keyhole saw

noun

Origin of keyhole saw

First recorded in 1770–80

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

The pieces, after being marked, are cut to shape with a keyhole-saw.
Boys' Book of Model Boats
Raymond Francis Yates
Cut the keyhole to the proper shape with a keyhole-saw or small chisel.
Handwork in Wood
William Noyes
The keyhole-saw, which is even smaller than the compass-saw, is used for cutting quicker curves, as for a keyhole.
Woodworking for Beginners
Charles Gardner Wheeler