Complicated Oval Inlay Question?

[Shamrock]

Here's a question for all you gifted woodworkers, engineers, mathematicians, and just all around bright and talented folks. How would YOU cut out this oval and then inlay?

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Obviously I did it but I am not happy with my ability to repeat the process again. I'm looking for a better more repeatable way. Here's what I did and the problems I had.

1st I made an ellipse cutting jig and cut the 1st "template" ellipse with my router:

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Knowing that I would have to contour the underside of the template to match the curve of the serpentine front on the apron I used the 1st template to transfer the ellipse to a thicker piece of wood I could then contour the back of:

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View image in gallery​

At this point the 2nd template was flat on the top. With a flat top the template would not transfer evenly to the apron as the thickness of the template varies as it follows the curve of serpentine apron. So the bit would cut fine in the center but not at all on the edges:

View image in gallery​

View image in gallery​

So I contoured the top of the 2nd template to also follow the curve of the serpentine front. I then went ahead and cut the ellipse into the apron. The BIG PROBLEM here was that as the router was riding the VERTICAL walls of the template it also started to tilt as I followed the contoured shape and this caused the bit the be in contact on the top of the template but actually cut about 1/8 inch inside of the template. Hopefully you can see what I'm talking about in the pictures

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View image in gallery​

So folks... what's the right way to do this? I've talked with a few different folks that say the walls on the template would have to angle in to follow the angle as it changes with the serpentine front. How do you cut that?

How would you do it-- tell me all your secrets:gar-La; I'm just confused

 

[Gotcha6]

Try making your template in a piece of Carter Flex. This a rubberized product that can be cut and sanded like wood. It's used to make mouldings for curved walls. It should then bend to conform to the curve of the workpiece. You may want to make some sort of collar to keep it from flexing in the 'y' axis. I've bought this product in 5-1/2" x 3/4" x 12' rolls & molding profiles are also available at Stewart Enterprises in Mineral Springs.

 

[mshel]

What about freehanding it with your router setup, clean up with a chisel.

 

[mkepke]

What Dennis described is the approach I'd use for a template.

But given that this is just one inlay, I'd probably just freehand it.

All of the stars in this crib are freehand. Almost necessarily so because they are set in curved head- and foot-rails. The curvature is different for most of them.

-Mark

 

[striker]

Mike,

Having never done exacting what you're attempting I might be completing off base here but anyway....

My thought would be to make the oval template in the flat in some pliable material (thinking like 1/4 thick) that would conform to the curvature when clamped in place. Making it in the flat then bending will ensure the guide edge of the template is square to the cut surface. Make it plenty oversize so clamping in place would not interfere with the router.

Add 2 dowels equidistant from the bit and parallel to one another on the base of the router. The dowels hold the base off the template and allow the the router to travel square to the surface (like a car traveling over a hill). The router must be held in the same X-Y plane as you make your way around the oval.

Good source for stubby length endmills that fit dremel w/Stewmac:
http://www.drilltechnology.com/sapfm.html

I hope this isn't too confusing....

Stephen

 

[Shamrock]

Thanks everybody for the ideas, everybody seems to agree on the bendable material option. I've also heard to make the template flat and then kerf the back so it bends to conform. I think this is the way to go because then the walls will stay vertical to the piece to be cut.

The dowel idea with the router base is cool too

I like the material Dennis suggested and was wondering if the heat from the router bit might melt the material?

Freehand could be an option also, this was the 1st time I had ever cut an ellipse though and it was actually just as easy to cut a template with the router as it was to draw one. I made my own ellipse cutting jig and realized after looking at all the ones sold on the market their follower pins(guides) are all dovetailed and I learned why after having my router move every so slightly when it came through the x-y intersection.

Again thanks for the ideas I think I've got a good handle on the situation now.

 

[Larry Rose]

Ditto with the free handing. Its much quicker.