Mancala board design


Newbie here. I am trying to design a mancala board to cut on my CNC. What would be a good way to draw the indentations or pits seen in the photo? Thanks for any help.


Hi @sweymouth - One easy way to model the indentations would be to start with an Ellipsoid (which you’ll find in the Solid Tools side bar). You can rebuild it to a degree 3 in both directions and control point edit it until you get the desired shape. You should be able to BooleanDifference this from the main board.

Thanks Vanessa, worked great. Have a nice day.

you can try using pipes with round caps

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If you need a total control over the shape and size, then the easiest way to do these shapes is:

  1. Turn on the snap to “End” and “Cen” via the the Osnap toolbar.
  2. Create two 180-degree arcs in the desired position (coloured in red) and connect them with straight lines (coloured in black).
  3. Use them to cut a hole into the plane either with the “Trim” or “Split” command.
  4. By snapping to the center of each arc, create a vertical line with the “Line: Vertical To CPlane” tool and make it with the desired length (coloured in cyan).
  5. Use “Arc: start, end, direction at start” to create a profile arc that starts from the bottom of the vertical line and ends at one of the ends of the arc (coloured in green).
  6. Select that profile arc and use “Revolve” whose axis is the vertical line. Make it 180 degrees so that it follows the arc. Do the same with the opposite arc (or simply create a mirror copy of the revolved surface).
  7. Use “Arc: start, end, point on arc” to create another arc that connects both ends of the horizontal arc, and for its middle point snap to the bottom of the vertical line (coloured in blue).
  8. Select that newly created arc and use “Extrude straight” to extrude a profile between both revolved surfaces.
  9. Join these surfaces and use “Copy” or “Array” to create more pockets where you want.
  10. Open a beer and smile. :slight_smile:

Pocket.3dm (366.6 KB)

Thanks for the additional responses. The 10-step process ending with a beer worked great.

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Glad to hear it helped. I forgot to mention above that during step #6 you can also use “Rail revolve” instead of “Revolve”. The latter is a quicker way to make a 180-degree revolve with less mouse clicks, while “Rail revolve” shines where the rail is not an arc. If you use “Rail revolve” in this particular model, you don’t need the blue arc from step #7, but in this case the extruded surface #8 will be split in two halves since it will use both edges of the revolved surface #6 as profiles. This is why for simple shapes it’s better to create a dedicated profile curve instead.

Here is an example where “Rail revolve” is used to create free-form end surfaces for a more complicated pocket shape with as few control points as possible. Many people try to do these shapes with “Sweep 1 rail”, but the resulting surface has an excessive amount of control points and is not tangent to the middle straight section: