Add $slop docs to modules that use $slop, fix stroke to accept

singletons, and fix cylinder to handle zero length case

attachments.scad

@@ -2469,7 +2469,7 @@ function _find_anchor(anchor, geom) =
             bot = point3d(v_mul(r1,axy), -l/2),
             top = point3d(v_mul(r2,axy)+shift, l/2),
             pos = point3d(cp) + lerp(bot,top,u) + offset,
-            sidevec = rot(from=UP, to=top-bot, p=point3d(axy)),
+            sidevec = rot(from=UP, to=top==bot?UP:top-bot, p=point3d(axy)),
             vvec = anch==CENTER? UP : unit([0,0,anch.z],UP),
             vec = anch==CENTER? CENTER :
                 approx(axy,[0,0])? unit(anch,UP) :

cubetruss.scad

@@ -105,7 +105,7 @@ module cubetruss_segment(size, strut, bracing, anchor=CENTER, spin=0, orient=UP)
 
 // Module: cubetruss_support()
 // Usage:
-//   cubetruss_support([size], [strut]);
+//   cubetruss_support([size], [strut], [extents], [anchor], [spin], [orient]) [ATTACHMENTS];
 // Description:
 //   Creates a single cubetruss support.
 // Arguments:
@@ -166,7 +166,7 @@ module cubetruss_support(size, strut, extents=1, anchor=CENTER, spin=0, orient=U
 
 // Module: cubetruss_clip()
 // Usage:
-//   cubetruss_clip(extents, [size], [strut], [clipthick]);
+//   cubetruss_clip(extents, [size], [strut], [clipthick], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a pair of clips to add onto the end of a truss.
 // Arguments:
@@ -175,6 +175,7 @@ module cubetruss_support(size, strut, extents=1, anchor=CENTER, spin=0, orient=U
 //   strut = The width of the struts on the cubetruss cubes.  Default: `$cubetruss_strut_size` (usually 3)
 //   clipthick = The thickness of the clip.  Default: `$cubetruss_clip_thickness` (usually 1.6)
 //   ---
+//   $slop = allowance for printer overextrusion
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
@@ -230,7 +231,7 @@ module cubetruss_clip(extents=1, size, strut, clipthick, anchor=CENTER, spin=0,
 
 // Module: cubetruss_foot()
 // Usage:
-//   cubetruss_foot(w, [size], [strut], [clipthick]);
+//   cubetruss_foot(w, [size], [strut], [clipthick], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a foot that can be clipped onto the bottom of a truss for support.
 // Arguments:
@@ -239,6 +240,7 @@ module cubetruss_clip(extents=1, size, strut, clipthick, anchor=CENTER, spin=0,
 //   strut = The width of the struts on the cubetruss cubes.  Default: `$cubetruss_strut_size` (usually 3)
 //   clipthick = The thickness of the clips.  Default: `$cubetruss_clip_thickness` (usually 1.6)
 //   ---
+//   $slop = make fit looser to allow for printer overextrusion
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
@@ -306,7 +308,7 @@ module cubetruss_foot(w=1, size, strut, clipthick, anchor=CENTER, spin=0, orient
 
 // Module: cubetruss_joiner()
 // Usage:
-//   cubetruss_joiner([w], [vert], [size], [strut], [clipthick]);
+//   cubetruss_joiner([w], [vert], [size], [strut], [clipthick], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a part to join two cubetruss trusses end-to-end.
 // Arguments:
@@ -316,6 +318,7 @@ module cubetruss_foot(w=1, size, strut, clipthick, anchor=CENTER, spin=0, orient
 //   strut = The width of the struts on the cubetruss cubes.  Default: `$cubetruss_strut_size` (usually 3)
 //   clipthick = The thickness of the clips.  Default: `$cubetruss_clip_thickness` (usually 1.6)
 //   ---
+//   $slop = Make fit looser by this amount to allow for printer overextrusion
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
@@ -373,7 +376,7 @@ module cubetruss_joiner(w=1, vert=true, size, strut, clipthick, anchor=CENTER, s
 
