# Making a Matching Radius on a Piece



## Flutemaker (Aug 18, 2012)

I have cut a groove 3/4" wide 1/8" deep in a piece of wood with a 3/4" straight router bit. So both ends of this have a radius or round where I stopped. I need to make a matching piece to fit fairly perfect in this groove.I can rip a piece the right width but how do I make the radius or round end? I tried cutting and then sanding but I was wondering if there is a better or simpler way.


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## Stick486 (Jan 4, 2013)

square the radius..


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## harrysin (Jan 15, 2007)

Photos 6 & 7 of this pdf show how I made a simple jig for rounding ends of stool legs which made them all identical. I'm sure that it would be easy to adapt this idea for your needs.


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## RickKr (Dec 30, 2018)

harrysin said:


> Photos 6 & 7 of this pdf show how I made a simple jig for rounding ends of stool legs which made them all identical. I'm sure that it would be easy to adapt this idea for your needs.


Nice jig work. I love jigs. They are a big part of the fun, figuring out how to hold and manipulate parts to achieve a goal. I did something quite similar for sanding gears to the desired radii recently. The jig had multiple holes for the center pin for the four different sizes I was making. 

The base plated was adjustable for setting the "final" distance of the center pins from the sanding belt. The upper plate rotated in the slot to allow progressively reducing the radius until the end of the slot was reached, which set the final radius. The radii of the gears were a consistent 1" apart. 

Mike's situation may be different in that he may not want a hole in the ends of his piece. That would require making a jig that would rotate but where the part to be sanded would be captured without using a pin/center hole. 

The base on which the part to be rounded is clamped would have to rotate on some sort of pivot point. The part to be rounded would need to be clamped on that pivot plate such that the end of it was centered over that pivot point. The whole assembly would need some manner of bringing the pivoting plate/part closer to the sanding disk/belt as the radius is sanded down. 

Nice challenge. Please keep us posted on your progress.

Rick


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## JIMMIEM (Apr 4, 2010)

Another option is to route a 3/8" radius on the corner of a template and use the template to route the radius on the ends of your inlay piece. The template piece needs to start with a 90 degree corner. Measure 3/8" down each edge and make marks there. Draw lines perpendicular to the edges. Where the lines intersect drill a small hole....this will be the pivot point. Put a sacrificial piece under this template piece and clamp it to your router table. Drill a hole in the sacrificial piece (don't drill all the way through) the same size as you made in the template. Put a small nail or flat end of a drill bit through the template and into the sacrificial piece. Position the router bit and fence so that the fence will stop the template as it is rotated counter clockwise into the router bit creating the radius. Attach radiused template to your inlay piece and use a flush trim or pattern bit to transfer the radius.


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## Flutemaker (Aug 18, 2012)

Thanks everyone..I believe I can work this out now.


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## Cherryville Chuck (Sep 28, 2010)

Along the lines of what Jim said. Buy a length of 3/4 dowel rod at the hardware store. Cut a straight piece for a template that is 3/4" wide, same as the groove. Cut a slice off the dowel rod the same thickness and then cut it in half and glue that half to the end of the straight piece for your template. Now you can clamp it to your runners and use a flush trim or pattern bit to round the ends. Nip the corners off the end of the runners first and that will make it easier to rout.


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## Flutemaker (Aug 18, 2012)

Oh gosh I love this...I have never used a pattern making bit...Love learning new stuff...Thanks!


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## harrysin (Jan 15, 2007)

JIMMIEM said:


> Another option is to route a 3/8" radius on the corner of a template and use the template to route the radius on the ends of your inlay piece. The template piece needs to start with a 90 degree corner. Measure 3/8" down each edge and make marks there. Draw lines perpendicular to the edges. Where the lines intersect drill a small hole....this will be the pivot point. Put a sacrificial piece under this template piece and clamp it to your router table. Drill a hole in the sacrificial piece (don't drill all the way through) the same size as you made in the template. Put a small nail or flat end of a drill bit through the template and into the sacrificial piece. Position the router bit and fence so that the fence will stop the template as it is rotated counter clockwise into the router bit creating the radius. Attach radiused template to your inlay piece and use a flush trim or pattern bit to transfer the radius.


You mean something like this?


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## harrysin (Jan 15, 2007)

RickKr said:


> Nice jig work. I love jigs. They are a big part of the fun, figuring out how to hold and manipulate parts to achieve a goal. I did something quite similar for sanding gears to the desired radii recently. The jig had multiple holes for the center pin for the four different sizes I was making.
> 
> The base plated was adjustable for setting the "final" distance of the center pins from the sanding belt. The upper plate rotated in the slot to allow progressively reducing the radius until the end of the slot was reached, which set the final radius. The radii of the gears were a consistent 1" apart.
> 
> ...


