The next week of class was consumed by each student presenting and speaking to their design what their main tenets would be for the project. Part of the previous week’s assignment had been to pick your tenet or tenets and be prepared to stick with them. My main tenet was to see the design through and devise a way to pull off the cantilever. I knew it was going to be tough just by all the drawing work I had put into SketchUp. Seriously, there are only 6 90-deg corners (aside from all the joints in the torsion box) in the whole design. I was truly worried I would be told this was too aggressive.
When my turn came to present my concept I prefaced my comments with the fact that I intended to attempt a design with a cantilever in it. I discussed my inspiration piece. Our instructor liked the beam table (see the previous blog entry). This was a good sign… I unveiled my second design concept and Willie (the instructor) instantly commented it was a strong design but in the same breath noted the complexity. I jumped right in and spoke to the ideas I had about how I could strengthen the joint by bolting the top to the main support. 
The gap in the torsion was intended as a slot for a flush-front drawer. He ultimately could see that I had put a lot of effort into accessing the problems I would face and supported my decision to build it as long as I 86’ed the drawer. I was ecstatic and surprised at the same time.
After everyone had talked about their proposed projects we each got to spend a little time in one on one !discussions with Willie. He reemphasized the challenge ahead of me but also told me he would like to see me succeed. We set about addressing the top and it’s weight. Rather than execute the design as it was, why not just make the whole top a torsion box? It would further cut down on the weight and since it was a torsion box, there would be plenty of strength even with a 5/16 skin of plywood on the top of the box. I agreed I would take the next week to modify the drawings. The only problem was, at the end of design presentations, our new assignment was to bring a model to class the following week…
Here are some views of the final design where the whole top would be a torsion box.
Plan View
Front Elevation
Right Elevation
Left Elevation
Isometric views
Now, all I had to do was build a model. Here is a sneak peak of the 1/6th scale model. In the next entry, I’ll discuss what the model helped reveal about the design.
-- Jeff, St. Paul, MN
8 comments so far
Dorje
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1745 posts in 483 days
posted 167 days ago
Intriguing!
-- Dorje (pronounced "door-jay"), Seattle, WA
Scott Bryan
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9104 posts in 308 days
posted 167 days ago
Jeff,
This is, in a single work, fascinating. You have a wonderful opportunity presented to you and are taking full advantage of it.
Keep us advised about your progress. I, for one, am enjoying this.
-- With God's help all things are possible- even woodworking. Woodworking is not just a hobby, it is an (expletive deleted) expensive hobby.
ben
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154 posts in 356 days
posted 167 days ago
Jeff,
It’s impressive to see you take full advantage of this course and instructor, and perhaps more importantly, pushing your own limits. The design looks excellent, but the model tease is cruel… We gotta see the whole thing!
-b
Greg3G
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641 posts in 571 days
posted 166 days ago
Great Design. I too would like to see the finished verison. Anythoughts at to wood selection and finsihes yet?
-- Greg - Charles Town, WV
Jeff
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964 posts in 580 days
posted 165 days ago
Thanks fellas. It really did take me to the limits and stretched my confidence to a point where I’m probably just cocky enough to be dangerous and will surely make a slew of massive mistakes on the next project. :-)
ben, I don’t mean to be cruel. ;) Next entry to come soon.
Hi Greg. The piece is Mahagony and will likely be dyed a couple of shades darker and then simply oiled. Perhaps a coat of more protective finish on the just the top. Not sure yet.
Thanks for following along. The posts will start to get more interesting now as I get into relating all the challenges with building it. I built no less than 5 jigs for this project…
-- Jeff, St. Paul, MN
johnjoiner
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143 posts in 379 days
posted 162 days ago
Hi Jeff.
This sounds like a very cool class. I will keep following this series as I’ve been interested in the MCAD classes too.
I really like your table design. Two questions:
1) Is the top of the upright part of the base going to come all the way through the table top? Or will you hide that under the skin?
2) It looks to me like the table will be a little tippy (in your ‘plan view’ image, tipping to the lower right). I wonder if you might have to make the end of the beam that touches the ground wider some how to add stability. Have you or Willie talked about that, or tested it somehow?
Best of luck.
-- johnjoiner
Jeff
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964 posts in 580 days
posted 162 days ago
Hey John. I don’t know how I haven’t made the connection in 217 days… I wondered if there was anyone else in the guild that frequented this site. I’ve shown it to Charlie but I don’t know if he is lurking or not. We’ll have to see what kind of questions I get the next time I go to a meeting wearing the LJ shirt I received as random selection in the bookshelf challenge (thanks again, Martin).
To your questions -
1) At one time there was a consideration to go through the top and use wedged tenons but as this is going to be our desk in the office/spare room, I didn’t want to kludge up the surface of the top. So, it will go all the way through the torsion and stop at the underside of the skin.
2) Plan view – Did you mean lower left rather than lower right? If so, good eye and good question. It was a concern I had too but I decided to leave it to the model as an experiment. And, the model did tip but I had no way know how much pressure in the real world it would take to tip it. I’m happy to say that the Mahogany is plenty hefty and keeps it well grounded. I think the top would actually be damaged first before any tipping but that remains to be seen.
As for stability, there is a solution that I will elaborate on in a future entry.
Thanks for the compliment and your interest.
-- Jeff, St. Paul, MN
Karson
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12910 posts in 886 days
posted 162 days ago
Jeff a nice looking job.
-- Karson Southern Delaware karson_morrison@bigfoot.com