 // Module: cubetruss_uclip()
 // Usage:
-//   cubetruss_uclip(dual, [size], [strut], [clipthick]);
+//   cubetruss_uclip(dual, [size], [strut], [clipthick], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a small clip that can snap around one or two adjacent struts.
 // Arguments:
@@ -382,6 +385,7 @@ module cubetruss_joiner(w=1, vert=true, size, strut, clipthick, anchor=CENTER, s
 //   strut = The width of the struts on the cubetruss cubes.  Default: `$cubetruss_strut_size` (usually 3)
 //   clipthick = The thickness of the clips.  Default: `$cubetruss_clip_thickness` (usually 1.6)
 //   ---
+//   $slop = Make fit looser by this amount
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`

drawing.scad

@@ -25,7 +25,10 @@
 //   Draws a 2D or 3D path with a given line width.  Joints and each endcap can be replaced with
 //   various marker shapes, and can be assigned different colors.  If passed a region instead of
 //   a path, draws each path in the region as a closed polygon by default. If `closed=false` is
-//   given with a region, each subpath is drawn as an un-closed line path.
+//   given with a region or list of paths, then each path is drawn without the closing line segment.
+//   To facilitate debugging, stroke() accepts "paths" that have a single point.  These are drawn with
+//   the style of endcap1, but have their own scale parameter, `singleton_scale`, which defaults to 2
+//   so that singleton dots with endcap "round" are clearly visible.  
 // Figure(Med,NoAxes,2D,VPR=[0,0,0],VPD=250): Endcap Types
 //   cap_pairs = [
 //       ["butt",  "chisel" ],
@@ -84,6 +87,7 @@
 //   endcap_color2 = If given, sets the color of the ending endcap.  Overrides `color=`, `dots_color=`,  and `endcap_color=`.
 //   joint_color = If given, sets the color of the joints.  Overrides `color=` and `dots_color=`.
 //   dots_color = If given, sets the color of the endcaps and joints.  Overrides `color=`.
+//   singleton_scale = Change the scale of the endcap shape drawn for singleton paths.  Default: 2.  
 //   convexity = Max number of times a line could intersect a wall of an endcap.
 // Example(2D): Drawing a Path
 //   path = [[0,100], [100,100], [200,0], [100,-100], [100,0]];
@@ -100,7 +104,7 @@
 // Example(2D): Mixed Endcaps
 //   path = [[0,100], [100,100], [200,0], [100,-100], [100,0]];
 //   stroke(path, width=10, endcap1="tail2", endcap2="arrow2");
-// Example(2D): Plotting Points
+// Example(2D): Plotting Points.  Setting endcap_angle to zero results in the weird arrow orientation. 
 //   path = [for (a=[0:30:360]) [a-180, 60*sin(a)]];
 //   stroke(path, width=3, joints="diamond", endcaps="arrow2", endcap_angle=0, endcap_width=5, joint_angle=0, joint_width=5);
 // Example(2D): Joints and Endcaps
@@ -147,6 +151,12 @@
 //       ]
 //   ];
 //   stroke(paths, closed=false, width=5);
+// Example(2D): Paths with a singleton.  Note that the singleton is not a single point, but a list containing a single point.  
+//   stroke([
+//           [[0,0],[1,1]],
+//           [[1.5,1.5]],
+//           [[2,2],[3,3]]
+//          ],width=0.2,closed=false,$fn=16);
 function stroke(
     path, width=1, closed,
     endcaps,       endcap1,        endcap2,        joints,       dots,
@@ -155,7 +165,7 @@ function stroke(
     endcap_extent, endcap_extent1, endcap_extent2, joint_extent, dots_extent,
     endcap_angle,  endcap_angle1,  endcap_angle2,  joint_angle,  dots_angle,
     endcap_color,  endcap_color1,  endcap_color2,  joint_color,  dots_color, color,
-    trim, trim1, trim2,
+    trim, trim1, trim2, singleton_scale=2,
     convexity=10
 ) = no_function("stroke");
 
