A Motor-Controlled Device for Slow-Motion Cutting with the Ultramicrotome

Abstract

The preparation of ultrathin sections of high quality with a Porter-Blum microtome requires that the drive wheel be rotated at a slow, uniform rate during actual cutting. A mechanical device to control the motion of the microtome drive wheel consists of a synchronous motor connected to a drive shaft (4 rev/min), which can be intermittently coupled to the rim of the microtome wheel by a friction drive of 1/2-inch diameter. The microtome drive wheel is rotated manually at a rapid rate until the specimen is about to come into contact with the knife; then the mechanical drive is engaged for slow movement during cutting. When the section has been cut, the drive is disengaged by a lever operated with the left hand; after which, the microtome wheel is turned quickly back to the cutting position with the right hand.