We are not engineers...

The post on lag bolts/coach screws/threaded inserts got me thinking.
Do you realise we do things in our hobby that are at total odds as to the
"correct" way of using them? Here are some that came to me off the top of the head:
White glue thinned 2: or even 3:1 for ballast - if you don't use matte medium or something else.
White glue thinned 10:1 and used as a ground foam fixer - sprayed through a mist bottle.
White glue (OK, I got a thing for white glue) used to bond caneite to pyneboard for track roadbed. One member at a train club I was at, an architect by profession wanted to use liquid nails as this was the "correct adhesive for the task". We didn't come to blows, but voices were raised.
Caneite used as roadbed. Strange that after being flooded with wet water/ diluted white glue for ballast, wet plaster, water from spray bottle between plaster coats, paints and stains applied with brush and spray bottle, the damn stuff - which is supposed to self-destruct at the mere mention of water - remains firm and stable under the tracks.
Acrylic or plastic paint diluted 3:1 and 6:1 for various scenery techniques.
Wiring (less said the better)
And so on. Oddly enough, we wildly over-compensate in some areas, especially layout legs. Oregon has a compression strength of 1000psi roughly. So a single 2 x 2 oregon leg could support 4000lbs of layout, or 16,000lbs if we use 4 legs. Thats near enough 8 tons! Now count the legs under your layout and work out what it could support. My old HO layout would, I estimate, support 28 tons! A freaking Peterbilt! OK, you can add all the riders I omitted here - tensile, shear and twisting forces that may be at work, but the point remains.
We are not engineers! Gee, I'm glad. Imagine a layout designed to correctly meet all engineering standards...
Steve Newcastle NSW Aust
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etc etc etc
A fellow reader of the board who lives in Oregon (the state) asked for clarification of Oregon (the wood). Oregon, locally, is a softwood, pinkish in colour with a marked grain. He commented that it may be known in the US as Douglas Fir. I'm not a carpenter, success to me is cutting a straight line. Are there any readers here more learned than I who can confirm that these woods are identical? TIA.
Steve
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Steve Magee wrote:

A Google search for Oregon, wood and Australia turned up several references to "plantation Oregon," then a Google search for "plantation Oregon" turned up references like "oregon, or Douglas Fir." From a further search of [Australia "douglas fir" Oregon], it *appears* that Aussies have abbreviated the full name "Oregon Douglas Fir" to Oregon.
--
John Miller
Email address: domain, n4vu.com; username, jsm
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John Miller wrote:

A more transparent linguistic path than "seppo", at any rate.
--
Steve Caple

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Aw, c'mon Steve, 'seazy! Yank = septic tank = septic = seppo!
What's so hard about that? Just don't tell any of my sep - er, American mates what it means though, OK? :)
Steve Speaking Strine, NSW, Aust
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Chief, Caneite? Pyneboard? These words are Dark and Mysterious. I feel as I do when reading my old copies of THE MODEL ENGINEER magazine. Now I should go and build something from plasticard, stuck together with Araldite, and then go to the hardware store for a tin of meths for cleaning brushes. Now there's a way to raise some suspicions at the hardware store. Ask for Drano and plastic tubing and they think you're making methamphetamines.
Engineers have a long and honorable history of ingenious material misuse. If it works, then it works; you go by the common practice if it helps you, and if it doesn't you ignore it. I read that the Skunk Works used Kotex to absorb oil spray from the U2's engine before it hit the windshield. Cordially yours, Gerard P.
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snipped-for-privacy@gannon.edu (Gerard Pawlowski) wrote:

That's a pretty neat trick...
... especially since the U2 is a single _jet_ engine aircraft, with even the _intakes_ a significant distance BEHIND the cockpit windows, and the engine itself in the fuselage even further back...
Mebbe they ought to use those things to plug up the gaping holes in that old tale! <<grin>>
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I recently raised my main train table from 32" to 40". The old legs were 2x2 (actually 2x4s ripped in half). My neighbor convinced me to use 2x4s for the taller legs since he had a whole pile of extra lumber.
The 2x2s were plenty strong enough with cross-bracing. With the 2x4s we could dance on the table and it wouldn't budge. And I don't dance well!
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On Wed, 07 Apr 2004 22:03:00 GMT, snipped-for-privacy@mindspring.com (Joe Ellis) purred:

    Though I do know Kotex pads were uses as emergency wound dressings in many situations.
                                cat
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Chief, Hmm, maybe it was a cooler leak or a hydraulic line. I don't remember exactly what the book said was leaking. I just remember it was oil and they used Kotex. Cordially yours, Gerard P.
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On Wed, 07 Apr 2004 22:03:00 GMT, snipped-for-privacy@mindspring.com (Joe Ellis) wrote:

