Can anyone explain what this means? I assume it means a standard DC motor appropriately sized would have a rack and pinion setup like the stepper on the Y-car (on the opposite side of the stepper) but would be persistently energized to conter the force of gravity pulling the Y-car to the base bottom of a vertically mounted Y axis. However, wouldn't the motor windings burn out if the Y-car stayed stationary for a long time? Please correct me if my assumptions are incorrect. Thanks in advance.

Your assumption is correct, it's just a DC motor holding teh z up.

The motor would not burn if it's suitable for the job.

As per comparison: my stepper motors arrached to the z-plate doesn't have the spring yet, but the stepper holds the whole z-plate + router up perfectly, constantly energized!

Ries

Ries, thanks for the clarification.

David,

I wanted to add that not any DC motor is just suitable. DC motors are designed for rotational workload generating a airflow through the engine. If yo want to use a DC motor to do this sort of work, you properly need to upscale it so that the mass of the engine is enough to coil the coil down enough.

Ries

I think what Gerald meant was that a "constantly energized Stepper motor" could act as a "counterweight"...
but that is just my understanding :rolleyes:

Nope, I meant a DC motor. All DC motors will tolerate a certain amount of current before they need cooling. Motors used as "servo" motors should publish the constant current and peak current values......it is the constant current value that is of interest for this application.

Think of the z-axis on a "servo"-driven router. . . . . it sees little movement/cooling.

Ok, got it. How would one size such a motor? Would it be based on the weight of the entire Y-car after it was mounted to such a slated table? Would this be a better solution than a counter weight contraption like the "Pullman Industrial Balancer" sold by McMasters mentioned in another post? I believe that post is here for those who have no idea what I'm talking about http://www.mechmate.com/forums/showt...ring#post18959

OK.. I stand corrected. but in my opinion a counter weight would make more sense... as in an elevator.

A counterweight would have to run on its own rails (it can't swing around like a pendulum from the moving carriage)..........or slide with a good fit inside the gantry tubes........

yes! and since this would be a slanted design it could be placed in what would normally be the under side of the machine...
But also I think it would have to be very heavy to counter the Z carriage... :cool: