Routing a juice groove in an oval cutting board

[Dan Hahr]

I'm making an oval cutting board to give as a wedding gift. I'm trying to figure out how to route a juice groove so that it is perfectly concentric with the outer edge. I plan on using the three nail method to draw the oval, and I am a little concerned that the oval won't be perfectly symmetrical. My only plan is to use a round spacer to trace an offset oval around the board and cut out a template to use to register the round router base against.

Is there an easier way to cut this groove? I'm mostly concerned with cutting and smoothing a perfect concentric oval template. Any suggestions will be appreciated.

Thanks, Dan

[Martin Wasner]

Cut the groove first, set your margin with a jig of some sort to make the final size?

[Jim Morgan]

This is an opportunity for you to make (or buy if you must) an ellipse cutting jig. Once you have one, you will no doubt find other projects in which to use it. Use double-faced tape to stick the center of the jig to your blank, rout the perimeter, then adjust the jig and rout the juice channel.

[Mel Fulks]

Make a plywood ellipse a little smaller than where you want the groove. Spot glue it to your material ,you can use cardboard between them to avoid any holes from nails. Use a flute router bit and pattern bushing against pattern edge to cut groove. Remove pattern and scribe finished perimeter edge line using the groove as a guide. Bandsaw perimeter edge
and sand.

[ChrisA Edwards]

Youtube has a few good videos on how to make a fairly simple jig that would work for cutting the circumference as well as the juice groove.


https://www.youtube.com/watch?v=76ORjTIU4DM

[Mel Fulks]

Those jigs draw a true ellipse but you still need to draw ONE line and scribe any others. If the jig is used to draw two lines they will not be equidistant at all points. I draw the smallest one with trammel then scribe out using a disk with a hole in center for pencil point. Easy to make a big door frame with glass, casings, backbands that look right until assembled!!

[keith micinski]

Why not just cut the outside and then put the fence on the router and set it at about 2” and just follow the perimeter?

[Pat Barry]

Why not just cut the outside and then put the fence on the router and set it at about 2” and just follow the perimeter?

I would use this method. Simple and pretty foolproof.

[Dan Hahr]

I don’t see how that would work with a changing curve. Is there a mathematical formula that would define two concentric ovals or ellipses? I could make a jig like in the video, but how would you find the measurement between the pins that defined an oval 22” by 16.5”?

Dan

[Jim Morgan]

I don’t see how that would work with a changing curve. Is there a mathematical formula that would define two concentric ovals or ellipses? I could make a jig like in the video, but how would you find the measurement between the pins that defined an oval 22” by 16.5”?

Dan

For the perimeter, measure 11" from the (inside) edge of the bit to one pin and 8.25" for the other.

[john bateman]

I think I would make the oval tray first. Then hot glue a rough cut oval, slightly smaller, of tempered hardboard to your tray.
Next use a bearing guided rabbet cutter to trim the hardboard to match the perimeter of the tray, only smaller.


Then use a V-groove bit inside a pattern collar, following around the edge of the hardboard.

[Mel Fulks]

I agree with Dan's caution. Yes,it's a cutting board. And a WEDDING GIFT.

[john bateman]

I pictured the wrong guide collars for use with thin hardboard.
They would need to be shallow like these:

[Cary Falk]

I say your only 2 options are an elipse jig or a template.

[keith micinski]

How is going through trouble of making a template the exact same shape but smaller, and attaching the template exactly centered in all directions and using it as a guide to ride against any easier then using the outside edge as a guide? For me centering ovals is always the trickiest part of an oval. The only tricky part of using the outside edge is maintaining the router 90 degrees to the edge but it’s actually not that hard to do at all. At least not any harder then making sure your template is in the right place, the exact right shape, and your guide does the same exact thing on the inside edge.

[Mel Fulks]

Keith, you might well be able to hold the router exactly oriented. I've seen some attempts that were failures. It's a lot easier to do a circle like that than an ellipse. What I suggested requires one plywood template with one edge, elliptical casings routinely
need two edges and one of them has to be scribed from the other as the jigs will not make two equidistant edges.

[Eduard Nemirovsky]

If you already create outside edge, why not use an edge guide with your router, something like this - https://www.youtube.com/watch?v=QHQxPkIVfT4. Check about 1 minute in the video.
Ed.

[Roger Feeley]

what if you cut a template in the negative. An eliptical hole in a larger piece of wood that is 1/4" larger in all dimensions than the desired size. Using a core box router bit and a very large bearing, cut the groove first. Then, using a 1/4" pattern bit, plunge right next to the template and cute the board out of the larger piece. You are using one reference template with no alignment change. I wouldn't cut all the way through on that last step. Leave a 16th of in inch holding it together and saw it apart. A little sanding and then a roundover bit would clear away the flash.

Cutting the part away would be the tricky part of this. If the router moves away from the template, it's eating the part you want, not the waste.

Can you get bearings that big? Hmmm... I just googled it and Infinity has a set. https://www.infinitytools.com/routing/router-arbors-bearings/16-pc-ultimate-router-bit-bearing-kit (https://www.infinitytools.com/routing/router-arbors-bearings/16-pc-ultimate-router-bit-bearing-kit)
They have cheaper sets. Just noodle around.

So my suggestion is not to cut the oval and then try to cut the groove. That's hard. My suggestion is to cut the groove and then cut the oval. The key is to use a single reference for both operations.




(https://www.infinitytools.com/routing/router-arbors-bearings/16-pc-ultimate-router-bit-bearing-kit)

[Andrew Gibson]

I like using an edge guide with a couple dowels glued to it.
395513

[keith micinski]

Most guides have the cutout in the middle positioned in such a way that the two inside edges do the same function as the dowel pins do, I forgot to mention that in my post but the dowel pins is a much more secure way to do it and a really good idea.

[Dan Hahr]

I ended up going with a temporary edge guide attached to the base. I cut a curved edge with two points to act as dowels. I had to space them relatively close, 1.5 inches apart, so that the distance from the groove to edge didn’t change noticeably around the different curves. I used a full size router and had to have my son turn it for me as I went around it so I could always keep pressure on both points. It worked very well as I took light cuts and made several passes. Thanks for all the suggestions.
Dan