I thought that's what they WERE used for.
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On 7 Apr 2004 10:59:01 -0700, snipped-for-privacy@gannon.edu (Gerard Pawlowski) purred:

    The atomic sub, Nautilus was planning to traverse the North Polar route from the Pacific to the Atlantic . During final trials they discovered a small water leak that the only way to get to it was to de install the reactor. This would mean a hideous delay. The Captain asked for suggestions and the Chief Engineer said "I've got one.". They put in to San Francisco the chief sent his crew out, dressed in civvies to all the auto parts stores and garages in the area. Buying 1 or 2 at a time, the sailors virtually cleaned the city out of the material the Chief had ordered. The stuff was poured into the water system and it worked. The Nautilus made it's famed trip thanks to hundreds of bottles of "Bars Leaks". To the end of its days the sub never had the deinstall to fix the leak as the radiator stopper continued doing its job perfectly. I doubt if there are many Chief Engineers on subs and surface vessels who don't have a case or 2 of Bars Leaks stashed away, "just in case".     This tale came from the Captain of the Boat and he recounted it in his book "Nautilus 90 North".     Creative innovation is the thing of Engineers and movie makers. (King Kong was only 2' tall, and the trip through the stargate in "2001" was done using a shoe box)
                                cat
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Don't forget heat treating your silver steel tools with a parafin blowlamp. Can you cut BA threads in gunmetal for rustless steel screws?
--
Bill Kaiser
snipped-for-privacy@mtholyoke.edu
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Steve Magee wrote:
> > And so on. Oddly enough, we wildly over-compensate in some areas, > especially layout legs. Oregon has a compression strength of 1000psi > roughly. So a single 2 x 2 oregon leg could support 4000lbs of > layout, or 16,000lbs if we use 4 legs. Thats near enough 8 tons! Now > count the legs under your layout and work out what it could support. > My old HO layout would, I estimate, support 28 tons! A freaking > Peterbilt! OK, you can add all the riders I omitted here - tensile, > shear and twisting forces that may be at work, but the point remains. > > > We are not engineers! Gee, I'm glad. Imagine a layout designed to > correctly meet all engineering standards... > > Steve Newcastle NSW Aust > > Actually, some of us are! One thing you missed on the legs is the column strength. If they are "slender" they can buckle long before the load reaches their compressive strength. Here is a discussion:
http://www.efunda.com/formulae/solid_mechanics/columns/inelastic.cfm
MacIndoe
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wrote: 2000

The point does not remain. Columns very rarely fail in compression. Mostly they fail by buckling. There is also the problem of stiffness. You don't want your layout to sway when you lean on it. Cross bracing will solve most of these problems but is not practical on a portable module. It is far simpler to overdesign and use larger cross section legs to support the stuff. My module legs are in the shape of an L made of 1/2" plywood and being 1-1/2" on each outside dimension. The cross-sectional area of a 2x2 which in the US of A is 1-1/2 x 1-1/2 is 2-1/4 square inches. The area of my legs is 1-1/4 square inches. I went to the trouble of building these legs because weight was important and was worth the trouble. I could have used thinner plywood yet but had reached the point of diminishing returns. There are many factors involved with compressive strength being the least important.
The other consideration is the number of legs. Obviously you (and most of the rest of us) have too many support legs for your layout. The number of legs is determined by the allowable deflection of the horizontal beams. More support means less deflection.
Is this bad design? More likely no design. In general there is no significant benefit to careful design of the benchwork, just make sure it is strong enough.
--
ernie fisch


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correctly
I've always thought that a good engineer is judged not by what he designs but by what he doesn't design (KISS principle). Really elegant designing takes into account economics too, so you might say that engineering is applied economics.
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http://groups.yahoo.com/group/MRPics http://groups.yahoo.com/group/vintageHO
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wrote: 2000

"wanna be" is the operative term here. Once you are forced to debug one of your masterful creations you will opt for simplicity or become a manager.
--
ernie fisch


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: wrote: 2000 : : > : > We had a layout designed by electrical engineers (or at least "wanna be" : > engineering students) in college. : > : > The guiding principle seemed to be NEVER use a spst toggle switch when you : > can do the same thing with two pushbuttons, 3 IC's, 27 transistors, four : > relays and 6 pounds of assorted hardware! : : "wanna be" is the operative term here. Once you are forced to debug : one of your masterful creations you will opt for simplicity or become : a manager. : : -- : ernie fisch : I always wondered why I became a manager... you're absolutely right! <G>
--
73 de KTT
Bob Schwartz
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