Oval shaped cribbage board

[Jerry Lawrence]

Hi all, I was wondering if anyone could help me with this problem: I recently had someone ask me if I could make a cribbage board similar to the one in the attached picture, but not with the Harley logo, but something else in the center instead. My problem is with laying out the holes. There has to be 120 holes around the board in each lane, (plus maybe an extra hole at the beginning for a starter hole) all evenly spaced out in sets of five. I'm not sure how to go about laying this out so the holes follow the contour of the oval, and also come out even with the size of the board (which is also not written in stone, so I have some leeway there). Any good ideas for this project?
Thanks in advance for any help!
harley cribbage.jpg

[John Coloccia]

Do you happen to own some decent dividers?

Of course, you could just draw it in a CAD program, and then have it printed full size and use that as a template for your layout.

[Andrew Hughes]

Looks like it can be done with some common drafting tools.Since your friend asked you to make it maybe he wants it to look like it was made by hand not a machine or store bought?

[John Coloccia]

That Harley one looks pretty drilled by hand. If they have some sort of machine doing it, they need to fix it.

[Wayne Lovell]

Take a photo of it straight on enlarge or reduce to the size you want?

[Yonak Hawkins]

Jerry, here's a site about tangents to ellipses. There's a box to check to show the perpendiculars to the tangents. This should give you an idea of what you need to line up the holes. I haven't checked out the page to see just what information it supplies, whether the formulas, or what, but it is interactive and may be of some help. It's helpful to note that the perpendiculars are bisectors of the angles created by the generator lines.

http://www.mathopenref.com/ellipsetangent.html

Of course, all you have to lay out is one quadrant. If you have access to CAD it should be pretty easy. If not, it may do you well to contract with someone who can lay it out for you in CAD, in order to make it look accurate.

You may choose to use an oval design instead. It would make it much easier to lay out but it may or may not be as attractive.

[Bill Huber]

Well I guess now is the time to go buy a CNC machine, I am sure you could find a used one for under $10K.

Really, I would go with something like SketchUp or Visio for that or any good CAD program you can use.

I made a Sorry board not to long ago and use Visio and it worked great.

[Myk Rian]

Looks like the holes are referenced off a center point, but that point is a divided line. Maybe 2-3" across the center of the board.
Like this.

elypse.jpg

[Harry Hagan]

You could lay that out with SketchUp.

[John Coloccia]

Looks like the holes are referenced off a center point, but that point is a divided line. Maybe 2-3" across the center of the board.
Like this.

elypse.jpg

I think they're just layed out normal to the curve.

[Pat Barry]

Look up Ellipse in Wikipedia for a great explanation of ellipse construction and the discussion related to Trammel of Archimedes for a solution to placing the points on each track so they are uniform. I would use the method of construction to layout the concentric ellipses, then place the points on one track so they look right, then using the 'trammel' method to translate those points to the adjacent ellipse track. Other comments above about just getting 1/4 of the layout correct are right on.

[Mel Fulks]

If you do use CAD ,do the smallest ellipse ,then add to line . If you simply add to axis length and generate another ellipse it
will not be concentric to the other. Seen a couple of CAD guys miss that. When using trammels I have always made the
"real ellipse" the smallest one ,then scribed out with a disk with a hole in center for a pencil.

[Yonak Hawkins]

Choosing to align the holes on concentric ellipses seems right but there are two ways to do it.

You can use the same ratio ellipses, just scaled down. The problem with this is that the holes will be closer together at the long sides than on the ends and may not look uniform.

The other option is to use narrower ellipses the closer you get to the center, which may actually look uniform, as correctly sized ellipses will make the holes equally spaced, outer rings to inner rings.

[Jerome Stanek]

I did a quick DFX of this but can't upload it

[Yonak Hawkins]

I did a quick DFX of this but can't upload it

Jerome, what I do when I need to post a drawing is take a screen shot of it and post a .jpg.