[Trevelyan]

Hello,

I'm new to this forum, and not sure if this is even the right place to look for this type of help. I'm new to mechanical engineering, and am building a cylindrical robot arm that will be used to pick up and move CDs (compact disks). Basically, the base of the arm will rotate 180 degrees, and the tool tip on the arm will move up and down vertically.

I was planning on using one stepper motor to rotate the base, and another stepper motor for the vertical motion of the tool tip. However, I'm kind of stumped with a few things:

1) Can anyone recommend an affordable and well built stepper motor that will accomplish this?

2) What would be the best way to use the stepper motor for vertical motion? I was thinking the motor would turn a threaded rod and move a platform. Or perhaps use a pulley system. Someone told me a threaded rod would cause too many problems since I need about 2 ft of vertical motion, and the rod would most likely not be totally straight.

Any help would be appreciated!

[mxtras]

Well - there's no way to answer the motor question without all of the speed, acceleration and mass data. Yes - a stepper will do this. Might be a big one, might be a small one. Might be a gear-reduced one.

How to make the motion depends on your design and space constraints. Have you though of using a rack and pinion? Or a ballscrew? Lots of ways but it depends on a lot of things and we do not have anywhere near enough info to make a recommendation.

Scott

[keebler303]

For average accuracy and ok speed at a decent price, what you are probably looking for, I am thinking something like this would work for you.

Matt

[Trevelyan]

Thank you both for your replies. I really do appreciate the help.

Basically, I want to keep this as simple and cost effective as I can. I would like to spend less than $150 for all the parts I need, maybe $200.

The key thing here is precision and stability. My main concern is that the tooltip will be bouncing all around.

Keebler, thank you for the design. Could you perhaps describe your design in words along with the picture? I'm having a hard time understanding the image you attached.

[Trevelyan]

For average accuracy and ok speed at a decent price, what you are probably looking for, I am thinking something like this would work for you.

Matt

Ok, so the manipulator is connected to the leadscrew with a nut so that it moves vertically as the stepper motor turns. But how does the manipulator stick out of the cylindrical tube? Is there just a vertical space cut out along the lengt hof the tube?

[TAB]

Since you are only moving CDs I would recommend using a belt drive system. It will be lighter and possibly faster than a lead screw. You will suffer on accuracy but you will get compliance which can be a benefit in automation applications.

Additionally, the belt layout will be much less expensive than a lead screw.

As for a stepper recommendation, they are all pretty much the same. You can get ones with breaks or encoders as options, but typically the smaller they are and the more powerful, the more expensive.

http://www.maxonmotorusa.com/ Maxon is known for small high output motors. They are not cheap.

You can check into these as well http://www.micromo.com/

Parker, oriental, and Danaher make larger NEMA frame stepper and hybrid units.

Let us know how it turns out.

Todd

[mxtras]

If your motion is going to be limited, just use a small air cylinder. Mount it to a beam that you manually coarse adjust. Adjust the speed with flow controls. Adjust the force with the air pressure. Done.

Scott

[keebler303]

I was vague because you were vague. Are you just moving around CD's, still don't know for sure. What accuracy do you need? .001 in or .05 in is a big difference both in cost and complexity. Remember cheap, accurate, and fast. You can only have 2.

With more detail into what is required, some useful design ideas could be proposed.
Matt