PROJECTS IN FARM MACHINERY REPAIR 307 



8) Miscellaneous See that all covering devices, hitch, 

 braces, etc., are in place and properly adjusted. 



277. Adjusting a Grain Drill. Calibration The prin- 

 cipal adjustment on a grain drill is the one for accuracy of 

 planting when the indicator is set at different positions on 

 the scale. The adjustment is accomplished by calibrating 

 the machine. The drill must be calibrated for each kind of 

 grain. The method is as follows: 



Set the drill on stands or saw horses so that the wheels 

 clear the ground. Put the grain in the hopper, place the in- 

 dicator for certain rate of seeding per acre, put paper bags 

 under each of the spouts, throw in the clutch and you are 

 ready to begin. Turn the drive wheel thru 100 revolutions. 

 Weigh the seed caught under each spout. By measuring the 

 circumference of drive wheel in feet and multiplying by 100, 

 the number of turns, the distance traveled is found. Multiply 

 this by the width of seeded strip in feet and the area is ob- 

 tained. Knowing the area and the total pounds of seed drilled, 

 the rate of drilling is easily obtained. By comparing the rate 

 from test with the actual setting of indicator, the accuracy of 

 the machine is determined. By making several tests at differ- 

 ent settings of indicator, the proper adjustment for a certain 

 rate of planting can be established. Unless a drill is care- 

 fully tested, the rate of planting is not definitely known, due 

 to the inaccuracy of the indicating device. 



278. Repairing Corn Planter. (Fig. 320.) 



1) Seed Box and Plates See that a full set of plates is 

 available and suitable for planting seed at hand. Ex- 

 amine the parts in bottom of seed box and the plates to 

 see that they are not worn. Renew parts as needed. 



