Borrowed a seed drill to plant an acre of buckwheat and most likely the drill had been used last for oats so I needed to reset the gearing. An older farmer friend found a chart in a small farmer magazine that was very helpful. Wheel diameter on one side, drill width at the top and the number of revolutions of the wheel to seed a tenth of an acre at each intersection. Jack up one wheel, put something on the ground to collect the seed, turn the required turns and then weigh the seed that was dropped. Finally ended up with the drill set as light as possible and still ran out a bit before finishing. Will buy about 4 more pounds today and finish it off. I could have done the calculations by hand but it was much quicker reading the chart.