From 4cd30e411b3db70ecbd2ec4c6910a024e3098d05 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Fri, 30 Dec 2016 16:35:31 +0000
Subject: [PATCH] sewing-table: interlock

---
 sewing-table.scad.m4 | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/sewing-table.scad.m4 b/sewing-table.scad.m4
index e8f6b7a..eb7dc2a 100644
--- a/sewing-table.scad.m4
+++ b/sewing-table.scad.m4
@@ -103,10 +103,20 @@ module RoundLeftCorner(this_post, right_post) {
 }
 
 module InterlockCore(r) {
+  dx = sqrt(3) * r;
+  $fn= 80;
   translate([0, -thehd[0], 1]){
     mirror([0,0,1]){
       linear_extrude(height=tile_th+2){
-	circle(r=r, $fn=40);
+	circle(r=r);
+	difference(){
+	  translate([-dx, -0.1])
+	    square([ dx*2, r/2 + 0.1 ]);
+	  for (xi = [-1, 1]) {
+	    translate([ xi*dx, r ])
+	      circle(r=r);
+	  }
+	}
       }
     }
   }
-- 
2.30.2