Modeling Moulding and Paneling on Curved Stair Case

AGiam9 · 25 Jun 2018, 16:18

Hi all,

I am having some trouble getting the moulding in the image below to follow the curve of a staircase I am working on. Using the Follow me tool doesn't work because it starts to twist. Using Curviloft (Loft around Path) almost works but creates a pinching effect towards the middle curve. And using Shape Bender creates additional geometry and in the closest I've gotten to getting it correct also has that odd pinching effect towards the main curve.

Does anyone have any suggestion as to how to accomplish this? I've attached two images showing what I'm trying to do if that helps.

Thank you!

Best,
Andrew

StaircaseHelp.pdf

boofredlay · 25 Jun 2018, 18:15

Upright Extruder by Christina Eneroth (Eneroth3)

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AGiam9 · 25 Jun 2018, 20:04

Thank you Boofredlay, unfortunately that doesn't seem to be working either, that sharp middle turn still corkscrews and pinches. It could be the hard curve of that corner actually causing the issue but I cant think of how to correct the path to avoid that issue.

nlipovac · 28 Jun 2018, 07:50

Well, just eyeballing I think that moulding profile is to thick (in real life to) to be bend on that corner. You should make it thinner to avoid pinch on that turn.

boofredlay · 3 Jul 2018, 18:37

Can you post up your model so we can try with it. I can't seem to recreate a problem with any similar paths.

AGiam9 · 5 Jul 2018, 20:05

Certainly! Thank you for your continued help, I do have some updates to what was going on however.

The pinch is caused by the rapid change in slope around that sharp turn, if I was able to straighten out that line on a single plane you would see the slope go from steady to a sudden steeper part to a sudden shallow (for lack of a better term) part. By adjusting that line orthographically, I was able to get it to look closer to correct, however, because I was eye balling it and not going by a specific slope, the new version "wobbles" around the part where I made the corrections. I've attached the sketchup file with the CAD files I'm using. The model I'm up to currently I painted in red, the old model with the pinch I painted blue.

Please let me know what you think!

FoyerStairs.skp

Shared with Dropbox

Dropbox (www.dropbox.com)

Best,
Andrew

boofredlay · 5 Jul 2018, 21:11

So a quick look over your file I see a few things that are problematic.
First the path you have created for the profile to follow is not smooth at all. Second, the curves in the profile have way too many segments. For a profile that small, 3 or 4 max per arc will suffice. Finally, with a profile that small you might need to scale your drawing up before following the path as the small faces generated in the tight curves might not generate.

There are other plugins that might help like stair builder and Flowify but I still think Upright Extruder is your best bet. Just get a smooth path and a proper profile to start.

AGiam9 · 6 Jul 2018, 12:31

Thanks again Boofredlay!

Yes, the path I created was an approximation hence why its not so smooth, do you have any recommendations on how to create a smoother path? Currently I created tick marks along the plan of the stair dividing each step into 9 parts and then created little blocks which I used to raise at a constant slope determined by dividing the riser height into 9 (so 7 5/8 rise divided by 9 is 27/32nds). This led to the stringer with the deformity (blue) however, so I adjusted the blocks by eye to create a smoother line but since it was an approximation, it became a bit warped around the curve.

I am usually reluctant to reduce the number of segments as when I put this into Thea Render, I often notice it doesn't come out quite as smooth as I'd like, however I will definitely try to redraw the profile with less sides, as well as what you mentioned about scaling up.

Thank you again, you've been a huge help!

Best,
Andrew

boofredlay · 9 Jul 2018, 21:45

Try this for a start.

Basically I pulled up the void between the stairs to use as a surface to manually draw a somewhat smooth path then used Upright Extrude. I did not scale the model up so there are some holes in the extrusion but they can easily be stitched or you can run another but you should get the intent of how I worked this example.

stair path.skp

boofredlay · 17 Jul 2018, 15:56

How is your model coming along Andrew?