[jtb1234]

HELP!! Im building a 4x10 steel machine using cnc router parts components, the machine will have a lathe on one end.
My question is my gantry will weigh right around 200-225 pounds and I would like to use NEMA34 servos. Will I need to use a gear head for the servos
or can I use the 3:1 pulley and belt setup from CNC Router Parts. Also what size servos do you recommend
Here are some pics attached of the machine so far
Thanks

[jueston]

don't know anything about servos but i really like your donkey cart in the corner of your picture...

[jtb1234]

Work in progress....
Thanks
J

[semperrsx]

I've never built a machine so this might be completly wrong, but the best way I understand to go about motor sizing is to actually build your whole machine first then actually measure the torque required to move each axis. with all the variations between components there is no way to tell what you need you'd just be guessing.

[nlancaster]

What you need to figure is the Shaft RPM of the servo at full speed VS the pinion RPM needed at the rack and pinion to attain your desired Inches Per Minute.

example: 3000RPM Servo Desired IPM: 1200IPM With a pinion diameter of 1inch.

1 inch x pi = 3.1416 inches traveled per revolution

so 1200ipm / 3.1416 = 381.97 RPM of the gear pinion.

So 3000RPM / 381.97RPM = 7.85 reduction.

So you would have to have aproximatly a total of 7.85:1 reduction

Again that is just a quick maths example, and i could be wrong, but I know that it is going to be something like that.