Motor in-lb torque converting to actual weight? 3

[enzo2015]

I'm trying to figure out what size stepping motor I will need to push a piston at 500 Lbs of pressure. The motors I was looking at tell me a in-lb torque rating, but I need to be able to figure a good size to start with. I will be gearing this down as well.
But if a motor is rated at say 260 in-lbs. torque, and is geared 1 to 1 what pressure would that be able to push? I think I will be able to figure the gearing once I know this. Thanks for you help....

 

[tygerdawg]

do an internet search for a .pdf document called "Smart Motion Cheat Sheet"

TygerDawg

 

[Barry1961]

If you are in a frictionless world........

260 in-lb is the torque required to pull 260 lb on a 1" raduis. So if you had a 2" OD pulley you could pull 260 lb. With a 4" OD pulley, 2" radius, you could pull 130 lb.

The size motor you will need will also depend on how fast you want to move. One horsepower equation is:

(speed in feet per min.) x (force in lbs.) / 33,000

(60 fpm ) x (260 lb) / 33,000 = .47 hp

Of course we live in a world with friction so the gearing or mechanism you use to convert the motion of motor to the desired motion will use up some of your power. As a rule of thumb an acme screw will use up about 50% of you power.

If you give some more details it would help.

Barry1961

 

[enzo2015]

Thanks for the info. So with a motor rated at 260in-lb. torque, if I had a 1" gear(I guess the teeth count matters?)on the motor shaft directly connected to a 4" gear, would that multiply the torque 4 times (not counting friction)to 1040 lbs.? Or is it not that simple? Thanks in advance