Native grass calibration formulas and example – Great Plains 606NT Material Rate User Manual
Page 28
26
3P605NT, 3P606NT, 605NT & 606NT
Great Plains Manufacturing, Inc.
151-122B
2011-10-21
Native Grass Calibration Formulas and Example
For a metric example, see page 43.
Formulas
Example
Know your Desired seed rate in pounds per acre:
TargetRate
Example target seed rate:
55 pounds per acre
Choose the number of rows to sample.
Example:
3
Weigh the empty sample container(s):
ContainerWeight
Example container are three 1.5 pound buckets:
4.5 pounds
For a larger sample, we set the Drive Type high.
Suggested calibration Drive Type:
4
As there is only minor benefit in changing the final drive
sprocket for calibration, we leave it as is.
Example final drive sprocket:
18T
Examine the transmission for Standard vs. Seed Rate
Reduction/
Example transmission: Rate Reduction not installed:
Standard
Operate crank/gauge wheel for one tenth acre:
CalibrationRevs
For this example, a model 606NT:
99.5 revolutions (
1
⁄
10
th
of 995)
Weigh the collected seed plus container(s):
GrossWeight
Example:
GrossWeight = 8.25
Obtain the net sample weight:
Example:
8.25 - 4.5, or:
NetSample = 3.75
Determine the net sample weight per cup:
Example:
3.75
÷ 3, or:
NetPerCup = 1.25
Scale the sample to drill-wide:
Example:
1.25 x 9, or:
NetFullWidth = 11.25 pounds
Scale the sample to a full acre:
Example:
11.25 x 10, or:
NetPerAcre = 112.5
Look up the number of meter shaft revolutions per acre:
CalCharRevs
for the current Drive Type, final sprocket and
transmission configuration.
Example:
DT4, 18T and Standard is:
536.7 revolutions per acre.
CalChartRevs = 536.7
Determine the cup rate for this seed mix:
Example:
112.5
÷ 536.7, or:
WeightPerRev = 0.210
Determine the number of revolutions required for the
target field rate weight metered per shaft revolution:
Example:
55
÷ 0.210, or:
TargetRevs = 262
Look up the Drive Type and final sprocket for
TargetRevs
Example:
Drive Type: 2
Final Sprocket: 15 T
NetSample
GrossWeight
ContainerWeight
–
=
NetPerCup
NetSample
SampledRows
---------------------------------------
=
NetFullWidth
NetPerCup
9
×
=
NetPerAcre
NetFullWidth
10
×
=
WeightPerRev
NetPerAcre
CalChartRevs
--------------------------------------
=
T
etRevs
arg
TargetRate
WeightPerRev
------------------------------------------
=