Microtomes

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Cambridge Instruments GmbH, Reichert-Jung Biocut 2030

Cambridge Instruments, Reichert-Jung Microcut 2030 microtome. The hand-wheel on the left provides rapid traversal of the specimen relative to the knife. A clockwise rotation of the hand-wheel on the right cuts a section and advances the specimen toward the knife according to the setting of the dial at upper right of the front panel.

Principle of Operation

Two motions are significant in operation of a microtome. (1) is motion of the blade past the knife to cut a section. (2) is advancement of the specimen to adjust section thickness. Motion (1) is by a brass cylinder sliding in a brass barrel. This comes from rotation of a micrometer screw in the center of the cylinder relative to a nut in the cylinder. In the biocut2030, rotation of the nut with the screw stationary positions the specimen relative to the knife. Rotation of the screw with the nut stationary moves the cylinder toward the knife by a section thickness. Advance of a section thickness occurs at the end of the upward motion of the specimen, preceding motion (2). Motion (2) occurs by vertical motion of the sliding block holding the barrel. The block is held by rollers running in a pair of tracks.

Troubleshooting

Malfunction	Explanation	Corrective Procedure
Sections inconsistent in thickness	Release torque for Belleville spring clutch connecting lever to screw or torque for nut to cylinder is is insufficient.	Adjust Belleville clutches.
Coarse feed (small handwheel) seems tight	Friction between micrometer screw and nut or between nut and cylinder.	Remove barrel and cylinder. Remove micrometer screw, clean and apply fresh grease. Remove nut from cylinder, clean and reassemble with fresh grease. Check nut torque and adjust if required. Reassemble.

Adjust Belleville clutches

Remove knife, chuck and cylinder head.
Remove cowling.
Remove barrel-cylinder assembly from sliding block.
Remove cylinder from barrel.
Adjust clutch between lever and spindle.
Adjust clutch between cylinder and spindle.
Replace cylinder in barrel.
Replace barrel-cylinder assembly in sliding block.
Replace cowling
Replace cylinder head, chuck and knife.

Reassembly

The cylinder is inserted into the barrel. The micrometer screw must be adjusted to allow the bearing disk to contact the end of the barrel without loading the screw.

The pinion is engaged with the gear wheel and the two bearing blocks are fastened with four screws.

Orientation of the polymer link block in the groove of the barrel. This illustrates the orientation only. Refer to the following explanation for installing the barrel in the link block.

To fit the barrel into the sliding block, the link block is first fitted onto the crank pin with beveled corner down and toward the rear of the machine. The end of the barrel is then inserted into the bore of the sliding block while sliding the link block into the groove. Take to avoid damage to the polymer link block. The barrel can not be installed with the link block in the groove and not on the crank pin.

Add photo with the barrel being inserted to the sliding block.

While supporting the barrel and beginning at the top, install the six machine screws attaching the barrel to the sliding block. Leave the screws not tightened until the guide pin is fitted as follows.

Add photo showing installation of the uppermost screws connecting the barrel to the sliding block.

Add a photo showing the setscrew being tightened into the groove in the bolt.

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