Troubleshooting and Maintenance of Common Faults for Biological Microscopes
1. Self sliding of the lens barrel: This is one of the common malfunctions that occur in biological microscopes. The solution to the microscope with a shaft sleeve structure can be divided into two steps.
Step 1: Hold the two coarse adjustment handwheels with both hands and tighten them with relative force. See if the problem can be solved. If it still cannot be solved, use a dedicated double column wrench to unscrew a coarse adjustment handwheel and add a friction plate. After tightening the handwheel, if it is difficult to rotate, the added friction plate is too thick and can be replaced with a thinner one. The standard is that the handwheel rotation is effortless, and the lens barrel can move up and down easily without sliding down on its own. Friction plates can be punched with a punch using waste photographic film and soft plastic films less than 1 millimeter thick.
Step 2: Check the meshing status between the gear on the coarse adjustment handwheel shaft and the rack on the barrel body. The up and down movement of the lens barrel is accomplished by the gear driven rack. In theory, the optimal meshing state between gears and racks is when the dividing line of the rack is tangent to the dividing circle of the gear. In this state, the gear rotates easily and causes some wear on the rack. There is now a wrong approach, which is to add a shim behind the rack to tightly press it against the gear to prevent the barrel from sliding down. At this point, the dividing line of the rack intersects with the dividing circle of the gear, and the tips of the gear and rack are tightly pressed against each other's tooth roots. When gears rotate, severe grinding occurs between them. Due to the fact that the rack is made of copper material and the gear is made of steel material. So the mutual grinding will damage the teeth on the rack, and a lot of copper chips will be produced on the gear and rack. Finally, the rack will wear severely and become unusable. Therefore, it is absolutely not advisable to use a raised gear rack to prevent the tube from sliding down. The only way to solve the problem of the tube sliding down on its own is to increase the friction between the coarse adjustment handwheel and the eccentric shaft sleeve. But there is one exception, which is that the dividing line of the rack is separated from the dividing circle of the gear. When turning the coarse adjustment handwheel at this time, there will also be a phenomenon of idling and slipping, which affects the up and down movement of the lens barrel. If this is achieved by adjusting the eccentric shaft sleeve of the coarse adjustment handwheel, the meshing distance between the gear and the rack cannot be adjusted. Then it can only be solved by adding appropriate thin sheets behind the rack. The standard for adjusting the meshing distance between gears and racks by adding shims is: it is not difficult to rotate the coarse adjustment handwheel, but it also does not idle.
