# Is this impossible?



## aaronhl (Jun 2, 2011)

I would like to make two round (oval) cuts into a square piece of wood. Each cut would be 1/8" wide x 1/8" deep and each corner curved. Please refer to the diagram below because it's a little hard to explain. The cuts are the two thicker black lines.

I have made these cuts on a table saw when mitering four pieces, but each corner is square, not curved.

Is it possible to do this with a solid piece of wood?

Thinking I could do this on a router but don't know where to start! Would this be an inlay project with a template?










Thanks,
Aaron


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## cabinetman (Jul 5, 2007)

I would use a router and make templates.












 







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## Kenbo (Sep 16, 2008)

I'm thinking a hand held router with a guide bushing. You could make a template and router the grooves by running the router around your template. A simple solution but possibly an effective one.


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## aaronhl (Jun 2, 2011)

What type of 1/8" router bit would I use? I have a plunge router, but unsure how I would start the cuts. Do I need to make both sides of the template? I would have to keep an eye on lining the bushing up with the template when starting. Seems like if the router moved a hair the cut would not be straight. I have only done hinge rebates before where I start on the outside, follow the template and rout the whole inside. This is more of just a line.


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## aaronhl (Jun 2, 2011)

Is there a name for this type of cut?


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## Kenbo (Sep 16, 2008)

If you are looking for a 1/8" bit, I would suggest one like these.
1/8" router bit.


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## aaronhl (Jun 2, 2011)

Interesting...now would I start the continuous circle by holding the template bushing against the template and plunging into the wood?


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## jschaben (Apr 1, 2010)

aaronhl said:


> I would like to make two round (oval) cuts into a square piece of wood. Each cut would be 1/8" wide x 1/8" deep and each corner curved. Please refer to the diagram below because it's a little hard to explain. The cuts are the two thicker black lines.
> 
> I have made these cuts on a table saw when mitering four pieces, but each corner is square, not curved.
> 
> ...


 
Not sure, you looking for something like this with rounder corners?










Those were done with an 1/8" radius plunge roundover bit. Hard to see because of the black but it is actually a bead. Made two parallel passes 1/4" apart. Put guide strips around the outside edge, made one pass with a 1/2" bushing and the second pass with a 1" bushing. Didn't change the bit. To round the corners would just need to change the guide strips to put quarter circles on the corners.

To get the oval shaped grooves, I think a 1/4" roundnose at an 1/8" depth of cut should do it..


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## Kenbo (Sep 16, 2008)

aaronhl said:


> Interesting...now would I start the continuous circle by holding the template bushing against the template and plunging into the wood?


 
I would make the template so that you are running the router around the inside of the hole. Use a bushing that is large enough to have you bit's honed edge pass right through it. Make sure that you compensate for the size of guide bushing when making your template. Hold the router with the guide bushing firmly against your template, turn on your router and plunge into your material. Carefully run your router around the inside of your template and raise the bit. Should provide some pretty good results.


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## aaronhl (Jun 2, 2011)

I come to you guys because you know what you're talking about!!!!!



> made one pass with a 1/2" bushing and the second pass with a 1" bushing.


 So the bit was the same but required you to remove the bit and insert the other one with the larger diameter bushing? Is it possible to get a thicker template bushing? That way I would only need to make one template.



> Use a bushing that is large enough to have you bit's honed edge pass right through it.


 What do you mean? Use a template bushing designed for the correct diameter bit?


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## jschaben (Apr 1, 2010)

aaronhl said:


> I come to you guys because you know what you're talking about!!!!!
> 
> So the bit was the same but required you to remove the bit and insert the other one with the larger diameter bushing? Is it possible to get a thicker template bushing? That way I would only need to make one template.
> 
> What do you mean? Use a template bushing designed for the correct diameter bit?


