Veneer Jointing Jig
Anyone who has ever worked with veneer has either found or is looking for a way to accurately trim the edges of two pieces of veneer straight, so that they can be taped together without leaving gaps at the seam. What follows is not a comparison of all the possible methods, but rather one easy and efficient jig, intended to be used with a trim router bit. This is a jig that works as well for beginners with limited skills as for experienced woodworkers.
True the edges
Run the guide edges over the jointer and mark them immediately to ensure they don’t get mixed up during assembly.
Clear for take-off
Recessing the T-nut bolts allows the router to pass over the top of the jig without bumping into them.
The jig in action
Don’t try to remove more than 1/16" of veneer with this set up because you’ll likely tear the veneer rather than cut it. On fragile veneers try routing in the opposite direction known as climb cutting.
The jig consists of two pieces of bent Baltic plywood, assembled with knobs and bolts. The bent pieces have the curves in opposite direction to each other. When the knobs are tightened to the maximum, the parts meet, thereby creating the necessary pressure along the whole length of the jig to hold the pieces of veneer firmly along the edge. It is especially important to put pressure in the center (the maximum distance from the knobs) to ensure that the two pieces of veneer do not ‘flutter’ in that area. The jig gives you a firm hold and control of the veneer without having to use clamps that would hinder the use of a router to machine the edges.
Baltic plywood is the material of choice because it usually does not have gaps on the edges, which could affect the path of the bearing guiding the router bit. Being made of several plys of better quality birch, it not only looks better, but offers a firmer and more durable edge. The length of the jig depends on your present and future needs. My supplier had 60″ wide sheets, so I was able to maximize the future use of the jig. To benefit from the natural curl of the ½” plywood sheet, you have to cut the four pieces of 6″ wide plywood across the grain. You should aim at a curve of approximately ⅜” on a 48″ long jig. If you make the jig 60″ long, then go for ½”. If your plywood does not have much of a bend or curve, you can use the part ‘A’ that will be used to secure the jig in the vise, as a form to glue the parts together. I glued together two pieces of ½” plywood to form each part of the two parts jig, rather than using one single piece of ¾” plywood for each part because the ¾” ply did not have enough natural curl and was somewhat more difficult to bend.
As with any jig, it is important to be accurate. The critical part of the jig is that the two front edges should be even when bolted together and 90° to the top. This can be accomplished very easily by drilling the holes for the T-nut bolts so that the bolts do not have side play inside the holes. Assemble the boards together with the bolts and pass them on the jointer. At this stage you can write ‘FRONT’ on the two edges so that you do not inadvertently reverse the parts whenever you dismantle the jig.
You will note that the T-nut bolts are recessed into the plywood on top so that they will not be in the way of the router should you have to go as far as the ends of the jig. I used 4″ bolts because I wanted to have enough thread to keep the jig opened but held together when not in use. I think that it is better not to keep the upper part under tension when not in use. In the long run, if kept tight between uses, it could affect or diminish the bend in the upper plywood part. Longer bolts will also allow you to insert spacers at the ends to keep the two halves apart while you are adjusting the position of the veneer sheets.
In order to be able to handle the jig more easily, I screwed on a piece of hardwood under the bottom of the jig. If you have not already made this part to obtain a more desirable curve (as mentioned above), use the bottom part to trace the curve on the piece of hardwood and attach it with screws to the bottom half. This serves two purposes. Firstly, it maintains the curve of the bottom part permanently, which means that the upper part has to travel twice the distance of its own curve. This creates a lot of pressure in the center of the jig. Secondly, it also provides the necessary means for securing the jig in a bench vise in a way that will make it easier to use the router comfortably and safely.
Using the Jig
By now you have probably figured out that your next step is to place the veneer sheet(s) between the two curved parts, ensuring that more or less 1/16″ sticks out to be machined by a trim router bit. I have successfully trimmed up to six sheets at the same time and the veneer has to be relatively flat. Veneer with ‘bubbles’ will break or crack if not flattened properly before applying pressure in the jig. I prefer using a regular router rather than a trim router because it gives me a more stable feel. I use a pattern bit with two bearing for more stability and also a longer reach to compensate for the 1″ thickness of the upper part of the jig.
This jig will provide you with the ability to trim veneers square and true to ensure good seams. The jig can be made any size to match the type of work that you do. With a sharp router bit and good layout, gaps in your veneer seams will be a thing of the past.