What Is It?

[John Bowden]

I remember the reverse petal design............ I still use whenever I can...........

[Leif Ohlsson]

You've got to admit that the method would be ideal for Hamilton props. (Image from Milenio3's build of the Corsair, featured as picture of the week right now.)

[Gil]

Hi Leif,

You wouldn't believe the collection of different things that I tested by pushing it into the form. I'm preparing a tutorial on the method and have to make another roll up for some shots that need to be included for completeness. The following photo shows a nose cone produced from the resulting mold. It may not be necessary to assemble the first piece to make the mold...,

+Gil

[Leif Ohlsson]

V-e-r-y pretty! - L.

[Leif Ohlsson]

Gil has now produced his tutorial on this subject, but I didn't want to clutter up that thread with a request raised here, namely for the spreadsheet by Ricleite over at Kartonbau.de, which was the inspiration for this method.

You can read Ricleite's response to that here, over at Kartonbau.de (it's all in English).

As you will see, anybody interested can just ask Ricleite for his spreadsheets. He will also produce other similar spreadsheets for making wheels.

Plus, there is a link for Ricleite's math behind the spreadsheet. This, however, is all in Portugese, which is a real obstacle if you wish to understand it. But there are pretty photos further down in the thread (one of them attached below as a teaser).

From what I understand Ricleite is using the rolled paper strip method both as "male" molds for petal-shaped parts, as distinct from Gil's application of the rolled strip method to make a "female" mold.

Ricleite is also making extensive use of the rolled strip method for making parts as such.

This international & multi-forum cross-fertilization of ideas and methods is really most interesting. Note that we have three distinct, but related applications for a common idea of using rolled strips:

1. As male molds for petal-parts

2. As female molds for petal-parts

3. As a method of making dome-shaped or even doughnut-shaped parts.

Let me just add that the use of rolled paper strips for wheels and other parts based on cylinders of differing diameters to my knowledge was introduced by Robert Kaelin in his set of 1/25 aircraft models. (At least, that's where I saw it first.)

Leif

[milenio3]

I received a while ago Riclete´s spreadsheet, but I haven't try it. But his domes on the Architectural Paper Models he's done, are a very solid prove that this works.

Gotta try it!!

Leif, as always, thanks for the analysis on the method.

[milenio3]

Leif, I think your link on Gil´s tutorial should be this one instead:

http://www.papermodelers.com/forum/s...ead.php?t=1505

[Gil]

Hello All,

The following shows some of the development attempts that were, for one reason or another, rejected along the path of petal closure enlightenment (so to speak) and the one that worked.

The solution evolved through the observation that the petals self arrange if contained by a properly shaped female mold. An external mold does not offer this attractive feature and is more difficult to glue the seems neatly.

For awhile I was stalled with the idea that a first item had to be constructed in order to "fit" the mold to its shape. This was accomplished using various through hole diameter washers cut from 0.125 inch foam sheet. Slipped over the preformed nose cone brought the petals together so that they could be glued. A major drawback to just using this method for assembly was that the washers would leave an indentation in the nose cone caused by softening of the paper when the glue was applied (Small discontinuities in a curved surface are spectacularly noticeable).

The thought that a combination of the self forming aspect of petal designs and the flexibility of an adjustable mold occurred while I was working the rice flour into the layers of a test mold. This was tried and to my amazement it worked!

Features of the adjustable mold method:

1. The mold is reusable for any cross section curve up to it's outside diameter.
2. Each nose cone is slightly different due to slight differences in the way in which it's cutout. Having an adjustable form makes up for these differences.
3. It's easy to make.
   
4. Ease of use in assembly. Glue is on the inside.
5. Saves time.
   
6. No math required.
7. It's fun to use.

+Gil

[Don Boose]

I guess the resemblances to Buddhist stupas and lotus petals and Gil's path to enlightment is just a coincidence (good Karma?) as the Great Wheel of Being turns?

Sorry chaps. It's been a long day and I lived in East Asia for a long time.

Shanti, shanti, shanti.

Don

PS: In any event, it's a brilliant concept, Gil.

[whulsey]

Very good, the metaphysics of paper modeling as applied to creating conic forms.