[Solved] Double offset

[jfc4120]

See this image:



Do one of you know how to figure those two angles with a given offset dimensions.

Also if I was looking at xy plane and z was toward me (in and out from screen). I am trying to also figure out how much to do two rotations to a plane that is at first edge view to the view.

A. Rotation about Z
B. Rotation about Y

So I can slice (just easier).

[onekk]

As the sides are equal you coul position the sections and them make ruled surface between them to obtain a solid.

if you want it hollow simoly make two solids one smaller and use this to substract from furst solid.

Sadly I'm not at computer for some days so I could not make a script to make things.

Loft should be doable as it usually made ruled surfaces (if I remember well it has a "Ruled" property for this.

And as you have an equal number if sides it will work without problems.

The only problems could be to find correct angles for wires.

In the Loft wiki page there is a link to a page describing technicalities about Loft it worth a reading.

Hope it help.

Regards

Carlo D.

[jfc4120]

I am new so I am going to study the techniques everyone shared.

I solved by two sweeps, then polylines to recreate sections needed. Mid section I did not do but could, but not needed to figure the layout.

From these images you will be able to tell what I did, top image had to do first to get ends.





I did draft and used draft to sketch, I haven't figured out how to manipulate sketch made drawings yet.

EDIT: I guess I could loft mid section.

[chrisb]

If you use the Placement dialog for a sketch (or in case you use Part workbench, for a cuttee cube) you can check the "Incremental" box. Then you can do the rotations one after another.

[edwilliams16]

I didn't find a straightforward way of placing the cutting plane by compounding rotations. The expressions parser doesn't provide full access to the Rotation API - in particular to App.Rotation(vector, vector) to direct the normal of the sketch in a desired direction. My work-around was to create a construction line in the normal direction and attach the sketch to it.

Screenshot 2023-01-25 at 2.30.19 PM.png (16.91 KiB) Viewed 485 times

[jfc4120]

I get the angles by a small sweep first. Sweep one end then the other. Give me a few minutes I will post something.

Edit:

I have done this fitting 3 different ways in freecad, but I just cannot understand how sketches were used, I have the drawing, but not the steps to duplicate what was done.

Edit 2:

I draw a real quick traditional front top view with a quick auxiliary view to determine how much the compound elbow will take up, and if slicing two quick views to determine the rotation and revolution angles, the standard views go fairly fast since I only need rectangles and center lines to do the calculations.

But as I said including using slice I have solved this four different ways now in freeCAD, but for the life of me I cannot figure out how to solve this using sketches.

[edwilliams16]

@jfc4120


Here's another way with no math required. Create sketch scaffolding for an OXY attachment mode for the sketch.

Screenshot 2023-01-26 at 10.53.10 AM.png (29.64 KiB) Viewed 367 times

[jfc4120]

@edwilliams16 I will look over, thanks. One thing I do first is a quick 2D view to check for fitting "takeup" amount. An auxiliary view will show I have enough room for the ends.

Edit:

And an extra aux view gives angles and miter distances:

Newly attached image:

Also added completed, center is triangulated, ends not shown, but that is just simple parallel line development.

But I can now do the fitting at least 4 different ways in freecad, but I still cannot figure out how the one answer used the sketches to accomplish this.
I wonder if he used arbitrary angles. I was hoping for a more in depth explanation of how it was done. I am referring to @domad reply.