I've found an error in one of the dimensions. The radius of the points of the triangles is given as 0.228 inch but that's impossible with the diameter of the holes at 0.438.
Fitting a 0.228 radius tangent to the 0.070 thick bars makes it intersect the holes. Oops! Someone didn't sanity check the drawing... Changing the tip radius to the same as the hole diameter makes the design match the drawing. Alternatively, it could be the web bar thickness dimension is wrong, but they'd have to be a lot thicker and thus heavier to make the 0.228 triangle tip radius work. The bottom of the 8 is cut off so I figured it might be 0.338 but that's still too small. I'll go with 0.438 on them because it looks more like the drawing and photos of the grids. Perhaps this was McDonnell Douglas being like DaVinci, putting a deliberate error into a drawing not intended as a manufacturing document. Or it could be a typo, someone hit a 4 instead of a 3. Whatever the reason, proofreaders missed it. Proofreading, not like it's rocket science, eh? Should have a 3D model done in a few... --- On Thu, 4/11/13, jeremy youngs <jcyoung...@gmail.com> wrote: > From: jeremy youngs <jcyoung...@gmail.com> > Subject: Re: [Emc-users] A project I want to do on a CNC mill > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Date: Thursday, April 11, 2013, 8:49 PM > IT LOOKS TREMENDOUSLY STRONG AND > AGREE IT COULD BE USEFUL > > > On Thu, Apr 11, 2013 at 10:36 PM, Gregg Eshelman <g_ala...@yahoo.com> > wrote: > > > This seems to have been recently scanned, found it on > Wikipedia. Isogrid > > hadn't turned up in my previous searches for this. > > > > Isogrid Design Handbook, NASA CR-124075, McDonnell > Douglas, 1973 > > http://femci.gsfc.nasa.gov/Isogrid/NASA-CR-124075_Isogrid_Design.pdf > > > > And skipping through a tone of theory, math, more math, > lots more math and > > other 'this is how we do it' stuff... > > > > Page 42 has the dimensions of the panels as used on > Skylab! > > > > That would be so easy to have cut on a water jet. When > were those > > invented? I'd expect the originals to have been cut out > with an NC mill, > > which would've converted quite a lot of the plate to > chips. ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
