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Tuesday, January 30, 2018

Townsend Kneehole Bureau - Top & Butterfly Keys Step 7

The next step is to make and mount the bureau top.  This has to be completed before I can mount the crown molding under the top.

The drawings that I have display the detail for the top edge.  It is not very complicated.  It has a filet and then an ogee and a 1/4 round on the bottom. 

I am going to see if I have some router bits to make this or else I will use my hollows and rounds.

I forgot to film when I put the molding edge on the top. So I went back and did it again on a piece of scrap.  Here I am putting a fillet and a partial ogee on the molding.  This bit makes most of the shape that I need. But it is too large to complete the shape, so I set the fence to cut it off short.

Next I need to put a 1/4 round on the bottom and at the end of the ogee.

Using the 1/4 inch round over bit I put the round over on the bottom of the molding. 

Then I raise the bit and turn the molding over and put the 1/4 round on the inside of the ogee.

And this is what you get.  This shape is what I put on the edge of the bureau top.  It matches what is on the original piece.  I put this shape on three edges of the bureau top.  Nothing on the back edge.

Here is what the top currently looks like, I had put aside a piece of mahogany when I started the project.  It is 20 inches wide by 37 inches long.  I flattened it and sanded it to 150 grit.  Then I put the molded edge on it as I just showed you.

Next thing to do is to mount it on the bureau. Townsend glued the top in the front to the sub-top and attached it in the back with butterfly keys.  I am going to use screws in the front through the sub-top and put the butterfly keys in the back like Townsend did.

You can see that I have them drawn on back.  They are two dovetail sockets.  I will saw and chop them out by hand. They are 3/4 inch wide and 5/8 inch tall, the slope is 13 degrees. They are 3 inches deep.

Using a wood block as a guide I make two cuts along the lines of the dovetail socket.  It is 3 inches long.

Then I chop out the waste between the saw cuts just like making dovetails.  I used the router plane to flatten the bottom of the socket as I got near the bottom.

Now that I have the dovetail sockets, I need to make the butterfly keys to hold it together.  I started by milling a block of poplar to the correct thickness to fit exactly in the two sockets. That would be 1 1/4 inches.

This is the shape that we are going to make with the help of the table saw. I measured the dimensions on to the block of wood.

Then I set the tilt of the blade to match the dovetail slope with the sliding bevel that I used to mark out the dovetail sockets.

First I ran it threw on one side. Turned it over and ran it through again.

I had to flip it over to get the other angles, the blade height is set to one half of the distance through the block.

That's all there is to it. If you are careful in chopping out the dovetail and making the butterfly  it should fit right in.  The key way is  1/4 inch longer than the butterfly blocks to allow for expansion of the top.  The butterflies are glued in on the sub-top but not on the top.  This allows the top to expand an contract without cracking. I cut off the excess with a flush cut saw.

I put screws in the through the sub-top in the front to fasten the top to the case after I had slipped the top on to the butterflies in the back.

The top overhangs the back by 1/2 inch to allow for the back panel.

Now that the top has been mounted I can start to work on the crown molding that goes under the 1 1/4 inch lip created by to top overhang.

Here is today's video: