skewing in loft feature

[ndhanssen]

Hi all,

I am working on a part right now and am currently using a loft to accomplish my goal but the result is skewed. The situation is I am lofting from a 1.25x1.25 inch square with 0.3 inch filleted corners on the x-y plane. I move about 3 inches along the x-axis, 2 inches along the y-axis, and 4 inches along the z-axis, to a 0.9x0.6 inch square with 0.2 inch filleted corners. Using four 3D sketched guide curves I am able to complete the loft, however the top and bottom are skewed, creating large lips on the top and bottom, rather than a smooth face. Does anyone have any suggestions as how to solve this problem? Thanks

Jesse
Mechanical Engineer

 

[Theophilus]

Can you post an image? See FAQ for how-to.

Yes, this is probably easily solved, depending on what you need from the loft feature.

Jeff Mowry

http://www.industrialdesignhaus.com

Reason trumps all. And awe trumps reason.

 

[TheTick]

Does the profile remain square from end to end? You would then get more reliable results using a sweep with guide curves.

 

[rfus]

My bet this the problem lies within your Guide curves. Is this what you are trying to do

No end constraints only connectors

Normal to profile end constraints

RFUS

 

[ndhanssen]

I have to apologize, I was in a hurry to get the thread off before a meeting and I forgot to include that the 0.9x0.6 inch rectangle is on the x-z plane, which adds a bit of complexity for me. This pic will hopefully give you an idea of what I'm trying to do. The skew is visible as an indentation on the side as it turns left and you will also notice that the bottom protrudes almost an inch from the main body. By the way, I added a third profile since the last post, a smaller rectangle in parallel with the other and offset 0.25 inches. I can remove it from this loft and use a separate one if necessary, but it doesn't seem to be impacting my profile very much. Once again, thanks for the help.

http://img179.imageshack.us/my.php?image=loftpic4sp.gif

 

[yanceman]

Have you tried adjusting the location of the alignment dots? I'm not sure of that is the proper term, but it appears that the blue dot in the lower right sketch profile of your image needs to shift right a little. View your part normal to that sketch and adjust both sketch dots to the same area of their respective sketches. If the far dot is centered on the top edge of its sketch, the near dot must be in the same (roughly) location within its sketch.

Hope this helps!
Yanceman.

(ps. RawHeadRex is one of my favorite stories by Clive Barker! Really cool logon names here!)

 

[yanceman]

oops, Rawhead was in PDM post!
Sorry guys.
Y

 

[ndhanssen]

Thanks for all your help, I think I have the issue resolved now. I had to remove the third profile from this loft and do some tweaking to my guide curves and connectors. It looks much better now. I really appreciate all your help.

Jesse

 

[Theophilus]

If you haven't tried it before, converting your sketch entities into a single spline works wonders for sweeps/lofts--with a slight hit on accuracy (very slight).

Something you may want to try by saving a copy of your part and converting your profiles to spline entities--and maybe even your guide curves--to compare the differences. It shouldn't take long. (Show your Spline Tools toolbar to see the conversion button.)

Jeff Mowry

http://www.industrialdesignhaus.com

Reason trumps all. And awe trumps reason.