Instrument Instructions |
Trimming Blocks with LKB (LEICA) 1 Microtome
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Block Trimming
To trim face of block:
- Holding block at level of knife, move knife toward block by turning the macro feed knob (back knob, right side of microtome) clockwise toward back of microtome.
- Move specimen past knife by pushing down on specimen arm and then returning arm to upper position above knife.
- Advance knife by turning the macro feed knob clockwise a short distance.
- Continue until excess plastic has been removed from block face and area of the specimen to be sectioned has been exposed.
To trim left and right sides of block:
- Move knife away from specimen by turning macro feed counter-clockwise.
- Rotate knife holder so that the knife approaches block at an angle.
- Tilt upper edge of block toward knife by unlocking and rotating chuck holder toward knife.
- Adjust knife position with lower screw on knife holder until edge of block is roughly at center of knife.
- Trim block edge by moving specimen past knife and advancing knife toward block with macro feed until block face is reduced by desired amount.
- Move knife to opposite side of block an equal distance past horizontal and rotate upper edge of block toward knife.
- Repeat procedure to trim other edge of block.
To trim top and bottom sides of block:
- Move knife away from specimen by turning macro feed counter-clockwise.
- Rotate head so that block is positioned at 90o angle to original position.
- Rotate knife to one side of block as above, but do not rotate block toward knife.
- Move knife toward block and adjust knife position with lower screw on knife holder until edge of block is roughly at center of knife.
- Trim one edge of block as above.
- Move knife away from specimen by turning macro feed counter-clockwise.
- Rotate knife to other side of block and adjust knife position and distance from block . Do not rotate block toward knife.
- Trim remaining edge of block. Turn block 90° to initial position.
- The top and bottom edges of the block should be parallel to each other and to knife edge.
- Rotate knife holder to horizontal position so that knife is parallel to block face.
- Remove knife from holder.
- Using brush or canned air, dust plastic shavings from microtome.
Notes on trimming:
- Amount of trimming depends on size of section desired.
- In general, the smaller the block, the easier it will be to section.
- The most desirable block face does not exceed 0.5 mm.
- The above procedure yields a block in the shape of a trapezoid.
- The top and bottom edges of the block must be parallel.
- The left and right sides of the block are angled so that the top edge is shorter than the bottom edge.
- It will be necessary to use several glass knives during the trimming process.
- Change knives when they develop deep nicks or become dull so that it is difficult to force the knife through the block.