Making Glass Knives
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MAKING GLASS KNIVES
Most of the following information was taken from these publications:
"Electron Microscopy", B.R. Jones(editor), Library research Associates, New York, 1983.
"Thin Sectioning", Dupont instruments, Dupont de Nemours & Co, 1973.
Please read Chapter 4 in "Electron Microscopy", J. Bozzola, Jones & Bartlett, 1991,
DANA/QH/212/.E4//B69/1992
Instructions for use of the LKB Knifemaker are stored on a shelf at the base of the
instrument. See Figure 1 for knifemaker parts description.
1. Fork used to remove the glass knives
2. Locking lever
3. Shaft b
4. Adjusting sleeve for (8)
5. Bracket
6. Set screw for (4)
7. Cover screw for (6)
8. Clamping head
9. Locking screw for (28)
10. Support studs
11. Locking screw for (12)
12. Rear dial
13. Score selector
14. Cover plate
15. Scoring shaft with cutter wheel
16. Support plate for glass strip from the apparatus
17. Locking knob for (21)
18. Breaking kno
19. Operation Instructions
20. Angle setting plate
21. Guide plate
22. Front glass holder
23. Locking screw for (22)
23a. DPA-lever (Lever for Damping Pressure Adjustment)
23b. Damping pad
24. Locking screw for (25)
25. Front dial
26. Breaking pins
27. Center line
28. Rear glass holder
29. Arresting stud for 25 mm glass strips width
30. Foundation block
31. Disengage knob
FIGURE 1. LKB knifemaker machine (courtesy of LKB Instruments, Inc.).
From: Electron Microscopy, B.R. Jones(editor), Library research Associates, New York,
1983.
NOTE: Do not change any of the settings, unless instructed to do so.
Cleaning of Glass Strip
1. Clean glass strip under warm running tap water from faucet with mild detergent
solution (7X in wash bottle).
2. Rinse with distilled water and then acetone for final rinsing.
3. Allow glass strip to drain dry in an upright position. If time is a factor dry the glass with
several pieces of lint-free paper tissues.
NOTE: Try not to touch edges of glass that have been cleaned. A KNIFE IS MADE FROM
DIRTY GLASS IT CANNOT BE CLEANED, IT CAN ONLY BE DISCARDED.
Positioning and Breaking Glass Strip
1. Place clean glass strip on knifemaker.
2. Place needle edge of glass strip in downward position to obtain 45°
angle knives. See Figure 2
FIGURE 2: Appearance of glass strip position under knife-maker for obtaining 45º knife
angles. From:Electron Microscopy, B.R. Jones(editor), Library research Associates, New
York, 1983.
3. Place glass so that you will score and break into 2 equal strips. Line up glass strip with white guide plate (21).
4. Hold in position: Score and break glass as in steps 5-9 below; except that glass strip will not rest against arresting stubs(29).
The resulting product here is two 8 inch glass strips. Remove one strip and store for later use.
Making Glass Squares
5. Place locking lever (2) in rear position. Push scoring shaft (15) in and turn breaking
knob(18) all the way counter-clockwise. Turn disengage knob (31) all the way
counter-clockwise and pull out to lock it in this position.
6. Slide glass strip to arresting stub (29) allowing it to rest against guide plate (21).Use
locking screw(23) to position front glass holder (22) flush with guide plate. See Figure 3.
Figure 3
7. Hold glass strip and then lower clamping head (8) with locking lever (2) until it rests
on the glass. Swing locking lever all the way down, clamping strip. See figure 4
Figure 4
DO NOT USE UNDUE FORCE IN PRESSING LOCKING LEVER DOWNWARD.
8. Place score selector (13) in position and fork (1) under left end of strip. Slowly pull
scoring shaft (15) forward until it stops. Turn breaking knob (18) clockwise until glass
breaks. Then turn knob counterclockwise until it stops.
9. Lift up scoring shaft (15) and swing locking lever to rear position. Push scoring shaft
(15) to rear position. Remove square with fork.
10. Repeat the above process until several glass squares are made.
Making Glass Knife Diagonals (i.e. your Glass Knife edge)
NOTE: The Forward Left Hand Corner of Glass Square is Called Corner 1. See Figure 5.
FIGURE 5. Glass knife square under knifemaker. (a) before rotating (b) after rotating
From: Electron Microscopy, B.R. Jones(editor), Library research
Associates, New York, 1983.
