Problem with spiral staircase

[shreesti]

hi all,
i m making a spiral staircase for a residence . but i cant put the waist slab on it. please experts help me with it. have attached the file.

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spiral problem.skp

[Gaieus]

Hi Shreesti,

I must sound dumb now but what is a "waist slab"?

[Wo3Dan]

@gaieus said:

Hi Shreesti,

I must sound dumb now but what is a "waist slab"?

Gaieus,
waist ===> ... that you don't fall off. (slab...like concrete sides)

Shreesti,
The waist slab is not that difficult but before you go on:
-first group what you already have created!!!
-note that the outher arc radiï are not the same, nor are the inner radiï!!!
this could get you in trouble when going on.
Make one slab for one tread and rotate/copy it for the other treads.
Here you see why one center(line) is importand. You have more than one, a whole bunch of centers.

Wo3Dan

[guite]

Hi folks,

Please see attached.

Just ideas,
Guite
trying to imitate Jean

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spiral problem.skp

[Wo3Dan]

@unknownuser said:

Hi folks,

Please see attached.

Just ideas,
Guite
trying to imitate Jean

Guite, exelent peace of (concrete) work.

Sheesti, here you see that you don't need the arcs to be divided in so many segments. Only one segment/tread will do to get good results (in which case converting it (the arc) into an edge will probably reduce filesize!)

If you examine the bottom surfase of Guite's model, also in 'View Hidden Geometry' you can see how you will get the smooth top surface of a 'waist' slab

Make one tread+slab(s) into a group and use 'Rotate/Copy' like Guite did.

Wo3Dan

[Gaieus]

Hm... I see... Thanks...

[Jean Lemire]

Hi folks.

To save some time, try this:

1 - Make one thread.

2 - Copy/Rotate it and move it up to proper place.

3 - Smooth any junction lines between the two instances.

4 - Copy this new module of two threads to get four.

5 - Move, smooth the two modules of 2.

6 - Repeat with 4 to get 8.

7 - Continue doubling each time to get what you want.

For example, if you use, for the base circle, the standard number of segments of 24, you will use the above procedure untill you get 8 treads. Then, for the last copying, you will ask for two copies at 120° from each other to get 24 instances around the circle.

That way, you get a whole circle of ascending threads with only four copy/rotate, move and smooth operations.

1 --> 2
2 --> 4
4 --> 8
8 --> 24

Just ideas.

[shreesti]

thanks guys ...you ppl have made me happy
bye

[GreyHead]

Here's one I made earlier - for a lighthouse model. A simpler slab than used here but the nested components/groups show how it's put together.

Bob

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spiral_staircase.skp