Creating a solid

 From: gunter511 27 Sep 2014  (1 of 14)
 I'm trying to create a solid shape by sweeping the two highlighted curves along two rails. The problem is I can't figure out how to cap the top... it remains 'open'. Could someone please tell me how to make a solid object rather than a hollow one? Thanks much. Attachments:

 From: Michael Gibson 27 Sep 2014  (2 of 14)
 6944.2 In reply to 6944.1 Hi gunter, usually it's only planar ends on things that will get capped automatically. With a non-planar end shape like you've got there it will usually require you to custom build the cap surface yourself rather than it getting automatically filled in. But if your capping shape is straight in one direction (like it looks like is the case here, since it has a single silhouette in the front view), it's usually better to form such things by initially making an extended shape and then doing a boolean difference with a 2D profile curve to cut off the end, leaving the imprint of the 2D curve's extrusion as the cap. I'll see if I can make an example for you. - Michael

 From: Michael Gibson 27 Sep 2014  (3 of 14)
 6944.3 In reply to 6944.1 Hi gunter, so the sort of most common way you'd usually go about it would be something like this where you'd initially build a larger solid with planar ends on it like this: Then rather than trying to construct things directly to the wavy top, you'd form the wavy top by drawing in a side profile curve like this (it usually tends to be good to use 2D curves as much as possible rather than doing things with all wavy 3D curves): Then select the main solid and run Construct > Boolean > Difference, and use the 2D curve as the cutting object. That will cut the solid into 2 pieces like this: Then you delete the piece you don't want and you'll be left with the result like this: Now the way the cap works in this case is it comes from a surface that is extruded out from the 2D curve and then cut by the main solid. So if you turn on control points of the cap surface you'll see it has control points like this: And if you remove the trim curves you can see the full surface for the cap underneath the trimmed away areas looks like this - it's an extrusion of the 2D curve: That's basically the usual way you'd want to do it. In your particular case here you may have to do something a bit different because of how your object is shaped with your one side zooming off at a steep angle and the wavy cut kind of waving above what would normally be the top plane of the object. So you may need to do a somewhat customized version of this type of thing by building an extended surface that does not actually have a planar end on it and then using Edit > Trim to cut that extended surface with a side extrusion. I'll try to make an example of that next. But I hope this example here shows the sort of main way you want to get those types of caps in place, they usually should come from an extruded surface that has stuff cut away from it. - Michael

 From: gunter511 27 Sep 2014  (4 of 14)
 6944.4 In reply to 6944.3 Hi Michael, Thank very much for your detailed explanation. I tried what you said before but the final form I need is for the top surface to be a tad 'scooped' out. So up until the Boolean difference I'm good. How would I deform the top so that it is a little concave? Thanks again.

 From: Michael Gibson 27 Sep 2014  (5 of 14)
 6944.5 In reply to 6944.1 The part that makes your case a bit difficult is how your profile curve runs up above the ends: You may need to do something like make the initial surface bowed upwards something like this: Then since you would not have a solid you'd need to build the cutting surface as an extrusion and use Edit > Trim to trim each of those surfaces with one another instead of using the booleans. There is another sort of shortcut way to go about it as well which might be easier for this particular case, which is to cut your top open ellipse edge into 2 pieces using Edit > Trim with the "Add trim points" option, then when you have 2 pieces use Construct > Loft to build a lofted surface between them. The resulting surface will be compressed down into single points at either end but it will probably be ok. If you want to post the 3DM model file for your object that you have the screenshots of in your first post I can show you how to do that on your existing model. - Michael Attachments:

 From: Michael Gibson 27 Sep 2014  (6 of 14)
 6944.6 In reply to 6944.4 Hi gunter, sorry I did not see your reply before writing my last post above. If you've already got the shape you want with your current uncapped version, it's probably easiest to try the "loft between 2 halves" method to build the capping surface. If you can post your 3DM model file I'll show you how to go about doing that, but the basic steps are to use Edit > Trim to cut the top edge into 2 pieces then do Construct > Loft between those pieces. The cap surface will be a somewhat more complex surface than one extruded from a 2D curve but it will probably be ok. In other cases when it's possible it tends to be better to use the 2D cutting curve method I showed above since it results in better quality surface structure which is why I was trying to explain that method. - Michael

 From: gunter511 27 Sep 2014  (7 of 14)
 6944.7 In reply to 6944.6 Thanks Michael. Here's the file. I tried creating a point 'below' the to surface and lofting and it worked but now, obviously, the concave surface comes to a point rather than a smooth surface. Attachments:

 From: gunter511 27 Sep 2014  (8 of 14)
 6944.8 In reply to 6944.7 Michael, I've got a kind of solution by drawing a circle below the top surface and lofting. Attachments:

 From: Michael Gibson 28 Sep 2014  (9 of 14)
 6944.9 In reply to 6944.8 Hi gunter, ok now I understand better what you're looking for. All my stuff above was talking about making a straight cap... So yeah putting in a circle and lofting is a good idea. To make it fully smooth, also put a point object in the center of the circle (draw curve > more > point), and then select all 3 of the top curve, circle and ending in the point to do the loft. Then set loft style = "loose" in the loft options. Check the attached 3DM file for an example. Making a loft that ends in a point object is one of the new features in v3, there are some examples here: http://moi3d.com/3.0/docs/moi_command_reference7.htm#loft - Michael Attachments:

 From: blowlamp 28 Sep 2014  (10 of 14)
 As another variation, you could also try the new 3D Rail revolve option in MoI v3. Sample attached. Martin. Attachments:

 From: blowlamp 28 Sep 2014  (11 of 14)
 I forgot to mention in the previous post that there is also a hidden surface that was created with the Blend tool that joins a tiny disc surface at the top and the extruded surface below. Now a query for Michael... Would it be possible to have a 'blend to point' facility for cases like the above surface so it's not necessary to include a small disc surface as a target for a blend? I think it'd be handy for keeping surfaces tangent in these capping situations. I'm really enjoying the latest release, thanks Michael. Martin.