Need Help and Advise Nema Motor types

Hi, I have a tray that is 17" x 14" and have several parts placed on the tray which do a certain task. The tray needs to travel on a vertical type CNC along the 3 Axis(X,Y,Z) in front of a 16X16 matrics placed on a vertical surface(like a wall). The tray weighs 20 pounds and I am thinking to mount the tray on a Cross X and Z axis and then have the whole setup including the X,Z axis and the tray placed on a Gantry type Y axis which will need to raise and lower this heavy weight which now including everything it must be about 50 pounds. I am thinking Nema 34 with 100 Lbs. holding ability for the Y axis but since want to use 2 motors on Y axis one on each side then which Nema would be best?
What type of Nema motors will I need for this setup? I appreciate your help and advise. Thank you and Happy Thanks Giving.

You aren't providing enough information for anyone to give you a meaningful answer. What kind of mechanism is moving these parts around? A leadscrew? A ball screw, or a roller chan, rack and pinion, or belt drive? Each of these has its own mechanical advantage you need to figure in. What kind of slides are you using? Different types have different resistance to motion. How fast does this thing have to move? Stepper motors lose torque with increased speed, but the torque curve is unique to each different motor. Holding torque, when the motor is still, doesn't tell you how much torque will be available at a given speed - only the torque curve chart tells you that.

A picture or sketch would certainly help.

Reading through your description, I have a probably inaccurate picture in my head of what you are trying to do. What I am picturing is basically similar to a typical gantry router but instead of using a router or spindle, you have mounted this tray with various objects that perform some function on a vertically mounted workpiece facing the gantry and work tray. You then intend to move the tray around to position the various tools into place to perform their intended actions on the workpiece.

The weight of your tray is not much of an issue. Many have Z axis well over 100 lbs. There are many ways to deal with the weight. You can use counter balances, pneumatic or gas cylinders, or simple mechanics by using an ACME screw that can hold the weight without slipping even without a motor or counter balance connected.

The bigger question left unanswered is your tray. How are you mounting all of the various tools and what are you doing to prevent unintended interaction of the various tools with the workpiece. I.E. you use tool #1 to do some work, then move the tray so that tool #2 can do work. When using tool n, all other tools are still mounted to the tray and can all still interact with the workpiece, just at a location you have not intended. Think of a hairbrush. You place it on your head and multiple bristles all touch your scalp at the same time. The same will be true with your tray and the workpiece unless you take measures to somehow activate each tool individually while keeping all of the other tools out of the way.

Hope that this helps.

John Z

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