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 Entertainment Center Credenza Design and Construction |
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We decided that, sometime in the next several months, we'll replace a 48" projection TV in our family room. So, the question arose about what to put a new flat screen TV on when the time comes. After considering some options, I started drawing plans for a credenza style cabinet. Over a period of a few weeks, I settled on a design with input from my wife.
This page will document the
process of designing and building the credenza. Its basic
dimensions are 74" long by 20" deep by 24" high and will have a radius
front. Solid wood components will be mahogany; door panels will be covered
with sapele pommele veneer and the field of the top will be bubinga veneer.
When completed, it will hold a 55" LCD flat screen on top with other
equipment on shelves below.
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| Concept | |||
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This is a graphic representation of our family room wall where the credenza will be located. For reference, a 55" LCD TV is shown for scaling, but a 60" could be used. The cabinet height of 24" will place the center of the TV screen just above eye level as seen from the sofa across the room. | ||
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Here are graphic views of the top, front and end of the cabinet. It's about 20" deep in the middle and about 12" on each end. The radius front design will reduce its footprint and add interest to the design. | ||
| Bending Form | |||
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To ensure that all bending form ribs are identical, I made a routing template from 1/4" plywood. | ||
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The routing template is 3/4" longer at each end to guide the bottom-bearing router bit onto the bending form rib material. This keeps the bit from rounding the corners of the rib. I use a spiral upcut bit for this type of operation so the dust and chips are drawn into the collection box below the router table where they are extracted by my dust collector. | ||
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This is a completed rib. Twelve will be needed to build the bending form as planned so it will support the pressure of a vacuum pressing system. I use a moderate amount of vacuum on my system and still achieve a clamping pressure of 1440 pounds per square foot. | ||
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Here's the bottom view of the assembled bending form showing the ribs. They are held in position with three strips of 1/4" plywood across the bottom and 3/4" thick MDF strips between the ribs. The overall size of the form is 18" wide by 5.5" high by 36" along the radius. Continuous radius components, such as the apron, will be built up of multiple segments in lengths of about 28". All other components will fit completely on the form. | ||
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This side view shows an outside rib and the top of the form. The top is made from two pieces of 1/4" plywood glued to the form and to each other. This form has a radius of 83", so 1/4" lauan plywood is flexible enough to match the radius. For tighter radii, one would use 1/8" bending ply. The plywood top was pressed into position and held there by placing the assembly in my vacuum bagging system. | ||
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Addition of a layer of formica to the top of the form ensures that any adhesive that squeezes out of parts being formed does not stick to the form. All edges and corners of the form are sanded to smooth them so the plastic bag doesn't get punctured. We're ready to make some bentwood now! | ||
| Forming the Radius Parts | |||
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The first thing I wanted to form the radius on is the top and bottom rails for the four doors and segments of the top apron. I used mahogany that was resawed and planed to 1/8" thick pieces. Six of these will make the 3/4" thickness of the rails. | ||
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The resawed mahogany needs to be cut into slightly oversized lengths for each of the components. I marked the lengths on the top strip and labeled them before I made the cuts. | ||
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Here are the individual stacks of mahogany strips after I cut them to length. Next, I'll apply adhesive to both sides of strips that face each other to ensure there is adequate coverage. As a matter of convenience, I'm pressing two sets of strips at a time. Each set will make two components by sawing them along their length to produce 1.5" wide pieces. | ||
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This is a view
of the first two sets of mahogany strips in the vacuum pressing bag.
The bag will remain under vacuum for several hours to ensure that the
adhesive sets up properly. Note: For these components, I'm using a PVA glue (Titebond II). For projects that require a tighter radius, I prefer a plastic resin glue because it sets up harder and will cause a component to retain a radius better. |
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The first two sets of radius parts have been in the bag for several hours, so I turned off the vacuum and removed them. You can see that they now have the desired radius. | ||
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This is a photo of all four sets of mahogany strips after vacuum pressing. Each set will be cut along its length to make a total of eight parts. Then, four of those will be crosscut to make the lengths necessary for the four doors. | ||
| Making the Top Frame and Panel | |||
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This is a mahogany board I chose to make the frame for the top of the credenza. I ripped it to the widths needed for the curved parts on the front as well as the straight piece for the back. | ||
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Patterns will make it easy to cut the curved parts. In my design file on my computer, I divided the long, front curved piece into three components to reduce waste of the wood. | ||
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Each component that makes up the curved front rail has been identified on the board prior to cutting. | ||
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Now I have five smaller pieces to work with. Three will form the front curve; the other two are straight side pieces. | ||
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The first step in milling an individual component to final shape is cutting the miters while it's still straight and square. | ||
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The bandsaw is used to cut the curved pieces using the paper pattern as a guide. | ||
| This page will be updated as work progresses on the build of the credenza. | |||