diff --git a/src/part/joint_T.scad b/src/part/joint_T.scad
index d291ee61..e24c9d24 100644
--- a/src/part/joint_T.scad
+++ b/src/part/joint_T.scad
@@ -1,4 +1,4 @@
-module joint_T(shaft_r, shaft_h, t_leng, ring_thickness, spacing) {
+module joint_T(shaft_r, shaft_h, t_leng, ring_thickness, spacing = 0.5, center = false) {
     ring_r = shaft_r + spacing + ring_thickness;
     module joint_ring() {
         hollow_out(ring_thickness)
@@ -6,13 +6,20 @@ module joint_T(shaft_r, shaft_h, t_leng, ring_thickness, spacing) {
     }
 
     ring_height = shaft_h / 3 - spacing;
-    linear_extrude(ring_height) joint_ring();
-    translate([0, 0, shaft_h - ring_height]) 
-        linear_extrude(ring_height) joint_ring();
-        
-    translate([t_leng / 2, 0, shaft_h / 2]) 
+
+    translate(center ? [0, 0, -shaft_h / 2] : [0, 0, 0]) {
+        linear_extrude(ring_height) 
+            joint_ring();
+
+        translate([0, 0, shaft_h - ring_height]) 
+        linear_extrude(ring_height) 
+            joint_ring();
+            
+        translate([t_leng / 2, 0, shaft_h / 2]) 
         linear_extrude(shaft_h / 3, center = true)
             square([t_leng, shaft_r * 2], center = true);
 
-    linear_extrude(shaft_h) circle(shaft_r);
+        linear_extrude(shaft_h) 
+            circle(shaft_r);        
+    }
 }
\ No newline at end of file