There's nothing magical about a tambour. It's just a sliding door that's flexible. This flexiblity allows the tambour to slide in a curved track.
The way to make a tambour flexible is to join a series of individual slats with some sort of flexible hinge. The most common method of hinging these slats is to glue them to a fabric backing.
But, there's more to making tambours than just gluing fabric to wood. In fact, making the tambour is the easy part — the tricky (and interesting) part is designing it. • I've seen tambours with vertical slats that move side-to-side and tambours with horizontal slats that move up-and-down. Is one way preferred over the other?
As far as construction goes, both of these tambours are made exactly the same way. So the choice between using vertical or horizontal slats in a tambour is determined by the design of the project and the amount of space you have to work with.
design. The design of the project will often determine the way the tambour moves. For example, if you're making a traditional roll-top desk the tambour typically moves up-and-down. On the other hand, if you're making a cabinet that's wide but not very tall (such as the CD Case on page 6), it looks better if the slats are vertical (the doors slide side-to-side).
space. Another thing to consider when determining which way the tambour moves is the amount of space you have. When you open a tambour door it doesn't just disappear, it has to go somewhere. This means a loss of space inside the cabinet, either on the top, sides, on maybe even the bottom. Also, any interior dividers, shelves, or partitions have to be designed so they won't interfere with the way the tambour operates.
• It seems that every large roll-top desk that I've seen has a gentle S-shaped curve to the tambour. Is there some reason for this S-shape?
It has to do with the width of these desks, most of which are four to five feet wide. If the tambour were to angle straight back, its weight would cause it to sag over such a long span. But, by curving the tambour it will resist sagging.
• Are there any sjjecial characteristics of an S-shajied tambour?
Yes. an S-shaped tambour has to bend forward as well as backward, see Fig. 1. In order for an S-shaped tambour to work, the slats must be designed so they don't pinch together when bending forward. This can be done by cutting the edges of the slats at an angle to create a V-shape between the slats. This allows clearance when the tambour bends forward, see Fig. la.
SINGLE Cl'RVE. Making single-curve tambours is easier. (This is the type I used on the CD Case.) With a single curve, the tambour always bends in the same direction — back on itself. So the edges aren't relieved.
• I need to make a tambour that follows a tight curve (small radius). How do I know the tambour slats will slide through it without binding?
A tambour is a two-part system — the tambour slats are one part, and the grooves the slats slide in are the other part. The trick is making sure both parts work together.
The simplest way to do this is to draw everything on paper first. Start by determining how wide the groove needs to be. Since the groove will most likely be cut with a router in one pass, the width of the groove is limited to the size of the router bit. So you have to match the size of the slats to the size of the bit (groove).
Design Note: If you need to use thick slats but don't want to make a wide groove, the ends of the tambour can be rabbeted.
After determining the width of the groove, draw the curve that you need the tambour to follow. Now here's where things get interesting. To get the slat to follow the curve, you have three variables to work with — width, thickness, and profile.
width. The first variable is the width of the slats. While you can make a wide-slat tambour follow a tight radius, it won't move sm<x>thly. The rule of thumb is: the narrower the slat the tighter the curve, see Fig. 2.
thickness. Once you've determined the width of the slats, the next thing to consider is the thickness of the slats. First, the slats need to be slightly narrower than the width of the groove. If they're the same size as the groove they won't fit around the curve, see Step A in Fig. 3.
But, if the slats are made loo thin they will rattle around in the straight sections of the groove. I've found that if the thickness of the slat is Vi6" less than the width of the groove, it's just about right for most tambours.
profile. The final consideration for getting the tambour to follow the curve is its profile. Profile refers to the way the slat looks when viewed from the end. This is usually a chamfer or a routed round-over (like on the CD Case).
Without the routed profile, the edges of the slats can bind against the outside wall of the groove, see Step B in Fig. 3. But, by routing a profile on the edges, the same size slat will track smoothly through the groove, see Step C in Fig. 3.
The more I work with tambours, the more I realize the importance of careful planning. Because the challenge is making a tambour look good and work properly.
TAMBOUR TO BEND FORWARD
TAMBOUR TO BEND FORWARD
wide slats J work better with a gentle curve wide slats J work better with a gentle curve narrower > slats will work around a tight curve narrower > slats will work around a tight curve
A THOUGH SLAT WILL FIT IN STRAIGHT SECTION OF GROOVE, IT'S TOO WIDE AND/OR TOO THICK TO GO AROUND CURVE
B THINNER SLATS WILL GO AROUND CURVE BUT SHARP EDGES MAY CAUSE THE SLATS TO BIND IN GROOVE
C ROUND OVER OR CHAMFER EDGES FOR SMOOTHER TRACKING IN THE GROOVE
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