Many thanks.

In the end I rebuilt it with a loft command after carefully aligning all the points and sections. It's not a joined surface but with no naked edges. Not perfect, but nor was the original vehicle!

Sorry!

Managed to make a new bonnet but it won't remain as a solid, but joined surfaces, which works. However, I now find it impossible to 'glue' solids, such as rivets, to the surface. Is this impossible.

I realise I am working way beyond my skill grade here though!

Tx G

Gord,

I had posted saturday a fixed version of your file.

I explained I took the structure of edges to fix the points where the were not good.

Regards

Hi Gord, so to find out what is preventing your object from being a solid set up a shortcut key as described here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

Then trigger that shortcut key which will select all naked edges. If you do this with your model and then look at the object properties panel in the upper right corner of the window you can then see it says 3 edges are selected.

These edges are quite small so hard to see at first glance. But if you push the "Reset" button on the toolbar at the viewport bottom, that will zoom in to them and then you can zoom out to get an idea of where the problem is at.

In your case here it's in this area:





I separated out those surfaces and untrimmed them to examine the surface geometry and the problem is they don't touch cleanly along the mirror plane, there is some overshoot:





So this was caused by a misalignment between the surface end and the mirror line. Instead of ending right on the world y axis line, this surface went past it a a bit and then when mirrored that area does not line up.

I'll see if I can tune it up for you.

- Michael

Hi Gord, I've attached a fixed up version here that is now a solid and should boolean ok.

There were some other problematic areas of the model, the entire bottom wasn't all aligned to be on the same plane and there was a kind of awkwardly squashed corner spot in one area.

To make this fixed up version and have it be smoother, I set it up like this and selected these 2 edges:



And then used Construct > Blend to put in a smooth blend surface:



- Michael

Hi Gordon, here's a different method that makes fewer surfaces. For this one I started with lines put in for the straight areas:



Then put in these curve blends:



Then I used the rebuild command to make these curves made up of one single segment and then used Construct > Loft to make the surface:



Then I used Edit > Trim to divide the edges, then Construct > Sweep of the bottom profile up along those edges to make this piece:



Then select these edges:



And use Construct > Blend to put in a blend surface there:




The part that's difficult about modeling things in a "patch by patch" manner like this is that you need to use Blend or Fillet in some areas to fill in a smooth surface for you rather than trying to construct every single surface directly.

- Michael

Brilliant, thanks. Not used the blend command before.

Gordon