Bending metal

Angle tolerance is a setting (document property) not a global preference. The templates have these values stored in them, I suggest you alter your standard templates with the lower angle tolerance value.

–Mitch

Hello,

I’d be interested to see how you’re creating your line work. If you made a short video of this part of your design process it may help to see how you’re creating these inaccuracies in your model which is causing it to fall apart at a later stage.

HI there OStexo.

I’ll try to do that. I reset my template Mitch - thanks

@Helvetosaur, it was indeed the angle between lines which i measured after filleting with a radius of 0 to extend them. Then i´ve found they where not fully planar and fixed the vertical line.

It could happen just on the fly, eg. when you asume you have Ortho enabled but it is disabled. Not a big deal, just use _GCon occasionally if things look or behave unexpected. It may also be a good advice not beeing too attached to simple geometry, if it can be re-created with a few steps, just delete it and do it again. If you then succeed, you can more and more securely rely on your work.

c.

Several other “mysteries” about the outline polycurve when it is exploded:

  • Why is the combination of the elliptical arc and straight line a single degree 2 curve with weight of the control point at the corner apparently of zero or virtually zero instead of distinct straight line segment and elliptical arc. How did this occur?

  • Why is the combination two straight line segments at the upper interior corner a single degree 2 curve with weight of the control point at the corner apparently of zero or virtually zero instead of two distinct line segments? How did this occur?

  • Why are the “arc” of the tabs almost but not quite circular arcs?

  • Why are portions of some of the straight lines and arcs single degree 2 curves rather than straightforward individual line segments and arcs?

The simple and efficient fix for all of these problems is to delete the geometry and start over. But these mysteries suggest some methods/techniques of creating geometry being used which may continue to result in problems.

Wanting a quick and easy solution, I created a profile wire for the finder side, extruded it, and copied it.

For the top, I created an edge profile, extruded it. You may find that I made 2 generations of wire for this part, merging the angle part and the cap, so that it’s one piece. The top was filleted on the outside. I then made a boolean tool to hollow the inside. I filleted the inside, which went okay, except for the left-hand corners, which I filled with a three edged edge curve.

Three Boolean tools were to chop out the angled edge. To avoid problems, I usually made all boolean tools a little larger than they need to be, so that they overshoot the edge.

The result appears valid, done with high tolerances, and has no naked edges. It probably has surfaces that could be merged, but I wanted to make the edge-curves first because I wanted the edges still split. Looking at it, I forgot to fillet the corners of the angled part.

I forgot to resize the screenie.

I’m inclined to create boolean tools that I assign to my ‘cutting’ layers so that I can regenerate components when needed. I then save copies of succesful steps to in effect ratchet my way up the process.

I ended up exploding and recreating a number of surfaces until all would join together. It was tedious but paid off. I hope I’ll develope my line creation skills to the point most of the remedial work is unnessasary.

ViewfinderCover.3dm.zip (1.2 MB)

David,

Gremlins.

I can’t get to the link you posted.

I get this:

Sorry, you don’t have access to that topic!

Deleted

I made this intentionally exaggerated, and ugly. I was trying to emulate what a somewhat cylindrical tab would do if were bent over something.

I first made a profile, and extruded it to make a solid.

I also extruded a curve to make a cylindrical surface profile.
I unrolled developmental surface on the cylindrical profile to make a source plane.

I flowed along surface the solid object using a flat source, and the curved target.

I chopped it and rotated the remainder, leaving a gap in the middle.

Yes, it is exaggerated.

If it were really bent over something, the tab would be a simple flat from the edge radius. I used extruded curves to make the corner-most surfaces.

I lofted the edges between this and the radiused parts, using the make tangent options. I did this for both sides, both surfaces.

(There were no edges at this point in the bent area.)

I copied the edges along both sides, and joined the curves.

I used these 2 curves for rails, and used the straight edges as cross-section curves.

(Now, I had all the parts.)

Before I could make a solid from this I needed to join the surfaces. I also needed to flip the dir, so Rhino could understand what kind of solid I was trying to make. This happens sometimes with weird things. Which is the outside, inside?

It made a solid.

JKayten, your part looks good : )

Sometimes, things get strange geometry-wise. Every day I use a walk signal that has co-planer radii that look something like this. I can’t use these things without figuring out where the splits go, or if it could be filleted like it is.

That’s funny. I’ve also come to observe everthing in terms of modeling it in Rhino. Sometime I miss the light contemplating the forms in automobiles.

:relaxed: