Home |
Search |
Today's Posts |
|
Woodworking (rec.woodworking) Discussion forum covering all aspects of working with wood. All levels of expertise are encouraged to particiapte. |
Reply |
|
|
LinkBack | Thread Tools | Display Modes |
#41
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"Michael Daly" said:
We still haven't seen a decent definition of what "equivalent width" means, only a vague statement. Yes, I answered this question - meaning that the width of the wood makes no difference. -- McQualude |
#42
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
|
#43
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
Too bad you didn't just say the same circumference. You would
have avoided all the "what do you mean by same size" questions. If THAT were the question I'd say round has a slight advantage, not in terms of taking a blow that breaks it in two, but the lack of square corners begging to be dented and splintered makes the entire structure more "sound". If you took the same amount of material and shaped it with alot of delicate edges and thin areas, the structure is weaker due to its shape, and the many vulnerable points. But if you're just wanting to know which shape would snap under a destructive load test, you'll have to ask an engineer. -- The software said it ran under Windows 98/NT/2000, or better. So I installed it on Linux... "Fred the Red Shirt" wrote in message om... McQualude wrote in message ... I found this question in another group (misc.rural)... Which is stronger, a round post or square post? Assume the posts are both made from the same wood and are both equivalent in width. Answering a different question, here but: If you start with a tree trunk which is typically what you start with for a fence post, it will be stronger if you leave it round than if you square it up. -- FF |
#44
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
On 12-Nov-2003, McQualude wrote:
"Michael Daly" said: We still haven't seen a decent definition of what "equivalent width" means, only a vague statement. Yes, I answered this question - meaning that the width of the wood makes no difference. If the width makes no difference, then you're comparing apples and oranges. A round post 12" in diameter will be stronger than a square one 1" on a side. OTOH, a square 12" on a side will be stronger than a round one 1" in diameter. Bets are off it you're comparing balsa to white oak with arbitrary dimensions. Mike |
#45
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
todd wrote in message . 1...
(larry) wrote in om: McQualude wrote in message ... I found this question in another group (misc.rural)... Which is stronger, a round post or square post? Assume the posts are both made from the same wood and are both equivalent in width. Don't listen to all these engineers. Wood should be used based on its properties, not their theories. Moment of inertia? If they ever touched a real piece of wood I would be surprised. Well, I guess you should be surprised. You must be one of those folks who doesn't let a little thing like physics get in the way of what you think is right. Maybe you want to enlighten us on how wood resists bending in a different way conceptually than other materials. Until then, crawl back into your hole and leave the heavy lifting to someone who has both the theoretical and practical experience. No material is going to match the formulas exactly. Wood complicates matters further because it is anisotropic (that means it has different physical properties in different directions). However, the formulas (these aren't just theories, by the way, much less *my* theories) will still give good guidance in answering a question such as the one posted originally. todd Sorry Todd. I'm new to this posting thing(no pun intended). I had sent a reply before the short one that did have some content. I must have deleted rather than sent it. My point was basically that we are talking about fence posts. On wood of that scale used for that purpose, the limiting factor for strength would be grain runout. I assumed that anything "round or square" would be from a mill. The sawing process cuts across grain lines leaving weak spots. Using any shape of split timber would be preferable. When splitting posts I generally don't take the time to round them off or square them up. So, if the question was which shape, round or square, should I buy from home depot the answer is it doesn't really matter. It will take me a while to recognize the difference between a woodworking question and one that is thrown out there to noodle out. By the way, I know a couple of engineers that are woodworkers as well. They would be the first to admit that they take the material properties thing a little too far. I'm used to ribbing them for it. Out of context that short message did deserve that answers it got. Larry |
#46
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
todd said:
folks who doesn't let a little thing like physics get in the way of what you think is right. I'm listening, explain why a round or square wooden fence post is stronger if the width of the post is not a factor. I, and one or two others, postulated that the round post would be stronger because it maintains the integrity of the tree (assuming the post started as a whole tree). No engineers have responded to rebut any of those comments. -- McQualude |
#47
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
McQualude wrote in news:Xns9432E7CBE3C78mcqualude@
24.25.9.43: todd said: folks who doesn't let a little thing like physics get in the way of what you think is right. I'm listening, explain why a round or square wooden fence post is stronger if the width of the post is not a factor. I, and one or two others, postulated that the round post would be stronger because it maintains the integrity of the tree (assuming the post started as a whole tree). No engineers have responded to rebut any of those comments. Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. Therefore, the square post contains all of the material of the round post, plus the material in the square corners. Unless you can explain how added material in the corners weakens the post, consider your postulate rebutted. Note I haven't spent much time talking about whether a square post is an efficient means of making a post (though I did touch on this point a couple of posts ago). You could probably make an argument of why the hell are we talking about this anyway. How much load is a fence post likely to see in the first place? I answered a general question with a general answer. We would have to have a *lot* more information to arrive an an in-depth answer. A notable example would be what would the failure mode of a wooden post in bending be? It could fail in tension (at the top of the post (opposite side to the direction of load), in compression at the bottom of the post, or in shear in the center. You could make a case for being concerned about the shear strength of a post with the center of the tree (not an area known for high strength) being located at the area of highest shear stress. Unless you're prepared to enter into such a discussion, I'd leave the postulating alone. todd |
#48
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
McQualude wrote in message ...
