Dificuldade com scollbar

Olá pessoal.
Tenho o seguinte codigo:

public class Principal extends javax.swing.JFrame {

    /** Creates new form Principal */
    public Principal() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTable1 = new javax.swing.JTable();
        jPanel2 = new javax.swing.JPanel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jPanel1.setBorder(javax.swing.BorderFactory.createEtchedBorder());
        jPanel1.setPreferredSize(new java.awt.Dimension(900, 90));

        jButton1.setText("Adicionar");

        jButton2.setText("Remover");
        jButton2.setEnabled(false);

        jButton3.setText("Imprimir");
        jButton3.setEnabled(false);

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jButton1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButton2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 627, Short.MAX_VALUE)
                .addComponent(jButton3)
                .addContainerGap())
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2)
                    .addComponent(jButton3))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );

        jTable1.setBorder(javax.swing.BorderFactory.createEtchedBorder());
        jTable1.setModel(new javax.swing.table.DefaultTableModel(
            new Object [][] {
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null},
                {null, null, null, null, null, null}
            },
            new String [] {
                "1", "2", "3", "4", "5", "6"
            }
        ) {
            boolean[] canEdit = new boolean [] {
                false, false, false, false, false, false
            };

            public boolean isCellEditable(int rowIndex, int columnIndex) {
                return canEdit [columnIndex];
            }
        });
        jTable1.getTableHeader().setReorderingAllowed(false);
        jScrollPane1.setViewportView(jTable1);
        jTable1.getColumnModel().getColumn(0).setMinWidth(500);
        jTable1.getColumnModel().getColumn(1).setMinWidth(500);
        jTable1.getColumnModel().getColumn(2).setMinWidth(500);
        jTable1.getColumnModel().getColumn(3).setMinWidth(500);
        jTable1.getColumnModel().getColumn(4).setMinWidth(500);
        jTable1.getColumnModel().getColumn(5).setMinWidth(500);

        jPanel2.setBorder(javax.swing.BorderFactory.createEtchedBorder());
        jPanel2.setPreferredSize(new java.awt.Dimension(880, 45));

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 876, Short.MAX_VALUE)
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 41, Short.MAX_VALUE)
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 880, Short.MAX_VALUE)
                    .addComponent(jPanel1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 880, Short.MAX_VALUE)
                    .addComponent(jPanel2, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, 45, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 476, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap())
        );

        java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
        setBounds((screenSize.width-916)/2, (screenSize.height-638)/2, 916, 638);
    }// </editor-fold>

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Principal().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTable jTable1;
    // End of variables declaration

}

Não estou consguindo fazer com que a barra horizontal acompanhe as linhas, como eu posso resolver isso?
Grato!