Today in the shop (template with rounded corners)

[reible]

The title says today but it was really yesterday in the shop.... hope you don't mind.

A while back I was trying to make tempates for guide bushings routing and was trying to come up with a good way of making rounded corners. For a while I used a jig saw/scroll saw.... it works but it is slow. I tried drilling but sometimes you don't get the hole right where you want it....

The drilling method is by far the fastest but of course at the very least it takes more time layout hole locations, or does it?

In today's example I wanted a radius in each of the corners but wanted to not have to figure hole locations and then take the extra effort to get the hole in the exact position it needed to be. I stated with the typical way of using some cut off boards to create a "box" of the correct size as seen here:

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I selected a drill bit with the correct radius and set up to drill and using the tangent points I can locate the hole.

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Then I drill all the hole.

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To finish the job I went to the router table where I had installed a small bit with top bearing. I marked tangent points so you could visual see where I was going to start and stop routing. In real life I wouldn't even take the time but if for first timers it might help.

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Ready to route.

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Route

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Repeat and make sure you support the part that will come free on the last cut.

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Now on to removing the double sided taped on wood and sanding the edges and if you have some transition bumps get rid of them and you are done.

I'm now going to take the rest of the day off and enjoy Easter, hope you are too.

Ed

[Ed in Tampa]

Would not routing it entirely with a bit with a guide bushing and setting the scrap wood to compensate for the bushing size give you the same curved corners?

Check your pm in box

[dusty]

Would not routing it entirely with a bit with a guide bushing and setting the scrap wood to compensate for the bushing size give you the same curved corners?

Check your pm in box

You would get rounded corners but corners with what radius?? The radius of the corner is determined by the router bit and is offset by the "radius of the follower bearing minus the radius of the router bit".

I think Ed wanted a specific radius; he got that by using a specific Forstner bit .

EDITED: To include some clarification of what I I believe happens. I guess this is what JPG is saying also.

[Ed in Tampa]

Would not routing it entirely with a bit with a guide bushing and setting the scrap wood to compensate for the bushing size give you the same curved corners?

Check your pm in box

You would get rounded corners but corners with what radius??

I think Ed wanted a specific radius; he got that by using a specific Forstner bit .

I think the size of the follower bearing would determine the radius. 1/2 inch diameter bearing would produce a 1/2 inch diameter radius. I think.

[reible]

So before I answer this let's look at a what if.

What if you had just the base of the router and no guide bushing as the controlling side and then routed along a board until you reached another board at a right angle then routed along that. What radius will be created?

Keep in mind you will be half the router sub base distance away in all cases. So will you have a radius as large as that? I'll let you think on it.

Answers later today after a DR. appointment, so much later this afternoon I expect.

Ed

[JPG]

Would not routing it entirely with a bit with a guide bushing and setting the scrap wood to compensate for the bushing size give you the same curved corners?

Check your pm in box

You would get rounded corners but corners with what radius??

I think Ed wanted a specific radius; he got that by using a specific Forstner bit .

I think the size of the follower bearing would determine the radius. 1/2 inch diameter bearing would produce a 1/2 inch diameter radius. I think.

Really? That a multi-dimensional curve?

Bearing(or guide bushing) determines the limits of travel. Bit size will determine the corner radius.

[reible]

Looks like Dusty got to a sketch before I could. Thank you Dusty!

As it turns out the smaller radius can be done with just the right angle box but it has to be a common bit size like 1/4", 3/8", 1/2" the like sizes that still fit in what ever guide bushing you have. Typically that would be 1" and if you want an off set of say 1/4" then the template dictates the largest bit that can be used and what radius you can get.

The template bushing gives you the off set but the bit size will dictate the radius you end up with.

For larger radius projects then you need to employ another technique such as I have shown in this post.

I hope you are all following this. If not ask and I'll get back to you with more examples or drawing.

Ed

[Ed in Tampa]

Code: Select all

So before I answer this let's look at a what if.

What if you had just the base of the router and no guide bushing as the controlling side and then routed along a board until you reached another board at a right angle then routed along that. What radius will be created?

Keep in mind you will be half the router sub base distance away in all cases. So will you have a radius as large as that? I'll let you think on it.

Answers later today after a DR. appointment, so much later this afternoon I expect.

Ed

WELL I'll be dipped! I just proved to myself that what I thought was wrong. I took a pencil and two rules with a paper cut out and followed the rules. The radius produced was exactly the diameter of the pencil lead.
I would have sworn it would have produced a different radius but after I tried it, it was obvious I was not "thinking" it through. SORRY!
Now after embarrassing myself I will shut up on this subject.

[masonsailor2]

The simplest rule is you can't router a tighter radius then the guide bushing you are using. Even if the router base is the guide. There are times when you have to use the router base as the guide. Good example there is when you are running really large diameter bits that won't fit inside a guide bushing. A while back there was a need for someone, I think it was Ed to make a curved crown moulding for a clock. I decided to demo the concept and in doing so was using large cove bit which involved using the router base as a guide. Using the forstner bits to creat the radius was a great idea. I always try to use the largest guide that will work for the radius being routed. Larger guide bushings or bearings tend to smooth out the imperfections in the template.
Paul

[JPG]

[quote="masonsailor2"]The simplest rule is you can't router a tighter radius then the guide bushing you are using. Even if the router base is the guide. There are times when you have to use the router base as the guide. Good example there is when you are running really large diameter bits that won't fit inside a guide bushing. A while back there was a need for someone, I think it was Ed to make a curved crown moulding for a clock. I decided to demo the concept and in doing so was using large cove bit which involved using the router base as a guide. Using the forstner bits to creat the radius was a great idea. I always try to use the largest guide that will work for the radius being routed. Larger guide bushings or bearings tend to smooth out the imperfections in the template.
Paul[/quote]

Maybe!

Template, guide bushing, and bit size all(individually or in combination) will determine the smallest radius.

Ed's template had a zero radius(NO radius) therefore the bit determined the smallest radius.

With a curved template all three determine the smallest radius(template radius - guide radius + bit radius). All radii from a common center.

In Ed's case the common center was the bit center. There was no template radius center.