HI folks, I have a Project i need to use a 12v DC geared motor to lift something. Specs below.
Timber shelf - 100mm deep x 500mm high by 800 wide
Weight - 5kgs
Needs to rise - 500mm
Uses 1/2 inch threaded rod with about 5 threads per cm to raise the container.
Needs to rise within under 10cms.
What sort of motor do I need?
Thank you heaps for all your help, really appreciate it.
Jamie
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Hi Jamie,
Welcome to the forum!!
For a mechanical system like this first, let’s work out a couple of knowns. Finding the RPM will be easy as 1 rotation raises the screen 2mm. Giving us 1500 RPM.
The torque required is a bit more involved as we get a bit of mechanical advantage. With the rod, you are using we get about a 1:20 reduction from the pitch. Then again factoring in the radius of the rod to get the torque required of around 0.7kg/cm, all of this doesn’t factor in any frictions or losses. A value of 2 or 3 kg/cm would be a safe bet here!
Controlling the motors is a whole other can of worms as with selecting a controller (there’s an active post here: Pololu Tic T834 USB Multi-Interface Stepper Motor Controller (Connectors Soldered) (POLOLU-3132))
Let us know if you have any questions!
Liam.
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Hi Liam, thank you for that. I did however make a mistake, it should have read, Needs to rise within under 10seconds…does your above reply still stand? Thanks again mate. Jamie
Opps near forgot, do you have a motor on your site that you would recommend? Thanks again 
Jamie
Hi Jamie,
I can’t speak for Liam’s calculations but it looks like he did factor it in. 1500RPM > 25 rotations per second > 50mm/s >500 mm/10 seconds.
He might not have completely factored in any inertia in the system so bumping that 2 or 3 up to 4 kg/cm might be a safer bet if you were looking to make sure that it simply just worked(you’ll also need some lubricant, staying away from conductive ones like graphite here is a must, motor underneath plus a decent amount of energy can be catastrophic!)
Core stocks this one that SHOULD work: https://core-electronics.com.au/catalog/product/view/sku/Pololu-4747 but has 3kg/cm of torque so getting the system moving might be a bit difficult without pulsing the motor at full - in the product page it mentions that its extrapolated data in the tables.
Hope I could help.
Liam.
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Thank you heaps, i dont mind it taking 10-15 seconds to rise and the weight is really only 4 kgs to push up at most. I just wanted to be over cautious. Thanks again, appreciate it greatly. Jamie
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