Marking out Plastics Flashcards
measuring and marking out on plastics begins from a ______ face and a ________ edge
flat face, and a straight edge
what are flat face, straight edged surfaces you measure and mark out on in plastics called?
DATUM surfaces
Sheet plastics normally have a protective film of paper or ________ lightly stuck to their surfaces
polythene
what can you do to prevent scratches?
leave the polythene film on for as long as possible
what are the 2 main methods for marking out on plastics?
marking out on a paper covering
marking out directly on the surface
what could you use to stick a paper covering onto the surface if you are marking out on a paper covering?
pritt stick, copydex or dilute PVA glue.
how is the paper covering then marked?
with a sharp pencil or a fineline marker
what tool is used to rule lines at 90º to an edge?
a TRY SQUARE
A Try Square is also used to check that one edge is at ___º to another
90
What is an advantage of the paper method?
the easy-to-scratch surfaces are always protected
How do you mark out an irregular shape?
Cut out the paper covering in the form of a TEMPLATE and glue it onto the surface for cutting around
What kinds of glue might you stick the template on with?
Pritt Stick or white PVA glue
What kinds of things can ou use to mark directly onto the surface of plastics?
a chinagraph pencil or fine spirit felt-tip pen
What are the advantages of using a chinagraph pencil or fine spirit felt-tip pen to mark directly onto the surface of plastics?
The marks are easily removed if you make a mistake
how can you mark out circles with a chinagraph pencil?
use ordinary compasses
