cnc for marble

[yasser]

The distance traveled per revolution with rack and pinion is the pitch circle of your pinion gear diameter * pi, for example 1inch 25.4mm pitch circle diameter pinion gear, 25.4*3.145 = 79.883mm distance traveled per revolution. Divide that by your stepper motor step count which is normally 200. 79.883/200=0.399415. So the resolution is 0.399415... so to get that 0.001 resolution I was talking about you'd need a 300:1 gear ratio, which is crazy. 0.001 might be a little optimistic... but the point being that the problem of smooth slow feeds will be much worse with rack and pinion.

Don't get me wrong rack and pinon is great for soft material routers that need high speeds but I don't think it's correct for your application. Of course you could probably make it work but it wouldn't be the ideal solution.

ok then i will stick to the screw system but i am worried about the length 3 m , and i think there is a problem in my setting of the driver i am using ,this is the setting i am using on the driver

[Rufe0]

What specifically do you think is 'wrong' with it? As is do you think there is malfunction with the driver or are you wondering if another setting would be more appropriate?

[Rufe0]

Just to reiterate on earlier 0.001 resolution was a bit optimistic. 0.01 is more realistic and would be fine.

[yasser]

i was wondering if another setting would be more appropriate

[Rufe0]

Maybe, try a few out. It depends on your steppers, drivers and how well they work together, there is probably a sweet spot. I would stay clear of the really high ones though, mircosteps aren't always as good a thing as you might think they would be for a number of reasons. Have a read about it http://www.micromo.com/microstepping...-and-realities . Obviously remember if you change your microsteps you will need to adjust the settings on your computer otherwise it will come out the wrong size.