We were running some stuff through the JVN design calculator for a linear mechanism, and realized we weren’t 100% sure what the “current draw per motor (loaded)” box was specifically talking about. We’re guessing that it’s the amount of current each motor draws when moving the load entered, but we would like confirmation from someone who knows for certain.
You are correct. The current draw per motor (loaded) indicates how much current each motor is drawing when sustaining the load you input in the spreadsheet.
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Yeah that is essentially it.
Are you familiar with a DC motor power curve?
The power curve is created by graphing the torque (blue line) from stall (full torque) to free speed (0 torque) and then multiplying the torque by the rpm to create a graph of the power output of the motor (yellow line).
Current (red line) is highest at stall and lowest at free speed. By dividing input power (amps*volts) by output power you can graph efficiency (green line).
All the JVN calculator does is take your requested load and multiply it by the selected gear ratios to determine where on this graph your motors will be. You generally want your mechanisms to operate on the right side of the power curve where efficiency is better, and added load will cause the motor output more power as it approaches the center of the power curve.
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Thank you! This information is very helpful.
You might also be interested in the AMBCalc mechanism calculator, which does all of the stuff JVN’s does and more. Plus it’s fully documented if there’s something you don’t understand.
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