Better way to write a string slicer
You could already create the StringBuilder with the text you want to 'splice', rather than building it up again. Then you can just determine how many newline characters you want to add (and you should use Environment.NewLine instead of specifying it explicitly), and insert them in the right place.

    private string SpliceNoteText(string text, int maxWidth)
    {
        StringBuilder sb = new StringBuilder(text);

        for (int i = 0; i &lt; (sb.Length / maxWidth); i++)
        {
            int insertPosition = i * maxWidth;
            sb.Insert(insertPosition, Environment.NewLine);
        }

        return sb.ToString();
    }