# Sweep2 with maintain height is not maintaining height on a small object

**URL:** <https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718>\
**Category:** Rhino for Windows\
**Tags:** windows, rhino-7\
**Created:** [April 26, 2022, 9:22pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718 "2022-04-26T21:22:57Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Young\_Kim](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/young_kim/32/376043_2.png) [@Young\_Kim](https://discourse.mcneel.com/u/Young_Kim)\
**Post date:** [April 26, 2022, 9:22pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718/1 "2022-04-26T21:22:57Z")

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Hello,  
Sweep2 with maintain height is not working on a small object. When I added few slashes the height went down a bit, but it still wasn’t the same height as the profile curve. Does anyone know why this is happening?

Attached is the file I used for this.  
[Sweep2 Maintain Height not maintaining height.3dm](https://discourse.mcneel.com/uploads/short-url/bYFFPGf8efcOtKJPjjgEnwVd1KB.3dm) (660.7 KB)

Thank you.

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**Author:** ![Tom\_P](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/tom_p/32/766520_2.png) [@Tom\_P](https://discourse.mcneel.com/u/Tom_P)\
**Post date:** [April 26, 2022, 10:14pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718/2 "2022-04-26T22:14:01Z")

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dear @Young_Kim  
i think you expect to much from a single \_sweep2 surface.

if you need / want to stuck to a nurbs-Setting - maybe this is a starting-point:  
do a  
sweep2 (red) for the initial part  
railrevolve with full profil (blue)  
railrevolve with half profil (green)

 ![Screenshot 2022-04-27 at 00.07.47](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/c/d/4/cd4816eaba9725e0bce18421d341bfdf2a1a181e.png)  
this will still require some fine-Tuning with \_setPt and \_matchSrf

for sure a sub-D approach will be possible and faster - but maybe a bit of topic ?

kind regards -tom

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**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [April 26, 2022, 10:16pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718/3 "2022-04-26T22:16:58Z")

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Hello - Sweep2 will look better if you put a small cross section curve at the small end rather than the converging rails.

-Pascal

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**Author:** ![Tom\_P](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/tom_p/32/766520_2.png) [@Tom\_P](https://discourse.mcneel.com/u/Tom_P)\
**Post date:** [April 26, 2022, 10:22pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718/4 "2022-04-26T22:22:32Z")

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there is also some similar topics -

> [@C Scroll surfaces](https://discourse.mcneel.com/t/c-scroll-surfaces/15319/5):
>
> Hi John- the way your original curves are set up, one hits the planar area ‘hard’ with a sharp corner, and one dips slightly behind then comes back to the planar area. I cleaned up the latter but left the hard intersection as this seemed to be part of the design. I would make that intersection planar as well, myself, and avoid that slight kink at where the scroll meets the flat. -Pascal

> [@How to create this shape?](https://discourse.mcneel.com/t/how-to-create-this-shape/69437):
>
> I need to model the ceiling panel in the attached image. I have two areas I’m struggling with here. First, how does one create the converging arc shapes that are increasingly wider as they spread? Secondly, how does one then have those shapes extruded with an increasing thickness as it gets to the middle of the circular shape? Thank you.[51%20PM]

but there was a newer one - i cant find - i tried:  
acanthus ? helix ? spiral ? scroll ?

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<div class="post-metadata">

**Author:** ![Young\_Kim](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/young_kim/32/376043_2.png) [@Young\_Kim](https://discourse.mcneel.com/u/Young_Kim)\
**Post date:** [April 26, 2022, 11:00pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718/5 "2022-04-26T23:00:31Z")

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@Tom_P That works to create the shape. Very easy to understand. Thank you for the suggestion 😃  
I was wondering if my Rhino program file was corrupted or something since maintain height wasn’t working. When I scaled the curves much bigger the maintain height worked perfectly though.

Best

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**Author:** ![Young\_Kim](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/young_kim/32/376043_2.png) [@Young\_Kim](https://discourse.mcneel.com/u/Young_Kim)\
**Post date:** [April 26, 2022, 11:01pm UTC](https://discourse.mcneel.com/t/sweep2-with-maintain-height-is-not-maintaining-height-on-a-small-object/141718/6 "2022-04-26T23:01:22Z")

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Thank you for your advice 😃