The Sheet Metal Bath Tub. Copyright Bud Goodman 2004

Transcription

1 The Sheet Metal Bath Tub. Copyright Bud Goodman 2004 Here is a great way to have some fun, strengthen your layout skills and create a useful product that you can use yourself or pass on as a gift. The old galvanized bathtub. These bathtubs for kids were made, as are most products are, many different sizes, some plain and some with intricate stampings on the side. Today you ll find these old tubs in antique stores with a pretty hefty price tag attached. These old bathtubs found a second life; today they are used as planters, fountains, and Champaign coolers, magazine holders etc. We only discuss in a few measurements in the beginning to give you a basic idea of size and proportion, it is only for cosmetic sake, you will design yours as you like with the using the same method as we have here. To begin developing the pattern for the bathtub, draw both the top view and elevation as shown in Figure 2. There are three separate sections + the base that need to be developed for the bathtub. These sections are (1) the foot end, (2) the mid section and (3) the head end of the bathtub. The top view illustrates that even though there are three different areas of this pattern to develop, we still have a two halves that are symmetrical, the center being line 1 2, allowing the pattern maker to only need to develop one half of both the foot end and the head end of the tub. The bathtub two ends and mid section are of both equal and unequal tapers. The foot of the tub is shown to be an equal taper and is proven by having one radius center (marked A) for both the top and base of the tub. The equal taper follows through the mid section of the tub; this is shown in the shaded area of Figure 2 The head end of the tub has two centers (B) for the base and (C) for the upper head end of the tub. These two centers offset from one another creates an unequal taper; unequal tapers need to be developed using triangulation. The foot end of the tub can be developed using triangulation or because of its equal taper, it may be developed using the radial line method. As shown in the elevation view of Figure 2, the foot end as a very slight pitch, making it more difficult to use radial line method. The apex of which would need to be

2 located for the radial line method would be several feet to center and not very practical. Both ends of this bathtub will be developed using triangulation. Begin the layout by drawing a straight line as shown from 1 to 2. (Top view, Figure 2) Near one end, mark on the line a reference mark A; A will be used to strike an arc for both the top and the base on the foot end of the tub, The radius for the foot end can be of any radius you choose, we wanted the width at the foot of the tub to be around 15 inches, so our radius would be 7 ½ inches, using A as center strike an arc as shown from 3 to 4. Keeping one end on (A) center and extending the length of the trammel points by 1 inch, strike another arc from 3 to 4 as shown. Now we have established both the base and the top of the foot end of the tub. We will use this in obtaining the necessary information needed to create a true length triangle for the foot end of the tub. On line 1 2 measure over from point A about 20 inches and mark point B, This becomes the radius center for the base at the head end of the tub. The width at the base (head end) for this particular pattern is about 17 inches for a radius of 8 ½ inches Using B as center Strike an arc from 5 to 6 as shown. On line 1 2 measure over 1 ¾ inch to establish point C, we struck a 10 inch arc using C as center from 5 to 6 to develop the upper flare for the head end of the tub, it should be understood that you may choose any pitch that you desire. There is no reason for the dimensions we have chosen other then the final look we choose to accomplish with our layout. Connect 4 and 6, 3 and 5 with a straight line. Draw lines parallel to lines 4 5, 3 6 as shown from 4 to 5 and 3 to 6. From the top view in Figure 2, we can see the true length of both the base and the top rim of the bathtub. Project lines down to establish the height of both ends of the tub in the elevation drawing as shown in red the two inside

3 red lines establish the base, line 7 to 9; point 8 and 10 in (figure 2) is the height of both the foot and head end of the tub. We chose 14 inches for a height at the head end of the tub and 9 inches for the foot end of the tub, once again; these can be of any height that works for your design. Connect 7 to 8, 9 to 10 and draw a line from 8 to 10. Preparing the drawing to establish the true lengths needed to develop the pattern. As stated earlier, we only need to generate the true lengths for one half of both the foot end and the head end of the tub (see shaded area in top view of Figure 3) These true lengths will work for the other half of each end. The first step is to divide the arcs drawn from B and C into equal spaces as shown. (We used 5 equal spaces on the head end) Label as shown starting with number 1, the number 1 being the beginning of the arc drawn from point B. The base shall have odd numbers, 1 through 11. The top (rim) of the tub at the head end is divided into the same amount of spaces and labeled with even numbers starting with 2 through 12. Number 2 being the beginning of the upper arc. Connect 1 to 2, 2 to 3, and 3 to 4, etc. as shown by the dotted line in the top views shaded area, until you connect 11 to 12 as shown. Connect the beginning of both arcs drawn from B and C (Figure 3) by drawing a line from 1 to 2; typically this would be an edge or seam for the sidepiece. To develop a seam that would run perpendicular to the base, we added point A (shown as line A A, in the elevation view). These dotted lines drawn in the shaded area in the top view of Figure 3, all represent the length of the base of a particular triangle, all even numbers 2 through 12 shown in the top view of Figure 3 represent the height of each triangle. Because the upper rim of the bathtub is slightly pitched from the head end to the foot end of the tub (Figure 3, line D E) the heights of 2, 4, 6, 8, 10, and 12 are not equal, to determine the height of