@@ -168,7 +178,7 @@ module stroke(
     endcap_extent, endcap_extent1, endcap_extent2, joint_extent, dots_extent,
     endcap_angle,  endcap_angle1,  endcap_angle2,  joint_angle,  dots_angle,
     endcap_color,  endcap_color1,  endcap_color2,  joint_color,  dots_color, color,
-    trim, trim1, trim2,
+    trim, trim1, trim2, singleton_scale=2,
     convexity=10
 ) {
     no_children($children);
@@ -201,8 +211,8 @@ module stroke(
         assert(false, str("Invalid cap or joint: ",cap));
 
     function _shape_path(cap,linewidth,w,l,l2) = (
-        (cap=="butt" || cap==false || cap==undef)? [] : 
+        cap=="butt" || cap==false || cap==undef ? [] : 
-        (cap=="round" || cap==true)? scale([w,l], p=circle(d=1, $fn=max(8, segs(w/2)))) :
+        cap=="round" || cap==true ? scale([w,l], p=circle(d=1, $fn=max(8, segs(w/2)))) :
         cap=="chisel"?  scale([w,l], p=circle(d=1,$fn=4)) :
         cap=="diamond"? circle(d=w,$fn=4) :
         cap=="square"?  scale([w,l], p=square(1,center=true)) :
@@ -239,47 +249,47 @@ module stroke(
     endcap_width1 = first_defined([endcap_width1, endcap_width, dots_width, endcap1_dflts[0]]);
     endcap_width2 = first_defined([endcap_width2, endcap_width, dots_width, endcap2_dflts[0]]);
     joint_width   = first_defined([joint_width, dots_width, joint_dflts[0]]);
-    check3 = 
-      assert(is_num(endcap_width1))
-      assert(is_num(endcap_width2))
-      assert(is_num(joint_width));
 
     endcap_length1 = first_defined([endcap_length1, endcap_length, dots_length, endcap1_dflts[1]*endcap_width1]);
     endcap_length2 = first_defined([endcap_length2, endcap_length, dots_length, endcap2_dflts[1]*endcap_width2]);
     joint_length   = first_defined([joint_length, dots_length, joint_dflts[1]*joint_width]);
-    check4 = 
-      assert(is_num(endcap_length1))
-      assert(is_num(endcap_length2))
-      assert(is_num(joint_length));
 
     endcap_extent1 = first_defined([endcap_extent1, endcap_extent, dots_extent, endcap1_dflts[2]*endcap_width1]);
     endcap_extent2 = first_defined([endcap_extent2, endcap_extent, dots_extent, endcap2_dflts[2]*endcap_width2]);
     joint_extent   = first_defined([joint_extent, dots_extent, joint_dflts[2]*joint_width]);
-    check5 = 
-      assert(is_num(endcap_extent1))
-      assert(is_num(endcap_extent2))
-      assert(is_num(joint_extent));
 
     endcap_angle1 = first_defined([endcap_angle1, endcap_angle, dots_angle]);
     endcap_angle2 = first_defined([endcap_angle2, endcap_angle, dots_angle]);
     joint_angle = first_defined([joint_angle, dots_angle]);
-    check6 = 
+    
-      assert(is_undef(endcap_angle1)||is_num(endcap_angle1))
+    check3 =
-      assert(is_undef(endcap_angle2)||is_num(endcap_angle2))
+      assert(all_nonnegative([endcap_length1]))
-      assert(is_undef(joint_angle)||is_num(joint_angle));
+      assert(all_nonnegative([endcap_length2]))
-
+      assert(all_nonnegative([joint_length]));
+      assert(all_nonnegative([endcap_extent1]))
+      assert(all_nonnegative([endcap_extent2]))
+      assert(all_nonnegative([joint_extent]));
+      assert(is_undef(endcap_angle1)||is_finite(endcap_angle1))
+      assert(is_undef(endcap_angle2)||is_finite(endcap_angle2))
+      assert(is_undef(joint_angle)||is_finite(joint_angle))
+      assert(all_positive([singleton_scale]))
+      assert(all_positive(width));
+      
     endcap_color1 = first_defined([endcap_color1, endcap_color, dots_color, color]);
     endcap_color2 = first_defined([endcap_color2, endcap_color, dots_color, color]);
     joint_color = first_defined([joint_color, dots_color, color]);
-    paths = force_region(path);
+
-    check7 = assert(is_region(paths),"The path argument must be a list of 2D or 3D points, or a region.");
+    // We want to allow "paths" with length 1, so we can't use the normal path/region checks
+    paths = is_matrix(path) ? [path] : path;
+    assert(is_list(paths),"The path argument must be a list of 2D or 3D points, or a region.");
     for (path = paths) {
-        assert(len(path)==1 || is_path(path,[2,3]), "The path argument must be a list of 2D or 3D points, or a region.");
+        pathvalid = is_path(path,[2,3]) || same_shape(path,[[0,0]]) || same_shape(path,[[0,0,0]]);
+        assert(pathvalid,"The path argument must be a list of 2D or 3D points, or a region.");
         path = deduplicate( closed? close_path(path) : path );
 
