Green’s Dictionary of Slang

chaff-cutter n.2

[SE chaff-cutter, a machine that cuts chaff for fodder; i.e. the noise of the keys]

(Aus.) a typewriter.

[Aus]News (Adelaide) 27 Feb. 1/4: ‘Stop that chaff cutter a moment,’ said Mr. A. J. Radford in No. 4 Adelaide Police Court today. The clerk ceased using the typewriter while Mr. Radford addressed counsel.
[Aus]Western Mail (Perth) 31 Aug. 28/2: To make you quite au fait with the situation let me explain the "chaffcutter" referred to was no agricultural implement but my well used and much maligned typewriter.
[Aus]Advertiser (Adelaide) 21 Aug. 6/5: My 15-year-old type writer, famous for its chaff-cutter clatter which disturbs the peace in press boxes everywhere.