Laying out for arched top doors (pics)

[Fred Voorhees]

At least this is how I accomplished it.

Fellow creeker Frank Shic asked about how to layout for an arched door top in another recent post of mine over the weekend. It’s a relatively easy process, one that I use fairly often when laying out for fishmouthed joints in metal work and other areas in my occupation as an industrial and commercial insulator. I was going to tackle this tomorrow after work, but I had some time tonight before the Soprano’s came on so, what the heck. Now, everyone follow along.

Of course, first you need to determine the exact width that you want your doors to be. In this demonstration, I am using the number of 22” as my total door width. That means that I want to set my wing dividers at 11” – or half the total door width.

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson1.jpg

With the dividers set at 11”, I then draw two lines that intersect as shown to make a ninty degree angle. The place where they intersect, we will call point A.

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson2.jpg


Place one of the legs of your dividers at point A and swing an arc from one line to the other, in effect, making a 90% arc

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson3.jpg

The places we contact the original lines with the 90% arc, we will call points B and C. At points B and C – take your dividers, at the original setting of 11” and place one of the legs on – first either point B or C and swing another arc where shown. Place the leg of your dividers on the remaining point B or C and swing again to get Point D

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson4.jpg
http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson5.jpg

As shown, above use a straightedge to draw a straight line from Point A through point D.

Now, using the width of your door framework, subtract that from your original divider setting, in my case 11” , in my case 2” – with the result being 9”.

Set one leg of your newly set dividers on point A and swing another arc.

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson6.jpg
The result will be the following.

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson7.jpg


Here I am showing the template that I used to form the segments for the arched doors that I built for my Brothers corner hutches in the other post. I also have one sample of a piece of the poplar that I milled using the template. I milled up a few extra in case of chipout or any problems along the way. Just good common sense to do so, in my case since it was the first time trying this and I didn’t know what to expect with the flush trimming and routing operations.

http://img.photobucket.com/albums/v202/Freddieboy/Message%20board%20photos/archlesson8.jpg

[Jim Hager]

Thanks for the demo. Just a little basic drafting but a good reminder none the less. I'll probably use that sometime in the future.

[Fred Voorhees]

I'm bumping this just once for the sake of Frank Shic who requested to see this method. I had informed him that I was going to post it today, but I did it last night, so he may be looking for it tonight.

[Frank Chaffee]

Fred,
I commend you on your layout method. Scribed arcs intersecting at 90° are the most mathematically accurate as well as the easiest to see for setting an intersecting line.
Frank

[Mark Rios]

This was a great tutorial. Thanks very much Frank.

May I ask a queation here, please? Why wouldn't you make half of the arch (1/4 circle) at one time instead of 1/4 of the arch (1/8 of a circle) such as you show us here? Is it to save material? Easier to work with? Or something else that my amateur brain isn't seeing? Thank you very much.

[Fred Voorhees]

This was a great tutorial. Thanks very much Frank.

May I ask a queation here, please? Why wouldn't you make half of the arch (1/4 circle) at one time instead of 1/4 of the arch (1/8 of a circle) such as you show us here? Is it to save material? Easier to work with? Or something else that my amateur brain isn't seeing? Thank you very much.
Mark, it was me, Fred, that posted that and I can answer that for you. Basically, you want to eliminate as much short grain area as possible. I think that you would say it that way. You want to orient the segments with as much of the grain running the long way of the segment instead of across it's width. They are much stronger pieces and less prone to snapping from any stress. If you take a look at the piece of poplar in the final photo in the post, you can see that the grain of the piece runs along the length rather than across the width. The more of an arc you make in one piece, the more difficult it would be to maintain this kind of grain orientation.

[Mark Rios]

Ahhhh....that makes sense. Thanks again and sorry about the name mix-up.

[Dave Malen]

Fred,
When I have a project involving arched doors I will refer to your tutorial. Thanks for posting.
Dave

[Vaughn McMillan]

Mark, it was me, Fred, that posted that and I can answer that for you. Basically, you want to eliminate as much short grain area as possible. I think that you would say it that way. You want to orient the segments with as much of the grain running the long way of the segment instead of across it's width. They are much stronger pieces and less prone to snapping from any stress. If you take a look at the piece of poplar in the final photo in the post, you can see that the grain of the piece runs along the length rather than across the width. The more of an arc you make in one piece, the more difficult it would be to maintain this kind of grain orientation.
If I learn nothing else from SMC today, that alone was worth the price of admission. Thanks Fred.

- Vaughn