Helix - not one full turn - HOWTO?

Gaieus

Okay, 17 treads (I think that's the English term) for the total height of the helix. But how many degrees of turn?

lexje

@tig said:

DrawHelix13.rb by Peter Brown 4/8/2004
has more options than that AND lets you do any number of turns...
http://www.crai.archi.fr/RubylibraryDepot/Ruby/drawhelix13.rb
Is this the one you are having problems with ?[attachment=0:59tf7bb0]drawhelix13.rb[/attachment:59tf7bb0]

Thanks for helping out.
I'm in need of this in order to draw a spiral stair.
But, I repeat, I CANNOT enter a value < 1 as a value for number of rotations ....

Now I do realize that with differing settings depending on localization sometimes a [.] becomes a [,] just like, apparently sometimes in VCB you have to enter either [,] or [;] to distinguish between entries.
In this case I've tried all of them...

No entry smaller than 1.
What am I doing wrong?

Gaieus, chopping would work I assume, but I need my spiral stairs to have 17 marches or threads (?) (not sure about the naming in English ) and they need to sum up to the total arc length of the helix to be drawn....

I'm not quite there yet...
Apparently you can't enter anything other than a full integer in number of rotations or section per rotation.

Erwin

lexje

Total of 324,431767 degrees
1 tread = 19,0842216 degrees

lexje

Final result would be something like these...

Erwin

lexje

Done some more playing with 1001bit tools from Goh, and I think this will fit the bill.
Will have to do extensive editing, but with drawhelix13.rb or spiralstair11.rb this would have to be done too anyway..

Would still be glad to see how to build a helix in less than a full turn

Gaieus

As I said, you can always break a helix - just like any other curve. I realise that these dimensions (324,xxx and 19,xxx degrees) are a bit "crazy" so to speak so I have been thinking hard how to achieve it (a simple segment count division would definitely not work - but it there were 18 treads and only 320 degrees, it would be easy).

lexje

@gaieus said:

As I said, you can always break a helix - just like any other curve. I realise that these dimensions (324,xxx and 19,xxx degrees) are a bit "crazy" so to speak so I have been thinking hard how to achieve it (a simple segment count division would definitely not work - but it there were 18 treads and only 320 degrees, it would be easy).

I've been following the same line of thought..
I did the math with numbers I got from a professional stairmaker, but I would like to 'build' the model in SU
I have to admit: I can find my way around SU more than average after a couple of months of SU-ing and sipping Aidan Chopra's excellent video's, but crunching these ruby plugins is a complete other cup of beans!
I've also tried to add a couple of treads, just to have > 1, but no comma allowed..

I'd be glad to listen / read how you would go about with 17 treads and only 320 degrees...
Where would the difference be?

Erwin

Gaieus

No 17 treads but say 16 - and as you can see from the picture, there is a very lowest tread which is not even too much part of the helix but a kind of pedestal like step so I believe the cheat would not even be that obvious as that can be added later.

lexje

Well, the pictures I posted are from the stairmakers website, so they don't correspond with our stair to be. We'd need to cover a height of 3100 mm in 17 treads, so each riser would need to be 182,35 mm. Also, there's something as the 'walkline' (translated literally, maybe it should be line of walk (?)) This line of walk would indicate that each tread be 230 mm across at a radius of 650 mm...
If I'm not mistaken you're thinkering of 16 or 18 to be a multiple of a pair?

Erwin

Gaieus

Well, true that not exactlythe same dimensions... Especially the "walkline" - I used completely different measures so this is just an example.

The 18 is handy because 360 can be divided by 18. Then you take two of them and have a very similar number as your 324,xxx degrees (exactly 320).

When working with segmented curves in SU, it is extremely hard to count with those long decimal digits.

SpiralStair.skp

TIG

Had I realized you wanted to make 'spiral stairs' I would have suggested my 'Grow' tool...
Unzip this Grow.zip file and put the resultant Grow.rb into the Plugins folder and the growCursor.png into the Plugins/Icons folder [just as they are zipped].
The attached skps have some tutorials on how to make a helical [spiral] stair and also helices in general...Grow.zip GrowHelicalSteps.skp GrowHelix.skp

TIG

When making spiral steps there are often rules/codes to adhere to..
In the UK on narrower flights <1m [typically domestic or small commercial flights] you must have at least 50mm of plan-tread at the innermost part and the plan-tread on the centerline should be even for every step, and follow the rule 2R+G >=550mm <=700mm - where R is the Rise and G is the Going [plan-tread].
If you draw this in plan it limits the relative angle of adjacent nosings and effectively sets a limit on the taper angle between them = ~15degrees depending on the configuration etc...
For wider stairs you measure in from both edges [strings] 270mm and the same max/min pitch applies, 2R+G >=550mm <=700mm to the two locations
Any landings shall be the same length as their width measured along their centerline.
The minimum/maximum allowable Rise and Going varies with the building type too.
'Private Stair'[one dwelling] R >=155mm <=220mm and G >=223mm <=300mm [vertical pitch is also limited to 42 degrees - usually trapped by 2R+G rules]
'Institutional and Assembly Stair' R >=135mm <=180mm and G >=280mm <=340mm
'Other Stair' R >=150mm <=190mm and G >=250mm <=320mm
BUT AD-Part-M [accessible/disabled=all commercial/public building etc] R <= 170mm G >= 250mm
It's best to draw some test treads and place rotate a couple to see it they are right before committing to a complex 3D assembly...

