[James CNC]

I have been reading quite a bit lately and have some questions.

1. What size of CNC machine would you switch to a dual x-axis motor system?

2. Does the center of gravity matter on the z-axis?

3. should I build 2 CNC machines (one for circuit boards and one for larger projects)?

4. Is there certain steppers/servos to avoid and controllers?

5. What is the advantage of using a gear box vs. direct drive?

6. Is MDF better than Polyolefin material (what they make plastic cutting boards out of).


Thanks in advance

James

[ger21]

1) Not really a size issue, but more of how it's constructed. There are many 4x8 machines driven by a single center mounted screw. Here's a good example. http://www.oneoceankayaks.com/madvac/madvac_index.htm

2) More a question of leverage I think. The taller it gets, the easier it'll flex.

3) A precise large machine should be able to do double duty.

4) Avoid steppers with high inductance. Ideally you want steppers with very low rated voltage, preferably less than 3V. Don't buy steppers until you know what drives you'll use. Then get steppers that'll work best with that drive.

5) You'll get more torque. But gear boxes usually have backlash, which is bad. Gearing down is normally only used with rack and pinion or belt drive.

6) Depends on what you're doing with it.