Been trying to model a knife blade using the sweep command but I keep getting extra geometry at the tip. Any ideas what I am doing wrong?

Hi GenX, it can help if you attach a 3DM file with your curves in it instead of only a screenshot. Like for example in this case it would be good to be able to zoom into your tip area and be able to see more clearly what exactly is going on in that area of your model.

What kind of sweep are you doing exactly? There are a few different variations like "one rail sweep with a scaling rail added", or "two rail sweep" or "two rail sweep with a scaling rail".

I would zoom in and take a close look at the tip area to make sure the curves are touching there, if they are not aligned with one stretching out a little ways past the other it can make for bad results similar to what you show there.

- Michael

It happens with the "one rail sweep with a scaling rail added" option.

Hi GenX - make sure the scaling rail extends all the way to the very end of the other curve, and in fact with a scaling rail it's not a bad idea to let the scaling rail go a ways past the other curve to make sure it fully covers all areas of it.

You can get that kind of little spike at the end when there is an area that the scaling rail did not cover, basically the sweep pops up to full size if it could not intersect the scaling rail at any one spot.

You may find using 2 rails for such a shape (select both curves as rails instead of using one as a scaling rail) make work better for your case there. When using 2 rails rather than 1 rail + scaling rail you would want to make sure both rails come together to touch at a single common point, you don't want one the end of one curve to be unaligned to the other curve's end.

Check out these previous posts for some more description and related discussion of scaling rails:

http://moi3d.com/forum/index.php?webtag=MOI&msg=4434.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=1807.7
http://moi3d.com/forum/index.php?webtag=MOI&msg=4785.7

- Michael

I've been messing with this for days and finally changed my profile from a triangle to 2 thin half crescents and it turned out very nice.