Hi PILOU,

But I think no matter how fast or slow u go the pencil will move in linear fashion! which results in a zig-zag line! what do u think?

In my opinion, the mechanism would draw a zig-zag line, not a sine (nor cosine) curve,
because the rotating circle is driving the bar at a constant speed, between reversals.
The red drive gear would have to be linked differently, to a point on its circumference, so that the lateral motion is tied to the x? coordinate, to do the trig wave.

I could be wrong?

But you need WD40, and grandfathers attic collection:
https://www.google.com/search?q=sine+wave+drawing+mechanism&sxsrf=APq-WBs8yL5E1O6n_oFoVBrYLFHk7_Jwpw%3A1649523307751&ei=a7pRYoGzLeiq0PEPufqKgAE&ved=0ahUKEwjBlLqWuYf3AhVoFTQIHTm9AhAQ4dUDCA4&uact=5&oq=sine+wave+drawing+mechanism&gs_lcp=Cgdnd3Mtd2l6EAMyBQghEKABOgQIIxAnOgQIABBDOgUIABCRAjoKCC4QxwEQrwEQQzoLCC4QgAQQxwEQrwE6CAguEIAEELEDOggIABCABBCxAzoHCAAQsQMQQzoECC4QQzoNCAAQgAQQhwIQsQMQFDoKCAAQsQMQgwEQQzoLCAAQgAQQsQMQgwE6BQgAEIAEOgYIABAWEB46BQgAEIYDOggIIRAWEB0QHkoECEEYAEoECEYYAFAAWKlJYI9OaABwAXgAgAF6iAH5EZIBBDIzLjSYAQCgAQHAAQE&sclient=gws-wiz#kpvalbx=_rbpRYuWtKaLO0PEPz9WaeA22

- Brian

Hi Brian,

I also think it would draw a zig-zag line and not a trig wave.

This video looks partly like yours, with different linkage:

https://www.youtube.com/watch?v=g3MOvsFWcd8

Hi Bemfarmer,

Yes, So the car I made is called Zig-Zag car :-)

From Tgoy:

Frenchy Pilou:

Your advice about using Aldodoo to build a four bar linkage was greatly appreciated. Algodoo is used find interference points of a linkage, reducing the design time before milling a part.
Thank you MOI Forum members who helped with ideas.

Regards,
Tim Goymerac

Cool ;)
It's a very fun tool for 2D experimentations in many different subjects in real time !

Look this guy! ;)
https://www.youtube.com/channel/UClUIgNQOH-8WRms_awU-47A/videos

Hello guys,

Is there any of u who has free time and access to a 3d printer?

I want to publicly share some 3D files we made a while back.

But before full public sharing I prefer someone does a test for me and see if the 3D files are printable and the parts can be assembled and work smoothly. (I want to see if the size of the gaps between the parts are ok; because we had modified them!)

The 3d files are a type of Iris Dome Box. Note: It has thick walls so be ware it might take and consume lot of time and lot of FDM filaments!

If there is anyone who is willing to help me to discover possible issues; Please reply to this post and I will guide you on how u can get the 3d files (Pre-Public release test) and please start printing process as soon as u got the files ;-) and I will need your feedbacks so, also share them with me.

- Psygorn

Hi Psygorn,

3d printer available. Its an Ender 3. How big are you going? Asking cautiously.

Run the Analysis on Autocad's MeshMixer to verify model.

Wayne

Hi Wayne,

Well as I said earlier, I want to release some 3D files publicly, so anyone who is interested could use it.

for now I am in need of some volunteer help (some people with 3D printer and willing to test print the files) My intention is to figure out few things:

1- If the gaps between parts are calculated correctly (I mean the size of the gaps between parts will not create an issue for the user)
2- Discover some possible issues that I might not be able to discover myself. (so if you are going to do it, please do send me your feedback).

122 mm by 111 mm by 122 mm ( approximate dimensions of the finished model)

Let me know what your decision is?

_ Psygorn

Here is the model that was printed for Psygorn's design.

Wayne

Cool!

I was finally able to download the STL files for a six bladed iris.
Note the direction of leaf opening.

There is also a different design with 4 leaves that open like trimned sphere caps on a sphere, in the opposite directions. (The hinge pins are on opposite side of the leaf.) For six leaves, the sphere opening size would be constrained by the hinge pins. 360 degrees ÷ 6 = 60 degree pin spacing. The corresponding arc length, plus pin&support radius determines the arc Length to the north pole of the dome.

A node with all leaves moving together might be possible?

- Brian

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