todd said: folks who doesn't let a little thing like physics get in the way of what you think is right. I'm listening, explain why a round or square wooden fence post is stronger if the width of the post is not a factor. I, and one or two others, postulated that the round post would be stronger because it maintains the integrity of the tree (assuming the post started as a whole tree). No engineers have responded to rebut any of those comments. The integrity of the tree you are tying to maintain in this situation is the grain that runs from end to end in the tree. A tree trunk the size of a post would have all of the grain intact. A tree four times the size of the post split into four pieces would have the same unbroken grain end to end, like a handfull of straws. The cross section of the post is a secondary. So if you have two pieces of wood from the same tree with no grain runout,one round and one square in section and you assume that being the same size refers to cross sectional area, I would think they would be the same strength. From this point someone with a better knowledge of physics would have to take over. I just know wood. |
#49
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
todd schreef
Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. + + + From a practical point of view this assumption is not realistic. A round post is likely to be 'whole tree' A square post is likely to be sawn from a bigger trunk. This means that a round post consists partly of juvenile wood, a weakening factor. A square post will consist of mature wood. Ergo: the strength of the material will not be equal in these two cases. It will be less in a round post PvR |
#50
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
Ah, but your assumption is that the square post has been cut from the center of the tree and contains
only heartwood. How do you know it wasn't cut from a section of the tree sear the growth rings and thus contains both sapwood and heartwood? -- Al Reid "It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so." --- Mark Twain "P van Rijckevorsel" wrote in message ... todd schreef Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. + + + From a practical point of view this assumption is not realistic. A round post is likely to be 'whole tree' A square post is likely to be sawn from a bigger trunk. This means that a round post consists partly of juvenile wood, a weakening factor. A square post will consist of mature wood. Ergo: the strength of the material will not be equal in these two cases. It will be less in a round post PvR |
#51
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
todd wrote: Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. Therefore, the square post contains all of the material of the round post, plus the material in the square corners. Unless you can explain how added material in the corners weakens the post, consider your postulate rebutted. Because where the grain exits/ enters the post it creates uneven stress. You could probably make an argument of why the hell are we talking about this anyway. Mental masturbation. -- Mark N.E. Ohio Never argue with a fool, a bystander can't tell you apart. (S. Clemens, A.K.A. Mark Twain) When in doubt hit the throttle. It may not help but it sure ends the suspense. (Gaz, r.moto) |
#52
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"P van Rijckevorsel" wrote in
: todd schreef Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. + + + From a practical point of view this assumption is not realistic. A round post is likely to be 'whole tree' A square post is likely to be sawn from a bigger trunk. This means that a round post consists partly of juvenile wood, a weakening factor. A square post will consist of mature wood. Ergo: the strength of the material will not be equal in these two cases. It will be less in a round post PvR I'm telling that from a practical point of view, you don't have the first clue how the post will fail. (For the record, I've already stated that I don't know what the compression strength, tensile strength, and shear strength is for various woods, although I'm sure I could google it if I was so inclined). Your assumption regarding the strength of juvenile only matters if shear is the primary failure mode. If the primary failure mode is tension or compression, then it doesn't really matter what's happening in the center. todd |
#53
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"Mark" wrote in message ... todd wrote: Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. Therefore, the square post contains all of the material of the round post, plus the material in the square corners. Unless you can explain how added material in the corners weakens the post, consider your postulate rebutted. Because where the grain exits/ enters the post it creates uneven stress. I suppose that sounds good, but I don't think in practice it's really going to have a very large effect at all, if any. In the worst case, if we assumed that the shear strength between growth rings was very low, you might be able to argue that it really wouldn't help, but I don't see how it would hurt. This isn't like machining a notch into the additional area that would create a stress concentration, which could actually produce an overall weaker member (heh, heh....he said "member"). todd |
#54
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
On Fri, 14 Nov 2003 09:17:34 -0600, todd wrote:
