A Method to Solve the Self sliding of Microscope Tube
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 rough adjustment handwheel and add a friction plate. After tightening the handwheel, if the rotation is difficult, the added friction plate is too thick and can be replaced with a thin one. It is based on the effortless rotation of the handwheel, easy movement of the lens tube up and down, and without self sliding. Friction plates can be made from waste photographic film and soft plastic sheets less than 1 millimeter thick using a punch.
Step 2: Check the meshing status between the gear on the rough adjustment handwheel shaft and the gear rack on the mirror tube body. The upward and downward movement of the mirror tube is completed by the gear driving the rack. In theory, the optimal meshing state between gears and racks is that the indexing line of the rack is tangent to the indexing circle of the gear. In this state, the gear rotates easily and there is currently a wrong approach to wear and tear on the rack, which is to add shims behind the rack to tightly press the gear to prevent the mirror tube from sliding down. At this point, the indexing line of the rack intersects with the indexing circle of the gear, and the tooth tips of the gear and rack tightly support each other's tooth roots. When the gears rotate, severe grinding occurs between them. Due to the fact that the rack is made of copper material, the gear is made of steel material. So mutual grinding will damage the teeth on the gear rack, and a lot of copper shavings will be generated on the gear and gear rack* The rear rack will be severely worn and unusable. Therefore, it is important not to use a raised rack to prevent the lens tube from sliding down. The solution to the problem of the mirror tube slipping by itself can only be achieved by increasing the friction force between the rough adjustment handwheel and the eccentric shaft sleeve. But there is an exception, which is that the indexing line of the rack is separated from the indexing circle of the gear. When turning the coarse adjustment handwheel at this time, there will also be a phenomenon of idle slipping, which affects the up and down movement of the mirror tube. If this is achieved by adjusting the eccentric shaft sleeve of the rough adjustment handwheel, the meshing distance between the gear and the rack cannot be adjusted. It can only be solved by adding appropriate thin sheets behind the rack. The standard for adjusting the meshing distance between the gear and rack with shims is that it is not difficult to rotate the coarse adjusting handwheel, but it also does not idle.
After adjusting the distance, add some neutral lubricating grease between the gear and rack. Just move the mirror tube up and down a few times* Afterwards, it is necessary to tighten the two compression screws on the eccentric shaft sleeve. Otherwise, when turning the coarse adjustment handwheel, the eccentric shaft sleeve may rotate along with it, causing the gear rack to become stuck and preventing the mirror from moving up and down. If the force of turning the rough adjustment handwheel is too large at this time, it may damage the gear rack and eccentric shaft sleeve. If it is found that the eccentric shaft sleeve still rotates after tightening the compression screw. This is caused by the screw hole thread of the compression screw not being properly adjusted. Because manufacturers use machines to modify threads, there are often one to two threads that have not been properly modified. At this point, even if the screws are tightened, the eccentric shaft sleeve cannot be tightened properly. To discover this fault, simply use an M3 tap to thread through the screw hole and solve the problem. I have thoroughly solved the problem of eccentric shaft sleeves following rotation for 30 biological microscopes in our school using this method.
