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#41
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mike hide wrote:
A tight joint in my book is as perfect a fit as one can get, that is not a force fit.. A loose tenon in my book is a sloppy or ill fitting joint and that is what this thread is about isn't it? obviously CW and David disagree....mjh Nope - it's about an end grain to edge grain mortise and tenon joint that puts a mortise in both parts and then a separate piece of wood to go into those mortises.. "Loose' menas that the tenon is not part of either piece to be joined together.. charlie b |
#42
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George wrote:
You don't. Best is to leave the pins square, so they cut rather than wedge against the face grain. Sam principle as cut ends on a nail. Since we're talking about a 1/32 - 1/16th offset between the hole in the mortised piece and the hole in the tenon, and the the tenon may be 1/2" thick, I don't think a wooden "nail" cut end or not, will "cut" that much wood. And if it could, if it's a through peg, it'd also "cut" the other side of the mortise as well? I suggested chamfering both the peg and the tenon's hole to make drawing the joint easier - remember, we're talking about a draw peg M&T joint and I had a through draw pegged joint in mind. I made the chamferring the hole suggestions based on splitting the end of a walnut peg in a draw peg M&T joint on my work bench base unit. Of course the tenons were 3/4" thick maple and the mortise was in a 3x3 spruce leg - not your typical M&T joint. More info please as to peg cutting cross grain. charlie b |
#43
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"LRod" wrote in message ... On Mon, 23 May 2005 11:49:18 -0400, "mike hide" wrote: "David" wrote in message ... I never said to make a "sloppy joint". But "as tight as you can make them"? I take that to mean you'd make a glued M&T so tight you have to "persuade" it together. If by "as tight.." you meant, PROPERLY snug, then we are in agreement. Dave A tight joint in my book is as perfect a fit as one can get, that is not a force fit.. A loose tenon in my book is a sloppy or ill fitting joint and that is what this thread is about isn't it? No, actually, it isn't. It was a discussion of the loose tenon method of joinery employed by David Marks. Loose tenon, as in two mortises and a separate tenon glued into each. I suspect that you're not so completely dense as to have missed that and are just being your usual obtuse self. obviously CW and David disagree.... And rightly so. You're the one who's screwed up -- LRod Being my usual Obtuse self, I read the original post by Stoutman, perhaps you should also . There is no mention of the method of constuction, just that they are loose tenons ..Even though I have never seen David Mark's program let alone ever heard of him . So what would a brilliant person like yourself by name a loose tenon might be ? surely not a lousy fitting tenon.....mjh |
#44
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On Mon, 23 May 2005 16:02:58 -0400, "mike hide"
wrote: "LRod" wrote in message .. . On Mon, 23 May 2005 11:49:18 -0400, "mike hide" wrote: A loose tenon in my book is a sloppy or ill fitting joint and that is what this thread is about isn't it? No, actually, it isn't. It was a discussion of the loose tenon method of joinery employed by David Marks. Loose tenon, as in two mortises and a separate tenon glued into each. I suspect that you're not so completely dense as to have missed that and are just being your usual obtuse self. obviously CW and David disagree.... And rightly so. You're the one who's screwed up Being my usual Obtuse self, I read the original post by Stoutman, perhaps you should also . There is no mention of the method of constuction, just that they are loose tenons The one whose subject is "David Marks and Loose Tenons" as can clearly be seen in the subject line of this post as well as the others to which you've responded? I read it. .Even though I have never seen David Mark's program let alone ever heard of him. Then what earthly reason is there for you to insert yourself in a thread in which fully half of the subject concerns David Marks and the other half a process with which you are clearly unknowledgable? You're as bad as toller giving electrical advice. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 |
#45
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"charlie b" wrote in message ... George wrote: You don't. Best is to leave the pins square, so they cut rather than wedge against the face grain. Sam principle as cut ends on a nail. Since we're talking about a 1/32 - 1/16th offset between the hole in the mortised piece and the hole in the tenon, and the the tenon may be 1/2" thick, I don't think a wooden "nail" cut end or not, will "cut" that much wood. And if it could, if it's a through peg, it'd also "cut" the other side of the mortise as well? I suggested chamfering both the peg and the tenon's hole to make drawing the joint easier - remember, we're talking about a draw peg M&T joint and I had a through draw pegged joint in mind. I made the chamferring the hole suggestions based on splitting the end of a walnut peg in a draw peg M&T joint on my work bench base unit. Of course the tenons were 3/4" thick maple and the mortise was in a 3x3 spruce leg - not your typical M&T joint. More info please as to peg cutting cross grain. Principle is well-known. Round peg in round hole splits. Square edge, breaks fiber to make passage. |
#46
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David Marks calls them 'Loose Tenon'. As does Gary Rogowski in his book
JOINERY. http://www.djmarks.com/stories/djm/L...nery_90627.asp Above is a link to Marks's web page with an explanation for his madness. I found it AFTER i posted my question. "Patriarch" wrote in message . 97.136... "mike hide" wrote in : A loose tenon in my book is a sloppy or ill fitting joint and that is what this thread is about isn't it? Loose tenons and floating tenons are often used as synonymns, hence some of the confusion. For example: http://www.taunton.com/finewoodworking/pages/w00118.asp I disagree with none of what you, Mike, have written in this thread. Patriarch |
#47
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"LRod" wrote in message ... On Mon, 23 May 2005 16:02:58 -0400, "mike hide" wrote: "LRod" wrote in message .. . On Mon, 23 May 2005 11:49:18 -0400, "mike hide" wrote: A loose tenon in my book is a sloppy or ill fitting joint and that is what this thread is about isn't it? No, actually, it isn't. It was a discussion of the loose tenon method of joinery employed by David Marks. Loose tenon, as in two mortises and a separate tenon glued into each. I suspect that you're not so completely dense as to have missed that and are just being your usual obtuse self. obviously CW and David disagree.... And rightly so. You're the one who's screwed up Being my usual Obtuse self, I read the original post by Stoutman, perhaps you should also . There is no mention of the method of constuction, just that they are loose tenons The one whose subject is "David Marks and Loose Tenons" as can clearly be seen in the subject line of this post as well as the others to which you've responded? I read it. .Even though I have never seen David Mark's program let alone ever heard of him. Then what earthly reason is there for you to insert yourself in a thread in which fully half of the subject concerns David Marks and the other half a process with which you are clearly unknowledgable? You're as bad as toller giving electrical advice Proud participant of rec.woodworking since February, 1997 Again read the first post in this thread by Stoutman ,not the one you choose to suit your purposes. I was not concerned with the author but with the subject, loose tenons. I assure you I do know what a tenon is and exactly what a loose tenon is by general woodworking standards. Your assumption that I am unknowledgable about " Loose Tenons" as defined by Marks has absolutely no basis ,you have no idea what I do or not know. As a matter of fact you would appear to be a nasty little know-it-all yourself., Being that it is surprizing you bother with mister Marks or the subject matter as it all has to be old hat to you.....mjh |
#48
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On Mon 23 May 2005 05:18:59p, "George" george@least wrote in
: Principle is well-known. Round peg in round hole splits. Square edge, breaks fiber to make passage. Yah but, but, I thought the whole idea was to apply pressure on the mortised board so the whole thing stayed together better. If you deliberately whack the pin in so a piece of it actually breaks off, then you basically got nothing but a pinned mortise, not a drawbored one. |
#49
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Mike may not know (probably) what a "loose" tenon is, but he sure knows
how to back pedal. |
#51
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To every one who made a comment here tonight on M&T, thank you from
someone who is trying to learn somethin, Glad to see none of that@$&^%(*@ stuff back and forth. This is enjoyable reading. Looking forward to more and again thank you all |
#52
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Accidently sent this to Mike instead of here. So -this is sort of
like trying to hold a conversation with a 10 hour delay between parties. Hopefully the diagrams that show the six degrees of freedom of movement which must be resisted and which parts of the M&T joint resists which movement. This may clarify things a little - showing the six (yup - six) degrees of freedom of movement that need to be fixed if two pieces of wood are to be joined together and not come apart. A mortise and tenon joint resists 5 of the six. http://home.comcast.net/~charliebcz/MtPrimer4.html As for having a "sloppy joint" - there are instances where a little "slop" actually can be a good idea - a table apron to leg joint for example. Having a little slop at the top of the tenon gives the tenon a place to expand without blowing the top of the leg off. You've got vertical grain for the legs and horizontal grain for the apron. The cross grain in the tenon will expand more than the vertical grain in the leg. If there's not place set aside for that expansion it will try anyway. The tenon will either compress and get tighter OR it will make the space by moving some wood above it at the top of the leg. It seems "spit tight" is what to shoot for. The tenon should fit snug enough to go in and out with just moderate hand pressure - no dead blow hammer, no mallet whacking etc.. But if you spit on the tenon and then seat it, it should swell enough to make getting the joint apart difficult. And tight also means leaving some place for a) glue inside to go (mortise a little deeper than the tenon is long) and b) some place for compressing the air trapped in front of the tenon as it seats or someway for it to get out of the joint. The beauty of "traditional joinery" is that it lets you dry fit things and the parts will a)self align and b) be self supporting. That's real handy if you make things "on the fly" - make step 1, make parts for step 2 to fit what you have in step 1 and so on. Has the advantage of letting you see things at full scale each step of the way. If you've ever worked from a "plan" and cut all your parts BEFORE putting them together you know that somewhere amongst all the given dimensions there's at least one that's wrong. Working progressively you can get dimensions off what you have. It isn't important that a part be 22 31/32nds but rather that if fit between the parts it's suppose to fit between. I can "take the line", "split the line" and "leave the line" more often than I can read a tape properly ; ) (ok - tell me you've never made a part an inch short) charlie b |
#53
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Dan wrote in
: On Mon 23 May 2005 08:37:15p, (John) wrote in news:17300- : Mike may not know (probably) what a "loose" tenon is, but he sure knows how to back pedal. Hm? Oh. I think you're looking for the Loose Tenon Definition subthread further down. This is the Drawbored Tenon subthread, which has degraded to the Square Pins vs Chamfered Pins in Drawbored Tenons subthread. Sorry. When do we degrade to wiring for 220? ;-) |
#54
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"charlie b" wrote in message ... As for having a "sloppy joint" - there are instances where a little "slop" actually can be a good idea - a table apron to leg joint for example. Having a little slop at the top of the tenon gives the tenon a place to expand without blowing the top of the leg off. You've got vertical grain for the legs and horizontal grain for the apron. The cross grain in the tenon will expand more than the vertical grain in the leg. If there's not place set aside for that expansion it will try anyway. The tenon will either compress and get tighter OR it will make the space by moving some wood above it at the top of the leg. This is where all of the discussion here about wood swelling with moisture etc., goes a little astray. First off - yes it does swell with moisture, I am aware. But... look at the myriad of jointery around you that has survived decades or longer without suffering the expansion problems that are talked about here so frequently and ask yourself what is wrong with this picture that there is so much discussion about 1/8" of movment across grain, or 8% humidity, etc. but there are so few broken joints in the furniture around you. We get so focused on one aspect of things that we sometimes overlook everything else. Sure, moisture causes swelling - to exposed and uncontrolled wood. Wood that is secured as a tenon in a mortice does not absorb moisture in the same way that unsecured wood does. The rates that we see published for wood expansion and moisture absorbtion are for raw, unsecured wood. They do not apply to sealed wood and they do not apply to wood that is secured as in a mortice and tenon. The mortice acts to keep the tenon compressed such that it can only absorb a certain amount of moisture, therefore a very controlled amount of expansion. Throw it under water if you want, but unless the glue disolves, the joint is not going to fail