Hi, I am a new user of MoI,

On a model I am looking for a way of putting a curved cushioned surface on a button such that the top resembles a membrane that has had pressure applied from bellow.

Rail Revolve doesn't work too well on the shapes I have.

These buttons are for my Canon camera model in the gallery but as I was struggling with the shape I gave them flat tops.

Pointers appreciated,
Doug

Hi Doug, welcome to MoI!

> putting a curved cushioned surface on a button such that
> the top resembles a membrane that has had pressure
> applied from bellow.

It's a bit hard for me to really clearly visualize what you are describing here - do you possibly have any image of that kind of membrane shape that you could post to give a clearer picture?

One method that may help is if you model the membrane more directly all by itself as a separate surface, something like this (here using sweep with one curve as the profile and the other as the path):



That will make a broad curved surface like so:



Then you can use either the Trim or a boolean command to combine those pieces and have the outside of that broad extended sweep piece get cut away. If you've got 2 open surfaces that form a volume in their inside area you can select them and run the boolean Merge command to get this type of result:



So note there that this technique does not try to construct a surface that follows directly along the boundary of your starting piece - instead an extended simple surface is created and then it gets attached to your other shape by a cutting process. Often times this technique of using intersection between pieces to generate the final edges is a key construction technique for NURBS modeling, rather than trying to focus only on constructing surfaces that follow directly along some already existing edge structure.

Also see here for some links to more descriptions of this kind of rounded end cap technique:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4851.3

- Michael

A nice way of doing buttons that have a curved top is to offset the surface the buttons are on. Then use the offset copy to trim the buttons in the way Michael has described.

Hi Michael, Hi Steve thanks for your help,
The effect I was looking for was a blistered surface similar to the image bellow where the curved top surface meets the edge surfaces on the same plane all round.

The surface in the image was achieved using revolve rail to revolve a spline around the profile which works well on simpler profiles but on these buttons it doesn't meet the edge properly so is difficult to join properly.

May try trimming curved surface flat and attempt to join with a rad.

Thanks,
Doug

Like this?
Here with Rail Revolve seems works, no ?
Call the Edit / "View Points" on the arc and move the control points for have a pendicular on each vertex so tangency!

Here on view top Profil is at the middle of the edge, you can also put it at the perpendicular from center to the edge.

Hi Doug,

> The surface in the image was achieved using revolve rail
> to revolve a spline around the profile which works well on
> simpler profiles but on these buttons it doesn't meet the
> edge properly so is difficult to join properly.

Can you please post the 3DM model file that has the pieces that don't join properly so I can take a look at what's going on there?

- Michael

Hi Michael,
Scrub my comment about not joining, I had another go at using rail revolve and used Boolean union instead of join and top and bottom became a solid OK.

Anyway this is what I ended up with, which is pretty close.

Time to come up with a design of my own maybe.

Thanks,
Doug

Hi Doug - so probably what happened is your rail revolve result was a solid that had an end cap on the bottom.

Join only tries to join together open unattached edges between things, so your revolve would need to have its end cap deleted (or uncheck the "Cap ends" option so it's not created in the first place) in order for it to be set up for join.

Basically Join does not try to intersect objects or remove material, unlike the boolean commands.

- Michael