A doffer grinding mechanism constructed in accordance with the teachings of the present invention consists of a rotary file type grinding stem which is larger in diameter than the cotton picker spindles of a machine. The grinding stem, which temporarily replaces one of the conventional spindle assemblies in a row of spindles, is screwed into the picker bar which remains in the machine. The row unit is run, and the doffer is adjusted against the grinding stems. Doffers can be quickly trued in the field without the need for a doffer grinding machine and without complete disassembly of the doffer column from the row unit.