Hi All

I am currently modelling a gearbox with some cooling fins around sides and under side (deeper on the underside). The fins are a different shape depending on if they are on the sides or the underneath. My question is, to get the basic shape, is there a way to extrude a box which follows two different profiles to get a kind of concertina effect? See badly illustrated sketch for what i mean. I have tried the sweep method but just makes a big mess of lines. I was thinking for this to work it would need to know a centreline of the extrude . . .

As ever any help on how this could be done would be gratefully received as its getting late . . . .

Just extrude a staight box, then in those side views, create the profile and boolean difference it from the box.

Hi Matt, yeah like Burr says doing a boolean would probably be the easiest way. You can just cut a base shape directly with those profile curves.

A lot of times carving off pieces of a base simple block is easier rather than trying to build every surface directly to some irregular profile like it sounds like you were trying to do initially.

You just need to make sure that the curves fully divide the object when viewed from their drawing plane - if they don't fully divide the object into 2 pieces you can't cut with them.

To do the boolean select your base block, run construct > Boolean difference and select one profile (or both but maybe when they intersect one at a time might be a bit easier) as the cutting object and then the boolean will slice the solid with the extruded surface of the cutting profile and leave the cut up pieces behind. Select the pieces you don't want to keep and delete them, then repeat with the profile in the other direction.

- Michael

Here's what something like that looks like - it tends to be easier if you have made the base object to be a little bit extended in the area that it is going to be sliced off instead of something like trying to make a wavy cut that barely touches the end of the base block at multiple points along the wave, that will make for a much more complex intersection calculation and probably a lot of little fragmented pieces involved instead of just 2 pieces for each cut.


But the basic process here is just have your base block and 2 cutting profiles, and run boolean difference 2 times using each curve as the cutting object, after it is cut delete the piece you don't want:











- Michael