Bizarre request - how would you do it?

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Been given a request by a friend who is doing an engineering course in college. Currently his project entails strength of materials and he has been asked to aquire 4 boxes made of 4 different materials, his choice. They are to be tested to destruction. How I don't know, neither does my friend. Well he's asked me to make a box out of wood and I've been told to make it strong. Box has to be hollow for equipment. 6 inches inside space, exterior no more than 12 inches. No foreign material, i.e screws, nails etc etc but epoxies and glues are. I was thinking of getting something like a roof joist, 6inches thick/ 12inches wide cutting two squares out of it, carving out the centre and gluing the two halves together with long wooden dowels or biscuits.
Well what do you think? Is there another way? What would you do different?
TR
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How about MASSIVE??
Massive blocks of wood - selections from a post and beam structure. Massive mortise and tenon with massive dowel pins - as in post and beam. Massive dove tail - may not be a strong as above but will not pull apart easily.
IMO the biscuits will be the weakest link if going for strength.
-- PDQ
--
| Been given a request by a friend who is doing an engineering course in | college. Currently his project entails strength of materials and he has | been asked to aquire 4 boxes made of 4 different materials, his choice. | They are to be tested to destruction. How I don't know, neither does my | friend. | Well he's asked me to make a box out of wood and I've been told to make | it strong. Box has to be hollow for equipment. 6 inches inside space, | exterior no more than 12 inches. No foreign material, i.e screws, nails | etc etc but epoxies and glues are. I was thinking of getting something | like a roof joist, 6inches thick/ 12inches wide cutting two squares out | of it, carving out the centre and gluing the two halves together with | long wooden dowels or biscuits. | | Well what do you think? Is there another way? What would you do | different? | | TR |
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You may want to consider a laminate sytem. The box will only be as strong as its joints. By building up smaller pieces laminated on top of each other in different directions you will have more overall strength.

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Tom H wrote:

You mean sealing in the sensor equipment as I go? Sounds like a lot less hardwork too.
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Then find out how the box will be tested. All engineering projects(especially student ones) will have criteria to be met, including how testing will be done. Lacking this info it is nearly impossible to do a good design.
Part of an engineering course is to test the students and find out which ones are too stupid to ask questions. These ones usually flunk out and transfer to liberal arts.
Art

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Ok after emailing my mate, I have managed to get three things out of him that he has managed to get out of his teacher. One, there will will be water and pressure involved. Two, intense heat but not fire. Three, a car. And there will be six tests.
That is all the teach will give him.
TR
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Much better but don't stop there. Try and find a student that has already taken the class and go for anything you can get.
Also, start speculating about the tests. 1. Water may be a soaking which would weaken some glues. 2. Heat will weaken epoxy glues and most plastics. 3. Pressure may be internal pressure(via a water balloon type device) to test the ability to contain expansion. 4. The car may be a deadweight compression test or an impact test.
Art

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Wood Butcher wrote:

This isn't it. The box is sealed with equipment inside. No holes for an air line and I can't see a gas canister in the little polystyrene box of gizmos my friend gave me. Theres a whole range of little sensor, i've determined one is for measuring heat and another for moisture. I might be having a stab but the other might be a g-reader.

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Wood Butcher wrote:

"Water and pressure" suggests an immersion to some depth (possibly bottom of the local pool, possibly something more strenuous with a pressure chamber). Heat is just heat; probably an oven, possibly a ceramic kiln. As for the car, my guess is "thrown out of".
Is the objective explicitly to build the box that's hardest to destroy? Or is that just something everyone's assuming? Given the description of "four boxes", I'd be tempted to make one out of corrugated cardboard, maybe with saran wrap duct-taped to the outside for waterproofing. :)
(Actually, three-inch-thick slabs of corrugated cardboard laminated together would probably be reasonably sturdy, as such things go.)
If he's got the instrumentation and can build it inside the box, that's definitely the way to go, whatever you're building.
- Brooks
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The assumption is toughest to destroy, they ain't been told a lot i've seen the paper work given to the pupils.
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To me it suggests a fire hose!
Brooks Moses wrote:

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Did as you instructed and found a student who has had the same teacher. This teacher is smart. The parameters are different. Either the teacher lied to his students or changes his tests.
Same parameters for the boxes but the conditions don't sound the same. No water, no car. Six tests are as follows. 1: Squeeze press 50 ton load, 10 minute - Check for damage/shape change 2: Dropped out a window, 6th floor, time the ascent. Check for damage/shape change 3: Ball bearing blast (equivalaint to a sandblasting) 5 minutes one surface. Check for damage/shape change. 4: Intense heat with flame, (blow lamp) One face 5 Minute. Check for damage/shape change 5: Sledgehammer, narrow 15lb head one hit each face. Check for damage/shape change 6: 10ft drop onto 1inch steel plate. Check for damage/shape change
Then they had to examine what was left and say how the structure of the chosen materials had changed.
Wood Butcher wrote:

