Aspire question... chair back

[Ajcoholic]

I am trying to model a chair back, which has a half-oval depression in the center, and then both sides taper from the center up and out.

The 1/2 oval depression is OK for me to model well. But I cant seem to figure out how to slope the sides.

Think of it as a rectangle, that you want to draw a line connecting opposite corners, and then taper from the drawn center line to one point.

here is a pic..

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0083-2.jpg

Thanks for any assistance..

AJC

[tmerrill]

Hard for me to see details but I would do a vertical 2 rail sweep with 2 profiles, one for the lower radius shape and one for the upper.

Then cookie cut the final shape out of this then subtract the depression.

Tim

[Ajcoholic]

For the central 1/2 oval depression, I modeled the full oval, then cut it slightly high off center so my round nose bit would make a clean cut off the edge of the back.

The two chamfers I am having difficulty with, would be easy to mark out, and sand on the edge sander (how I did the originals) but I figured since I am using the CNC to both do the rounded section, and cut out the back outline I might as well try the chamfers as well.

I was thinking two-rail sweep, but all the sweeps I have done have been curves, with an inside and outside profile, then the profile/cross section of the sweep itself.

To to this on a flat plane, do I work around a point?

AJC

[tmerrill]

Sorry, you have lost me. Finished dinner and did a quick example but may not be close to what you are describing.

Any chance of better pictures?

Tim

[Ajcoholic]

Tim,
That photo I posted shows the back up close and with good lighting - at least on my computer (17" macbook).

The back isnt "curved" like a normal chair. It is flat, with two large chamfers.

I dont know what you are seeing photo wise, so I cannot comment.

Ill take a better pic tomorrow and post. My wife and I are going out for the evening - baby sitter just got here so I have to go!

AJC

[tmerrill]

That helps.

If this attempt is better here are the big steps:

Create overall shape as a planar surface using the Create Shape tool.

Draw 2 angled rails and create the profile you want. Do a 2 rail sweep to create one chamfer, set combine mode to Low.

Select that 2 rail sweep component and use Ctrl-Shift-H to create an identical copy on the other side (assuming you design with origin at the center like I do).

Do the oval using Create Shape tool and subtract.

Select all components, bake and cookie cut to final shape.

Tim

[Ajcoholic]

Wow.. thanks for the help!

Much appreciated :)

AJC

edit - I did it, worked great thanks again!