Near Intersection of I-35 & I-90 Southern Mn. | Agent86 - 12/28/2024 07:22
Will I need different calibration numbers for each product?
In general Yes. Since the density often varies from product to product and even within the same product, the meter cal may need to be changed. Some controllers have some methods to make this easier.
Remember the purpose of the calibration number is to convert the number of revolutions of the shaft sensor into the weight of the product dispensed. That way the controller can compare what it feels it is applying to the target rate which is in effect at that time. If the calculated applied rate does not agree fairly closely with the target rate, the system can change the speed of the bed in an attempt to get them to agree.
If all other factors were the same, if a new product was twice as dense as the previous product then twice the weight would be applied. This means a different meter cal would be appropriate.
With simple controllers, I advise operators to make a cheat sheet listing the calibration numbers that they have found to work with different products. The cheat sheet could also include, suggested ground speed, spinner speed and any other factors that are important. When the operator switches products they can refer to the cheat sheet for their own suggested meter cal, spinner speed etc.
Some Raven controllers that were a variation of the classic 440 had a granular setting. In the granular setting, instead of a meter cal, a value referred to as the spreader constant was used. This number was a combination of the shaft sensor, gate height, width etc. This was a hidden value that would show as a flashing number if the meter cal key was pressed for a long time. This spreader constant was a constant value which didn't change for that particular spreader.
The value shown for the meter cal (not flashing) was then actually the density. The idea being that the spreader constant would remain the same and the operator would just enter in the product density and target rate for a particular job. Internally the system would modify its math routine to take in account the density.
Ag Leader systems for granular application handle this a bit differently. With an Ag Leader system you create a product list. The product list contains information about the product such as its density etc.. When the operator goes to a new field, he is asked to choose the product from the list and the target rate or Rx file. The density from the product list is then used in the math to compute the applied rate. This makes it quite easy to switch to a different the product since it is not necessary to enter the product density or a new cal number In effect it is really an internal cheat sheet with information about each product.
Edited by tedbear 12/28/2024 08:16
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Calibrate dry spreader for vari-rate
