I helped to build a new table recently. Doing metalwork is one of those things that puts me into a flow state. It’s like Vulcan style Zen. If you ever stop by the ship, please take a peek at our table.
Wood top:
The wood is cypress and was sourced from a local carpenter. It was meant to match other wood on the ship. It has an edge finish that is pretty cool–I’d like to learn how to create an edge finish like this. The wood was very precisely milled.
The location:
The table was installed in an L-shape surrounding two sides of the skylight on the ship. There are a few pictures of the skylight being installed. That was done many years ago in Iceland while the ship was in dry dock. These pictures just give an idea of what the table frame bolts to.
The table frame:
I chose a cantilever design for the frame. The advantage of the cantilever is that the frame has no legs–its basically attached to the wall (or in this case, the skylight). This makes the frame unobtrusive. It disappears away beneath the table. There are no table legs to knock your knees against or to sweep around.
I chose extruded steel angle for the structural members of the frame. They were made in left-handed and right-handed pairs, and have a broad symmetry that somehow reminds me of origami. Another option that I considered was using a T-shaped extrusion. That would have resulted in each individual bracket being symmetrical. The more I thought about how this would look, the more I felt it would be too monotonous.
The frame members were sized to support a maximum theoretical loading of one human per linear foot with a maximum of 5mm deflection. The calculations for these boundary conditions resulted in a selection of structural members mad of 3″x3″x3/16″ angle made of hot rolled steel. It was supplied by Bayshore Metals in San Francisco. At the time of purchase, a 20′ joint of that metal cost $71.
The frame members were cut by the metal supplier and were put together using the MIG welder at Langton Lab. When attaching the frame members to the skylight, I had the great joy of learning to use two new tools: a Champion MiniBrute AC35 magnetic drill press (or “mag drill” if you’re cool), and a Nelson stud welder series 4000 model 101. The mag drill is basically a drill press that uses a strong electromagnet instead of a clamp. It is a really wonderful tool for putting holes into large ferrous objects. The stud welder is a serious affair. I had to run a 480v 3 phase power line to the work area to feed this beast. The stud welder is for attaching, well, studs, to metallic bases. Both of these tools are essential for maintenance on a steel ship.
Studs come in many forms. They can be rods, hooks, eye bolts, or in this case threaded rods. For this project, I attached 1/2″ threaded studs to the base of the skylight. Each bracket had a slightly oversized 3/4″ hole drilled in it to slip over these studs, and the two were bolted together. Oh yeah, I used the mag drill to pop holes into the frame brackets. Yes, pop holes into them. That’s how easy it is with the mag drill.
My plumb bob’s existential epiphany:
The terrestrial guarantee of “level” does not exist on ships. This is because ships are always in motion. The traditional carpentry tools for ensuring flatness, bubble levels and plumb bobs, give only probabilistic answers. Using a level on a ship is a bit like using a magic 8 ball. In the absence of objective truths about what “level” means, we are left to construct our own. At first glance, the best you can do for ship in motion is to make things colinear and coplanar with existing reference surfaces. This is complicated by the fact that there are no flat floors on the ship. They are all crowned to shed water. Also, just generally none of the structural members on our ship are straight in any dimension–they are curved, twisted and warped all around. We’ve learned this the hard way during other construction projects on the ship.
The level and square of the table is a topic that I was very worried about.
The one thing I really had going for me was that the skylight frame that the table surrounds was built in dry dock, and appears to be quite square. It might be the straightest line on the ship. It was a no brainer to build the table to be square to the existing skylight frame.
Getting the table square was the trickiest alignement job I’ve ever done. Luckily I had calm seas and some friends allowed me to borrow some precision scaffolding. By that I mean a very large camera tripod and an Ikea table with adjustable Vika legs. These allowed me to carefully align the wood before permanently attaching the frame pieces. In the end, the table came out great–it seems to be within +/- 1/8″ of colinearity with the skylight frame for the entire 29′ length, and each of the three pieces of the table are square with each other to 1/8″, and flush within about 1/32″.
