# Need help for choosing dc motor for my project

Discussion in 'The Projects Forum' started by eshai, Apr 22, 2018.

1. ### eshai Thread Starter New Member

Apr 22, 2018
3
0
im working on a project and i need help
i need to calculate the torque needed to spin a plastic disc to push a box Weighing 40kg To a distance of 20cm without friction (or minimal)
i have to choose a dc motor with gearbox

disc diameter = 240mm
disc thickness= 20cm
box weight = 40gk
sped from = 0-20rpm 1 sec (cyclic for pushing another box)
friction = minimal
Push distance = 20cm

Hopefully I formulated the question properly
best regards

2. ### MaxHeadRoom Expert

Jul 18, 2013
18,851
5,890
The torque will be maximum when the pin is 90° from its present position.
Calculate the position either side of the 90° position for a total stroke of 20cm from this you can calculate the minimum to maximum effort required in kg-cm.
An empirical way is to use a spring scale attached to the pin.
Max.

3. ### eshai Thread Starter New Member

Apr 22, 2018
3
0
thanks for the replay
too much physic for me
i know basic physic torque=rXF
what about moment of inertia

4. ### MaxHeadRoom Expert

Jul 18, 2013
18,851
5,890
3.4Kg-Cm = .34Nm?
Max.

5. ### eshai Thread Starter New Member

Apr 22, 2018
3
0
3.4 kg/cm = 0.3334261 Nm
3.4 kg/m = 33.34261 Nm
0.33 NM its to low?
33 Nm its to high ?
best regard