- Michael