Monday, February 18, 2008

"The Mothers Day Music Box Model"

Its not to early to start the planning for your Mothers Day turning!
I decided to take on another modeling and turning challenge.
Inspired by the book "Masterful Woodturning" (ISBN 0-8069-8709-X). I decided to combine woodturning and music boxes.

Design goals for the Music Box project:
  • Box with a removable lid
  • Made from a burl
  • Music box hidden inside
  • Animation
  • Wind the music box without opening top
  • Pleasing shape
This is a unique challenge because I wanted to make the top rotate with the power of the music box as well as using it to wind the mechanism.

This meant that the box would be multiple pieces that would need to fit together with relatively tight tolerances.

Here is how the entire project was then modeled on the Virtual Lathe in 1-1 scale.


Step1:

The music box itself was modeled. It became obvious that the center of rotation of the music box was offset. This meant that the bottom would have to be quite a bit larger than the music box.



Step 2:

Just as if you had sliced the final assembly down the middle, draw the 1/2 cross section of the entire assembly on the grid making sure to interpose all the components like they will fit in the final assembly. In this design there is a music box, base, top, finial and coupler. Notice how the model of the music box is used to get the dimensions correct in 2 and 3D.

HINT:
I like to create the cross section first then perform a few trial and error renderings by rendering it then "undoing". After I get the design the way I like it I make a copy of the cross section to the right on the grid. Always keep at least one copy of your 2D cross section "un-rendered" so that you can come back later and make modifications. You will also need the 2D version of the model to make a story stick.

Step 3:
This project has multiple components so make a copy of the 2D cross section to the right and then separate the components horizontally into individual pieces. Render them as four 3D components.
HINT: An easy way to do this is to select the line segments that belong to each individual component and group them. Then move all that components line segments as a group. Once the components are separated on the grid render and group them as individual 3D items. Then group all the 3D groups before you copy the entire assembly to the right off the lathe.


Step 4:

Move and copy the entire assembly to the right and then rotate it vertically. Note the music box offset in the bottom so the shaft is on the center line of the top.



Step 5:

Make yet another copy of the entire assembly. Explode it into separate grouped components. Then assemble the music box using these components to give a final view.



Step 6:

Using the section tool create a sectional view through the entire piece to check for internal interferences. As you can see the coupler has a problem it seems to long!


Step 7:

Using the dimensions from the 2D cross section as my guide, I found some redwood burl the right size. I guess its time to go to the shop!

Enjoy!
Donnie

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