-        check8 = assert(is_num(width) || (is_vector(width) && len(width)==len(path)));
+        check4 = assert(is_num(width) || len(width)==len(path),
+                        "width must be a number or a vector the same length as the path (or all components of a region)");
         width = is_num(width)? [for (x=path) width] : width;
-        check9 = assert(all([for (w=width) w>0]));
 
         endcap_shape1 = _shape_path(endcap1, width[0], endcap_width1, endcap_length1, endcap_extent1);
         endcap_shape2 = _shape_path(endcap2, last(width), endcap_width2, endcap_length2, endcap_extent2);
@@ -290,7 +300,6 @@ module stroke(
             (endcap1=="arrow2")? endcap_length1*3/4 :
             0
         ]);
-        check10 = assert(is_num(trim1));
 
         trim2 = last(width) * first_defined([
             trim2, trim,
@@ -298,8 +307,8 @@ module stroke(
             (endcap2=="arrow2")? endcap_length2*3/4 :
             0
         ]);
-        check11 = assert(is_num(trim2));
+        check10 = assert(is_finite(trim1))
-
+                  assert(is_finite(trim2));
 
         if (len(path) == 1) {
             if (len(path[0]) == 2) {
@@ -307,7 +316,7 @@ module stroke(
                 setcolor(endcap_color1) {
                     translate(path[0]) {
                         mat = is_undef(endcap_angle1)? ident(3) : zrot(endcap_angle1);
-                        multmatrix(mat) polygon(endcap_shape1);
+                        multmatrix(mat) polygon(scale(singleton_scale,endcap_shape1));
                     }
                 }
             } else {
@@ -685,7 +694,7 @@ function arc(n, r, angle, d, cp, points, corner, width, thickness, start, wedge=
     is_def(angle)? (
         let(
             parmok = !any_defined([points,width,thickness]) &&
-                ((is_vector(angle,2) && is_undef(start)) || is_num(angle))
+                ((is_vector(angle,2) && is_undef(start)) || is_finite(angle))
         )
         assert(parmok,"Invalid parameters in arc")
         let(

hingesnaps.scad

@@ -13,7 +13,7 @@
 
 // Module: apply_folding_hinges_and_snaps()
 // Usage:
-//   apply_folding_hinges_and_snaps(thick, [foldangle=], [hinges=], [snaps=], [sockets=], [snaplen=], [snapdiam=], [hingegap=], [layerheight=]) CHILDREN;
+//   apply_folding_hinges_and_snaps(thick, [foldangle=], [hinges=], [snaps=], [sockets=], [snaplen=], [snapdiam=], [hingegap=], [layerheight=], [$slop=]) CHILDREN;
 // Description:
 //   Adds snaplocks and create hinges in children at the given positions.
 // Arguments:
@@ -26,6 +26,8 @@
 //   snapdiam = Diameter/width of locking snaps.
 //   hingegap = Size in mm of the gap at the bottom of the hinge, to make room for folding.
 //   layerheight = The expected printing layer height in mm.
+//   ---
+//   $slop = increase hinge gap by twice this amount
 // Example(Med):
 //   size=100;
 //   apply_folding_hinges_and_snaps(
@@ -93,7 +95,7 @@ module apply_folding_hinges_and_snaps(thick, foldangle=90, hinges=[], snaps=[],
 
 // Module: folding_hinge_mask()
 // Usage:
-//   folding_hinge_mask(l, thick, [layerheight=], [foldangle=], [hingegap=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
+//   folding_hinge_mask(l, thick, [layerheight=], [foldangle=], [hingegap=], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a mask to be differenced away from a plate to create a foldable hinge.
 //   Center the mask at the bottom of the plate you want to make a hinge in.
@@ -105,6 +107,7 @@ module apply_folding_hinges_and_snaps(thick, foldangle=90, hinges=[], snaps=[],
 //   layerheight = The expected printing layer height in mm.
 //   foldangle = The interior angle in degrees of the joint to be created with the hinge.  Default: 90
 //   hingegap = Size in mm of the gap at the bottom of the hinge, to make room for folding.
+//   $slop = Increase size of hinge gap by double this amount
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
@@ -124,7 +127,7 @@ module folding_hinge_mask(l, thick, layerheight=0.2, foldangle=90, hingegap=unde
 
