Hi Rudy, what you need to do for extrude is to draw just one profile shape. You've actually got a bit too much drawn there.

So instead of this:

what you really need is this:

That's just the front flat part - this is what you can then extrude straight out to make your brick:



So when you want to use some of those construction tools like extrude or revolve, you want to try to identify sort of one profile shape more than the entire wireframe of the object.

Another thing to be careful of is to make sure that the pieces of your profile have exactly matching endpoints. If there are any little holes or gaps between different segments it will prevent you from making a fully closed solid. I noticed you had a small gap in your original curves, to do my extrude I erased everything except for the 2 curved pieces in the front plane and then drew 2 new lines to connect them, making sure to snap the endpoints of the lines right on to the ends of the curved pieces. To do the snapping, make sure that the "Object Snap" in the bottom toolbar is highlighted in orange, that means that it is enabled.


Then shelling should work quite well on a simple shape like this. I'm not sure where you want the opening to be, but here is an example - first I selected the top face of the brick by doing 2 clicks on it, one click to select the entire brick, and then the second click "drilled-in" to select just the top face, that should look like this:



Then running Construct / Offset / Shell with a thickness of 1.0 gives this result:



Let me know if you need any more details on any of these steps!

- Michael

Thank you Michael,
yes, I was thinking some profile but I could not figure it completely out.
Yes, and I did it quickly, so did not check the junctions well.


Thank you again for all your patience....
Rudy

Michael,
How do I do a variation of the same.

Take a look at the file...

Thank you,
Rudy

Maybe this :)

Hi Rudy, Pilou showed one possibility, a couple of other ideas:

One easy way to get a similar type of shape is to draw a box, and then select the top 4 edges and then do Construct / Fillet. That will basically automatically put rounded edges there, ending up with this:



You give up some of the direct control over the rounded shape by doing this, since it is calculated for you, but that is definitely the quickest way to get that kind of a shape.


Probably the easiest way to make it conform more precisely to your sketch would be to create 2 extrusions and then combine them together into a single shape by doing a boolean operation.

Here I drew a line along the bottom, and then used Extrude with the "Both sides" option to create this piece first:



Then repeat that with your other curve:



The "Both sides" checkbox inside Extrude allows the curve to be used as the centerline for the extrusion which is useful in this case.

Then you take those 2 objects that are stacked on top of each other, select one of them and then run Construct / Boolean / Intersection, and then select the other one and push Done, that calculates a new volume that contains the portions that are common to both objects, this is the 2 objects and then the combined result:






Sometimes this is a good way to build up objects - try to build things in more simple pieces separately, and then combine them together into a single object using booleans.

But if you generally want to create some rounded corners easily, the box + fillet way is probably better.

- Michael

Thank you Pilou,
Thank you Michael. Now I have understood the purpose of the ISECT operation in the boolean.
I have two things.

1- First I did not understand Pilou's way to make that shape into a solid (See JPG)
2- I am trying to shell the new, all curved, brick shape and cannot do it. See file (shell from bottom). Am I doing again something wrong?

Thank you for your time.
Well appreciated,
Rudy

Dear Michael,
The new shape is shelled.
However, I tried few times, I could not succeeded.
I saved, then I closed MOI, re-opened, then I did my shell . It worked this time.

Thanks,
Rudy

Hi Rudy -

> 1- First I did not understand Pilou's way to make that shape into a solid (See JPG)

Pilou used the "rail revolve" tool. To do that, run Construct / Revolve / Rail revolve, and then when prompted, pick the profile curve and rail curve that Pilou shows, and after that you will be prompted to pick a revolution axis line, similar to regular revolve. Pick the 2 axis points on the endpoints that Pilou shows the dotted line between, and you will get that result.


> 2- I am trying to shell the new, all curved, brick shape and cannot do it. See file
> (shell from bottom). Am I doing again something wrong?

Shelling is really pretty sensitive to small inaccuracies or irregularities in models. Similar to fillet, it can get confused pretty easily in situations where there are several small edges or corners coming together.

In this case the shell will succeed with small values (like up to 0.05 or so), but it gets confused with pieces running into each other with larger values.

Your model has these kinds of corners:



That's basically not a very clean and simple structure where the different parts are meeting up, things are kind of broken up into different little edge pieces there, that's what is problematic.

It looks like this is the result of small differences differences between your different arc curves that make up the shapes - like you've got one that is about a 53.4 degree arc and a different one is like a 53.5 degree arc. They also not quite in line with each other, the bottom of one does not quite line up exactly with the bottom of the other set: (shown here zoomed in a bit)




Everything is fairly close to being lined up, but isn't quite close enough. Small inaccuracies and little mis-alignments tend to get magnified as you do more operations to the results of the curves, and that eventually ends up creating more complex corners and little tiny edges on the final results instead of simple structures.

So to create something that can be shelled successfully, you've got to be quite rigorous about the accuracy of your original curves, things need to be aligned more precisely to get a cleaner result.

One big tip for this is if you want to create symmetrical pieces, draw one and then duplicate it using tools like Transform/Mirror or Transform/Rotate, rather than trying to sketch a close equivalent. Creating an exact duplicate will help to ensure alignment. And it is actually quicker to duplicate than to re-draw.

I've attached a reconstructed version of your model as curved_brick_3.3dm (in the .zip file), this version should now shell properly.

The way I reconstructed it is I threw away everything except for one of your arc curves. I did a Transform/Rotate with checking the "Make copies" checkbox to make one copy at 90 degrees rotation, and then did Transform/Mirror on each of the arcs to create an exact mirror image duplicate. Then I drew lines to connect them and went through the extrude + boolean intersection procedure.

This result has a nice simple edge structure because all the pieces lined up exactly, so the intersections between the different objects were very clean and predictable, and symmetrical. So the final resulting edges come right together at a single shared point instead of being slightly off.

For some purposes you don't need to worry so much about such detailed accuracy, some things can tolerate it more than others. But shelling and filleting tend to be the least tolerant.

I hope this helps!

- Michael

Thank you Michael!

Have a nice afternoon.

Rudy