The North pole arc is on a great circle, whereas the sphere cap arc is not on a great circle.

The arc length between hinge pins is also not on a great circle. It is a "latitude" arc.
The different arcs are confusing. I am unsure whether or not I drew the "correct" sphere cap...
There seem to be some small differences in arc lengths...

- Brian

For the sphere cap model of leaves, using a sphere of radius 10, without any overlap of leaves, nor overlap of hinge pins:

For 5 leaves, the latitude angle of the circle where the hinge pins plus support are located, is about 32.2312 degrees, from the equator.
This leave about 0.5473 units (e.g. cm) for each of the 5 hinge pins plus support.
This is about the minimum angle so that blades will not overlap the hinge pins of adjoining leaves.

For 6 leaves, there is not enough latitude circumference, until 60 degrees from the equator is reached.
At this angle there is zero space for the hinge pins.

At 61 degrees, there is only 0.0923 cm of room for 6 pins, which is extremely little.
The opening in the top of the sphere is small.

- Brian

Besides rotation about a fixed point ON the Sphere (and leaf), a leaf can also travel on the Sphere surface by rotation about the Sphere center.

- Brian

Hi bemfarmer,

> There is also a different design with 4 leaves

Yes, indeed :-) I believe that was done by LOBOCNC (Jeff Kerr) you can search him on youtube but he claims his design is forked from Emmett Lalish's design (who made a five-leaf iris-dome box)

> A node with all leaves moving together might be possible?

I think it is!

- Psygorn

Hi Bemfarmer,

Could you add some photos of what you mean exactly :-)

Maybe I can help.

- Psygorn

Hi Brian,

> For 6 leaves, there is not enough latitude circumference, until 60 degrees from the equator is reached.
At this angle there is zero space for the hinge pins.

> At 61 degrees, there is only 0.0923 cm of room for 6 pins, which is extremely little.
The opening in the top of the sphere is small.

Sorry, I have difficulties to get what you exactly mean? Could you add some shapes for better elaboration?

- Psygorn

Hi Psygorn

Here are ImgBox views of 3 examples:

The first image is a test image for 6 leaves, with 60 degree latitude. The arcLength of half of the (Red) sphereCap * 6, just about equals the arcLength of the Hinge Latitude.
There is no meat to mound a hinge hole.
Curiously, the arcLength of the hinge latitude is 10 * PI. There must be a reason for this?



The second image is at 30 degree Hinge Latitude, with 6 leaves. The neighbor leaf overlaps the hinge area. So a guide slot is likely needed, and the hinge abandoned...



The next image is with 5 leaves, with the latitude circle at 32.23 degrees from the equator. Sphere radius is 10 units.
Hinges have been placed, but no engineering has been done as to strength. This is not a final model, just a mockup.
Using the line from the sphere center, to the center of the hinge pin, as a rotate axis, permits rotation of the leaf.
In a node, six rotation axi, for the 6 leaves, should result in simultaneous opening and closing of the iris(?).



The next image shows the radius of the SphereCap in Red, along with the Hinge Latitude circle. MoI quickly calculates the arc length of each.
The Red length is to be multiplied by 5, to be equal to the Latitude arclength + hinge radius*5.



- Brian

Hi Brian,

I hope you are doing well.

What you want to do? are you going to make a 6-leaf Iris Dome Box?

>The first image is a test image for 6 leaves, with 60 degree latitude. The arcLength of half of the (Red) sphereCap * 6, just about equals the arcLength of the Hinge Latitude.
There is no meat to mound a hinge hole.
Curiously, the arcLength of the hinge latitude is 10 * PI. There must be a reason for this?

Are the above showing your process of making a 6-leaf Iris Dome box?

Could u explain in simple terms what you are going to do?

the 6-leaf IrisDomeBox is shared to the public you can download it's STL files and have it 3D printed yourself :-)

There would be an instruction on how you can print an assemble it, however, you have to wait for it.

If you want to know the mathematics behind it I have to tell you, I did not find any mathematical methods out there (and I did not search for it!) to be honest I think there are some but they are not like an instruction on how one can make an Iris Dome Box with any number of leaves he/she wants.

Now let me thank @Michael :-) Because:

I have to say MOI can be used for creation of mechanisms and mechanical devices, Yes, of course it lacks some fancy features -mating feature, assembly ,etc.- of some CAD softwares such as Solidworks Yet, it's speed and intuitiviety compensates those shortcoming and here it is demonstrated that by only using MOI one can create a mechanical device such as a 6-leaf Iris Dome Box Which has no other equivalent as of yet!

Needless to say I am an ex-user of Solidworks and I believe if one wanted to make 6-leaf Iris Dome box using Solidworks he/she would reach old ages and no 6-leaf Iris Dome Box would be made!

if you search Youtube you can find 5-leaf iris dome box made by Emmett Lalish -> https://www.youtube.com/watch?v=-m8uWz-qf7Y

Later Jeff Kerr (LOBOCNC) forked Emmett's design and made a 4-leaf iris dome box of his own -> https://www.youtube.com/watch?v=pdFCBuTAVp4

there is also Brien Allison with a 7-leaf design -> https://www.myminifactory.com/object/3d-print-orbox-192727

Emmett and LOBOCNC's designs inspired the design of 6-leaf Iris Dome Box but the design of 6-leaf iris dome box is an original design! and I think as of yet it is the only 6-leaf Iris Dome Box out there! and it is designed only By Using MOI! Thanks to @Michael :-)

All in all, if I want to say it in simple words it is a show-off of MOI's capabilities in designing of a mechanical device which actually works.

