Newbie question on pulse width using the Stepper library

Other Hardware Motors, Mechanics, Power and CNC
3

ah, i see--the 4x makes sense now. is there a way to determine max pulse rate, and therefore max speed?

sorry to have neglected to show the code before--here's the code that resulted in a quarter turn with 2x microstepping:

#include <Stepper.h>

const int stepsPerRevolution = 400;
Stepper myStepper(stepsPerRevolution, 8, 9);

void setup() {
myStepper.setSpeed(20); 
Serial.begin(9600);
}

void loop() {
Serial.println("clockwise"); //controls the direction of the stepper motor;
myStepper.step(stepsPerRevolution);
delay(500); //the delay time between turns;
Serial.println("counterclockwise");
myStepper.step(-stepsPerRevolution);
delay(500);
}