Q. Can you explain Corners and fillets ?
Corners and fillets
The intersection of the surfaces in casting must be smooth and forms no sharp angles. For this, the external and intern corners of patterns are suitably rounded. They are called round corners and fillets respectively.
Rapping or shake allowance
To take pattern out of the mould cavity it is slightly rapped to detach it from the mould cavity. Due to this, the cavity in the mould increases slightly so the pattern is made slightly smaller.