diff --git a/full_assembly.scad b/full_assembly.scad
index e21fb09..e9cffa8 100644
--- a/full_assembly.scad
+++ b/full_assembly.scad
@@ -165,6 +165,7 @@ module full_assembly()
 			xrot(-90) yrot(180) {
 				z_sled();
 				z_sled_rollers();
+				z_sled_nuts();
 			}
 
 			translate([0, 0, platform_length/2]) {
diff --git a/lifter_nut_part.scad b/lifter_nut_part.scad
index e664827..76dc595 100644
--- a/lifter_nut_part.scad
+++ b/lifter_nut_part.scad
@@ -38,6 +38,7 @@ module lifter_nut()
 		}
 	}
 }
+//!lifter_nut();
 
 
 
diff --git a/roller_cap_parts.scad b/roller_cap_parts.scad
index 36cf5ae..c8840bc 100644
--- a/roller_cap_parts.scad
+++ b/roller_cap_parts.scad
@@ -3,21 +3,24 @@ use <GDMUtils.scad>
 
 
 
-module roller_cap(r=roller_axle/2-3, h=10, wall=3, cap=2, lip=1.5)
+module roller_cap(r=5.0, h=10, wall=3, cap=2, lip=1.5, shelf=2.4, slop=0.25)
 {
+	$fn = 16;
 	color("Pink") difference() {
 		union() {
 			translate([0,0,-cap/2])
-				cylinder(r=r+lip+wall, h=cap, center=true, $fn=32);
+				cylinder(r=r+lip+wall, h=cap, center=true);
+			translate([0,0,0.3/2])
+				cylinder(r=r+shelf, h=0.3, center=true);
 			translate([0,0,h*3/8])
-				cylinder(r1=r-0.5, r2=r, h=h*3/4, center=true, $fn=32);
+				cylinder(r1=r-slop, r2=r-slop, h=h*3/4, center=true);
 			translate([0,0,h*7/8])
-				cylinder(r1=r, r2=r-wall/2, h=h*1/4, center=true, $fn=32);
+				cylinder(r1=r-slop+0.6, r2=r-wall/2, h=h*1/4, center=true);
 		}
 		translate([0,0,h/2+1])
-			cylinder(r=r-wall, h=h+1, center=true, $fn=12);
+			cylinder(r=r-wall, h=h+1, center=true, $fn=8);
 		zrot_copies([0,90]) translate([0,0,h*5/8])
-			cube(size=[1,r*2,h],center=true);
+			cube(size=[1,r*3,h],center=true);
 	}
 }
 //roller_cap();
@@ -32,7 +35,7 @@ module roller_cap_parts() { // make me
 		xa=[-spacing*(num_x-1)/2:spacing:spacing*(num_x-1)/2],
 		ya=[-spacing*(num_y-1)/2:spacing:spacing*(num_y-1)/2],
 		za=[2]
-	) roller_cap(r=roller_axle/2-3, h=10, lip=2, wall=3);
+	) roller_cap(r=roller_axle/2-2.5-0.2, h=10, wall=3, lip=1.5, shelf=2.5);
 }
 
 
diff --git a/slider_sled.scad b/slider_sled.scad
index 6f3d805..726af20 100644
--- a/slider_sled.scad
+++ b/slider_sled.scad
@@ -10,6 +10,8 @@ module slider_sled(show_rollers=false)
 {
 	axle_rad = (roller_axle/2) - 0.2;
 	axle_len = roller_thick;
+	pedestal_lip = 1.5;
+	cap_snap_len = 10*3/4;
 
 	union() {
 		difference() {
@@ -49,12 +51,17 @@ module slider_sled(show_rollers=false)
 			grid_of(ya=[-(platform_length/2)/2, (platform_length/2)/2]) {
 				// Roller pedestals
 				translate([0,0,roller_base/2]) {
-					cylinder(h=roller_base, r=axle_rad+1.5, center=true, $fn=32);
+					cylinder(h=roller_base, r=axle_rad+pedestal_lip, center=true, $fn=32);
 				}
 
 				// Roller axles
 				translate([0,0,axle_len/2+roller_base]) {
-					tube(h=axle_len+0.05, r=axle_rad, wall=2.5, center=true, $fn=32);
+					difference() {
+						cylinder(h=axle_len, r=axle_rad, center=true, $fn=32);
+						cylinder(h=axle_len+0.05, r=axle_rad-2.5, center=true, $fn=16);
+						translate([0, 0, -axle_len/2+(axle_len-cap_snap_len)/2])
+							cylinder(h=axle_len-cap_snap_len+0.05, r=axle_rad-2.0, center=true, $fn=16);
+					}
 				}
 			}
 		}
diff --git a/z_sled_part.scad b/z_sled_part.scad
index 72952f5..91fb933 100644
--- a/z_sled_part.scad
+++ b/z_sled_part.scad
@@ -2,6 +2,7 @@ include <config.scad>
 use <GDMUtils.scad>
 use <slider_sled.scad>
 use <nut_capture.scad>
+use <lifter_nut_part.scad>
 
 
 
@@ -39,6 +40,22 @@ module z_sled_rollers()
 
 
 
+module z_sled_nuts()
+{
+	// Quantize nut housing spacing to the thread lift size.
+	nut_spacing = floor((platform_length-20)/lifter_thread_size) * lifter_thread_size;
+
+	// Drive nut capture
+	grid_of(
+		ya=[-nut_spacing/2, nut_spacing/2],
+		za=[(roller_base+roller_thick/2)]
+	) {
+		zrot(90) yrot(-90) lifter_nut();
+	}
+}
+
+
+
 module z_sled_part() { // make me
 	zrot(90) z_sled();
 }