Bent Laminated End Table - Part 2
Recently, Doug Hicks decided to build a much-needed end table for a spot between two easy chairs in his home. After spending some time with his wife Cathy, designing the table and making a cardboard mock-up, Doug got to work by making the bending jig. The jig makes bending the thin laminated leg strips to shape easy.
MAKING THE BENDING JIG
In building the table, I figured I would start with the most difficult part – the legs. And since the legs were to be relatively thin (1”) I decided that the strongest way to make them would be using a bent lamination technique. This involves gluing together a number of very thin, flexible strips and placing them in a bending jig to dry.
So the first step was to build the jig. I found some old exterior 3/4″ plywood left in the attic by the previous homeowner and decided to use that. Something like MDF (medium-density fiberboard) probably would have been better, but hey, “ya use what ya got,” right? Anyway the plywood worked fine.
I started by laying out the full size dimensions right onto the plywood. For a smooth arc I drove in three nails and then bent my aluminum yardstick around the nails. Next, I drew along the yardstick with a pencil. Then I opened up my compass to 1” (the thickness of the legs) and ran it along the yardstick to draw another line exactly 1” from the first, see Fig. 6.
Figure 6
Finally, I measured and drew lines on the jig perpendicular from the edge of the jig to indicate the top and bottom of the legs.
Once I had the leg drawn, I glued and screwed another piece of 3/4″ plywood under the first so that the finished jig would be 1-1/2” thick. Now I cut along the lines with my band saw, see Fig. 7. Of course I didn’t cut right on the line. I left room to sand up to the line.
Figure 7
Note of caution: You might assume that you can just cut one line and you would have a perfectly matched mold. That won’t work. The two arcs are different and you have to allow room for the leg to fit between them. So the waste (between the arcs) is actually the final shape and size of the leg. You might want to save the waste piece as a reference later.
While sanding I noticed that there were some voids along the edges of the plywood pieces. I filled these with wood putty and sanded them smooth. (This is not a problem if you’re using MDF.) When building a jig like this, the surfaces don’t have to be perfectly smooth and the arc perfectly consistent. The thin pieces of wood in the legs will bridge over small gaps, but try to get them close.
One other thing I did at this point that saved me a lot of hassle later: You’ll note on Fig. 7 above that I labeled the “BOTTOM” and the “TOP” as well as drew some reference arrows to show how the jig should fit together. Since I didn’t want a perfect arc (the center point is closer at the top of the table than the bottom), these reference lines and words proved valuable later during assembly of the laminated legs.
Next, I cut a third arc roughly 3” parallel from the outside one. This would allow a place to fit smaller clamps directly in line with where the pressure should go.
With all of the cutting done on the band saw I switched to the drill press. I drilled a series of 1”-dia. holes, about 3/4″ inside the inner form, see Fig. 8. These holes will accept clamp heads during glue-up.
Figure 8
The last step in building the jig was to screw the inside piece down to a 3/4″ plywood base, see Fig. 9. (Note: I did NOT glue this piece down. Later I wanted to be able to remove it and use it for cutting the legs to length.)
Figure 9
The only thing left to do was to wax up all of the jig parts so that glue wouldn’t stick to them. Now I usually use a little block of paraffin wax to do this, but this time I decided to try using some Pam cooking spray instead, see Fig. 10. It wasn’t such a good idea. The cooking spray came off the jig and soaked into the outside pieces of the leg. I had to use mineral spirits and do some sanding to get it all off. My advice: just coat the jig really good with paraffin before every use. (Note: Paraffin wax is available at most local craft supply stores.)
Figure 10
Continued on Wednesday, July 26th.