5.4.
LKB ULTROTOME
141
cutting speed sufficiently. At best, much depends on the practice and
skill of the operator. A gear train added to the instrument makes achieving these ends a simple matter.
As we constructed the gear train illustrated in Fig. 20(d), we employed
standard brass gears that are available commercially. The large gear had
120 teeth, the small gear 60 teeth (or 30). The large gear necessarily had
to be exactly centered on the flywheel, but any machine shop can make a
simple spindle to do this accurately. The small gear with its attached
handle had to be mounted on a custom-made axle which was fitted to the
microtome base in such a way that some adjustment of the meshing
pressure of the gears was possible. This is not a difficult problem for a
machinist. A 2 to 1 reduction of the original cutting speed was all that
was really required to make good sectioning a much more reliable process
than it had been before.
When we first modified a Porter-Blum microtome by adding a gear
train we were much worried that vibration from the gears would affect
the sectioning. We have not, however, been able to detect any adverse
effect in more than two years of operation. In actual practice we operate
with the gears relatively loosely meshed, and with a lubricating grease on
the teeth. One easily adjusts to an operational pattern that quickly turns
the microtome through most of its cycle, but makes the actual cutting
stroke slowly.
5.4. LKB "Ultrotome"
This microtome, introduced shortly after the 4th International Congress of Electron Microscopy in Berlin (1958), has attracted much attention in Europe and has been widely sold in the United States. This is an
almost completely original design of the LKB-Produkter Ab., Stockholm,
incorporating many unique advantages. It relies upon thermal expansion
for specimen advance, but incorporates a blower which quickly dissipates
the heat before starting a new phase of operation. Control of the microtome is entirely by electronic circuitry. This seems fairly reliable. The
microtome operates on a fixed cycling period of 3 seconds, irrespective of
the actual cutting speed. A choice of five different speeds is available,
although only the two slower ones are really useful for biological work.
LKB ULTROTOME
141
cutting speed sufficiently. At best, much depends on the practice and
skill of the operator. A gear train added to the instrument makes achieving these ends a simple matter.
As we constructed the gear train illustrated in Fig. 20(d), we employed
standard brass gears that are available commercially. The large gear had
120 teeth, the small gear 60 teeth (or 30). The large gear necessarily had
to be exactly centered on the flywheel, but any machine shop can make a
simple spindle to do this accurately. The small gear with its attached
handle had to be mounted on a custom-made axle which was fitted to the
microtome base in such a way that some adjustment of the meshing
pressure of the gears was possible. This is not a difficult problem for a
machinist. A 2 to 1 reduction of the original cutting speed was all that
was really required to make good sectioning a much more reliable process
than it had been before.
When we first modified a Porter-Blum microtome by adding a gear
train we were much worried that vibration from the gears would affect
the sectioning. We have not, however, been able to detect any adverse
effect in more than two years of operation. In actual practice we operate
with the gears relatively loosely meshed, and with a lubricating grease on
the teeth. One easily adjusts to an operational pattern that quickly turns
the microtome through most of its cycle, but makes the actual cutting
stroke slowly.
5.4. LKB "Ultrotome"
This microtome, introduced shortly after the 4th International Congress of Electron Microscopy in Berlin (1958), has attracted much attention in Europe and has been widely sold in the United States. This is an
almost completely original design of the LKB-Produkter Ab., Stockholm,
incorporating many unique advantages. It relies upon thermal expansion
for specimen advance, but incorporates a blower which quickly dissipates
the heat before starting a new phase of operation. Control of the microtome is entirely by electronic circuitry. This seems fairly reliable. The
microtome operates on a fixed cycling period of 3 seconds, irrespective of
the actual cutting speed. A choice of five different speeds is available,
although only the two slower ones are really useful for biological work.