 // Module: snap_lock()
 // Usage:
-//   snap_lock(thick, [snaplen=], [snapdiam=], [layerheight=], [foldangle=], [hingegap=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
+//   snap_lock(thick, [snaplen=], [snapdiam=], [layerheight=], [foldangle=], [hingegap=], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates the central snaplock part.
 // Arguments:
@@ -135,6 +138,7 @@ module folding_hinge_mask(l, thick, layerheight=0.2, foldangle=90, hingegap=unde
 //   layerheight = The expected printing layer height in mm.
 //   foldangle = The interior angle in degrees of the joint to be created with the hinge.  Default: 90
 //   hingegap = Size in mm of the gap at the bottom of the hinge, to make room for folding.
+//   $slop = increase size of hinge gap by double this amount
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
@@ -159,7 +163,7 @@ module snap_lock(thick, snaplen=5, snapdiam=5, layerheight=0.2, foldangle=90, hi
 
 // Module: snap_socket()
 // Usage:
-//   snap_socket(thick, [snaplen=], [snapdiam=], [layerheight=], [foldangle=], [hingegap=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
+//   snap_socket(thick, [snaplen=], [snapdiam=], [layerheight=], [foldangle=], [hingegap=], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates the outside snaplock socketed part.
 // Arguments:
@@ -170,6 +174,7 @@ module snap_lock(thick, snaplen=5, snapdiam=5, layerheight=0.2, foldangle=90, hi
 //   layerheight = The expected printing layer height in mm.
 //   foldangle = The interior angle in degrees of the joint to be created with the hinge.  Default: 90
 //   hingegap = Size in mm of the gap at the bottom of the hinge, to make room for folding.
+//   $slop = Increase size of hinge gap by double this amount
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`

nema_steppers.scad

@@ -14,7 +14,7 @@
 
 // Module: nema_stepper_motor()
 // Usage:
-//   nema_stepper_motor(size, h, shaft_len, ...) [attachments];
+//   nema_stepper_motor(size, h, shaft_len, [$slop=], ...) [ATTACHMENTS];
 // Topics: Parts, Motors
 // Description:
 //   Creates a model of a NEMA standard stepper motor.
@@ -25,6 +25,7 @@
 //   ---
 //   details = If false, creates a very rough motor shape, suitable for using as a mask.  Default: true
 //   atype = The attachment set type to use when anchoring.  Default: `"body"`
+//   $slop = If details is false then increase size of the model by double this amount (for use as a mask)
 //   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `TOP`
 //   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards, after spin.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
@@ -117,7 +118,7 @@ module nema_stepper_motor(size=17, h=24, shaft_len=20, details=true, atype="body
 
 // Module: nema_mount_mask()
 // Usage:
-//   nema_mount_mask(size, depth, l, ...);
+//   nema_mount_mask(size, depth, l, [$slop], ...);
 // Topics: Parts, Motors
 // Description: Creates a mask to use when making standard NEMA stepper motor mounts.
 // Arguments:

partitions.scad

@@ -399,7 +399,7 @@ function _partition_cutpath(l, h, cutsize, cutpath, gap) =
 
 // Module: partition_mask()
 // Usage:
-//   partition_mask(l, w, h, [cutsize], [cutpath], [gap], [inverse], [spin], [orient]) [ATTACHMENTS];
+//   partition_mask(l, w, h, [cutsize], [cutpath], [gap], [inverse], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a mask that you can use to difference or intersect with an object to remove half of it, leaving behind a side designed to allow assembly of the sub-parts.
 // Arguments:
@@ -449,7 +449,7 @@ module partition_mask(l=100, w=100, h=100, cutsize=10, cutpath="jigsaw", gap=0,
 