Last question first. What do you mean? Use a template bushing designed for the correct diameter bit
Not necessarily, just make sure the ID of the bushing is larger than the cutting diameter of the bit.:yes:

I didn't remove the bit nor mess with cutting depth. Just changed the bushing. However, that worked for me as I was doing square corners. You have two radii involved. The outer groove has a 1/2" radius and the inner a 1/4" radius. The attached drawing assumes a 3/8" guide bushing, a 1/4" diameter bit and the template/guide strips around the outside of the pattern. Dimensions will change if any of the assumptions change:smile:


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## aaronhl (Jun 2, 2011)

OK, I'm going to try this soon and report back. Thanks for the bushing tips, I think that will help me a lot!


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## clampman (Oct 20, 2006)

> Not necessarily, just make sure the ID of the bushing is larger than the cutting diameter of the bit.:yes:


Usually true, though not exactly in this case. The cutter he's using will be a 1/8" diameter on a 1/4" shank. So his bushing - if he uses one - will have to be bigger than the shank diameter and will likely have a 3/8" OD or perhaps more depending on manufacturer.

My largest bushing I can find is 1 1/8" OD. This spread will result in grooves about 3/8" apart, center to center. I do not think you will like the results because I really don't think you want concentric rounds with that great a percentage difference in diameter between them. Your picture shows closer to the same diameter rounds. 

I would use only one bushing and two templates. If you do want the rounds closer to cencentric then do use two bushings, but still use two templates. If you do want them 3/8" or less apart then use one template with two bushings.

It is no big deal making a template. All you need is a rectangle cut on a table saw (or whatever you have) and make it exacly the length and width you want the center of the groove minus the OD of the bushing.

Draw an "X" corner to corner on whatever you are routing before you start - to make clamping/screwing/ double-stick taping, the template properly easy. Do the outside routs first, then rip the template down and do it again for the inner one - or for concentric ones, skip the ripping and just change the bushing.

To draw them before routing, go to the hardware store and buy bunch of washers of different sizes. stick a square block of wood on some paper, a pencil in the washer hole and draw around the corner of the board. That will give you a visual without a bunch of diddling around buying stuff and wasting material.

Cheers,
Jim


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## aaronhl (Jun 2, 2011)

Concentric meaning each curve is the same diameter? If so, than you're right since each curve will be a different diameter in order to keep the equal distance.

What do you mean by "All you need is a rectangle cut on a table saw"? Would the template be a piece of wood with a square cut in it? Or a square piece of wood?

Thanks for the washer tip!


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## jschaben (Apr 1, 2010)

aaronhl said:


> Concentric meaning each curve is the same diameter? If so, than you're right since each curve will be a different diameter in order to keep the equal distance.
> 
> What do you mean by "All you need is a rectangle cut on a table saw"? Would the template be a piece of wood with a square cut in it? Or a square piece of wood?
> 
> Thanks for the washer tip!


Hi Aaron - let me back up a bit. I had to read clampman's post a couple of times myself to figure it out. 
Basically there are two general types of templates, male and female. A male template, you run the router around the outside of, female template traces around the inside of the cutout. I was talking, and so were you, about a female template. A board with a hole in it. 
Clampman is referring to using male templates and he is correct in that they would be much easier make and likely much easier to handle the corners with. 
Assuming you will be using a 1/8" bit with a 3/8" bushing, all you would need would be a square template, 1/4" smaller than your proposed outline in both the X and Y directions. You can handle the corners by simply marking the corners radius you want and using a belt sander to round the corners to your mark. 
If you do the outside one first, you can simply rip that one down to the correct size, do the corners again and you're good to go. 
Just two things to watch: When you place the second template, it need to be placed EXACTLY right or your second pass will not be concentric. You should also place support strips around the work piece equal to the thickness of the template plus the workpiece to help support the router and prevent tipping. Actually, steps to avoid tipping should be taken irregardless of the type of template.
Hope this helps:smile:


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## aaronhl (Jun 2, 2011)

John, thanks for all your help! Thanks for clarifying the male/female templates. I didn't realize you can do so much with a router...glad I bought one!

I am going to try this as soon as I order the 1/8" core box bit. You guys have been more than helpful!!! Wish I could give back, but I can't teach the professionals!!


