I wanted to make a shell of my partially reverse engineered shoe last.
It's only partially reverse engineered because I only need the lower region to slice off the top, the remaining part would be 3d printed to be an upper part of a shoe sole.

The model consists of the following items, from left to right :
toe cap/first part from left is sweep, 2nd is sweep, 3rd is loft in x direction, heel is loft in z

Here is what I've tried so far :

1st: I've created a single surface, I used inward shell on each part, The problem is that I get good solids but also microgaps where the parts join and that messes up the 3d print, I get an ugly weld at the place of the gaps . I've tried many things to join/union the surface and shell as one piece but nothing worked so far .
The other problem with the shell, is that the toe cap, the first part from the left ended up with some really abnormal extra parts .

2nd
I took the time to offset all the curves I use manually one by one certain ones by copypasting and moving manually, then I made the shell manually, the best I got out of this is joined surfaces, but I'm unable to turn them into solids .

I could really use some help :)

Hi Roni, can you please post the 3dm model file?

You may need to do something more like model the interior surfaces directly similar to modeling the exterior, rather than actually using the Shell command.

Maybe another possibility for your gap areas could be to cut away a strip between pieces and put in a blend surface between them to make them all one connected skin rather than in separate chunks.

It's pretty difficult to give very good advice when looking at a screenshot instead of at the actual model though. Also another thing that can help is to simplify the model so it contains just some stuff around a particular problem area rather than say a hundred pieces. It makes it easier to figure stuff out.

- Michael

Hi Roni, so reading your post again your 2nd approach where you made the shell manually is probably the way to go. If you could post that one I will take a look at why it's not able to be made a solid yet.

- Michael

I've sent you a PM, please feel free to respond here is anything is ready .

I tried to blend the separate shells by filling in the gap with triangular sweeps, then I tried to cut them off and re connect them with no success.

Hi Roni, so the reason why your object isn't a solid is that edges need to be no more than 0.005 units apart from one another in order to be joinable and your surfaces have many areas with larger gaps than that.

Each of your surfaces has at least one edge that is close enough to another to get joined, but not all edges. So that's why it selects as one connected object because it is connected together through some edges but not connected in other areas.

To get it into a solid all edges need to be connected, not just some of them. So some pieces need to be deleted and remodeled with higher accuracy to get it into a solid.

To find out where you have open edges you can set up a script on a shortcut key as described here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

Then you need to inspect those areas closely to see what is wrong there, you can use the Zoom Area viewport tool to do that, here are some areas that I saw with a couple of initial looks:


There are some big gaps along the bottom strip:



- Michael

Hi Roni so a good starting place is to go over your starting outer shell and get that tuned up first.

I extracted your outer 6 surfaces using Edit > Separate to break them into individual unconnected surfaces and then also reset their trim boundaries back to their original natural trim boundary by doing an "untrim" operation. That's where you select all edges of a trim boundary and use Delete to remove them. Some information on untrim here: http://moi3d.com/forum/index.php?webtag=MOI&msg=444.4 .

Then I started by joining these 3 surfaces which joined cleanly (I use the highlight naked edges script mentioned above to check that there are not naked edges in what should be joined spots):



That part was fine. So then I joined these 3 together:



Those were also fine. So then I joined those 2 pieces together and that is not fine, there is a naked edge here:



So the edge on one side there was close enough to get joined but the one indicated above has a gap of about 0.0054 units between them, so just barely outside of join tolerance.

One trick you can sometimes use when things are really close to being joinable is to scale the objects down and then join the down-scaled objects and scale back up again. When you down scale the gaps between edges also down scales as well.

If you do that you can get the outer surface to be all joined properly which is a good initial step.

The process for the down scale goes like this - after you have joined the 3 pieces on the back to each other and the 3 pieces on the tip to each other, before you join those 2 resulting pieces together select the 2 objects, run Transform > Scale, then type 0 and push Enter to specify 0,0,0 as the scale origin. Then type 0.1 for the scale factor and push Enter. Your objects will now be scaled to 1/10 of their previous size. Now use Edit > Join. Then scale back up again by repeating the previous steps but use 10 for the scale factor.

That will result in your outer surfaces being all properly joined.

The next thing I'd probably look at would be repeating this on the inner shell surfaces and get those all joined to each other properly. Once you have inner and outer pieces that are well formed themselves then we can look at doing the bridging pieces.

If you get stuck along the way please resend your file with your current result so I can see what's going on.

Hope this helps!

- Michael

Thanks for the detailed response, at first it seemed like a very labor intensive fix. I wish I could just sweep and loft planes.
I hope it will not come through as a waste of your time, but I tried one more thing before your solution .
It's not elegant, it's really dumb, but so far it seems to be working.
All I did was to overlap the single surfaces by a fraction of a millimeter, turn them to shells, so the shells overlap, I still can't union them nicely or at all, but the slicer software I use for 3d printing does union them during slicing.
I attached a photo, it's a before and after.
I still have one tiny gap on the newest iteration.
I hope this is going to work now, thanks for the help.