September, 2009

Nesting Table Prototype

My next project is a set of nesting tables, copies of a set that my father has, which are as old as I am. He sent me photos and dimensions to base my design on. The originals are elm, and I decided to use cherry, but I wanted to build a prototype first out of pine.

The basic construction is fairly simple - the sides are attached to the top with half-blind dovetails and there is a rail at the back of the table which is joined with a wedged mortise and tenon. The most unique and visually pleasing aspect of the design is the scalloped hand-holds on the sides.

The material I started with was 2 six foot 1x6' planks. The first challenge was getting the rough-cut lumber flat and ready to be glued up into wider (the prototype is 10" wide) planks, as I dont have a jointer or thickness planer yet. I ended up just using the table saw to rip clean edges on the boards and then I sanded the glued up planks as flat as I could manage.

Each table has an elegant groove under the front edge for your fingers to find when pulling the tables forward. I tried to make this by rounding out a groove cut with a straight bit in the router using a file and sandpaper, but I didn't really achieve the shape I was looking for which I think would have been a lot easier to accomplish using a core box bit instead.

Still, the end result is functional if not quite as aesthetically pleasing (and this part is rarely visible in use). Next I tackled the mortises for the rail, while I had the router out. I used my edge guide and clamped some stops in place to ensure a consistent length to each pass as I plunged deeper into the wood.

I planned on making the hand-holds and the pattern of the feet with the router too, so I created some templates.

The hand-holds required a mostly semi-circular through-cut inset within the vertical scallop, which I planned on cutting with a core box bit to get the softly curved edge and then a straight bit to remove most of the material in the middle of the scallop. To make the scallop progressively shallower, I planned on placing the template at an angle to the wood surface.

Below you can see the completed template for the scallop with wedges attached with double-sided tape. What hadn't occurred to me until I tried using it, was how to clamp it to the piece when it was raised at an angle and still give the router enough clearance.

I solved the clamping problem by making another set of wedges and inserting a caul under the end of the template. I practiced first on a piece of scrap.

It was a bit tricky getting the depth of both bits to match and the practice run was a bit of a mess - but I thought I had figured out how to do it.

The next time around, it came out pretty well.

Next step was trying out the dovetail jig. I had done a test run a couple of weeks earlier and I grabbed the dovetail bit and bushing without checking to make sure I still had the right one - and this was the result:

I somehow had picked up the through-dovetail bushing instead of the half-blind dovetail one, so everything was way off.

I dealt with this setback by cutting off half an inch from the sides and the top to remove the bad dovetails and tried again. Tragically, this time in my distraction I must have forgotten to tighten the bit in the router properly, as it immediately wandered an extra 1/4" too deep and ruined the dovetail again...

So, by the time I finally had the dovetails cut the hand-holds were quite a bit higher up than planned.

Moving on to the tenons, I used the dado set on the table-saw to cut the tenons to size and then a handsaw to cut the slot for the wedge. The wedges were made from some red oak scrap I had lying around.

After some initial sanding, I was ready for the glue-up.

I used a brace opposite the rail to keep the sides square during clamping. With all the dovetails, the rail tenons and the wedges to glue, it was a bit of a scramble getting everything together before the glue started setting.

Once the glue had set fully, I sanded down the dovetails and finish-sanded the whole piece. I love these little bench cookies by the way - really great for resting a workpiece on for sanding.

Then, I gave it 4 coats of polyurethane. I had a lot of problems with drips, brushing on the first 3 coats, so I wiped on the final coat which helped and also gave it a waxing. I'm thinking of using a shellac seal-coat and wiping varnish for the cherry.

Overall, I'm pretty pleased with how it came out. So now I'm ready to start a set of three.

October, 2009

Cherry Nesting Tables

I've decided to build all three cherry tables at the same time now that I have built a prototype.

I tried to pick out matching boards with straight grain, but it was tricky - the lumber yard stock was mostly 10', so finding a board that was clear of defects and matched tone and grain was challenging. What I ended up with was straight grain for the tops of the three tables and reasonable well matched boards for all the sides.

After selecting the wood, I cut the boards to rough size and ripped a straight edge so that I could begin gluing them up.

I have been debating what the best method is for gluing up boards. With the prototype, I had reasonable luck pressing the boards flat against my table (on a piece of paper) and then clamping them, but I found that with three boards they tended to buckle up. My conclusion is that resting the boards on my D-clamps is the better option, but I only have two sets so that limits how many glue-ups I can do at a time.

With all the boards glued up, I decided to start with the dovetails this time so that there was some chance to recover from mistakes without upsetting the layout of the rest of the piece.

I did have to redo one set of dovetails - after doing one side of a table, I forgot to recheck the alignment of the template when doing the other side which resulted in a crooked set of dovetails. Fortunately, one of the sides was long enough to be converted into a top, so I was able to cut off all the dovetails and start again.

There were a couple of other hiccups getting all the dovetails to fit, but I was able to adjust the jig and try again to fix them.

With the dovetails all done, I moved onto routing the profile of the feet.

For the finger-pull under the front edge of the table-top I tried using a core-box bit this time around. However, I found that the semi-circular end to the routed groove was unappealing compared to the graceful original (photo inset):

So I resolved to doing a descending plunge cut at the start of the groove and then a matching ascent at the far end - I did a few practice runs first.

The scalloped handholds were by far the most challenging part of the table. Here you can see the template in action after the sides have been routed with the 1/2 inch core-box bit.

I then fitted a half-inch straight bit and cleared out the middle, being very careful to match the depth of the core-box bit at its deapest point and not wander into the curved edges - if I had had the right router bushing sizes I could have ensured this by using two different bushings, but I didnt have a pair with the necessary 1/4 inch difference in clearance, so I had to ensure this all by eye.

Finally, I drilled out the bulk of the hand-hold itself and then routed the final shape with the smaller template.

After 6 hand-holds, and 6 sets of mortises and tenons, I was ready for the glue-up. I realized that I had to keep everything pretty square otherwise the tables weren't going to be able to nest, as there is only 1/4 inch of clearance between each table.

It was at this point, in the haste of one of the glue-ups, that I made an unrecoverable error - I managed to reverse the top on the middle table. This meant that the finger-pull for sliding the table out from under the larger table is at the back instead of the front of the table. Not much I can do about that (although I did briefly consider routing another, shorter groove on the front edge). So it will remain, a mostly-hidden idiosyncracy of this set.

After some final sanding at 220 grit, I sealed the cherry with a shellac coat and then applied 2 coats of wiping varnish (thinned polyurethane), and a third coat to the tops. I probably should have put on a bit more, but I was worried about the polyurethane getting too thick and robbing the cherry of its natural look.

In the end, I was really pleased with the way they turned out, and they give me great pleasure to use.