How to make the transition from a chamfered edge to an unchamfered edge?

fred_wild

I'm modeling a porch column in Onshape. The top and bottom parts are square in cross-section, extruded from separate planes. The middle part is an octagon in cross-section (basically a deeply-chamfered square), extruded from a separate plane. Between the parts are short transitions where the octagon becomes square, where the chamfer tapers to nothing. My attempts to loft the transition failed. Is there a way to diminish a chamfer along an edge or otherwise transition from an octagon to a square? Thank you.

Fred Wild

Porch Deck | Column

nick_papageorge_dayjob

Is this what you want?

There may be a simpler way of making it, but I used individual curves and surfaces to form the transition. Loft does not work very well unless there are a matched number of edges on both ends of the loft. (unless there is a modifying trick to loft I'm not familiar with).

Link:

https://cad.onshape.com/documents/f069d26ee3fe7cd998f1921d/v/d82e9542b29413ae62668554/e/f14f2e8d8029b489319810c4

nick_papageorge_dayjob

Is this what you want?

There may be a simpler way of making it, but I used individual curves and surfaces to form the transition. Loft does not work very well unless there are a matched number of edges on both ends of the loft. (unless there is a modifying trick to loft I'm not familiar with).

Link:

https://cad.onshape.com/documents/f069d26ee3fe7cd998f1921d/v/d82e9542b29413ae62668554/e/f14f2e8d8029b489319810c4

fred_wild

I believe I have it. The answer applies a surface loft from an edge on the octagon section to the corresponding vertex on the square section to create each separate face of the transition. An enhancement for each loft adopts the side line of the adjacent face as a guide. It needed sixteen lofts, but they served the purpose. Thank YouTube and thank you.

fred_wild

Thank you very much.

GregBrown

In this document (https://cad.onshape.com/documents/a059937493dfe00304609db6/w/571737312ebae8a479dcd4b7/e/4c217bed875f3399cb6f08cd) I have a slightly different way that is less picky - had only 8 lofts
I use a solid loft but with the "remove" option. The loft is between a triangular face to a vertex.

Update: as always I try to find ways minimize the feature count, and here is an option that uses just 3 lofts and a pattern :)
(https://cad.onshape.com/documents/a059937493dfe00304609db6/w/571737312ebae8a479dcd4b7/e/4518bf2f561d8e8dd45f7211)

Finally: I made this parametric column creator - the number of base sides is configured.

https://cad.onshape.com/documents/a059937493dfe00304609db6/w/571737312ebae8a479dcd4b7/e/cb8ac2449412e4f5115b986a