11. Place working parts in same position as Step 5.
Use locking screw(23) to position front glass holder (22) to black line.
Set score selector on 25 and glass square on breaking pins (26) with corner 4 in notch in front of glass holder (22). (See Figure 6)
Push disengage knob (31) in and turn clockwise. This is done to move rear glass holder (28) forward to corner 2. See Figure 7.
Set DPA lever (23a) to 45º; this hold glass diagonal in position. Swing locking lever (2) forward to locked position.
Figure 6
Figure 7. Positions where glass knives should be handled during breaking
From: Electron Microscopy, B.R. Jones(editor), Library research Associates, New
York, 1983
12. Place fork (1) under glass square and pull score shaft (15) forward until it stops.
Turn breaking knob (18) clockwise to break glass. After breaking return to counter-
clockwise stop.
13. Lift score shaft (15) and at the same time swing locking lever (2) to rear position.
Push scoring shaft to rear position. Set DPA lever(23a) back to 0º.
Pull out disengage knob (31) to locked position. See Figure 8.
FIGURE 8 (a) Position of diagonal score line. (b) end product after break; two usable
knives. NOTE CUTTING EDGE. From: Electron Microscopy, B.R. Jones(editor),
Library research Associates, New York, 1983.
REMOVE KNIVES CAREFULLY WITH FORK.
Handling of Glass Knives
14. Remove the glass knife on the right with the thumb and middle finger of the right
hand, handling it at corner 3. See Figure 7.
15. With the left hand remove glass knife on the left, handling it at corner 1. See Figure 7.
NOTE: USUALLY THE LEFT KNIFE IS THE BETTER ONE. KNIVES SHOULD BE
HANDLED WITH CARE IN ORDER NOT TO DAMAGE THE CUTTING EDGE
Examination of Glass Knife Edge
16. Examine the upper edge of knife corner. A good knife should be sharp, thin, straight,
and without nicks or irregularities. See Figure 9
Figure 9: Parts of a glass knife. From: Electron Microscopy, B.R. Jones(editor), Library
research Associates, New York, 1983.
17. Use stress arc to determine the best side of knife edge for thin sectioning. See Figure
10.The knife edge nearest the top part of the stress arc is best. Carefully check the
back of knife. It should show a smooth back surface. If there are whirl marks on the
back of the knife the glass square has been rotated clockwise instead of counter-
clockwise. This is a poor knife. Repeat the procedure following directions carefully.
See Figure 11.A poor knife will not show a direct straight line of bright light on the
edge when viewed under the dissecting microscope. Whiskers on the back face of a
knife indicates glass chips and a poor cutting edge. See Figure 10. Poor knives may
be saves for rough trimming of specimen blocks.
Figure 10 a) Knife edge showing areas that can be used for sectioning. b) Knife back
showing whirl marks or whiskers. From:Electron Microscopy, B.R. Jones(editor),
Library research Associates, New York, 1983.
18. The length of a knife satisfactory for sectioning is dependent upon the shape of the
cutting edge of the glass. See Figure 10 and 11.
Figure 11 b) knife edge okay for thin sections. B) knife edge good for thin sections
19. Various knife defects can be observed in examining poor knives. See Figure 12.
Figure12 various knife defects and usable parts for sectioning: (a) Portion for thin sectioning
(b) Portion for thick sectioning (c) spine region unusable for sectioning (d) unusable
double edge. From: Electron Microscopy, B.R. Jones(editor), Library research
Associates, New York, 1983.
Attaching Knife Reservoir
1. Heat dental wax, using hot plate set to the “arrow” setting. Make sure boat is flush
with or slightly above knife edge. See figure 13.
2. Seal sides and back. See Figure 13.
Figure 12: a) Appearance of a sealed knife. b) Some common problems in sealing a knife
reservoir. From: Electron Microscopy, B.R. Jones (editor), Library research Associates,
New York, 1983.
Use of Glass Knives
1. For good practice break two to four knives at one time to be used for sectioning.
2. Practice using knives on the same day they are broken.
3. Knives not used on the same day can be used for several months. Knives for thin
sectioning should be used within 2 weeks, since the edge will deteriorate as the glass
flows. Knives for thick sectioning last 2- 3months.
Storage of Glass Knives
1. Store knives in upright position in dust-free storage container.
2. Use double sided tape on bottom of dish to hold knives in place.