A seed potato 
cutting system includes a 
cutting roller unit, including an endless 
roller chain, having a plurality of parallel roller sets with longitudinal gaps therebetween, configured to convey seed potatoes resting in the gaps in a longitudinal direction through a plurality of pairs of upright 
cutting blades, a laterally-slidable 
thumb rake, disposed in each longitudinal gap parallel to the roller sets, having a plurality of upwardly extending thumbs, and a 
thumb rake alignment device, configured to sequentially laterally slide all 
thumb rakes in first and second directions, respectively, to contact and laterally align each seed potato with a corresponding pair of cutting blades as the 
roller chain conveys the seed potatoes theretoward.