List of possible toolpath/pocket shapes

(William Adams) #1

Working through this now and thus far have:

  • 0
    • circle
    • oval/ellipse (requires some sort of non-arc curve)
      • egg-shaped (requires some sort of non-arc curve)
    • annulus (one circle within another forming a ring)
    • superellipse (see astroid below)
  • 1
    • cone with rounded end (arc)
  • 2
    • semicircle/circular segment (arc and a straight line)
    • lens/vesical piscis (two convex curves)
    • lune/crescent (one convex one concave curve)
    • heart (two curves)
    • tomoe (comma shape) — requires non arc curves
  • 3
    • triangle
      • equilateral
      • isosceles
      • scalene
      • sector (two straight edges, one convex arc)
    • two straight edges, one concave arc
    • Deltoid curve (three concave arcs)
    • Reuleaux triangle (three convex arcs)
    • Arbelos (one convex, two concave arcs)
  • 4
    • square
    • rectangle
    • parallelogram
    • rhombus
    • trapezoid/trapezium
    • kite
    • astroid (four concave arcs)
    • salinon (four semicircles)

any obvious corrections or additions?

Other suggestions?


(Nathaniel Klumb) #2

What type on constraints are you applying? I obviously do a lot with G-code directly and SVG for design work, with G-code constrained to circular arcs and straight lines and SVG loosening that to elliptical arcs and (up to cubic) bezier curves.

Are you attempting to name everything? For example, if you overlap two identical circles and take the boolean intersection, you get the classic lenticular shape, but what about if you take the boolean union? The same source shapes and the same intersections, but concave instead of convex at the two intersections. Is that just an “overinflated lens”? If you relax the constraints (non-identical circles? ellipses?), things rapidly go beyond my label vocabulary.

1 Like

(William Adams) #3

I’m trying to work up a reasonable list of module names/macros for making pockets for some reasonable subset of the above shapes — I figure the code will be easier if I have a module (in OpenSCAD) and a macro (in METAPOST) which accept (for example):

pocketrect --- cuts rectangular pocket of
--- at location
--- elevated by
---- of depth
--- using an endmill of

Looking things over, the name which I seem to be short by is the one for a shape with three points and two straight edges, and one concave arc — did I miss something or is there no name for such a figure?


(Nathaniel Klumb) #4

I don’t know the name of the shape, other than to call it the “Asteroids spaceship” from the vintage vector arcade game.

Would you consider things like the “Tee” option for rectangles in Carbide Create to be a shape, or would that (and its cousins, “dogbone” and “fillet”) be something for elsewhere? I can see that they would be very useful to have somewhere, as they’re things that tend to be used extensively.


(William Adams) #5

Spaceship may be the option (and that reminds me of another 4-pointed shape, “shield” for two convex and two concave surfaces).

I really mislike voids, so will probably leave dogbones and so forth for someone else to implement — I actually worked up a really cool miter joint with spline, but unfortunately the end shape isn’t really easily machinable, so I’ve put it to the back burner for a bit.


(Luc) #6

I don’t see polygons; all the polygons will have similar shape possibilities (Concave/Convex).

How about stars?


(William Adams) #7

I’m planning on dividing polygons by placing a rectangle or circle within them, the sub-dividing as necessary — for instance a hexagon becomes a rectangle and two triangles, stars would need this specific shape name — place a circle in them, then the remaining area is made up of triangles with an arc chopped out of one end.


(Luc) #8

The issue with stars is that you have an inner and outer circle with triangles in the middle joining both circles. I guess you are looking at 2D pockets as stars may have a crease (in or out) in the middle of each triangle.


(William Adams) #9

I’m only considering 2.5D mostly flat-bottomed pockets at this juncture — it will be possible to do a perimeter pass with a ball-nosed endmill which adds a rounded bottom along the edge — debating on V as well — would folks want that?


(Luc) #10

Aren’t stars on the US flag not often depicted that way?


(William Adams) #11

Yes, they are, but I’m not planning for vexillology at this point, but boxes with dividers/pockets and possibly joinery.


(Luc) #12

Wow will, you had me look this up. Not knowing the exact nature of your request, my comments were along the line of possible geometry for CNC, nothing specific to boxes.


(William Adams) #13

My apologies, the pocket thing was implied by the context of it being for my Design into 3D project which is all boxes and so forth so far.

I’m hoping to do another Kickstarter next year for parametric decoration of CNC projects.