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Sunday, March 03, 2013

Dinette Table Lift Mechanism

This is what being cooped up in the garage during long winter nights yields...

I think I mentioned the design for this sometime ago in the blog. Over the last few months I had an experimental mockup setup in the garage, to determine feasibility. In particular, would the mechanics be enough to bear the load of the (expected) dinette table weight? Results were positive such that I took it into the boat. Though still experimental, here is what I have so far.
One of the lift assemblies

There are two lift assemblies (left and right) that slide in and thru bolt to the boat's glassed in framing structure under the side deck, giving a quite sturdy and stiff attachment. The assemblies are lifting arms on rollers held captive in a section of slotted aluminum. Attached to the lifting arms are lead screws coupled to a drive motor mounted on a bracket at the base. The lead screws and motors provide the up/down movement. The assemblies are designed to be installed/removed with one-person-one-tool without removing finish work (well, maybe a bit of trim). When finished, the lift mechanisms will be completely concealed behind the cabinet.
60 pounds of weight

With two assemblies installed, and motors synchronized  a load test is done, with a heavy piece of MDF and some dive weights placed at a 3/4 table width lever point. Total weight about 60 pounds. The motors had no problem lifting/lowering the load.

Of course the intended feature of this mechanism is to provide adjustable height for normal dinette use, but also

  • lower the surface to convert the dinette into a bunk
  • raise the surface to provide easy access to the boat's electronics underneath
  • all without tearing things apart.

Here are the sample height levels
Normal table height
Lower height for bunk conversion (17 inches up from floor)
Upper height for electronics access (note cabinet extended on slides)
By no means complete, there are still some refinements to be made. I am surprised how well this has worked so far. As I ain't no mechanical engineer, there is still a chance it will fail... completely.

More on this later.

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