Can downward pressure split a 2 x 4?

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Hi.
... beginning with a 6' 2x4 (110 S-DRY STUD)
... drilled a total of 30 (5/16") holes through the 2x4 (1 1/2") down the center spaced 2" apart
... so it's just a 2x4 with evenly spaced 5/16" holes down the center
... now the 2x4 is standing on its end, perpendicular to the ground
If a 5/16" bolt is pushed through one of the holes near the top, how much downward pressure on that bolt before the 2x4 splits down the center?
In other words, if that 5/16" bolt were a dumbbell, how heavy can that dumbbell be before it splits the 2x4 down the center?
The next 5/16" hole is 2 inches below (center to center).
If possible, an extremely rough estimate is fine.
Thank you.
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If i'm reading this right, *all* of the holes are through the same grain line, which has essentially destroyed the structural integrity of the piece for the purposes you describe.
I don't know what kind of weight it would hold, but I wouldn't trust it with anything I wanted to keep.
jc

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please don't answer someone's homework problem.

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I would have explained in detail, but I think most members of this group would be more interested in the problem as generically stated than in my specific circumstance. Usually less writing is better when asking a question IMO.
I really need and appreciate the discussion.
"Charles Spitzer" <charlie.spitzer nospam.stratus.com> wrote:

         
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Thu, Jan 26, 2006, 1:45am (EST+5) snipped-for-privacy@usenet.love.invalid (JohnDoe) doth clameth: I would have explained in detail, but I think most members of this group would be more interested in the problem as generically stated than in my specific circumstance. Usually less writing is better when asking a question IMO. I really need and appreciate the discussion.
Horse hocky. I'm thinking you just want someone to do your homework too. Either that or you're another troll. And, if you're gonna ask questions, the more details you can provide the better, if you want to get usable answer, that is.
JOAT You only need two tools: WD-40, and duct tape. If it doesn't move and it should, use WD-40. If it moves and shouldn't, use the tape.
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There's nothing in the question that suggests it's a homework problem.
Maybe I should be flattered for apparently defining the problem well enough to make the question look academic.
Troll.
Jakofalltrades webtv.net (J T) wrote:

         
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Thu, Jan 26, 2006, 5:04pm (EST+5) snipped-for-privacy@usenet.love.invalid (JohnDoe) doth say: There's nothing in the question that suggests it's a homework problem. Maybe I should be flattered for apparently defining the problem well enough to make the question look academic. <snip>
Sure there is - what suggests homework is because it's pretty similar to other questions from students wanting to get out of doing their school work - college freshmen usually. So, don't be flattered..
JOAT You only need two tools: WD-40, and duct tape. If it doesn't move and it should, use WD-40. If it moves and shouldn't, use the tape.
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That explains all the generic postings about woodworking and joinery here without references to actual projects. Have you actually read any postings in this newsgroup?
It's been my experience that you get better answers to specific questions than very general ones. The answer to the question you originally posed is "42". But you won't understand the answer until you truly understand the question.
John Doe wrote:

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My question was so well defined/specified that it was well discussed and very clearly answered. Much appreciated. I'm delighted.
A sarcastic, semantics game playing troll.
Mike Berger <berger shout.net> wrote:

newssvr29.news.prodigy.net> <dr8pn2$63g$1 transfer.stratus.com> <Xns9756C55EFB0F5follydom 207.115.17.102>

         
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snipped-for-privacy@usenet.love.invalid says...

So what is the application anyway?
I'd guessed from your example that you were doing something with weights (as in barbells and dumbells) and thinking serious kilogrammage.
If so, I don't know about anyone else, but I'd cross reinforce it.
Frankly, I hate questions that leave out the application.
Knowing what weight will cause a 2x4 with a pattern of holes to fail may be interesting, but knowing, that you will use a pair of the boards to store assembled barbells of 50 to 500 lbs up to a total of x lbs. is important because you, or others may drop one of them onto the rack... and cause it to fail.
Knowing if the board will be vertical or set back at an angle is also important because the weight will be transmitted differently.
etc. etc. etc.
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phorbin <phorbin1 yahoo.com> wrote:

My favorite part of the replies is the general rule about the consequential/important distance from hole to hole, the answer being given as five times the diameter of the dowel hole.
Message-ID: <1138246157.771503.41270 z14g2000cwz.googlegroups.com>
See you all later.

