Some things were made to last, this is definitely the case with this vintage 1960’s microscope. Purchased as a renovation project, a customer got in contact to solve a focus rack mechanism problem. A helical rack and pinion gear is used as a focus mechanism; the original manufacturers grease had long since dried up or wasted away leaving no gear lubrication.

The focus action was not smooth or precise, the tactile feel of the device was not correct and there was a potential wear issue with the gear teeth.

The original manufacturers grease had long since dried up or wasted away leaving no gear lubrication; the focus action was not smooth or precise, the tactile feel of the device was not correct and there was a potential wear issue with the gear teeth.

Challenges

The chosen grease needs to provide sufficient lubrication and damping of the helical gear plus due to the age of the device, the surrounding flat surfaces will interact so the grease should be able to cope with this sliding motion.  Unlike the original lubricant, the new damping grease should last the functional life of the microscope.

Proposed Solution

  • A low viscosity synthetic damping grease to smooth the focus mechanism that is also suitable for metal gear lubrication.
  • A Polyalphaolefin (PAO) based grease with PTFE is well suited for lubrication of the gear and adjacent sliding surface.
  • The damping grease must be durable, not dry out and last the functional life of the device.

Product Selection

Fluorocarbon Gel 868L  (Light)

 

Applying The Grease

The microscope focus rack required disassembly and any old grease residue wiped away. A coating of the Fluorocarbon Gel 868L grease was applied to the teeth of the rack and pinion gear plus the adjacent flat surfaces.

It should be noted that the Fluorocarbon Gel 868 range is available in 5 levels of viscosity, from the Fluorocarbon Gel 868VL (Very Light), through to the Fluorocarbon Gel 868VH (Very Heavy). The grease tackiness/viscosity choice generally depends on the gear load level, a higher load will suit a higher viscosity grease.

Results

The application of Fluorocarbon Gel 868L to the focus rack gearing system resulted in a smooth movement of the focusing mechanism, precise focus operation and improved tactile feel for the microscope user. The Fluorocarbon Gel 868 series of synthetic grease is ideal for metal on metal damping applications.

Prior to the damping grease application there was a tendency for the throttle to accidentally open if the twist grip is ‘swept’ by a gloved hand; this issue is now much more predictable and manageable.

THE APPLICATION OF fluorocarbon gel 868l smooth movement and precise focus operation of the microscope.

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