Step motors and Gear Ratios

[WoodyD]

Hi All,

New to this. I have done a good look at what is needed to convert both my lathe and Mill to CNC control. All looks like fun.

The bit I am having trouble with is that I see on some builds different gear sizes, which naturally translate to different number of ratios.

So how does the system "know" that x number of turns of the stepper motor, geared down to Y = this much travel of the tool?

Hope that makes sense.

TIA

[ger21]

You tell the control software how many steps it takes to move 1mm.

[mcphill]

To slightly elaborate, you define the "gear ratio" for each axis in the control software. They can all be different, and you don't actually need to calculate/know it as you can measure actual moves to get the answer (move what you think is an inch, measure it, use that to correct the scaling factor). It is very easy to change in MACH3, and I imagine EMC makes it easy as well.

[Crevice Reamer]

Hi Woody. Welcome to the Zone!

You can also let Mach3 do the calculations FOR you.

CR.