newssvr29.news.prodigy.net> <dr8pn2$63g$1 transfer.stratus.com> <Xns9756C55EFB0F5follydom 207.115.17.102>

         
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says... : : > I would have explained in detail, but I think most members of this : > group would be more interested in the problem as generically stated : > than in my specific circumstance. Usually less writing is better : > when asking a question IMO. : > : > I really need and appreciate the discussion. : : So what is the application anyway? : : I'd guessed from your example that you were doing something with weights : (as in barbells and dumbells) and thinking serious kilogrammage. : : If so, I don't know about anyone else, but I'd cross reinforce it. : : Frankly, I hate questions that leave out the application. : : Knowing what weight will cause a 2x4 with a pattern of holes to fail may : be interesting, but knowing, that you will use a pair of the boards to : store assembled barbells of 50 to 500 lbs up to a total of x lbs. is : important because you, or others may drop one of them onto the rack... : and cause it to fail. : : Knowing if the board will be vertical or set back at an angle is also : important because the weight will be transmitted differently. : : etc. etc. etc.
And unless I missed it, not a single person has yet mentioned that you'll very seldom find a 2 x 4 of any length where the same grains at one end appear at the other end. When we were testing benches, there were two split mechanisms expected: One where the wood bowed north/south first, and the other where it'd bow east/west first. Occasionally the first split to occur would be longitudinally the whole length, but not often. When that occurred, it was anyone's guess which way the bow would progress before the break started. Also, a sharp blow is much more likely to break the wood, where a steadily increasing pressure reached a much higher pressure psi. Vibrations set uip by a shapr strike are much more damaging to the structure than constantly increasing pressure. It's a whole science in itself. And then you get into angular displacements, as in someone leaning back on a bench... . Credit Hammond Organ for this part of my experineces. It was fun, but not as much fun as the later earthquake testing on rollers and shakers. <g>
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Charles Spitzer wrote:

It's not a homework problem. Homework problems have clear right answers. This one doesn't -- it depends too much on how the grain of the wood runs, for one thing, and for another thing there's no good way to _calculate_ an answer without either more guesswork than a homework problem allows, or lots of computer analysis.
Also, it includes irrelevant data, which homework problems generally don't.
- Brooks
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The "bmoses-nospam" address is valid; no unmunging needed.

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Wed, Jan 25, 2006, 9:35pm (EST-3) snipped-for-privacy@cits1.stanford.edu (BrooksMoses) doth burble: It's not a homework problem. <snip>
Really? Did I miss the original poster saying that?
JOAT You only need two tools: WD-40, and duct tape. If it doesn't move and it should, use WD-40. If it moves and shouldn't, use the tape.
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That is correct.
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No. Resistance against splitting is the strangth perpenticular to the fibers, so the question here is how much pressure perpenticular to the fibers will the bolt exert. If it fits snug into the hole that is rather little, so splitting the stud along the middle will probably not be the mist likely failure mode. A small bolt, however, might act like the tip of a wedge and get the thing split.
--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
mailto: snipped-for-privacy@physik.uni-bonn.de Phone: +49 228 73 2447 FAX ... 7869
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I agree, the smaller the bolt, the *earlier* it would split the 2x4 (given increasing weights), but I disagree in that regardless of the size of the bolt or how snugly it fits into the hole, the method of failure would still be the longitudinal splitting of the piece especially since gravity is pulling the bolt/weight/whatever down the long axis.. If you don't agree, we'll have to agree to disagree. Agree? ;-)
jc
Phone: +49 228 73 2447 FAX ... 7869

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I agree (maybe to disagree), I can't do the calculations (because they are rather complex as crushing of the wood around the bolt has to be considered). But another possible failure mode would be for the 2x4 to buckle and break under the load. Unfortunatly I am in no position to make a test...

--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
mailto: snipped-for-privacy@physik.uni-bonn.de Phone: +49 228 73 2447 FAX ... 7869
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wrote:
Buy some 2x4s. Drill some holes. Apply various pressures until they split. Let us know the results. You'll have to do it a few times and get an average.
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and a nut between the holes on the side 90 degrees to the side with all the holes you will add tremendous strength to the board.
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