 // Module: partition_cut_mask()
 // Usage:
-//   partition_cut_mask(l, w, h, [cutsize], [cutpath], [gap], [inverse], [spin], [orient]) [ATTACHMENTS];
+//   partition_cut_mask(l, w, h, [cutsize], [cutpath], [gap], [inverse], [$slop=], [anchor=], [spin=], [orient=]) [ATTACHMENTS];
 // Description:
 //   Creates a mask that you can use to difference with an object to cut it into two sub-parts that can be assembled.
 //   The `$slop` value is important to get the proper fit and should probably be smaller than 0.2.  The examples below
@@ -463,7 +463,7 @@ module partition_mask(l=100, w=100, h=100, cutsize=10, cutpath="jigsaw", gap=0,
 //   gap = Empty gaps between cutpath iterations.  Default: 0
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 //   orient = Vector to rotate top towards.  See [orient](attachments.scad#subsection-orient).  Default: `UP`
-//   $slop = The width of the cut mask, to correct for printer-specific fitting.  Min: 0.05.
+//   $slop = The width of the cut mask, to correct for printer-specific fitting. 
 // Examples:
 //   partition_cut_mask(gap=0, cutpath="dovetail");
 //   partition_cut_mask(gap=30, cutpath="dovetail");
@@ -492,7 +492,7 @@ module partition_cut_mask(l=100, h=100, cutsize=10, cutpath="jigsaw", gap=0, anc
 
 // Module: partition()
 // Usage:
-//   partition(size, [spread], [cutsize], [cutpath], [gap], [spin]) CHILDREN;
+//   partition(size, [spread], [cutsize], [cutpath], [gap], [spin], [$slop=]) CHILDREN;
 // Description:
 //   Partitions an object into two parts, spread apart a small distance, with matched joining edges.
 // Arguments:
@@ -502,6 +502,8 @@ module partition_cut_mask(l=100, h=100, cutsize=10, cutpath="jigsaw", gap=0, anc
 //   cutpath = The cutpath to use.  Standard named paths are "flat", "sawtooth", "sinewave", "comb", "finger", "dovetail", "hammerhead", and "jigsaw".  Alternatively, you can give a cutpath as a 2D path, where X is between 0 and 1, and Y is between -0.5 and 0.5.
 //   gap = Empty gaps between cutpath iterations.  Default: 0
 //   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
+//   ---
+//   $slop = Extra gap to leave to correct for printer-specific fitting. 
 // Examples(Med):
 //   partition(spread=12, cutpath="dovetail") cylinder(h=50, d=80, center=false);
 //   partition(spread=12, gap=30, cutpath="dovetail") cylinder(h=50, d=80, center=false);

screw_drive.scad

@@ -285,7 +285,7 @@ function torx_depth(size) = torx_info(size)[2];
 
 // Module: robertson_mask()
 // Usage:
-//   robertson_mask(size, [extra]);
+//   robertson_mask(size, [extra], [ang], [$slop=]);
 // Description:
 //   Creates a mask for creating a Robertson/Square drive recess given the drive size as an integer.
 //   The width of the recess will be oversized by `2 * $slop`.  Note that this model is based
@@ -295,6 +295,7 @@ function torx_depth(size) = torx_info(size)[2];
 //   size = The size of the square drive, as an integer from 0 to 4.
 //   extra = Extra length of drive mask to create.
 //   ang = taper angle of each face.  Default: 2.5
+//   ---
 //   $slop = enlarge recess by this twice amount.  Default: 0
 // Example:
 //   robertson_mask(size=2);

shapes3d.scad

@@ -2547,6 +2547,7 @@ module teardrop(h, r, ang=45, cap_h, r1, r2, d, d1, d2, cap_h1, cap_h2, l, lengt
                 chamfer, chamfer1, chamfer2,anchor=CENTER, spin=0, orient=UP)
 {
     length = one_defined([l, h, length, height],"l,h,length,height");
+    dummy=assert(is_finite(length) && length>0, "length must be positive");
     r1 = get_radius(r=r, r1=r1, d=d, d1=d1);
     r2 = get_radius(r=r, r1=r2, d=d, d1=d2);
     tip_y1 = r1/cos(90-ang);
@@ -2574,6 +2575,7 @@ function teardrop(h, r, ang=45, cap_h, r1, r2, d, d1, d2, cap_h1, cap_h2,  chamf
         r1 = get_radius(r=r, r1=r1, d=d, d1=d1, dflt=1),
         r2 = get_radius(r=r, r1=r2, d=d, d1=d2, dflt=1),
         length = one_defined([l, h, length, height],"l,h,length,height"),
+        dummy0=assert(is_finite(length) && length>0, "length must be positive"),
         cap_h1 = first_defined([cap_h1, cap_h]),
         cap_h2 = first_defined([cap_h2, cap_h]),
         chamfer1 = first_defined([chamfer1,chamfer,0]),