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Topic: Motor Division  (Read 308 times) previous topic - next topic

ThunderBlade

Hello all,
I'm working on a DIY project that will require a motor to lift 500 pounds.  I'm looking at using a Nema 34 Stepper Motor.

I was wondering, when it comes to lifting....would I be able to you multiple-smaller motors to lift the weight?

Robin2

A stepper motor seems a strange choice for lifting a weight. Why not use a geared DC motor? A motor with a worm drive gearbox has the advantage that it can't slip and let the load fall when the power fails.

500 lbs is a very heavy weight that could seriously injure you or someone else. I suspect you can buy a 12v powered winch in many auto stores.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

ThunderBlade

There is obviously more to my project than the motor.  There is also other mechanical devices as well as sensors that are going to be used.

This question is strictly about the ability to divide the necessary torque to lift the load.

ballscrewbob

#3
Feb 18, 2020, 03:34 pm Last Edit: Feb 18, 2020, 03:35 pm by ballscrewbob
With the correct gearing and a well set up pulley approach there should be few issues.

That said you really do need to supply a LOT more details.

MOTOR and specs ?
VOLTAGES to be used ?
Height to lift or pull from motor to load ?
Safety steps that will be employed to prevent slippage etc. ?
Many more Q. too.

Could you take a few moments to Learn How To Use The Forum.
It will help you get the best out of the forum in the future.
Other general help and troubleshooting advice can be found here.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

ThunderBlade

I don't have any specs as of yet....consider this as sort of "Thinking Out Loud".

The general idea is this,

Let's say I want to lift a table.  The table weighs 500 pounds.  I know that I can spec out a motor which would include a shaft and some sort of gearing in order to life the table evenly.

My true question is this....
If the Nema 34 is a strong enough motor to lift the load...would I be able to downsize that motor to the Nema 17, but add more motors.

The motors would not be rotating the same shaft, they would all work independently to lift the load.

The Nema 34 has a torque rating of 12Nm.  The Nema 17 can do 2Nm.

Can 6 Nema 17's lift roughly the same load as the Nema 34?
Even if the Nema 17's are all acting independently on the load?

ballscrewbob

Adding multiple motors to each act as an assist would involve even more gearing or pulley arrangements and if any go out of sync or have a small failure of any kind you are in trouble.

At the very most I would only consider two motors and then both running from a suitable single driver with extra headroom. (cost ++)

Or two motors with closed loop and seperate drivers (cost+++)
Most crane systems that use two motors for the main drum run on that principle.

Think about it as you would a proper crane where there are multiple pulleys.

Also discussed here and HERE.

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

ThunderBlade

I'm not talking about pulleys or gearing.

Let me rephrase this.

Think of Solar Panels...let's say you have (6) 24v/6a Panels that are wired in series.  You end up with an output of 144v, but your amps remain at 6a.  If you wire them in parallel, the output is now 24v, but you now have 36a.

So...Motors.

If I have 1 Nema 34 that has a Torque Rating of 12Nm that can lift the load....can I downgrade the motor, add more motors of a lower Torque Rating and still achieve the lift.

In other words...I can add more smaller motors and keep the voltage the same, but each motor adds to the overall Torque for the lift?

Or...do all of the motors that I use....no matter how many....need to be the Nema 34?


Paul_KD7HB

"Nema 34" means National Electrical Manufacturers Association standard # 34. And that ONLY applies to the mounting dimensions for electrical devices. Nothing more, nothing less. Has no relation to any other parameter of your motor.

Paul

ThunderBlade

So take Nema Out.....

I have "A" motor that has a Torque Rating of 12Nm

Robin2

I have "A" motor that has a Torque Rating of 12Nm
And how much torque do you need to lift your load?

IMHO compared to a 500lb load a 12Nm Nema 34 motor is puny - unless it is connected through a gearbox with a huge gear reduction.

500 lbs is about 230kg which is about 2,260 Newtons.

Suppose the winding drum is 0.05m radius (50mm) then the available torque will be 12 / 0.05 = 240N. Which suggests you would need a 10:1 gear ratio without allowing for friction losses. (Hope my maths is correct)

If 12Nm is the holding torque of the motor then that is the maximum and only available when the motor is stationary. The available operating torque might be 50% of that or less.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

ThunderBlade

No one is addressing the question of 1 vs many motors....and that is the real question.

TheMemberFormerlyKnownAsAWOL

No one is specifying "how fast?"
Please don't PM technical questions - post them on the forum, then everyone benefits/suffers equally

ThunderBlade

I think everyone is missing the point here.

Don't worry about the specifics of it all......just this

If I have a motor that can make the lift.....

Will 4 smaller motors perform the same lift?  The motors must be independent of one another.

That's the only question I would like the answer to.

Paul_KD7HB

Will 4 smaller motors perform the same lift?  The motors must be independent of one another.

Certainly not if they are independent of one another. One or more may not even have electric power or it may be turning the opposite direction.

Paul

Robin2

Will 4 smaller motors perform the same lift?  The motors must be independent of one another.
You could certainly connect 4 motors to a common shaft using gears and get the benefit of the power of all of them. Coupling motors is quite common - for example many airplanes have 4 motors. But, because of the gearing they would certainly not be independent and if any one of them failed the remaining motors may not be able to hold the load. To follow the airplane analogy all twin engined jets have engines that are big enough so they can take off on a single engine - the second engine is for safety rather than power.

But before spending money on 4 motors and 4 motor drivers and a gearbox you should calculate how much torque you need.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

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