topic Re: Extruding/Lofting Past Profiles in AutoCAD Forum

Extruding/Lofting Past Profiles

jonnyjr — Sun, 03 Nov 2019 22:36:23 GMT

I have been racking my brains and searching for a few hours on how to extrude a lofted surface, past the original profiles. I have a profile which I am using a hot wire cutter to cut. However the desired profile is angled at the front and back, I need to extrude the lofted profile to a square block face.

Please see attached files for a better idea of what I am trying to achieve.

https://we.tl/t-LKhBhN6y6q

Re: Extruding/Lofting Past Profiles

j.palmeL29YX — Mon, 04 Nov 2019 12:34:39 GMT

Sorry, I can't open your dxf-file. And from the jpg file I can't see what you have and what you want to achive. Perhaps you can post a dwg please.
An additional hint: you can attach the files directly here in your postings.

Re: Extruding/Lofting Past Profiles

jonnyjr — Mon, 04 Nov 2019 13:04:30 GMT

Hopefully this will work

Re: Extruding/Lofting Past Profiles

leeminardi — Mon, 04 Nov 2019 14:55:57 GMT

I assume you want to project the back end of the loft to the yellow plane.

Examining the shape I exploded the solid, removed a couple of surfaces, and changed the color of the lofted surface to cyan and green and the back surface to blue as you can see here.

Setting a UCS perpendicular to the direction of the loft (UCS ZA) by picking points on the edge of the cyan surface and then viewing the plan view of the new UCS yields this view.

The fact that the back and front surfaces do not line up indicates that the lofted surface is more likely conical than cylindrical. Was that the intent?

Since the radius of curvature is decreasing as you go from front to back (red profile to blue profile) you need to establish an additional point on the yellow plane in addition to the two tangent points to determine the radius of curvature of the profile on the yellow plane.

In the following image the white lines are rays extended to the yellow plane and the magenta curve is the profile for the extended loft.

Re: Extruding/Lofting Past Profiles

jonnyjr — Mon, 04 Nov 2019 16:00:08 GMT

Thanks for taking a look at this Lee. That’s exactly what I was trying to do but didn’t quite get to the point you did.

You are correct the loft is decreasing in radius at the blue profile compared to the red profile.

I shall try and replicate what you have done and take it from there.