This means that a round post consists partly of juvenile wood, a weakening factor. A square post will consist of mature wood. Ergo: the strength of the material will not be equal in these two cases. It will be less in a round post PvR I'm telling that from a practical point of view, you don't have the first clue how the post will fail. (For the record, I've already stated that I don't know what the compression strength, tensile strength, and shear strength is for various woods, although I'm sure I could google it if I was so inclined). Your assumption regarding the strength of juvenile only matters if shear is the primary failure mode. If the primary failure mode is tension or compression, then it doesn't really matter what's happening in the center. For posts made of a suitable wood in suitable size, the "usual" failure is that it rots at the ground line. If your post fails before it rots, it was too small. Usually, you string the wire on the inside of the line posts, so that an animal pushing against it doesn't pull the staples, and around the corner posts. There are as many ways to brace corners as there are fence builders. My preferred method was to have the line posts at 16', except at the corners, where I'd have the first line post 8' away with a horizontal member in compression, and a wire tensioner making SURE it STAYS in compression. This was woven wire for sheep, which carries a good bit more total tension than barbed wire for cows. Dairy farmers got away with smaller corner posts and less substantial bracing, but they needed twice as many line posts. Had a neighbor who had sheep AND a commercial cabinet shop. His fences were made from "scraps." It didn't hold sheep in (more importantly dogs out) any better than our fence did, but DAMN did it look nice. |
#55
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
Al Reid schreef
Ah, but your assumption is that the square post has been cut from the center of the tree and contains only heartwood. + + + Just the reverse. If a tree is sawn up into square posts only one of these will have 'heartwood'. In a perfect world this would be thrown out and not used as a pole. PvR |
#56
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
todd schreef in
If the primary failure mode is tension or compression, then it doesn't really matter what's happening in the center. + + + That is a good point, but still assumes posts of sufficient diameter that this outer part is free of juvenile wood. PvR |
#57
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
|
#58
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"Lawrence Wasserman" wrote in message ... Is this post for a fence or a ... MAILBOX? -- DUH, everyone knows you use steel, concrete and brick for a mailbox. That way any mail box bashers get their arms broken or better yet, die in a fiery crash. Please pass the popcorn. |
#59
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
todd said:
folks who doesn't let a little thing like physics get in the way of what you think is right. I'm listening, explain why a round or square wooden fence post is stronger if the width of the post is not a factor. I, and one or two others, postulated that the round post would be stronger because it maintains the integrity of the tree (assuming the post started as a whole tree). No engineers have responded to rebut any of those comments. Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. Therefore, the square post contains all of the material of the round post, plus the material in the square corners. Unless you can explain how added material in the corners weakens the post, consider your postulate rebutted. You still made the same assumption that the square post contains more wood, even after I've told you twice that isn't true. -- McQualude |
#60
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"McQualude" wrote in message ... todd said: folks who doesn't let a little thing like physics get in the way of what you think is right. I'm listening, explain why a round or square wooden fence post is stronger if the width of the post is not a factor. I, and one or two others, postulated that the round post would be stronger because it maintains the integrity of the tree (assuming the post started as a whole tree). No engineers have responded to rebut any of those comments. Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. Therefore, the square post contains all of the material of the round post, plus the material in the square corners. Unless you can explain how added material in the corners weakens the post, consider your postulate rebutted. You still made the same assumption that the square post contains more wood, even after I've told you twice that isn't true. -- McQualude So far, the sum total of your information from what I see looking back in the thread regarding the dimensions of the post has included the following "both equivalent in width" and "the width of the wood makes no difference". Personally, I don't have the faintest idea what the hell you mean by either of those. I've defined the assumptions I've made pretty clearly. If you'd care to be specific, I'd tailor my comments to your specific case. todd |
#61
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
On 14-Nov-2003, "todd" wrote:
If you'd care to be specific, I'd tailor my comments to your specific case. I think we should treat him as a troll. I've already asked him to clarify the width issue and all he does is blather some more. It would be trivial to clarify, but he just wants to be a PITA. Mike |
#62
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
On Fri, 14 Nov 2003 23:34:46 +0000, McQualude wrote:
