Doug D. wrote:

(snipping much good analysis of what's going on with flexure...)

I really hesitate to get out out of my quiet, comfortable spot in the corner
next to the cracker barrel.  I've been there stuffing my mouth full of
crackers to prevent any more too-quick comments.

But, Doug, phtooie, phtooie!....(oops, sorry, I'll clean it up that mess in
a minute...oh, are those your good pants?)

>   It's been a slow day on the oldtools list, so I had to fill out
>   my dinner break with _something_... :-)
Must have been an extraordinarily tiring one.

I really don't want to rekindle any long smouldering differences  between
theorists at their desks and engineers who have to actually face the "real
world", so don't take this wrong.  For the sake of those who might have
copied your plane sole deflection calculations onto the front of the
refrigerator, I gotta say, I think you missed (due to fatigue) some
important things that really mess up the results.

#1 - The interaction between the sides of the plane casting and the sole are
totally different than the way your math treats them, since they are
actually one piece.

#2 - I know that for the sake of the KIS principle you didn't deal with the
fact that the side thickness isn't XX" as you said, and is tapered - joined
to the sole with a rather large radius...Well, that alone throws the
calculation way off.  But not as much as #1.

#3 - My Phtooie alarm went off as soon as I read:
>   The Young's modulus, or modulus of elasticity, of cast iron, is:
>      E = 152.3 GPa = 22.1x10^6 psi
Among REAL WORLD practical people, it has become pretty standard to apply a
FF (Fudge Factor) to anything that comes from theoretical physics.

To be more constructive - 
A factor your formula needs is something I picked up at a public library
several years ago out of a 40 year old book.  It's a table of factors to be
used as divisors when using Young's modulus here on the surface of this REAL
world, where I spend most of MY time. 

Reginold T. Smith (of Austrailia somewhere) created a fudge factor table to
deal with the discrepancies I'm talking about.  (He even labeled the "units"
REGS  - must have been an ego thing)  

Well, I had copied it down, and had played with it before, so I dug it up
now, just to check out your theoretical  results. Because they just didn't
sound quite right to me.

The revised (your) formula for a piece 24" long says 10lbs. at the mouth can
deflect the surface .003.  Kind of a long way from what you suggested I think.

So (since I don't have cable TV) I checked it out on a #8.  Sure enough!
(although admittedly I got .004" with 10 lbs.)

But, going back to specific refinements needed for your formula -

#5 -  I calculate that the force directly downward on the knob and tote to
produce 10 lbs at the mouth at 18.6 lbs.  Ignoring the problem of doing that
with the shape of the tote, what it would take to deflect it .020" would
leave my feet off the floor.  How am I going to give it a push forward?

I'll reprint Mr. Smith's conversion table I suppose, for anyone really
interested.  But it's even longer than this post.

Long note just to say "Back to the drawing board, Doug."  And I hope this
week isn't as exhausting for you.  :^)

------
Gene