TIG

I have fixed the problems with drawhelix13.rb.
It now allows turns that are not whole numbers...
Here it isdrawhelix13_TIGd.rb

dylan

Nice information TIG.

Did you use another ruby for the stringer?

TIG

No - it's made as a part of the tread and Grown...

lexje

Hi TIG, thanks a tremendous lot for your input
Greatly appreciated (Gaieus too b.t.w)
I did explain the spiral stair stuff though, see herehttp://forums.sketchucation.com/viewtopic.php?f=79&t=26214

I'll give your attachments a whirl soon and post back.
Although I must say my last experiments with Goh's toolkit are promising. (I've not found how to change direction of rotation clockwise/counterclockwise though)
One advantage I see in using Goh's plugin is that the treads are more detailed i.e. the outside of the tread are 'curved' instead of straight.

Nevertheless a couple of questions:
I'm native Dutch (Flemish) speaking, our stairmaker is French, and out here we're talking English, certainly with this kind of lingo I need some vocabulary help

Let me first paraphrase the layout of our stairs to be:
Hellicoïdal with hollow core with R=200 mm
Riser = 182,3 mm for V1
Riser = 189,2 mm for V2
Going = 230 mm (Giron in French)
LF = Ligne de foulée ~= "walkline" ~= plan-tread (??)
Plan-tread @ R = 650 mm -> V1 = 3/4T + 1/8T +107 mm
-> V2 = 3/4T - 70 mm

I really think, in conjunction with what I learnt from the stairmaker, the best way is to draft a plan and side view (like the picture I posted before), and build your model from there, as I also found in a post from TaffGoh here http://forums.sketchucation.com/viewtopic.php?f=79&t=12511

I must say, although the ruby depot is a tremendous help, it's lacking responsiveness, and certainly for newcomers, clarity and a little more context.
E.g. most rb-scripts are already several years old and have often already been improved upon or contained within newer / other ones. Also a minimal documentation including ONE picture would often help to at least give an impression of what it's all about.

One request remaining:
For clarity's sake and certainly for others researching this 'specialized' knowledge - would you mind drafting a quick SU image adding the lingo 'terms' to exclude misinterpretation?

Thanks again for this great and responsive forum and all the help!!

Erwin

lexje

@tig said:

I have fixed the problems with drawhelix13.rb.
It now allows turns that are not whole numbers...
Here it is[attachment=0:1sjnwqr5]drawhelix13_TIGd.rb[/attachment:1sjnwqr5]

Jeez, TIG you fix faster than I can think & write ))

Erwin

lexje

B.t.w How do I get URL's right??
That is: to not show up as the full URL, but as a 'clickable' word?
I've had a look [url]http://www.phpbb.com/community/faq.php?mode=bbcode/]here[/url], but this doesn't seem to work..
Allthough the one below DOES work ?

@unknownuser said:

Linking to another site
phpBB BBCode supports a number of ways of creating URIs (Uniform Resource Indicators) better known as URLs.

    * The first of these uses the  tag, whatever you type after the = sign will cause the contents of that tag to act as a URL. For example to link to phpBB.com you could use:

      [Visit phpBB!](http://www.phpbb.com/)

      This would generate the following link, Visit phpBB! Please notice that the link opens in the same window or a new window depending on the users browser preferences.

Erwin

Gaieus

@unknownuser said:

I'm native Dutch (Flemish) speaking...

Haha... We know that1s not the same (I had a Flemish room-mate when I went to an American univ. for a semester )

Anyway, for staircase building, TIG's Grow is definitely a good tool (and thanks TIG for a revised version or the helix plugin, too).

@lexje said:

B.t.w How do I get URL's right??

This is not the correct way:

[url]http://www.phpbb.com/community/faq.php?mode=bbcode/]here[/url]

But do it like this:

[url=http://www.phpbb.com/community/faq.php?mode=bbcode/]here[/url]

And the result will be this:
here

Edit: wow, does somebody read the FAQ???
You have a bright future here, my friend! (Just look at what our other moderator, solo has in his signature about this)

lexje

Edit; wow, does somebody read the FAQ???
You have a bright future here, my friend! (Just look at what our other moderator, solo has in his signature about this)
;)

As a matter of fact, I did search the FAQ, and it simply is not there (correct me if I'm wrong)Off course being the better than average user, I searched phpBB's faq for this... Hence..

Solo doesn't seem to have too much of a Stoppelbaard

Erwin