How to spec DC motor for weld positioner

[brycew467]

Hello this is my first post here,

I am trying to figure out which motor I should use for my machine. I have a rotary table that I would like to transform into a weld positioner by adding a DC motor, gearbox (if necessary), speed control, and foot pedal. I would like the speed to be adjustable and controlled by a knob. I would also like to connect a foot pedal to the motor to function as an on/off switch. The rotary table has an 8" diameter and has a shaft diameter of 0.5" with a length of 1.5". The table's shaft needs to be cranked 40 times to complete one full revolution of the rotary table. I would like the rotary table to have a max speed of 10 rev/min meaning that the output speed to the shaft needs to be 400 RPM. I would also like to have a max load capacity of 50 pounds and the table itself weighs about 10 pounds. This is my first time doing a project like this, so I am looking for some help picking out a motor. I tried looking at existing weld positioners, but the motors used are either undisclosed or very expensive.

 

[BrianE22]

One more thing you need to figure out: The output torque required from the motor. You could probably estimate it by turning the knob yourself (with the 50# on the table). It's probably a small number.

 

[brycew467]

Thanks for your reply, Brian. I used a tool from Oriental Motor to calculate the torque and got 0.2739 oz*in. Does that number sound about right? It seems low to me, but like I said, I'm unexperienced with this kinda stuff.