How to change the pivot point of a link in URDF joint?

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I have built simple robotic arm, where the Link1 is joined to the base_link through a revolute joint. When i try to move the link1 it is revolving on its own center instead pivoting the bottom to base_link. Here, how to change the pivot point from the center of link1 to its bottom and fix it to the base_link.

My urdf:

<?xml version="1.0"?>
<robot name="myfirst" xmlns:xacro="http://www.ros.org/wiki/xacro">
  <link name="base_link">
    <visual>
      <geometry>
        <box size="0.5 0.5 0.5"/>
      </geometry>
    </visual>
  </link>

<joint name="joint1" type="revolute">
 <axis xyz="0 1 0"/>
<limit effort="1000.0" lower="-0.548" upper="0.548" velocity="0.5"/>
    <parent link="base_link"/>
    <child link="arm2"/>
    <origin xyz="0 0 0.5" rpy="0 0 0" />
  </joint>

<link name="arm2">
<origin xyz="0 0 -0.3" rpy="0 0 0" />
    <visual>
      <geometry>
        <cylinder length="0.6" radius="0.04"/>
      </geometry>
    </visual>
  </link>

</robot>

Result initial pose:

Result end pose: