Slowly lifting a weight help

As title suggests, I am looking for a motor which will slowly lift a weight, but I am getting myself confused with torque..

I THINK I am wanting a high torque motor, but I don't really know how to find out if it will be able to lift the weight I want (which is 1kg)

I have found this little one http://www.ebay.co.uk/itm/Uxcell-R-DC-12V-15RPM-High-Torque-Gear-Box-Reducer-Turbine-Worm-Geared-Motor-/291568669861?hash=item43e2d8d4a5:g:5tsAAOSwa-dWjK79

which I THINK is suitable, but I don't know what calculations I would need to do to work out if it is, can anyone help?

I would be supplying 12v though a battery (but assuming 10v for dropout) and a capacity of 7.2Ah, if that is at all useful.

Thanks

1 kg is not much and requires 9.8 Newtons force to raise at steady velocity. Here is a good intro to force and torque.

Motors rotate, not lift, so you have to decide on a mechanism for converting rotation to linear motion - whose characteristics will be vital.

There are belt drives and winches and leadscrews and lever arms and all manner of more complex arrangements.

Once you've decided on a mechanism, then you can size a motor to drive it.

Well, I was going to have the motor spin which turns the string lifting the weight up. I made a silly demo of it with a small 6v motor and it worked, but to lift the 1kg weight I need something stronger.

If the motor is just twisting the string, what calculations do I need to do?

The motor has a rated torque of 25 Kg.cm and Gear Box No-load Speed of 0.6RPM and a Motor No-load Speed of 3500RPM…what can I do with this information?

crelding: Well, I was going to have the motor spin which turns the string lifting the motor up. I made a silly demo of it with a small 6v motor and it worked, but to lift the 1kg weight I need something stronger.

If the motor is just twisting the string, what calculations do I need to do?

The motor has a rated torque of 25 Kg.cm and Gear Box No-load Speed of 0.6RPM and a Motor No-load Speed of 3500RPM.....what can I do with this information?

If you just twist the string, the load will spin round?

Perhaps you can describe your mechanical setup with a diagram?

Imagine holding the big circular bit of a yo-yo, and turning it with the string dangling down. The string will wind up until all the string is in the groove in the yo-yo.

My motor will effectively turn the yo-yo one way, and wind up the string, then turn the other way and lower the string.

Does that make sense?

More than happy to draw something for you guys, but I don't want to put you through poor drawing abilities ;)

No, not clear. Do you mean like a winch or like a rubber-band model plane?

Yes a winch! Sorry for not being clear.

And what is the drum radius? torque = force x radius

Incidentally you don't have a proper yoyo, the string loop is loose on the axle so it can spin without resistance until the string is flicked and the loose string tangles around the axle and then starts to spool up. How else could you 'walk the dog'?

Radius is 1cm, but it can be changed. (I'm assuming you mean by 'drum' the bit in the middle of my yo-yo) lol.

Force? Would that be gravity? so 9.8N?

so, 9.8x0.01 = 0.098...

Is this right? If so, what does it mean in relation to a 25 Kg.cm torque?

Yeah, I know its not a true yo-yo, but it was the best example I could think of :)

First convert units to SI. 25 kgf-cm is 2.5Nm

You have a 10N force (approximately) with 1cm radius drum on the winch that's 0.1Nm torque to support the weight. You have 25 times more torque than you actually need.

BTW the link you give doesn't seem to list the torque nor the motor current rating, which is enough reason to find a better option.

Another thing, you didn't say how slowly you want the weight lifted. You can determine the power needed from this (allowing for friction and gear losses) and select an appropriately rated motor.

Thanks for all the help so far - it is really appreciated!

I've looked at a few worm gear motors, but none of them seem to mention the current rating, this one does mention the torque though (25 Kg.cm torque):

http://www.ebay.co.uk/itm/DC-12V-0-6RPM-6mm-Shaft-High-Torque-Turbine-Worm-Gear-Box-Reduction-Motor-/191658444609

The speed of lift isn't too important, but I was planning on setting the speed through the arduino as I have with the small demo motor I've used.

Whilst I have your attention :) would the above motor be suitably compatable for this battery (http://www.amazon.co.uk/HQ-Universal-Sealed-Rechargeable-Battery/dp/B0013A7XOC) for lifting a 1kg weight?

I know I am asking a lot.... :)

The below cordless screwdriver or larger cordless drill motors may have the torque you need.

http://www.homedepot.com/p/BLACK-DECKER-6-Volt-Alkaline-Battery-Cordless-Screwdriver-AS6NG/202516259?cm_mmc=shopping-_-googleads-_-pla-_-202516259&ci_sku=202516259&ci_gpa=pla&ci_src=17588969&gclid=CLCK7qDXh8sCFY8bgQodo2oG-g&gclsrc=aw.ds

crelding: The speed of lift isn't too important, but I was planning on setting the speed through the arduino as I have with the small demo motor I've used.

I'm asking how fast you want to move the load, the answer to which involves actual numerical values - even if its quite a wide range a max and a min value are needed to decide anything at all. Maybe you need 10W, maybe 1W or maybe 0.1mW of mechanical power is all you need - we have no idea if you don't tell us...