SpindleCalc is an app for laying out spindles on a railing. Enter the length of the railing, the width of the spindle, the width of the maximum space in between spindles, if its a stair railing enter the angle, and then tap the calculate button. SpindleCalc will then give you the layout measurements in a “x-ahead” fashion.  If you are doing aluminum pipe style spindles you’ll probably want center marks instead.  To get center marks leave the spindle width boxes empty and the spindles on end box unchecked. Then, in the max space boxes, instead of maximum space between the spindles enter the maximum distance center to center.

Google Play listing