90 PATTERN MAKING 



serving as tenons to hold the arms together. After fitting, and 

 before grooving with saw kerf, the joints must be glue-sized and, 

 when dry, carefully scraped smooth with a sharp chisel. 



The grain of the wood in the tongues must run at right angles 

 to or crosswise of the joint to insure the greatest strength. 



When glued together and dry, from the center or intersection 

 of the five pieces, mark with dividers set to a radius of 5^ inches, 

 and cut off the ends of the arms so that they will project each half- 

 way into the rim. 



From the same center describe a circle 3^ inches in diameter, 

 forming the web of the arms; and from this Bg-inch circle, taper the 

 arms to ^ inch in thickness at the ends, care being taken to plane 

 the same amount from each side and to dress the arms evenly so 

 that they will revolve in the same plane. This being done, from 

 the center describe arcs on the outer ends of the arms, with a radius 

 of 4 inches (8| inches diameter, which is inch less than the 



e 



Fig. 170. Fig. 171. 



inside diameter of the rim), and divide the imaginary circle thus 

 formed into five equal parts w r ith the dividers. Draw radii from 

 the points thus obtained, to the center. These radii will be the 

 central lines of the arms, as shown by the dotted lines in Fig. 1C)'.). 

 On each side of the intersection of the radii and outer circle, 

 measure \ inch to the right and left, and on the circle denoting the 

 circumference of the web, mark \\ on each side of the radii; con- 

 nect the points thus obtained, and the result will be five arms If 

 inches wide at the web and 1 inch wide at the rim, as shown in the 

 drawing. The ends of the arms which enter the rim should be, in 

 this case, 1;^ inches wide, and the sides are drawn parallel to the 

 radius which marks the center of each arm. The curves which 

 connect the arms at the hub must be drawn of such radius as to 

 make the curve tangent to the circle forming the extremity of the 

 \\vlt.andalso tangent to the sides of the two connected arms as 

 shown at <l . The small circles at the intersections of the arms with 