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Wow, they really are different. Nothing in the current one about the box needing to be lighter than air! <G,D,&R>
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alexy wrote:

I did that on purpose honestly. The award for spot the typo goes to Alexy.
I meant descent honestly.
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[...]
You could also try to time the ascent during the rebound, if the box (and ground) should proove to be sufficently elastic.

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TrailRat (in snipped-for-privacy@o13g2000cwo.googlegroups.com) said:
| Did as you instructed and found a student who has had the same | teacher. This teacher is smart. The parameters are different. | Either the teacher lied to his students or changes his tests. | | Same parameters for the boxes but the conditions don't sound the | same. No water, no car. | Six tests are as follows. | 1: Squeeze press 50 ton load, 10 minute - Check for damage/shape | change 2: Dropped out a window, 6th floor, time the ascent. Check | for damage/shape change | 3: Ball bearing blast (equivalaint to a sandblasting) 5 minutes one | surface. Check for damage/shape change. | 4: Intense heat with flame, (blow lamp) One face 5 Minute. Check for | damage/shape change | 5: Sledgehammer, narrow 15lb head one hit each face. Check for | damage/shape change | 6: 10ft drop onto 1inch steel plate. Check for damage/shape change | | Then they had to examine what was left and say how the structure of | the chosen materials had changed.
Sounds like fun! I think I'd opt to build from a pair of 12x12x9 slabs. If the instrumentation allowed, I'd begin by routing out a 3"-radius hemisphere from the center of both. Next (6" from the outside bottom) I'd rout out a centered 4-1/2"-radius circle. Finally, I'd rout radial crenelations with sloped sides (imagine gear teeth).
Both top and bottom are routed the same, except that one is started with the grain running side-to-side and one with the grain front-to-back - for cross grain strength.
It isn't easy to visualize, so I'll post a sketch to ABPW. It shouldn't be much more difficult to lay out and cut than a full-blind dovetail joint. :-D
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Morris Dovey (in MkbBf.236$ snipped-for-privacy@news.uswest.net) said:
| I think I'd opt to build from a pair of 12x12x9 slabs.
Better make that 12x12x7.5 slabs.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Many thanks got the picture now. Looks interesting to try any way.
TR
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Morris Dovey (in MkbBf.236$ snipped-for-privacy@news.uswest.net) said:
| TrailRat (in snipped-for-privacy@o13g2000cwo.googlegroups.com) | said: | || 4: Intense heat with flame, (blow lamp) One face 5 Minute. Check || for damage/shape change
Hmm. I didn't handle this part very well. You might want to drill a tiny hole from each corner to the internal cavity and plug it with a small amount of wax to relieve pressure that builds up during this test...
Drilling from the corner should help prevent high temperature gasses from being blown directly into the cavity by the torch. The meltable wax seal /may/ help to prevent or retard flooding if there is a subsequent water test.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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On Tue, 24 Jan 2006 10:24:14 -0600, Morris Dovey wrote:

Nope. As a proto-type machinist / die-maker, I recognize the reflexive desire for symmetry .. but symmetry (that doesn't look like it's spelled right) is no advantage here and 'pretty' is not a design constraint / tested value.
Only drill from one corner. That will restrict the ability of liquid to flow into the cavity. Air is only about 1/16 as dense as water: make the hole tiny ... mebbe a #60 or so. Or. better yet, route / carve a WAAAAY shallow groove that curves 180 deg or more several times in a switchback pattern. The air under pressure will escape just fine (the test is for just a few minutes and all the designs so far provide for an insulating mass.) Incoming liquid will pressurize the compartment, slowing the flow of the liquid and allowing the fibers time to swell.
In fact, come to think of it, don't take the groove all the way to the cavity. Stop just a few thousandths short of it. The gasses will penetrate the cells but the liquid will not. If you overshoot the mark, glue a piece of craft paper over the oopsie. Same net result.
Paint the thing with fire-retardent paint such as used in restaurants. If the fire test comes first the swelling of the paint will give us bonus protection from the liquid. It might also shield the adhesives from heat failure.
We'll let the test, itself, provide the sealing, eh? ;-)
Bill
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