Trim is more for "Surfaces" and "Curves", Boolean for "Solids" or "2D curves"

thanks my friend

Hi Steve,

> Till this time I used Boolean Diff/Union is there a difference
> between this and edit/trim/join

Trim and join are sort of more "low level" tools than the booleans.

You might kind of think of the booleans as a sort of batch mode trim & join where they do a similar job but automatically decide which pieces to discard from the trimming according to what volume they are contained inside of.

Trim will cut things up but then it's up to you to pick which pieces you want to discard, and then you will need to follow it up with a Join afterwards - those steps are basically built in to the booleans so it's sort of more convenient to use the booleans when possible (which is basically when you are working with solids).


> Till this time I used Boolean Diff/Union

You could still use boolean union in this case if you made the pieces stick through each other a little bit instead of having that side piece sort of exactly skimming along the outer surface of the main body - it's that skimming situation that the booleans are having difficulty with in your particular case here, when they try to intersect the 2 surfaces they are not getting a clean intersection result because the side surface has just a tiny amount of empty space between it and the main body in a few areas.

- Michael

Hi Steve - attached here is what I mean by moving your object a little bit over so they push through each other.

If you look at this one, the side object is sunk down a little ways into the main body instead of just skimming right along its surface.

Now you can use boolean union with it as you were trying to do originally.

It's easier for the booleans if you make pieces push through each other a little bit like this rather than making pieces that barely touch.

- Michael

right gotcha,

Thanks again Michael

Hi,

Here's another example I seem to run into quite often. I'm trying to blend/loft these two pieces together however as you see the main piece is not a clean surface it has surface lines which seem to mess up the potential blend.

What would you do in this situation?

Hi Steve - so in a case like that if you want to use Blend you have to split up the long edge into pieces so that you'll have a 1-to-1 match between edges on both sides.

You can use the Edit > Trim command to cut an edge up into smaller edge pieces - select the edge, run Trim, then click the "Add trim points" button and then you'll be able to click the points on the edge where you want it to be split at.

I will be working on upgrading Blend in v3 so that you won't need to do that anymore, but for now you've got to arrange your edges so that there is a matching pair of edges.

- Michael

Another thing you might do to make things easier would be to take this curve here which is made up of 3 segments:



Join those together and run the Rebuild command on it
http://moi3d.com/2.0/docs/moi_command_reference10.htm#rebuild

You get those additional edges in your original one because the curve that you were extruding was made up of several segments - the segmentation of the curve will come through into surfaces that you construct from it, with one face for each segment of the original curve.

So you can eliminate those interior edges by reforming the curve to be made up of just one single smooth segment instead of being multiple segments - the Rebuild command is the easiest way to reconstruct a curve like that.

Then when you extrude it, you'll see it's just one surface instead of multiple faces:



- Michael

Thanks very much Michael,

Interesting............I give this a go :)


Cheers
Steve

Hi Steve,

I have attached my approach based on your example.
Yust hide the solid and switch on the controlpoints with the Show pts command.

What i did is projected the blue lines on the shape.
Then trimmed the curves at the border and turned on the controlpoints
With Line/both sides command(see green lines)snapping on the endpoint of the mastercurve(orange) and the nearest controlpoint.
I switched on the controlpoints of the cyan colored curves and snapped the nearest controlpoint on the green lines.
At last i used Sweep/two curves.

Ps. You can play with the rebuild command(R shortcut key) to add or reduce control points.

Hey thanks my friend, very good of you to do this

Much appreciated

Steve