The Drop Leaf Table Addition: The Incremental Cost of Design Complexity

This entry builds on a previous one where I described a part design paradigm based on complexity where every new feature added to a single part required more caution than the last, because once a part began to acquire more features along with the time and effort required to produce those features, the part itself began to incrementally increase in value. A mistake with each additional new feature machined would therefore prove increasingly more costly than the operation itself to complete that feature, as the number of features were added to a part to complete it.

I found myself trapped in that same concept as I routed the final half-inch quarter-round profile on the two opposite edges of this table top. Each part that makes up the top assembly is fairly simple in and of itself not counting the walnut panel quadrants with their computer numerically control routed circles, but the assembly of those parts was done in stages that included a complex cope and stick edging process between the center panel and its two opposing front and back edges. Routing the small dado that ran along both side edges underneath the top was difficult enough until I had to begin the last process.

The last process in completing the top was to route the large quarter-round profile on the two side edges without the router bit blowing out the ends. I really had no choice therefore but to use a hand-held router instead of the router table, and because of the larger router bit, I had to use a plunge router instead of one of the smaller, more easily controlled hand-held fixed-base routers I own.

No single one-pass, large removal of stock occurred as I routed the quarter-round profile. It was light passes all the way, taking off only a little at a time to insure a clean, smooth, issue-free profile using a tool not exactly well know for its finesse. A mistake here could have cost the whole top. I obviously pulled it off, but if I had not, that incremental cost concept would have come around to hit me hard. Very hard.

Like the saying goes, just because you can doesn't always mean that you should. Although in the end, risk paid off in the final result.

The Glue Strength Test: How It Informs Design

I began a simple project in the workshop that will wrap up soon to test the new cyanoacrylate glue that recently came on the market especially formulated for woodworking applications. This project is a simple tapered leg table with tenoned apron sections glued into mortises that are routed into the legs. The fast set time of the cyanoacrylate glue would greatly facilitate the assembly of the legset.

Recall that I conducted a strength test of the glue with the help of the engineering department here at the University of Minnesota before I began building the tapered leg table as described in a set of earlier posts that are listed below. The glue strength test indicated that the new cyanoacrylate glue did not bond as well as traditional woodworking glues, and for that reason I decided to assemble the legset using a traditional glue even though I think that the strength of the joinery used here would not have been an issue. I like to be sure about these things though when it comes to my work.

http://stevepanizza.blogspot.com/2013/11/the-glue-strength-test-results.html

http://stevepanizza.blogspot.com/2013/11/the-glue-strength-test-engineering-test.html

http://stevepanizza.blogspot.com/2013/11/the-glue-strength-test-introduction.html

The process of gluing and clamping the legset was done in two stages, and each stage took a full day of clamping. Using the cyanoacrylate glue would have meant that the glue-up phase of the legset could have been completed in only one day as quick dry time is its primary advantage. The benefit of strength won out over completion rate though.

Another way to look at the glue strength test results though as they relate to this project design is that I could have increased the size of the apron part tenons to increase the glue surface area if completion time had absolutely been an issue here as more glue surface area increases joint strength. It may help to know in the future that I have this option during the design stage of any project.

I think that uses for the new cyanoacrylate glue will eventually develop where its short drying time can be used to advantage in situations where strength is less important. So for now it stays in the shop as another tool to use when appropriate.