|
If you are lucky enough to possess a large format inkjet printer you may be able to print out your plans life size on an adhesive medium. Cut out the faces and stick them directly to the panel material you are using to construct the object. It then remains to accurately cut along the linework provided by the printed plan at the required solid angle. Keep in mind that the X and Y directions of the printer may not be precisely to the same scale, and that changes in humidity and temperature affect paper dimensions. A dimensionally stable plastic medium would ease this problem, but it would pay to check the accuracy of your printed plans before using them in this way.
L3DD’s face plans can be transferred to the panel material using a sharp 4H pencil, good-quality steel ruler and a compass or dividers. As illustrated, use a beam compass for medium to large work. The longest edge of a face and its two vertices are drawn first using the ruler and compass. For triangular faces, the position of the third vertex is then found by using the compass and the lengths of the two remaining sides.
The third vertex lies at the intersection of the two circles centered on the first two vertices and drawn using the appropriate edge lengths as radii. Draw the remaining sides with the ruler to connect up all the vertices. This method is more accurate than using a protractor and inter-edge angles. Although a protractor is useful in deciding if a face can be drawn within remaining panel material, it should not normally be used for accurate layout work.
|
|
For faces with more than three edges the diagonals shown on the plan will also be required for layout purposes. These can be supplemented, if needed, by other distances obtained directly from L3DD’s 3D view. In laying out a hexagonal face, for example, other diagonals can be obtained from the 3D view and jotted on the plan, so as to increase the accuracy of the triangulations used to find vertex positions. The most accurate triangulations are those that intersect closest to 90 degrees.
Provided sufficient care is taken, this method of layout will provide very accurately drawn faces that will join together perfectly if they are also cut with great care and accuracy. The precision with which the distances and angles are given in the plans is much greater than that required to actually build the objects.
Use cardboard templates when many identical faces are needed, as in the pentagons and hexagons of a soccer ball. Draw the faces on thin cardboard -- ivory board is best -- and carefully cut them out with a steel straight-edge and box knife. As illustrated, you may then transfer the faces to the panel material by scribing around the templates with a very sharp 4H pencil.
If your saw is unable to cut angles greater than 90 degrees, a template is useful where a face includes one or two ‘negative’ angles (the interfacial angle is concave). Turn the face over and cut the ‘negative’ edge angle(s) first. Now turn the face right side up and use the template to mark out the remaining edges.
The printed plans can also be used be used to try to find the best layout of faces on the panel material. First draw the panel material rectangle to the same scale as the printed plans. Use scissors to cut out all the faces from the paper plans. Now arrange the faces within the rectangle to generate the least waste. This problem is difficult to solve by computer and is best done by human eye.
|
|
Copyright © Ligno3D Systems, 2006
|
Layout Technique