4 each line, drop lines from points (A, 2, 4, 6, 8, 10, and 12) in the top view perpendicular to line FG (the base of the tub) in the elevation view, establishing points A, 2, 4, 6, 8, 10, 12 on the base and A, 2, 4, 6, 8, 10, and 12 on the top rim. The length of each of these lines A to A, 2 to 2, 4 to 4 etc, through to 12 to 12 will be transferred to a diagram of triangles as shown in figures 4 and 5. A diagram of triangles is one method used to determine the true length of lines and is easy to develop. To begin developing the diagram of triangles draw a horizontal line of random length as shown from A to 12 (Figure 4) Starting with A, take the distance from A to 1 from the top view in Figure 3, and establish this distance by using A as center and striking a reference mark at 1 along the line in Figure 4. Reset the dividers to the length of 1 to 2 from the top view in Figure 3, using 1 as center, strike a reference mark to establish point 2 on the line as shown. Repeat this with 2 to 3, 3 to 4, 4 to 5 etc. until all points through 12 are referenced on this line. Draw lines perpendicular to the line established from A 12, at all the even numbers, with using your dividers, transfer all the heights from the elevation view in figure 3 shown as 2 to 2, 3 to 3 to the proper line establishes in your diagram of triangles as shown in figure 4. Take notice that you will see that all odd numbers are referenced only on the line with no perpendicular line representing any height; this is because in the top view of figure 3, the odd numbers are established on the base of the tub and therefore have no height. The objective of developing the diagram of triangles is to establish the true length of lines (figure 3 top view) of 1 and 3 to 2, 3 and 5 to 4, 5 and 7 to 6, 7 and 9 to 8, etc.

5 Draw a line (Figure 5) that connects the odd numbers to the even numbers, 1 to 2, 3 to 2, 3 to 4, 5 to 4, etc. These red lines are the true length lines needed to develop the pattern of the head end of the tub. The true length lines for the foot end of the tub are established in the same manner. Develop the pattern for the head of the bathtub (Figure 6) by using the true length lines that are established and shown in red (figure 5). Set your dividers or trammel points to the distance of 11 to 12 in figure 5 and transfer this to 11 to 12 as shown in figure 6. This would be the center of the head end of the bathtub; the layout on the right side is the same layout for the left side. The distance of 12 to 10, 10 to 8 etc., 11 to 9, 9 to 7 etc. is the length of which you have divided the arcs drawn from B and C in figure 3. It would save time in the layout to have a separate dividers set for these two repetitious arcs. Once you have drawn the line 12 to 11, strike an arc from 12 to 10, using 12 as center. Set the trammel points using the distance of 11 to 10 from figure 5, and using 11 in figure 6 as center strike an arc that intersects with the arc struck from 12. This intersection becomes point 10. Do this on both the right and left side of 12 at the same time to save time by not having to reset the trammel again repeatedly for the second half. With the dividers set for the distance from 11 to 9 in figure 3, using 11 as center, strike an arc near 9 as shown in figure 6. Take the distance from 10 to 9 in figure 5 and using 10 as center (figure 6) strike an arc that intersects with the arc drawn from 11.Repeat these steps similar through to line 1 to 2, to locate A in figure 6, set your dividers to the distance of 2 to A in the top view of figure 3. The arc from 1 to A is taken from the diagram of

6 triangles in figure 5. The intersection of these two arcs becomes A. Develop the foot end of the bathtub (Figure 7) in the same manner as describe for the head end. This bathtub pattern may be completed in as many pieces as is convenient for you. To develop the pattern for the sides of the tub it should be pointed out the distance 1 to A is also the distance of the side near the head end of the tub, the distance from 21 to 22 is the height of the side near the foot end of the tub. These measurements will be used as we develop the two side patterns as shown in figure 8. The length of 1 to 21 is shown in the top view of figure 3. The bottom can be developed from the top view in figure 2. No allowances were made or given for any seams. The bottom of the tub can be attached by the use of a Bottom Double Seam. The sides can be attached using the grooved seam method or perhaps a pocket seam would work. The top should have a wired edge for strength.