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Team member Zoie and our Professor Chris Lee on demo day
Power Calculations
Power Calculations
The graph to the left is a plot of the estimated power consumption solely from cutting the wood (not from power losses along the transmission). It estimates this along various circumferences and the 3 lines indicate different rpms. The max power consumption was 0.3hp but it is unlikely to run into this situation because when dealing with a large circumference piece of power we will be operating at lower speeds. To get these values we estimated the energy required to shear a piece of wood. The shear stress was found online and the dimensions were gathered by examining actual shavings from the lathe.
Bearing Calculations
Bearing Calculations
For the bearing calculations, we made a couple assumptions to simplify the analysis. The first analysis is that the load force is equally distributed along the 2 bearings. We also assumed that the cut force and the force of gravity on the wood were equally disturbed to the head and tail stock (the tail stock is not modeled because it has a lower load due to the lack of a tension force from the belt). We felt confident that these assumption were good to make given that our bearing will not come close to failure given that the load is several magnitudes smaller than the rated load.
Motor Evaluation
Motor Evaluation
Due to the high power of our motor, we opted not to measure the stall torque. Instead, we assumed the power rating of our motor (1/2 hp) was our max power. Using a tachometer, we measure our no-load speed to be 1796 rpm. This was very close to the listed speed of 1725 rpm. Using our no-load speed and our rated power, we calculated our torque by exploiting the symmetry of the power curve. Since we didn't stall out our motor we didn't get our stall current, but our no-load current is 6.56 amps at 120V.
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