Casting Tools Part 5 - Casting a part
Hi All,
Finally got around to taking some pictures, I had to cast a new table locking ring for the Waldown drill press restoration, so this was a good opportunity to take some pictures.
The pattern is pretty simple, and the rough core was only added at the last minute, you would normally have designed the pattern with the core in mind..
The core in this case is just packed petrobond and a simple wooden pattern
http://www.backsaw.net/pics/Casting/DSCN1584.JPG
The pattern was made by covering the original part with plastibond, and plywood covers top and bottom.
http://www.backsaw.net/pics/Casting/DSCN1585.JPG
Ok, now flip the drag upside down and place on a flat board, put the pattern in place,
http://www.backsaw.net/pics/Casting/DSCN1590.JPG
and dust it liberally with casting powder, (talcum powder works I'm told). The parting powder is in a special applicator.. (sock that is)...
http://www.backsaw.net/pics/Casting/DSCN1589.JPG
Now riddle petrobond to cover the pattern, the riddle (sieve) is to keep out clumps and large bits
http://www.backsaw.net/pics/Casting/DSCN1591.JPG
Once the pattern is completely covered, you can just shovel it in and pack down with a rammer as you go.
http://www.backsaw.net/pics/Casting/DSCN1593.JPG
Pack it in nice and tight, and then screed off with a bit of light sheet metal angle.
http://www.backsaw.net/pics/Casting/DSCN1596.JPG
Now flip the drag over (the right way up)
http://www.backsaw.net/pics/Casting/DSCN1599.JPG
Ok, now define the parting line, a small spoon shaped spatula works a treat for this.
http://www.backsaw.net/pics/Casting/DSCN1600.JPG
Cut down to about half way on the part, this is so that we can get the pattern out of the sand later, if you are doing a proper pattern, then a split pattern avoids this step.
http://www.backsaw.net/pics/Casting/DSCN1601.JPG
Continued in the next post.... I think I'm going to exceed the limit on number of pictures..