Hi, I am new to this!

I am struggling to answer the following:

what size ( torque etc. ) 6 volt dc. planetary gear motor would I need to lift
a 3kg. load vertically.
I plan to couple the gear motor directly to a 12mm dia. steel acme lead screw
with a 3mm pitch.
The load I will attach to a brass lead screw nut.
A stainless steel guide will stop the nut rotating and so give it vertical travel.

Any better guesses out there than mine ?

Thanks all.

 

Could you provide a rough sketch? I have two very different mental pictures of your arrangement depending on how I interpret your description.

 

Also, what is the gear ratio of the planetary gear motor, or do you just need the torque after the planetary gear?

Do you need a theoretical response assuming loss-less gears and screws or do (quite likely relatively high) frictional losses have to be taken into account?

 

How about using this calculator? http://www.meadinfo.org/2009/07/acme-lead-screw-torque-calculator.html