KM PATTERN MAKING 



When turning on the inside of the rim, a fillet or curve must 

 be made where it joins the disc, of jf-inch radius, as shown at e, 

 Fig. 179. The same curve must be turned at the base of the hub. 

 Around the counter- weight block, and also around the wrist boss, 

 a i;-iiich leather fillet can be used. 



For convenience in 1 moulding, the two core prints x and // 

 should be turned with a tenon | inch in diameter and f inch long, 

 to fit into the holes in the face of the disc, so that they can 1><- 

 removed when the pattern is laid on its face on the moulding board. 

 The core prints v and s are turned without tenons, being glued and 

 nailed in position. 



FILLETS. 



The fillets spoken of in connection with Fig. 179, are used in 

 all except the most simple patterns. They consist of a small quar- 

 ter curve varying in size from inch radius upward, depending on 

 the size of the pattern and the room they can be allowed 

 to occupy. They should be placed in all corners, wher- 

 ever possible, so that there may be no sudden changes 

 Fig. 181. in the direction of the surface of the casting, which causes 

 weakness, the fillets adding greatly to the strength of the casting. 

 These fillets are made in various ways, the wooden fillet, cut 

 as in Fig. 181, being commonly used for all long, straight angles, 

 or for very flat curves to which it can be bent. 



For irregular angles and for short radius curves, beeswax was 

 formerly used, but the modern leather fillet has almost entirely 

 superseded beeswax and other material for this purpose. It is 

 easily applied, shaping and adapting itself to any arid all positions 

 and angles. It can be bought in all sizes from ^ inch up, the sizes 

 running by sixteenths. The method of applying it is to cut it to 

 the necessary length and lay it on a board where the glue can be 

 easily brushed over it. It is then laid in the angle and rubbed into 

 position by means of a dowel rod, the end of which must be rounded 

 off as shown for the connecting dowel pins of a parted pattern, Fig. 

 152. The dowel rod must be of such size as to impart the required 

 curve to the soft, pliable leather fillet. As soon as the fillet is 

 nibbed into position all surplus glue must immediately be wiped 

 f)IV before it sets. This is easily done with a small piece of wash- 



