PATTERN MAKING 



71 



this simple pattern, as in all others, a full size drawing, or sketch, 

 giving all the dimensions of the pattern, should be made by the 

 pattern maker before beginning work on the pattern. This is good 

 practice, and if carried out many mistakes and 

 much loss of time will be avoided. 



The lower core print should have the same 

 proportion of draft as the body of the pattern, 

 but the upper core print is given the excessive 

 draft of ^ inch to its length so that the cope 

 can be easily lifted off and returned again over 

 the tapering end of the dry-sand core without injury to the mould; 

 the parting of drag and cope being on the line a I. This pattern 

 may be turned from a solid block of wood, but if durability is 



SECTION THROUGH X-Y 



Fig. 142. 



desired the block should be glued up 

 from 4 pieces of --inch pine, care being 

 taken to reverse the annular rings or 

 yearly growth of the wood, as shown in 

 Fig. 141. 



Place the block in the lathe and 

 with the gouge turn to a cylindrical form 

 of slightly greater diameter than the 

 largest diameter of the pattern, say 3i\ 

 inch. All finishing should be done by 

 the use of scraping tools. For the body 

 of the pattern, a firmer chisel 1 inch wide 



Fig. 143. 



is a good tool, but the cutting edge must be ground and sharpened 

 slightly rounding, as described for plane irons ; otherwise the corners 

 of the tool are liable to catch and form grooves on the surface. 

 For smoothing and finishing the ends of the pattern and 

 flange, a diamond-pointed scraping tool, Fig. 142, is preferred to 

 all others. The core box for this pattern is shown in Fig. 143, 

 which is representative of the half box used for all symmetrical 



