# Medical Machines/Microtomes
## Cambridge Instruments GmbH, Reichert-Jung Biocut 2030

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. Rotation of the nut with the screw stationary gives rapid traversal. 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 the frame holding the barrel moving vertically. The frame is held by rollers running in a pair of tracks.

### Troubleshooting

| Malfunction | Cause | 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. | Check and adjust release torque for both 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. |

## Removing the cowling

* 1. Support the left side of the machine to reach four M5 screws. Two fasten the side cover and two fasten the left side of the middle cover.
* 2. Remove the screw fastening the side cover at the rear of the machine.
* 3. Remove the screw fastening the middle cover at the left rear corner.
* 4. Remove the screw fastening the side cover at the front of the machine.
* 5. Remove the screw fastening the middle cover at the left front corner.
* 6. Remove support block and left cover.
* 7. Support the right side of the machine to reach four M5 screws. Two fasten the side cover and two fasten the right side of the middle cover.
* 8. Remove the M5 screw fastening the side cover at the rear of the machine.
* 9. Remove the M5 screw fastening the middle cover at the right rear corner.
* 10. Remove the M5 screw fastening the side cover at the front of the machine.
* 11. Remove the M5 screw fastening the middle cover at the right front corner.
* 12. Remove the support block. Remove the section thickness knob and shaft by pulling out. The shaft is held in the dial by a spring loaded ball.
* 13. Remove right cover.
* 14. Remove the specimen chuck.14. Remove the specimen chuck.
* 15. Lift off the middle cover.

## Remove Barrel and Cylinder

* 1. Slotted setscrew fastening the rapid traversal cable in gear spindle.
* 2. Raise the left side of the machine and support on a block. Remove the rearmost M5 screw fastening the gear carrier to the chassis.
* 3. Remove the innermost screw fastening the gear carrier to the chassis.
* 4. Loosen the outermost screw fastening the gear carrier to the chassis.
* 5. Remove the setscrew.
* 6. With a small rotation of the gear carrier, the cable is disengaged from the gear spindle. Take care to avoid kinking the cable.
* 7. Using a 3 mm wrench, remove the 6 screws fastening the barrel to the sliding block. Remove 4 screws below the cylinder first. Then the two screws above the cylinder.7. Using a 3 mm wrench, remove the 6 screws fastening the barrel to the sliding block. Remove 4 screws below the cylinder first. Then the two screws above the cylinder.

## 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.
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.

### Top cover

The screw at each corner of the top cover is installed.

### Left side cover

The cover is fastened by a screw at each end.

### Right side cover

The cover is fastened by a screw at each end. The knob and shaft for adjusting section thickness is inserted with the cross pin fitting the notch in the hub of the thickness dial. The shaft is retained in place by a spring loaded ball.