todd said: folks who doesn't let a little thing like physics get in the way of what you think is right. Since you're assuming that the round post has the center of the tree as it's center, I'll assume that the square post is the same. Therefore, the square post contains all of the material of the round post, plus the material in the square corners. Unless you can explain how added material in the corners weakens the post, consider your postulate rebutted. You still made the same assumption that the square post contains more wood, even after I've told you twice that isn't true. Some people just can't see the forest for the trees... A 4" square post would be stronger than a 4" round post. The square post would be almost the equivilent of nailing a 2"x4" board of the same material to the round post. The only case I know of where a round post was stronger than a square post is the corner post my Father set when I was a teenager. It was about 8" diameter and about 9' long, fresh cut from a hedge tree and set in the spring of the year. Being fresh cut, it took root and grew, now is about a 16" diameter tree over 25 feet tall. It is still round though. It never did grow square. |
#63
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"todd" said:
So far, the sum total of your information from what I see looking back in the thread regarding the dimensions of the post has included the following "both equivalent in width" and "the width of the wood makes no difference". The question has already been answered, thanks anyway. -- McQualude |
#64
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"Jon Dough" said:
You still made the same assumption that the square post contains more wood, even after I've told you twice that isn't true. Some people just can't see the forest for the trees... A 4" square post would be stronger than a 4" round post. Yes, that would be true, but that wasn't the question. Thanks, but the question has already been answered. -- McQualude |
#65
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"Michael Daly" said:
I think we should treat him as a troll. I've already asked him to clarify the width issue and all he does is blather some more. It would be trivial to clarify, but he just wants to be a PITA. It was a simple question that several people already posted good answers for. As I stated in the first post, I lifted the question from another group because I thought a bunch of woodworkers might have good answers, I gave you all the information that was available in the original post. The original poster did not answer any questions that were in the original thread, so I gave you all the information that I had. I'm not sure how this makes me a troll, but you can go **** yourself. -- McQualude |
#66
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
On Tue, 11 Nov 2003 02:44:43 GMT, McQualude
wrote: I found this question in another group (misc.rural)... Which is stronger, a round post or square post? Assume the posts are both made from the same wood and are both equivalent in width. Wow, what a huge thread ! There's no way I'm wading through all the replies, as dinner is waiting and I've got to fly. If the "post" is a fence post and loaded on side I was taught that the grain line-up, that would decide As to whether or not it would resist the cow (Our fence posts were square, and not round but it's "how" the grain was a'running and not 'bout it's section t'would resist our big bull with a full-blow erection and, if our bull wanted to get out, when hot a square or a circle, it didn't mean snot) But, if you are saying a post is a column And holds up big buildings and things that are solemn Like kitchens and children and Grandfather's rocker I'll spin you a truth that's not much of a shocker A square that is six inch on each of it's sides Has an area greater than circles that wide The area's key, it's the thing that must rule And he who says dif'rent is not but a fool. Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania http://users.snip.net/~tjwatson |
#67
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
"McQualude" wrote in message
... "todd" said: So far, the sum total of your information from what I see looking back in the thread regarding the dimensions of the post has included the following "both equivalent in width" and "the width of the wood makes no difference". The question has already been answered, thanks anyway. -- McQualude No ****. I've answered the thing about 5 times by now just by myself, not including the other answers. Of course, I don't know how one could give an accurate answer because based on the limited amount of information available, there's no way to be specific. I included the assumptions that I made in my examples. todd |
#68
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
On 15-Nov-2003, McQualude wrote:
so I gave you all the information that I had. I'm not sure how this makes me a troll, but you can go **** yourself. What a lovely sentiment. Why didn't you just answer "I don't have a clue, I just copied the question" instead of giving ambiguous and vague answers about width. "Width doesn't matter" is an irrelevant comment. Mike |
#69
|
|||
|
|||
Wood Question: Which is stronger, a round post or square post?
Michael Daly wrote: "Width doesn't matter" is an irrelevant comment. That's what women tell us to make us feel better. -- Mark N.E. Ohio Never argue with a fool, a bystander can't tell you apart. (S. Clemens, A.K.A. Mark Twain) When in doubt hit the throttle. It may not help but it sure ends the suspense. (Gaz, r.moto) |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Footings crossing boundary | UK diy | |||
Further to my last post entitled 'Flushing and treating central heating question' | UK diy |