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Re: [luf-team] Re: Open Structures

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  • kevinrockel@rogers.com
    FYI, many years ago I visited a lumber mill, and asked why 2x4s were not 2 x 4 . Here is the reason they gave 2 x 4 is the rough cut size of lumber.
    Message 1 of 3 , Jan 8, 2013
      FYI, many years ago I visited a lumber mill, and asked why 2x4s were not 2" x 4". Here is the reason they gave

      2" x 4" is the "rough cut" size of lumber. Originally, people bought rough cut lumber, and then planed it down themselves.
      Then automatic planers came in to being, and you could by rough cut and planed wood from the mill. It was still the same 2"x4"
      rough cut, just run through the planer a few times. Then standardization of the planed size took over, and to get a good finish on the wood under
      all circumnstances (because millers are a lazy lot and don't like hand adjusting the planer for each peice of wood) they plane off a 1/4" inch on each side. Thus a 2x4 is 1 1/2 x 3 1/2.

      Now, modern mills are not nearly as wasteful, so they actually rough cut a lot tighter, and getting a true 2" x 4" rough cut wood has become a special order item. 

      Nothing mysterious, really.


      From: Eric Hunting <erichunting@...>
      To: luf-team@yahoogroups.com
      Sent: Tuesday, January 8, 2013 12:27:58 AM
      Subject: [luf-team] Re: Open Structures


      Utilihab is an open source hardware project and it could be scaled to integrate with the standards of the Open Structures project. There are some limitations in that we have to also accommodate standards for off-the-shelf T-slot framing but the system is intended to be 'parametric'--which is to say the specific dimensions are not critical to how the system works as long as some particular dimensions ultimately become standardized across a parts industry. I chose dimensions based on my experience studying T-slot products, common housing standards, and corresponding with other developers of aluminum frame building systems. Whether Open Structures integration would matter to the appeal of Utilihab is unclear. Open Structures' standards are, as yet, not recognized standards in the Maker/Open Hardware community. But there's nothing wrong with the idea.

      How they arrive at a 4cm base for their grid is not clear, unless it relates to the use of the American 2x2 wood stock used with Grid Beam and Ken Isaacs' Matrix. (you see, because apparently every damned thing in 20th century industry was compelled to be a scam of some sort, 'standard' 2x2s aren't actually 2x2 inches. Lumber companies slowly, mysteriously, shaved down the dimensions over decades until, by the 1970s, they became something roughly around 1.5x1.5 inches, which approximates to 4x4cm--which has always made me wonder why the US building industry had such a problem with converting to metric with the rest of the world. All their fake lumber dimensions are closer to whole metric than imperial numbers anyway!) The metric version of Grid Beam has thus become based on 40mm multiples. T-slot framing standards tend to be based on their own mysterious logic. They generally run in series of 20, 25, 30, 40, 45, 50, 60mm. But the most commonly available sizes are 25, 40, and 45mm. (imperial dimension T-slot is something of an oddity. It exists only in the US and is largely exclusive to the 80:20 company, which for a long time didn't make metric series and generally didn't pay much attention to what the T-slot industry in the rest of the world was doing) Maker Beam is a newcomer at 10mm. So there is T-slot that directly synchs with Open Structures' standards. But for housing most of the developers experimenting with aluminum profile systems (albeit usually proprietary in some way) have used framing in or around multiples of 50mm, hence my choice of 2, 3, and 4 times 50mm (light, medium and heavy) frame systems. 40mm series profiles top out at 160x160mm (4 times 40mm) which might suit a medium strength house-scale framing system, but few companies make that and the 40mm series connectors are rather low in strength for that role. It seems possible, but I lack the engineering skills to work the numbers on it.

      Open Structures shares roots with Utilihab in that it likewise was inspired by the 1960s work of Ken Isaacs, his Living Structures, Urban Nomadic design, and the history of Box Beam/Grid Beam. Open Structures is also heavily influenced by the work of Dutch design group N55 ( http://www.n55.dk ) and Bryan Bishop's and Ben Lipkowitz' Social Knowledge Database SKDB project ( http://opensourceecology.org/wiki/SKDB ), which seeks to develop combined human and machine readable information protocols for future automated fabrication and computer aided design.

      Eric Hunting

      On Jan 7, 2013, at 7:59 AM, luf-team@yahoogroups.com wrote:

      > Open Structures
      > Sun Jan 6, 2013 11:14 am (PST) . Posted by:"jdwheeler42" jdwheeler42

      > Here's an article I thought you'ns might be interested in:
      > http://www.lowtechmagazine.com/2012/12/how-to-make-everything-ourselves-open-modular-hardware.html
      > In particular I was wondering if Utilihab could fit into the Open Structures specification. This might instantly give it a much greater audience. I am particularly interested in any thought Eric Hunting might have.

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