Lofting with 3D Spline guide curves

[kcoffield]

Joseph. I have viewed your YT lofting videos. I especially like this one:

Very helpful, as complex as some of the lofted shapes are, unless I'm mistaken, the video never actually uses a 3D spline as a guide curve. It is a very important capability for me. I have invested a lot of time, viewed many related threads here, and am yet to see success using a 3D spline as a guide curve in Alibre. My latest endeavor is here:

Lofting Help

Need some help lofting fellas. The attached is the center section of a V8 automotive intake manifold. There are 8 pairs of port windows that need to be connected by loft. I have all of the sketches for the lofts in the correct positions except for two (more on that later). Attached is the file...

www.alibre.com

Would you mind having a look and seeing if you can successfully execute such a lofts? Ideally using my example but alternately, lofting between faces that do not reside in parallel planes, and using a guide curve that is truly a 3D spline.

Best Regards,
Kelly

 

[Joseph_L]

Hi Kelly;

You may have seen this video which uses a 3D spline as a sweep path.

This can be applied to centerline lofts as well. Planes can be generated on the spline path by selecting the spline and what percentage along the spline they should be placed. Would this be sufficient for your needs, or would a video still be needed?

Thanks for this post

 

[kcoffield]

I did see that. In fact I used a similar method to create the 3D spline guide curve. Driving sweeps along 3D spline doesn't seem to pose a problem. They just are not what is required in my desired features due to the need for changing cross section shape/area along the guide path.......but lofts guided by 3D splines certainly are posing problems.

It doesn't necessarily have to be the file I've posted in the forum thread. I'd just like to see an example of a loft that uses a 3D Spline as a guide curve from two different shaped faces that reside in planes that are not parallel to each other. In my case the faces were just filleted rectangles of different sizes guided through their geometric centers, but could be rectangle to circle or whatever. In all cases I've tried or encountered with others, even when the spline is connected to a perpendicular segments constrained normal to the faces it fails dues to this error. I just haven't discovered the secret to success.

The method for maintaining tangency and constrained perpendicularity (to the faces) of the guide curve described in your video(s) seems to work if the spline is constructed in 2D/planar environment, but when it's truly a 3-space spline......no joy.

Best,
Kelly

 

[kcoffield]

Ureka!!!! I took a different approach. I created the 3D spline first making the ends normal to model objects the intersected, then used the plane along the sketch option to create planes normal to the ends of the spline. I sketched the loft faces on those planes and they successfully lofted along the 3d spline guideline. I guess I just wasn't able to constrain the spline sufficiently normal to the planes I was sketching on without using the Alibre command to create planes normal to the ends of the spline. I'll do some work and see if I can get it to translate across my model.

Best,
Kelly

 

[Joseph_L]

I have ended up making a video on this already, it can be found here.

 

[Joseph_L]

P.S. It will go live a few hours from the time I make this post

 

[kcoffield]

Thanks much for that Joseph. That's quite the loft you created. I must say, I have tried for 2 days and not found a single way to construct a 3D guide spline that will work for previously created planes/faces.. The only way that seems viable is to construct the splne first and then allow Alibre to create the planes normal to the spline upon which the faces are constructed for loft. That method is robust and works every time but is more than a little inconvenient for me because the nature of the parts dictate the locations and orientation of the faces be created first where function constrains them to be..........but I'll certainly learn to make it work.

One additional thing I learned from your video, I hadn't realized you could loft through multiple shape transitions in the same loft. That could be useful in the future.

Thanks again,
Kelly

 

[Joseph_L]

Good luck with everything Kelly, thanks for the question

 

[kcoffield]

Good news Bad News. I did succeed with the lofting......but it throws errors and won't shell or fillet. It can be tough being a self taught novice. Everything seems to be hard when you don't know what you are doing. Thank goodness for the forum and YT......and your help. I have some novice (hopefully easy) questions about things I encountered along the way for which I'll start a new thread. Getting the model to shell and fillet may be another matter......probably poor modeling practice on my part. Thanks again Joeseph.

Best,
Kelly

 

[NateLiquidGravity]

If you have surfaces then try this method of shell doesn't work.

 

[kcoffield]

If you have surfaces then try this method of shell doesn't work.

Thanks for the suggstion. Much appreciated. I wasn't successful with it but will keep it in mind for the future. Project and discussion here:

Novice Qs and Shelling and Filleting Solids

I try to exhaust the Alibre Documentation, YouTube, and of course help here in that order. It's a bit of a leap from 2D to solid and parametric modeling. I struggle with getting sketches fully/properly constrained, good work flow, editing, and modeling as I'm sure is obvious. Attached is the...

www.alibre.com

Best,
Kelly