This thread is made for people who love mechanisms and mechanical devices maybe they can step forth and share their designs -Made in MOI only- with us so, we can enjoy them too :-)

If you have any other questions and I can understand them I would be happy to help :-)

- Psygorn

Thankyou Psygorn.

I'll check out the 7-leafer.

As for the 10*PI circumference at 60 degrees, it is simply because Cos(60degrees) = 1/2.
( Basic triangle characteristics, and/or basic trigonometry. )
ArcLength of latitude circle = ( 2 * PI * circle radius ) = ( 2 * PI * Cos( 6Odegrees) * Sphere Radius ).
Note that formulas vary depending upon use of degrees versus radians.

I relatively quickly used MoI to test every few degrees between 32d and 61d, for convergence of North pole arclength * 6 versus latitude radius. 60 degrees is not practical. I'll stay down around 30d +/-, and abandon fixed hinge pins for greater than 5 leaves.

Shell of leaf looked cool. Had to Flip surface normal.

Best method to create spherecap?
Choices include sphere trim or boolean with plane or line,
There can be some artifact surface(s).
Or revolve of North pole arc to latitude point.

Looking forward to release of your design.

- Brian

The 7 leaf orbox is mighty fancy!

Hi Brian,

The pivot point or anchor point for the leaves are located outside of the circumference of the leaves for the 6-leaf design (that's the trick I think).

>I'll check out the 7-leafer.

Do check that out as well. However, I think the movement of leaves for that design are limited (meaning the leaves do not rotate large degrees! and by large I mean more than 50 degrees this had caused the box to have small opening mouth when it is in it's open state, so, you can only fit objects that can pass through it's small mouth. I believe the 6-leaf design has a wider mouth in it's open state meaning it can swallow objects with larger diameters!)

>Looking forward to release of your design.

6-leaf design already released! (in STL Format) :-)

Check out here:

https://sketchfab.com/3d-models/6-leaf-iris-dome-box-a67fb51c99db4b359668996dfcdffa32
and here:
https://www.thingiverse.com/thing:6145744

There are intentions to release the original MOI file as well but for that you have to wait (a bit)

And there is an issue that might be interesting for you/others. if you like to know about it I can share it with you :-)

> The 7 leaf orbox is mighty fancy!
Indeed it is :-)

- Psygorn

Hi Psygorn
These designs are so interesting, especially the box with 7 leaves. I wish I could understand the math behind it! :)
This is the tutorial I studied to get the process of making it.
https://eleccelerator.com/3d-printed-mechanical-iris-dome-all-one-piece/

After several trial and error, I managed to make these nodes. (Attached)
The anchor point for the first node is on the corner of the leaf. (According to the tutorial. Max 6 leaves)

I played a bit with different anchor point positions on next 3 nodes.
In these nodes, leaf number can be set to a higher number, But I'm guessing they are not 3d print friendly?
I think moving the anchor point to the outside of the leaf is the key to have more leaves,
But where is the most efficient position for anchor point?

Hi MO (MO_TE),

Wooow! I am stunned by your nodes! :-) (I need time to study them carefully though!)

> This is the tutorial I studied to get the process of making it.
https://eleccelerator.com/3d-printed-mechanical-iris-dome-all-one-piece/

Yes, it seems it is the most robust tutorial on making Iris Dome Boxes out there (and it was mentioned by Brian here: https://moi3d.com/forum/index.php?webtag=MOI&msg=10641.6) , However, I did not study it (I think I should study it
at some point)

> In these nodes, leaf number can be set to a higher number, But I'm guessing they are not 3d print friendly?

Is it possible to rotate the leaves using your nodes? (I did not study your nodes carefully as of yet!) if the leaves do not bump into each other then surely u can make it 3D-printable! According to my personal experience the most two important things for making an Iris Dome Box are: 1- determining the shape of the leaves 2- determining the Anchor point around which a leaf can rotate without bumping into other leaves! the rest is easy!

Once again u showed how powerful Nodes are! and what crazy things one can do with Nodes + conventional modeling! Thank u (and of course Max) for that.

> I think moving the anchor point to the outside of the leaf is the key to have more leaves,

Indeed this trick is used to make the 6-leaf IDB (Iris Dome Box). ;-)

> But where is the most efficient position for anchor point?

Sorry, I don't have the answer for this question as of yet!

-Psygorn

>> Is it possible to rotate the leaves using your nodes?
Yes, Change the "Aperture" value. Also, use the other blue nodes as well. E.g "Leaves", "Height"

Hi MO,

I did use Aperture but it seems the leaves are rotated around the center, I mean they are not rotated around a pivot point on the lateral side of the sphere! ( I hope this explanation is good)

However, the way leaves rotate using your nodes is another type of movement which is interesting in its own rights! :-) And I can tell u it is possible to make a 3D printable design with such movement.

- Psygorn

Hi
>> it seems the leaves are rotated around the center
I guess you are using the "Iris_Box_3" node. I used the center point as anchor point there.

But you can see the anchor point in other nodes shown by a little cylinder.

>> it is possible to make a 3D printable design with such movement.
Cool! :)
It can handle up to 60 leaves!

Hi,

> But you can see the anchor point in other nodes shown by a little cylinder.

Yes, I saw it. :-) in "Iris_Box_4 node" it seems it works fine! (Or at least I am sure with your Nodes one can make as many Iris_Dome_Box designs as he/she wants) great job! :-)

>It can handle up to 60 leaves!

Let's make that one! :D

- Psygorn

>> Let's make that one! :D

35 Leaves :)

Isn't it satisfying?

:-)