Saturday, November 28, 2009

PRODUCTION-MADE DOVETAILED JEWELRY BOXES








          Some woodworking machines are only meant for production work. This is because it takes too much time to set them up for just one cut. On the other hand, if you plan on making the same cut or joint over and over again, a production machine is the way to go. The advantage of using a production machine is repeatable accuracy with speed. Time is money and quality is everything.
 

          Today, we will take a look at the JDS Multi-Router, an expensive but fairly compact stationary woodworking machine that can make a variety of joints including mortise and tenon, angled mortise and tenon, box joints and dovetail joints. This machine incorporates a router and various router bits to make highly precise cuts in wood. The joints are made by a ball-bearing-tipped stylus tracking in aluminum templates that are easily mounted to the machine. The workpiece is clamped on an aluminum table which can move in and out, left and right and up and down, and which is controlled by 3 hand levers, one for each axis.

           Movement along any axis can be stopped with clamping screws and collars incorporated into the machine. A particular cut may require that the machine be allowed to float freely in two directions while being restricted from any movement along the remaining axis.

           As an example of how this machine operates, I will discuss how I have made production runs of dovetailed jewelry boxes. The motivation to use a production machine is pure and simple: If you can do accurate, detail work in a short period of time, you can produce high-quality items in volume and thus make more sales and therefore more money. You can also demand more money for fine details like dovetailed corners.

           Before getting started with my jewelry boxes, I had to determine what dimensions would work best, considering that I would be using a machine to make equally-spaced dovetails of the same size. I found that I could make two dovetails in the corners of a jewelry box that measured 2 ¼” high. Three dovetails would have required increasing the height of the finished box and I decided that that dimension would not be as pleasing to the eye.

           The next step involved stock preparation. The finished stock had to be of consistent thickness and width to work in this machine. The final thickness was to be 3/8” for the sides and top. The bottom was to be 1/8” plywood, covered by a velvet pad. The plywood bottom fitted into a 1/8” saw kerf cut ¼” above the bottom of the box.

           For economy’s sake, I chose to resaw three pieces each out of each piece of  2” (8/4) lumber. Before resawing, I cut the 2” lumber into pieces a bit wider than the final dimension of 2 ¼” (about 2 ½”). I set the resaw to cut three equal pieces out of each piece of raw lumber. I then used my SuperMax Drum Sander to thickness dimension these pieces down to 3/8” thick @ 220 grit. These pieces there then trimmed to final width (both edges) on the table saw. The final lengths of 12” (fronts and backs) and 7” (sides) were then cut on the miter saw using a
Forrest ChopMaster blade that leaves a mirror-like cut.

           On the
Multi-Router, one template is used to cut the tails with a dovetail cutter and the other template is used to cut the pins with a straight spiral cutter. Setup takes a while and wastes some wood so it is advisable to have some cheap wood available of the same dimensions and thickness as the final wood species. Table adjustments have to be made on the in/out axis to get the correct depth of cut which is then locked in position. A detailed manual is included with the machine, so I won’t bother to duplicate that here. Suffice it to say that the workpiece is clamped into a fixed position on the table and the left/right and up/down axes are left to float free while the stylus tracks each template. Trial and error will eventually give you a perfect fit in your scrap wood and, once that has been achieved, you can start production on the final workpieces. Tails can be cut on both ends of the sides and pins on both ends of the front and back pieces or vice versa, if you prefer.

           Now, it’s back to the table saw to cut the grooves for the plywood floor. You must stop your cuts just short of going through the ends of the workpieces. Mark pencil lines on the table saw table to show you where to begin and where to stop. The idea is to lower the workpiece into the sawblade which is set to 1/8” above the table. When the workpiece hits the table, it should be just a bit ahead of the front stop line. Pull the workpiece back to the stop line before pushing it forward to the rear stop line. Stop the saw before lifting each workpiece off the blade for reasons of safety.

           The finished, dovetailed pieces are pushed together with a bit of Titebond glue while inserting the plywood bottom into 1/8” pre-cut groove. Clamp the box square for 45 minutes.

           Box tops can be made oversize, sanded to 3/8” @ 220 grit and then trimmed to fit the boxes, either overlay with hinges or inset with brass pins drilled into the back corners. Once you have determined the final dimensions of the top, you should be able to safely fit all of the boxes due to the accuracy of your
Multi-Router-made boxes. I like to rout all corners of the box and top with a 1/8” round-over bit before sanding.

           The boxes and tops should be sanded to at least 220 grit with a random orbital sander and by hand before finishing. I chose to spray on a gloss finish (catalyzed varnish). You may prefer something else. If you are going to spray, I’d like to suggest that you make yourself a lazy susan (parts available from
Woodworker's Supply). Take several pieces of 1/8” ply the same size as the box bottoms, drill a hole in each corner and insert bright flat head box nails into the holes. The holes should be drilled the same size or smaller than the shafts of the nails to keep the nails from slipping back out of the plywood. Place the ply, nail points up, on the lazy susan and place the box on top of the nail points. Once a box is sprayed, you can pick it up by the plywood and set it aside to dry. When spraying tops, the sharp nail points will not leave visible marks in the finish.

           The final touch is the velvet lining. You will need poster board, 3M spray-on adhesive,  1/8” foam padding and velvet. The velvet can be found at any
dry goods store and the other the other items at an arts and crafts store like Ben Franklin or Michael’s. Cut the velvet to extend 1” in all directions beyond the pre-cut poster board. Cut out 1” x 1” squares from each corner of the velvet (you may have to adjust this to accommodate the foam padding.) Spray glue the padding onto the poster board. The padding should be cut a bit undersize with reference to the poster board. Wrap the velvet over the padding and glue the flaps onto the back of the poster board. The poster board should be pre-cut to exactly fit the box with the velvet wrapped around the edges. This may take some experimentation but the final dimension can be repeated over and over again.

           In closing, I assume that you can now see that in such a production run, there is a massive amount of set-up time which should be more than off-set by the efficiency of repeatable accuracy. On the other hand, I could cut the dovetails for one box by hand but they would not look as tight and smooth as those cut by the machine. In short, if you are thinking about purchasing a new or used
Multi-Router, plan on making a lot of boxes in each production run.


HELPFUL LINKS
(related to this article)
JDS Multi-Router

Lazy Susan Parts

Michael’s Crafts


Velvet Supplier

Ben Franklin Stores


Forrest ChopMaster Saw Blade

Bob Gillespie
Woodworker

For similar articles and tool reviews see:http://www.perfectwoodworking.com


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