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Cranky Sailor Workshop - The retirement chest #1: Initial Stages

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Blog entry by DynaBlue posted 1194 days ago 1651 reads 2 times favorited 1 comment Add to Favorites Watch
no previous part Part 1 of Cranky Sailor Workshop - The retirement chest series Part 2: First cuts, first changes »

One of my prior Command Master Chiefs flattered my by requesting I build his retirement present, a ‘sea chest’ which would hold not only his shadowbox but also his collection of challenge coins and uniform items. We discussed general plans a few times until I showed him a nice blanket chest from a 2010 Woodworker’s Journal. He wasn’t sure about the arched configuration at first but after reflection it grew on him and I was underway!

I love quartersawn oak but I wasn’t sure that I wanted to just completely duplicate that as I thought the chest needed to stand out more, make more of a statement. I chose quartersawn Sapele panels and lid with ash forming the frame.

Now I should probably mention at this point that I realize the chest is certainly copyrighted by Woodworker’s Journal and I am not charging him for the box outside of materials nor am I claiming at any point that the underlying design is my own. I think (hope) I’m safe building the chest for free outside of the materials. I know that some magazines have allowances for their projects (one magazine says you can build up to 25 of their projects provided the project was designed by one of the editorial staff and not a guest author) but I’m uncertain of this magazine’s stance on the topic. Back to it.

I examined the design and liked it in the main but I had some concerns over the original design:

1. The arch pieces are attached to the stiles with a simple edge glue and I had concerns about the durability of that joint. I experimented and found that indeed it was a strong joint provided the edges were perfectly jointed and sufficient glue was used. I was going to use a stub tenon to connect the pieces but ultimately decided that it would be unnecessary as the chest should not be subjected to strong shearing forces along that joint plane. It only has to survive being picked up once in a while and holding up it’s own weight.

2. The breadboard ends, as shown, are solidly glued up, a concern with the environmental changes from the build site in San Diego to the final destination in Missouri. Fortunately I work at Rockler and have access to an adjunct professor of woodworking as well as several other experienced woodworkers and we discussed this point at length. The final result was that the breadboard end, as designed, was likely to fail sooner rather than later given changes in humidity and that feature should be replaced with true breadboard ends that allow for expansion.

3. The top, as commented in the article, is HEAVY! They used two toy box lid supports to hold up the top but given the dimensions of the top and the known density of quartersawn oak (about 47 lbs/cubic ft) I didn’t think that the supports were sufficient to actually prevent the lid from slamming closed if dropped. The basic formula is front to back distance (inches) X weight of the lid (lbs) / 2 = Inch/lbs of torque needed to prevent the lid from falling down on its own. The article explicitly states that children and this chest should not mix and that is correct. Even two of the strongest lid supports only offset 250 in/lbs of force and the lid requires over 500 in/lbs so for safety it would need four lid supports, one on either side and two center supports (125 in/lbs each). While the ends are so much of an issue I didn’t want the center supports fouling up with my shadowbox and coin trays. Torsion hinges are available up to 60 in/lbs and they act like the hinges on a laptop, holding the lid in whatever position it is released. Even though my sapele lid only averages 39 lbs/cubic ft it was still going to need 9 of those hinges which would, quite frankly, look hideous. I consulted with the customer and advised him of the issues and he just asserted that I should make it look right but not worry about kids using the chest and he was aware of the potential risks. I did decide to try three 60 in/lbs torsion hinges to at least slow the lid and I could add the side lid supports if required.

With my concerns partially addressed it was then time to procure materials and commence this project. Fortunately the customer gave me plenty of lead time as my full time job was going to greatly compromise my shop time.

-- Mistake? No, that's just an unexpected design opportunity....



1 comment so far

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DynaBlue

129 posts in 1824 days


#1 posted 1179 days ago

Glad you like the pen, Pat!

-- Mistake? No, that's just an unexpected design opportunity....

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