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## jschaben (Apr 1, 2010)

aaronhl said:


> John, thanks for all your help! Thanks for clarifying the male/female templates. I didn't realize you can do so much with a router...glad I bought one!
> 
> I am going to try this as soon as I order the 1/8" core box bit. You guys have been more than helpful!!! Wish I could give back, but I can't teach the professionals!!


Professional!!! hahahahahaha. hardly, have had to do at least my share of fumbling around with this stuff. Glad to help though.


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## clampman (Oct 20, 2006)

> You can handle the corners by simply marking the corners radius you want and using a belt sander to round the corners to your mark.


NO! 

The male template will be exactly as I said, a rectangle with 90 degree corners. The radius will depend on the diameter of the template bushing.

Do as I said and stick a pencil in some washers and pretend the outside edge of the washers is the outside edge of the template bushing.

You cannot go around a square corner with a template bushing in a router (or run a router base around one either) and wind up with a square corner groove. 

Actually, grab a quarter or a nickle right now and roll it around the corner of a book or something. Pretend a bit is spinning in the middle. You will see what I'm talking about.


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## clampman (Oct 20, 2006)

Aaron,

Concentic radii are like the ones John drew. The one on the outside has a large radius , the one on the inside has a small radius. To do that you need two different router bushings and the same template in the same position.

If you would like the same radius on the outside groove as the inside groove, you just rip down the template and use the same bushing.

That is why I said to get a selection of washers, so you can try different ways on paper to see which one you like the best. There are an infinite number of proportions to do what you are doing.

I often made numerous mockups for architects before finally building what they decided on. Slight changes in proportion can make a big difference in appearance.


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## jschaben (Apr 1, 2010)

clampman said:


> NO!
> 
> You cannot go around a square corner with a template bushing in a router (or run a router base around one either) and wind up with a square corner groove.


:icon_redface: Right - the inside corners reflect the bit radius, outside corners reflect the bushing radius given square corners on the template.... damn,,,, these things always give me a headache.....
Sorry.


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## clampman (Oct 20, 2006)

John,

Don't feel bad, I confuse myself all the time. If you'd have watched me a couple weeks ago trying to test fit a 1/4" plywood template for a bolt- on transom bait tank, you'd have thought I was a dyslexic village idiot. I finally got a huge magic marker and labeled the thing.


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## jschaben (Apr 1, 2010)

clampman said:


> John,
> 
> Don't feel bad, I confuse myself all the time. If you'd have watched me a couple weeks ago trying to test fit a 1/4" plywood template for a bolt- on transom bait tank, you'd have thought I was a dyslexic village idiot. I finally got a huge magic marker and labeled the thing.


Hi - The upside is that I likely won't screw that up again. One of the great things about a good forum :thumbsup:


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## clampman (Oct 20, 2006)

John,

Yes, the internet can be a wonderful thing. One of the disadvantages of using the female template with different diameter bushings is that with a large bushing and a not so large radius cut in the template, you can wind up with a short arc and not a quarter circle. To the extreme end, say a 1" radius in the template and a 1 1/8" bushing, there will be no radius at all except that of the cutter itself.

The disadvantage to the template I suggested for Aaron's job is that with large bits and deep cuts, the router can get away from the operator if he is not experienced. With his little veining bit and shallow cut that won't be a problem.

I put up a series of 3 videos on the video index page of my website on drawing, making a jig for, and cutting elipses the easy way with a router, virtually infallable. 

I used to do a lot of eliptical cased openings and it was easier for me to simply make the casings too instead of having to sub it out, then hope they were correct. I had to do the framing and jambs anyhow.

In making the casings, I discovered that there is no such creature as concentric elipses. You can make them close - but no bannana. I had an idea of how to modify the jig to get the outside cut very, very close with the router on one shot , but never got around to doing it. 

The videos will, however, show how to cut forms for both the jamb and inside edge of the casing. I never got around to showing how I do the outside edge. Life keeps happening to me. 

Cheers,
Jim


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## paragonremodeling (Sep 27, 2011)

This will be good project template.


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