A suitable panel pin would leave a tiny hole easily filled in.


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## JIMMIEM (Apr 4, 2010)

harrysin said:


> You mean something like this?


Yes. But, after thinking about it some more as I was going to sleep last night Cherryville Chuck's idea of the 3/4" dowel dawned on me. When I logged on this morning I saw that he had posted the dowel idea.


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## Tagwatts (Apr 11, 2012)

*Knowledge abounds*

Mr. Harry Sin, 

I am going straight to Hell without a doubt. Here I am an old man now and I can hardly cut a board straight and you have all this knowledge right on the tip of your tongue. Someone asks a question and bang, here is your answer. I not only envy this ability and a colossal amount of information that lives with this enigmatic mind. To envy is one thing, but I covet this. 

Great Job and I for one appreciate what you provide and the manner in which you do it. 

Tagwatts


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## Cherryville Chuck (Sep 28, 2010)

JIMMIEM said:


> Yes. But, after thinking about it some more as I was going to sleep last night Cherryville Chuck's idea of the 3/4" dowel dawned on me. When I logged on this morning I saw that he had posted the dowel idea.


You provided the germ of the idea.


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## Flutemaker (Aug 18, 2012)

I was thinking is there a way to do this without using a pattern bit or flush trim? I will get one but at the moment I dont have one.Probably have to order one. Just thinking.


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## harrysin (Jan 15, 2007)

Tagwatts1 said:


> Mr. Harry Sin,
> 
> I am going straight to Hell without a doubt. Here I am an old man now and I can hardly cut a board straight and you have all this knowledge right on the tip of your tongue. Someone asks a question and bang, here is your answer. I not only envy this ability and a colossal amount of information that lives with this enigmatic mind. To envy is one thing, but I covet this.
> 
> ...


I think that you're exaggerating Frank but thanks anyway for the compliments. You really do undersell yourself, I've seen some of your work and I've complicated you on it. Being in a new year, it's a good time to develop confidence in your projects.


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## Cherryville Chuck (Sep 28, 2010)

Flutemaker said:


> I was thinking is there a way to do this without using a pattern bit or flush trim? I will get one but at the moment I dont have one.Probably have to order one. Just thinking.


I often just sand them round by hand and by eye but I do it on a large vertical belt sander by rotating in an arc while I hold the end against the belt. If you had a disc plate to put on your saw you could do the same thing. Only other easy way with virtually no tools would be to mark the curve on the end, nibble away with a saw to get close, and then rasp the remainder. Yonico has some good deals on pattern and flush trim bits at precisionbits.com


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## Flutemaker (Aug 18, 2012)

I bought a router bit today.Now to find some extra time! Thanks everybody!


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## JIMMIEM (Apr 4, 2010)

Cherryville Chuck said:


> You provided the germ of the idea.


You're just being kind to me. Probably should have just counted sheep instead of thinking about ways to accomplish wood working tasks.


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## RickKr (Dec 30, 2018)

As I work on a rug loom for my daughter, I was presented with the need to round the ends of the uprights that hold the loom. I thought of the method mentioned here about using a pattern to rout the raduis on the ends. Pieces are 3/4" thick pine and had planed to 2", within a hair (defined as +_ 0.002" by my pattern making friend) wide and had a 1/4" hole in the center and 1" from the end. 

Based on how I could secure the pattern to the stick, I turned one disk from 1/2" thick MDF to 2" within a hair. I needed another MDF spacer down the stick a little for support on the router table and fortunately there is another 1/4" hole, 6" away. I used the same furniture bolts that will be used in the assembly and counterbored space for the heads. 









I used the pattern disk to draw the radius and then lopped off the corners on the bandsaw. 









The first stick radiused and the second set up and ready. 









The finished radiuses. The bit burned the edges a little (actually "browned" them is more accurate), so I must have been going too slow, but even thought there wasn't that much stock to be removed, I didn't want to go too fast. I guess that is a "feel" that I have yet to learn. Sanding cleaned them up pretty quickly so they were not burned very badly. I didn't want to bother setting up the corner rounding bit again, so I "manually" corner rounded the radiuses. 









I probably could have done this faster just sanding the radiuses to the lines, but this way was a lot more fun. I've had the new router and table for only two weeks but am pleased with how many things I've been able to use it for. 

Rick


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