[jerryrigge]

To answer DeeDee as to why I wanted to try direct drive on rack and pinion...it is that it is the most simple. I have been building this machine full time for 2 months and know first hand a lot of things that will not work very well. Often times an idea seems great but when tested proves to be impractical. Sometimes an idea gets a lot of scorn in the forums while in fact the idea might work well for some applications. If anyone is interested I'll share what I have learned in another thread.

As to my dual drive rack and pinion axis...seems to work fine. This axis is NOT direct drive, 3 to 1 reduction. They stay in correct timing unless one of them binds or experiences a mishap. Lots of builders use dual motors, Shopbot and Torchmate to mention two. Other expensive units also use two motors on one axis. Having done it, I doubt that I will use two on my next table ( I am trying to develop a plasma table that I can market). Unless someone needs the power or has some other reason, a one motor system is likely a better choice. (Torchmate makes a table that has one high side and one low side raill ...they really needed two motors)

As to the direct drive axis...it is a .75 to 1 ratio. That means it is in overdrive constantly. I worked with the motor tuning in Mach2 and got the acceleration and velocity tuned really nice. My bridge is very light and the motor is only accelerating and decelerating about 10 llbs. As most people know a stepper has its best torque at low rpm so I think this helps the 270 oz stepper to do the job. Acceleration and deceleration have not been a problems although I see potential issues.

Having said all other that, I do not think that I will use it on my next table.

Part II to follow after supper.

jr