Clay, Application to Refinement

 

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 Corvette Scale Model (pt 2)

Armature build (pt 1) (pt 2,page 1) (pt 3)

In part 1 of the tape drawing series I spoke about enlarging the photographs to one fifth scale and using Mylar Drafting Film as the medium to produce the tape drawing. Now I will show the basic requirements needed to progress the model to the buck building stage. This is the intermediate stage before we start to apply the clay for the beginning of the model.

With the Mylar sheet over the renderings, let's start with the first view, the side view.

Side view layout for foam build on C5 Corvette.

This side view shows tracing paper placed over the Mylar tape drawing with the ground line marked in black felt tip pen. The plywood structure marked in red is stepped to allow sufficient foam around the nose or front end of the model. 

When marking the offset of the foam from the finished model rendering it is better to allow for more clay than less clay for the simple reason, if you do hit foam during the modeling stage there will be less to cut out than if you try to cut the foam very close in the first instance. The trade off is the model will be heavier but it is less lightly that foam will be hit during the development stage.

I've decided to use 3/4 inch plywood for the base of this armature simply because it is easier to source. That is, you can get it from Lowes, Home Depot or any timber supplier regardless of what country you live in.

The double layer of plywood that will support the foam and then later the clay will provide a rigid and straight base that will be less lightly to twist or bend. The largest base size for this purpose is 27" x 8 7/8" x 3/4" or 685mm x 225mm x 18mm. The secondary base is 20" x 8 7/8" x 3/4" or 508mm x 225mm x 18mm. These two base boards should be glued together with a good quality waterproof wood glue such as "Titebond II or III Ultimate Wood Glue" available at all good hardware suppliers. 

The reason I recommend a waterproof glue is, if you are building the project in an outer building such as a garage then it can become damp during the winter time and if there is a chance that the wood will absorb moisture then it has a good chance of still remaining stable. As you may of noticed this project of mine has been going for some length of time already and I'm sure that it will be some time before it is completed so stability is a major concern.

Close up of the base board armature that will support the foam.

Let's take a closer look at the base frame for the model. As you can see the two layers of plywood are stepped to give additional foam in the critical area on the hood. The black horizontal line at the base represents the modeling table, the block underneath the model's plywood base board will be one of the towers that will hold the model in design height.

A close up of the rear part of the base board, as you can see the two layers are flush at the end.

The close up of the rear section of the base board shows the two layers of plywood flush together. There is no need to provide an offset here because there is sufficient material above with little deviation in form. The second tower for support is placed in a similar manner, central to the wheel position. This will be hidden when the wheels are in place for modeling and evaluation purposes. 

As you can see, I've marked on the tracing paper the dimensions for the two towers, 2 3/4" x 1 1/2" x 8 7/8" or 70mm x 38mm x 225mm, with the dimensions marked on the tracing paper there is no need to measure again when I need to make them.

Full rear end view showing plywood model base and foam outline.

The full front view shows the two layers of plywood, the foam block intention and the tower that will support the model. The base line of the table is also indicated. 

All this early preparation will ensure that the armature build will run smoothly, by indicating all the elements it is easier to identify anything that may have been left out.

The plan view shows the complete structure as far as the armature, with the red outline of the plywood base including the double red line at the front indicating the step. The black outline of the foam in comparison to the intended finished shape with the various angles to allow for adequate clay. 

You may think that the foam is a little close on the corners but those sharp edges will be softened off with garnet paper once the foam has been attached to the base.

Plan view of armature build intension showing both plywood and foam outlines.

Three views of the drawing for the armature of a C5 Chevy Corvette.

The complete working drawing for the armature build shows all the required elements, the position of the base board in relationship to the foam and the outer skin. Where the foam lies in relationship to the outer skin of the model, the tower positions that will support the model. With all this information now laid out I can now start thinking about cutting out the materials that will become the armature for the C5 Chevy Corvette.

This will be covered in the next section, Armature build (pt 2)

Copyright © 2006 - 16 Steven Austin

 

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