The Tambour

 The tambour consists of pieces of mahogany ¼” square in cross section, with one edge worked to a half round shape. I planed a piece of very cooperative straight-grained mahogany to ¼” and used a scratch stock to run the profile. I then sanded the profile and ripped the piece free on the bandsaw. With a sharp blade and consistent feed pressure the tambours will be extremely uniform in thickness. Only those tambours that show when the drawer is closed need to be shaped; the rest can be flat pieces 11/64” thick by ¼” wide strips of mahogany or cherry.  I determined the amount of each type of tambour, required by laying a string in the track and marking where the shaped tambours end and where the others meet the rear of the drawer when it is in the closed position.  The tambours are colored, shellacked and rubbed out, and then they are cut with the cross cut sled on the tablesaw, to a length that gives just the barest of clearance at each end ; 1/64” would be just about prefect, but 1/32” would be too  much.
  One or two plane passes are taken on the back side to remove the saw marks and provide a clean glue surface.

tambour
Ironing the canvas onto the tambours, while held in a jig

 

They are then carefully brushed with hot hide glue and placed face down in a jig. This jig is strips of wood nailed to a board to keep the tambours square, and fitting tightly to each other. The fabric backing, in this case canvas, but silk or better yet linen would work as well, is cut to leave a 1/4" on each end of the tambour exposed. Using an iron set on medium heat, the hide glue is re-liquefied, adhering the fabric to the tambours.
 Let the glue gel for a few minutes and remove the tambour from the jig, and flex to insure the no glue has seeped between the tambours; with the tambours being pre-finished it is unlikely they would bond together, but now is the time to be sure.


  When the glue has cured sufficiently, it is time to rabbet the face of the shaped tambours so that they will fit in the track. I did this with a router run in climb cut fashion. If there were ever a time to measure twice and cut once, this is it. The goal is to have a tambour that moves easily, but has a close fit to the turrets. I relied on the router to get the shoulder straight and accurate as far as side to side clearance was concerned, but I left the rabbet shallow, to allow for fine tuning its fit to the track with a shoulder plane. You want to avoid getting a too loose fit, because there is a fine line between a fit that moves nicely and one that is so loose that it will rack or “bunch up” and bind; waxing the track and the tambour ends (after finishing)  will work wonders. Now its time to fit the tambour to the case, so that when the writing surface and the drawer are closed the tambour fits down snugly to the writing surface and meets the back of the drawer. It is highly unlikely that the tambour will precisely meet the drawer bottom, so to remedy this, remove the last one or two unshaped tambours, with heat and water, and replace it with an appropriately sized strip of wood. The connection between the drawer and tambour is made with two pieces of steel, that have a slight kink bent into them, and screwed to the drawer bottom and the last strip of wood on the tambour. It will be a trial and error process to fine tune the connection to the point where the drawer closes flush and the tambour fits to the writing surface.

tambours in place
The tambour in place and fastened to the drawer bottom

Being so light, it will require both hands to open and close
The tambour; one on the tambour and one on the drawer, because there is no mass to push against, like there would be on a full size desk.

Finishing

  Like all the pieces I make in mahogany, this one is finished with a sprayed on mixture of garden hydrated lime and water. This will darken the mahogany to a nice deep red. I further enhance the finished color, by applying a base coat of yellow aniline dye, to provide some golden highlights.

The final coloring step is to pop the grain and tweak the color with a thin coat of Tried and True Danish oil, tinted with various colors of Trans Tints Dyes (mostly cordovan and green).The only thing complicating the project was the crotch veneer; the lime and oil would turn the crotch veneer nearly black. To avoid this, carefully brush on a coat of the lime to the strips of mahogany forming the boarder.

lime
Brushing lime on the solid mahogany edging

 Wipe a coat of plain Danish oil over the crotch veneer, and let the oil cure a few days. The entire piece is then given a thin coat of the dyed oil. By letting the plain oil cure a few days, it will act as a barrier to the dyed oil, preventing it from darkening the crotch veneer too much. I filled the grain with oil based brown filler, and followed this with one coat of dark shellac and several more of blond shellac. When cured the shellac was rubbed out with 400 grit sand paper using mineral spirits as a rubbing lubricant. The turrets are rubbed with steel wool to avoid cutting through the finish.  A nice sheen is brought up with 4/0 steel wool charged with 4/f pumice and mineral oil as lubricant.
  The lids are dyed with Trans Tint Dark Vintage Maple and then oiled and shellacked, before being rubbed out in the same manner.

oil
Applying tinted oil to enhance the grain

 

Hardware and Baize

  All the hardware and the baize were purchased from Londonderry Brasses. The hinges have to located carefully, so that when closed, the lid lines up on all sides, and when open there is as small a gap as possible between the fixed and hinged leaf. The knobs come with threads that were cast from originals that were hand filed, so they are somewhat crude by modern standards. This makes them a little difficult to install, so you’ll have to experiment in scrap to find a proper dill size that strikes a balance between holding power and ease of installation. The lock in inlet with a router and chisel, noting that the center pin is not on the center line of the lock, so the lock case will be offset to one side of center. Give the lock a tap to transfer the key pivot pin to the drawer front and carefully drill a hole using that mark as the center. The keyhole escutcheon is filed with a slight bevel on its perimeter, making the face larger, to aid in getting a prefect fit. Line the escutcheon up with the key pivot pin making sure they are centered and scribed around it. Carefully saw out the waste on the scroll saw. After checking to be sure the escutcheon will fit, use a C-clamp and a block of scrap to force the escutcheon into place.

 The baize is glued on with hot hide glue. The consistency of the glue is important, because if too thin, it would seep through the baize; I aim for a consistency that barely runs of the brush. Carefully brush on a thin even coat, with no puddles of glue, paying particular attention to getting good coverage at the edges. Press the baize in place with an iron set on low, using very little pressure, and with no pulling or stretching of the baize. It might help to very lightly mist the face of the baize with water. When the baize is adhered, let it cool for a few minutes and close the lid, to see if any glue has gotten onto the strip of baize visible when the writing surface is closed; if so gently wipe it off. Now trim the excess with a straightedge and a fresh razor blade. Work slowly and carefully. It helps to angle the razor blade towards the baize field. If you get a minor bleed through of glue on the baize, it can sometimes be cleaned up with a warm damp rag, but many times the spot will show when dry. Leave the writing surface open for a day or so, so you don’t trap the hide glue odor in the baize.

  The last step it to insert the tambour and screw the bottom in place. I also glued some baize to the bottom to hide the screws and allow the desk to be placed on a finished surface without fear of it scratching anything.

  This was an interesting project, combining precise joinery, layout, turning and veneer work, to make an unusual and useful object from the past.

 


Page 1 2 3
Click here to return to Article page


©2007 by Robert L. Millard
All rights reserved