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gr8ride101

gr8ride101

Mechanical
Dec 1, 2006
4
I have a stepper type motor driving a ball screw that lifts an arm that can weigh up to 100LB. is there a formula that i can figure what kind of power i need like This much weight + something = power. I need this in simple terms. LOL thanks
 
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I have a stepper type motor driving a ball screw that lifts an arm that can weigh up to 100LB. is there a formula that i can figure what kind of power i need

If you know how fast the 100# weight is being lifted, you can convert to horsepower.

If you lift it 5.5 feet in one second you are doing 100x5.5=550 ft-lb/sec of work, which is 1 horsepower.

1 HP =745 watts.

then you have the efficiency factor of the ball screw, motor, and the gear train. If you have no quatitative measurement of that, I would use a rectally extracted number of about 60% for an initial estimate. So for every 100 watts of electricity you put in you would expect to get approximately 60 watts (.08 HP) of mechanical work out.
 
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Wait a second...is this arm moving linearly or radially? How long is it? 100 pounds at 1 foot is a little different than 100 pounds on the tip of a 6 foot arm. Right?
 
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Sorry, guess it helps to read the post...I may have reacted too quickly. Not sure I understand your apparatus. Are you simply lifting a 100# weight, or is this arm lifting something else? Is your motor/ball screw lifting something directly, or is manipulating the arm and the arm potentially lifting up to 100# (including it's own weight)?
 
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Power involves units of time. So for us to do your job for you we need to know how quickly you want to move it, and how far.
 
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the arm is linear. the travel path is about 1500mm
 
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ok. i just need a formula or some way to tell what kind of motor i need. Its for a 300mm TEL indy tool.(samsung) The motor lifts a arm thats max weight is around 100Lb. Its not very fast kinda in the middle. i just need a basic way to be this much weight needs to be lifted this far = the motor i need.
 
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i think jim's post answers the question, but anyways ...
you want to raise 100 lbs 1500 mm (1.5m = 5ft)
which will need 5/5.5 = 0.9hp to complete in 1 sec,
to account for estimated losses use a 2hp motor.

less hp means it'll take longer (than 1 sec).
 
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