Proxxon UT 400 Manual page 11

The flange is supplied with graduation lines at
the edge (see 1, fig. 10): long line = 10 degrees,
short line = 5 degrees.
There is a corresponding 0-setting on the
housing.
CAUTION:
WHEN TURNING THE FLANGE, ALWAYS EN-
SURE THAT BOTH THE ALLEN SCREWS (SEE
FIG. 10) HAVE BEEN LOOSENED. WHEN MA-
CHINING THE WORKPIECE (PARTICULARLY
WHEN MILLING), THE FLANGE MUST BE
CLAMPED BY TIGHTENING THE ALLEN
SCREWS ITEM 2.
Dividing plates
4 replaceable dividing plates are supplied with
the dividing apparatus: On each of these, there
are 2 concentric pitch circles with various num-
bers of holes which means that the pitch of the
circles is also different.
Since, as already mentioned, each dividing
plate has two differently divided pitch circles,
there are 8 possible divisions available. The
number of holes is punched on the front of the
dividing plates. The following text provides
information on the significance and correct use
of the dividing plates.
Important and useful basic princi-
ples:
Although pitching a circle with this device
seems quite complicated at the beginning, it
actually isn't. Important to know:
THE WORM GEAR HAS A GEAR REDUCTION
RATIO OF 1:40.
In other words: The crank must be turned 40
times until the flange with the attached jigs and
fixtures (chuck) goes through exactly one
revolution.
The necessary number of crankshaft revo -
lutions is basically calculated according to the
following formula:
transmission reduction
------------------------------------- =
desired pitch
required crank
revolutions
For us this means:
A total revolution of the crank moves the flange
by 360°/40=9°/revolution. Put another way, this
means that to further rotate the flange 1°, we
must turn the crank 1/9 revolution accordingly.
Example 1
We want to create a "20" pitch. 20 pitch means
that the rotary movement of the flange or the
workpiece (etc.) is divided into 20 individual
increments. In other words: 360° degree (full
circle)/20 increments=18°/increment.
With the equation presented above, we cal -
culate:
40
---- = 2 crank revolutions
20
In other words, with two crank revolutions, the
flange revolves further by the desired amount,
i.e. as we have just seen, the flange rotates 9°
per crank revolution, produces 2 x 9° = 18°,
with 2 full revolutions, so precisely the "divid-
ing increment" calculated above.
Unfortunately, this does not always go smooth-
ly as in this example. If a 15 pitch is required
this looks as follows:
Example 2
We only wish to create one "15" pitch, i.e.
filling a full circle with 15 form elements, e.g.
drill holes in a pitch circle.
With a 15 pitch, an increment by which the
flange continues to rotate per "machining
operation" is 360°/15 increments = 24° / in -
crement.
If we calculate again with the new values and
the known formula, we find that with the crank
ratio of 1:40, an integer number of crank revo-
lutions is not required:
40
---- = 2.666 crank revolutions
15
Due to the remainder, we must now find a
suitable dividing plate that, with its number of
holes and the resulting pitch lets us "repro -
duce" our required angle of revolution.
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