# Builders/Config/Config Axes

Should I do calibration before, after, or instead of this process?

## Configuring the axes

The X, Y, and Z axis can be configured in exactly the same way. The distance each axis moves needs to be correct, otherwise circles will become ovals and squares become rectangles. Also, your prints will not work properly as the filament will be stretched or squashed.

This assumes you have a tested and "working" RepRap (see Builders/Config/Getting_Started)

• Home all 3 axes.
• Mark the position of your extruder nozzle on the bed using tape or pencil.
• Move the x-axis to 10mm, and then again in 10mm steps until it's about half-way across.
• Mark the position of the nozzle and measure the distance between the two marks.
• Open the preferences dialog and look up the setting XAxisScale (Steps/mm). The default is 7.93something.

You can now calculate the correct scale.

I believe the formula for calculating the correct number of steps is derived from the ratio

$\frac{Expected_{stepspermm}}{Actual_{stepspermm}} = \frac{Expected_{distanceTraveled}}{Actual_{distanceTraveled}}$

giving us

${Expected_{stepspermm}} = \frac{Expected_{distanceTraveled} * {Actual_{stepspermm}}}{Actual_{distanceTraveled}}$

This seems to gel with the example below.

Example values: I moved the x-axis 100mm using the host software.

So $Expected_{distanceTraveled} = 100_{mm}$

I measured the two marks to be 83mm apart.

SO $Actual_{distanceTraveled} = 83_{mm}$

The host software steps per mm for the x axis is 7.93

SO $Actual_{stepspermm} = 7.93_{mm}$

The host software asked the stepper to move: (distance recorded in host software) x (Current XAxisScale setting) 100mmx7.93steps/mm= 793 steps

The 793 steps actually moved 83mm, so steps/mm 793/83 = 9.55421687

OR diagramatically

${Expected_{stepspermm}} = \frac{Expected_{distanceTraveled} * {Actual_{stepspermm}}}{Actual_{distanceTraveled}}$

${Expected_{stepspermm}} = \frac{100 * 7.93}{83}$

${Expected_{stepspermm}} = 9.55421687$

So the new correct value of XAxisScale is 9.5542

• Test by restarting the host software and moving the x-axis 100mm and re-measuring. It should move 100mm.

Repeat for the other axes.