In the last blog entry, we left off with the 4×12 Maple Parsons table after adding the underside framework, running the length of the table.
After that step, we also decided to add cross bracing, running the width of the table, to make sure the outer framework would stay perpendicular to the table top. As you can see from the picture, all the framework was double layered 1″ thick Euro-Ply, glued on all surfaces, and pocket screwed to the table top and to the adjoining framework.
We designed the outer frame of the table as 3/4″thick solid Maple, which would add even more stiffness and strength to the table, and increased durability against the thousand of dents and dings over the years.
We milled our Maple trim pieces to the exact length needed, but left the width just a bit over sized. After attaching the trim, we flush trimmed the overhang on the top but, as you can see in the picture, the bottom was left proud by about 1/8″.
With the framework and trim complete, it was time to turn our attention to one of the most difficult and important sections of the table, the leg blocks.
Just like the underside framework, the leg blocks were constructed from a double layer of 1″ thick Euro-Ply, mitered at both ends, and notched in the middle to accept the leg.
We drilled three holes altogether, one in the middle to accept the hangar bolt, and one at each corner to accept lag bolts.
The corner blocks were simply glued and nailed into place. We thought about screwing each block to the table top and to the framework, but with the huge amount of glue surface, there was no movement to be found in any of the corner blocks.
We began attaching each leg by using a 3/8″ diameter, 3.5″ long hangar bolt. The hangar bolt is the preferred method to attach a leg to a table because the bolt is never removed from the wooden leg, so there is very little chance of the threads ever loosening inside the leg.
We drilled a hole into the corner of each leg and threaded in the hangar bolts. The hangar bolt was then passed through the pilot hole, which aligned the top of the leg with the face of the table top, and secured in place. The beauty of this system is that, simply by tightening the nut, the leg is pulled tight into the corner.
The hangar bolts do a great job pulling the legs tight into the corners, but they are not very good at counteracting the side to side racking forces that would be exerted on the table. To help strengthen each leg, we added two 5″ lag bolts.
Once the legs were fitted, we removed them and flipped the table over. We final sanded the top in preparation for veneering.
Since this table was 12′ long, it would not fit into our current 4’x12′ vacuum bag, so we had to purchase a brand new 4’x16′ vacuum bag just for this table!
To begin the process, we laid out the vacuum bag on our 5’x10′ building table and placed two pieces of 1/4″ MDF in the bottom, one at 4’x8′ and one at 4’x4′, in order to form a 12′ long plate for the table top to sit on. Next, we had four guys rolling glue onto the top surface to ensure the glue was still wet by the time we placed the veneer on the top. After rolling out the glue, we laid down the huge sheet of veneer, smoothed out any air bubbles, and placed two pieces of 1/2″ melamine, one 4’x8′ and one 4’x4′, on top to act as a platen. We then, using a grand total of 8 guys, loaded the entire monstrous assembly into the bag, which was by no means an easy task, given that the vacuum bag is soft, flexible, and has a tendency to snag on sharp edges during the loading process. Finally, we succeeded in getting the top completely loaded, with both the top and bottom platens nicely aligned. The end were closed up, the pump was turned on, and the veneering process was complete.
One other unique aspect of the veneering process was the fact that we had to contend with the four corners, which were hollow pockets. Whenever a part is placed into a vacuum bag, the bag itself will mold to every contour of said item. In the case of our table top, with the pump activated, the bag would have pulled itself down into the hollow 4″x4″ pocket of the leg holes with so much force that it would break the 1/2″ melamine and easily ruin the veneer on the top. So, in order to prevent that disastrous event from happening, we added spacer blocks into each leg cavity. As you can see, we also added homemade corner blocks to the top and bottom of all four corners. Each of the corner blocks have chamfered edges, which prevent the vacuum bag from being stretched and torn during the veneering process.
After a few hours, we removed the table top from the vacuum bag, flush trimmed the veneer, fixed any loose edges, and final sanded the top and sides. We also did one final fitting of the legs, adjusting the fit where needed. After the fitting process was complete, we dis-assembled the table and sent everything into the finishing room for a coat of sealer and two coats of conversion varnish.
The table, in its final resting place…a break room at a branding company in Detroit.
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