diff --git a/scad/bolex_base_plate.scad b/scad/bolex_base_plate.scad
index 9cfe511..b5a017c 100644
--- a/scad/bolex_base_plate.scad
+++ b/scad/bolex_base_plate.scad
@@ -7,8 +7,10 @@ PLATE_Y = 25;
 module bolex_debug (pad = 0) {
     cylinder(r = R(29) + pad, h = 10, center = true, $fn = 80);
     translate([0, 0, 8]) cylinder(r = R(29) + pad, h = 15, center = true, $fn = 80);
+    translate([0, 0, 12.51]) cylinder(r = R(33), h = 3, center = true, $fn = 90);
+    
     translate([3 + 18.5, 17 + 1.5, 50 - 4]) rotate([0, 90, 0]) cylinder(r = R(100), h = 36, center = true, $fn = 180);
-    translate([5.55, 0 + 3, 38]) rotate([0, 90, 0]) rounded_cube([50, 135, 67.9], d = 20, center = true, $fn = 50);
+    translate([5.55, 0 + 3, 39]) rotate([0, 90, 0]) rounded_cube([50, 135, 67.9], d = 20, center = true, $fn = 50);
 }
 
 module debug () {
@@ -24,11 +26,11 @@ module bolt_voids () {
 		//holes
 		translate([0, -(71.5 / 2) + 12, 0]) {
             cylinder(r = 10 / 2, h = 100, center = true);
-            translate([0, 0, 9]) cylinder(r = R(16.5), h = 10, center = true, $fn = 6);
+            translate([0, 0, 9]) cylinder(r = R(16.5), h = 25, center = true, $fn = 6);
         }
 		translate([0, (71.5 / 2) - 34, 0]) {
             cylinder(r = R(6.5), h = 100, center = true);
-            translate([0, 0, 9]) cylinder(r = R(13), h = 10, center = true, $fn = 6);
+            translate([0, 0, 9]) cylinder(r = R(13), h = 25, center = true, $fn = 6);
         }
 		/*translate([(-50 / 2) + 18, (71.5 / 2) - 62, 0]) {
             cylinder(r = R(10), h = 100, center = true);
@@ -38,22 +40,63 @@ module bolt_voids () {
 
 }
 
-module base_plate (pos = [0, 0, 0], rot = [0, 0, 0]) {
+module base_plate (pos = [0, 0, 0], rot = [0, 0, 0], rails = "15mm") {
+    Rails15mmZ = -1;
     translate(pos) rotate(rot) {
         difference () {
-           rotate([0, 90, 0]) rounded_cube([31, 90.5, 55.3], d = 4, center = true, $fn = 40);
+            union () {
+                rotate([0, 90, 0]) rounded_cube([31, 90.5, 55.3], d = 4, center = true, $fn = 40);
+                if (rails == "15mm") {
+                    translate([60 / 2, -20, Rails15mmZ]) {
+                        rotate([90, 0, 0]) cylinder(r = R(24), h = 20, center = true, $fn = 60);
+                        translate([13, 0, 0]) cube([12, 20, 10], center = true);
+                    }
+                    translate([-60 / 2, -20, Rails15mmZ]) {
+                        rotate([90, 0, 0]) cylinder(r = R(24), h = 20, center = true, $fn = 60);
+                        translate([-13, 0, 0]) cube([12, 20, 10], center = true);
+                    }
+                }
+            }
             translate([PLATE_X, PLATE_Y, -3]) {
-                bolex_debug(0.7);
+                difference () {
+                    bolex_debug(0.7);
+                    if (rails == "15mm") {
+                        translate([-PLATE_X + (60 / 2), - PLATE_Y - 20, 3 + Rails15mmZ]) rotate([90, 0, 0]) cylinder(r = R(24), h = 20, center = true, $fn = 60);
+                        translate([-PLATE_X - (60 / 2), - PLATE_Y - 20, 3 + Rails15mmZ]) rotate([90, 0, 0]) cylinder(r = R(24), h = 20, center = true, $fn = 60);
+                    }
+                }
                 cylinder(r = R(10), h = 60, center = true, $fn = 40);
-                translate([0, 0, -37]) cylinder(r = R(17), h = 60, center = true, $fn = 40);
+                translate([0, 0, -38]) cylinder(r = R(17), h = 60, center = true, $fn = 40);
                 bolt_voids();
             }
             translate([-20, 58, 0]) cube([40, 40, 40], center = true);
             translate([0, 7.8, -9]) rotate([0, 90, 0]) cylinder(r = R(5.25), h = 100, center = true, $fn = 50);
             translate([0, -37.8, -9]) rotate([0, 90, 0]) cylinder(r = R(5.25), h = 100, center = true, $fn = 50);
             
-            translate([15, -50, 0]) rotate([90, 0, 0]) cylinder(r = R(12), h = 100, center = true, $fn = 50);
-            translate([-15, -50, 0]) rotate([90, 0, 0]) cylinder(r = R(12), h = 100, center = true, $fn = 50);
+            if (rails == "15mm") {
+                translate([60 / 2, -50, Rails15mmZ]) {
+                    rotate([90, 0, 0]) cylinder(r = R(15.4), h = 100, center = true, $fn = 60);
+                    translate([5, 0, 0]) cube([20, 100, 1]);
+                    translate([14, 30, 13]) {
+                        rotate([0, 0, 30]) m4_nut(20);
+                        cylinder(r = R(4.25), h = 50, center = true, $fn = 40);
+                        translate([0, 0, -43]) cylinder(r = R(14), h = 50, center = true, $fn = 40);
+                    }
+                }
+                translate([-60 / 2, -50, Rails15mmZ]) {
+                    rotate([90, 0, 0]) cylinder(r = R(15.4), h = 100, center = true, $fn = 60);
+                    translate([-20, 0, 0]) cube([20, 100, 1]);
+                    translate([-14, 30, 13]) {
+                        rotate([0, 0, 30]) m4_nut(20);
+                        cylinder(r = R(4.25), h = 50, center = true, $fn = 40);
+                        translate([0, 0, -43]) cylinder(r = R(14), h = 50, center = true, $fn = 40);
+                    }
+                }
+            } else if (rails == "1/2in") {
+                translate([15, -50, 0]) rotate([90, 0, 0]) cylinder(r = R(13), h = 100, center = true, $fn = 50);
+                translate([-15, -50, 0]) rotate([90, 0, 0]) cylinder(r = R(13), h = 100, center = true, $fn = 50);
+            }
+            
         }
     }
 }
@@ -61,7 +104,7 @@ module base_plate (pos = [0, 0, 0], rot = [0, 0, 0]) {
 PART = "bolex_base_plate";
 
 if (PART == "bolex_base_plate") {
-    base_plate();
+    base_plate(rails="1/2in");
 } else {
     debug();
 }