due to moisture absorbtion until the entire asssembly absorbs enough water to distort the whole piece. That would be far more than you'd ever see in environmental changes. Joined pieces of wood (with such interactive techniques as mortice and tenon) are simply not the same as raw wood and do not behave the way wood charts would imply for moisture absorbtion. Once again - look around at how few joints you can see that have actually failed, and then look to see why they failed. Most did not fail due to the joint being too tight and not allowing for moisture absorbtion. It seems "spit tight" is what to shoot for. The tenon should fit snug enough to go in and out with just moderate hand pressure - no dead blow hammer, no mallet whacking etc.. But if you spit on the tenon and then seat it, it should swell enough to make getting the joint apart difficult. That does indeed make for a nice, precision fit, but it would not be correct to suggest that a dead blow tight fit is somehow less strong or long lived. I have put many joints together that took some pretty good persuasion to fit, and years and years later, they are still there, just as they were when the project was built. I have to admit, when I have to resort to a little persuasion, it's generally because I'm rushing it along in some way and simply did not want to spend any more time to make it that little bit more perfect - but - the joint does not fail. And tight also means leaving some place for a) glue inside to go (mortise a little deeper than the tenon is long) and b) some place for compressing the air trapped in front of the tenon as it seats or someway for it to get out of the joint. I agree but I generally find that all jointery has that required amount of slop just by the nature of the woodworking and the material at hand. If you've ever worked from a "plan" and cut all your parts BEFORE putting them together you know that somewhere amongst all the given dimensions there's at least one that's wrong. Working progressively you can get dimensions off what you have. It isn't important that a part be 22 31/32nds but rather that if fit between the parts it's suppose to fit between. Now that's a man that's talking some good stuff! I can "take the line", "split the line" and "leave the line" more often than I can read a tape properly ; ) (ok - tell me you've never made a part an inch short) All right Charlie - you've been looking over my shoulder, haven't you? -- -Mike- |
#55
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"Dan" wrote in message ... On Mon 23 May 2005 05:18:59p, "George" george@least wrote in : Principle is well-known. Round peg in round hole splits. Square edge, breaks fiber to make passage. Yah but, but, I thought the whole idea was to apply pressure on the mortised board so the whole thing stayed together better. If you deliberately whack the pin in so a piece of it actually breaks off, then you basically got nothing but a pinned mortise, not a drawbored one. No. The idea is to get the shoulders of the tenon to register against the face of the mortised board and keep them there. When you don't have clamps, or the clamps would be too large, as in house framing, you draw bore. You really need to learn some woodworking, and it will involve some thinking. If you drive a round peg into an undersized round hole it will split the piece. Force is applied evenly around the peg, finds the weakest place - along the grain - to gain room. With a traditional square or whittled peg, the force on the edges pushes fibers aside or even severs them to make room without splitting. |
#56
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"Mike Marlow" wrote in message ... This is where all of the discussion here about wood swelling with moisture etc., goes a little astray. First off - yes it does swell with moisture, I am aware. The rates that we see published for wood expansion and moisture absorbtion are for raw, unsecured wood. They do not apply to sealed wood and they do not apply to wood that is secured as in a mortice and tenon. You are incorrect. The fibers will expand and contract when the moisture gets to them, and at the same rate, less compression set. You may slow the arrival with occlusive finishes, but wood loves water and will find a way. The reason M/T joints work loose is related to this reality. What went together "spit tight" at 12% MC is less so at 8 or 4. The joint may then be subject to racking strain, compressing some contact areas which will make the joint sloppy even when the MC returns to 12%. That's why the glue and pegs - to deny motion even when the tenon tries to become smaller in the mortise. Works the other way, too, though more slowly. Joints made at 4%, if the don't split the wood getting to 12, begin to develop some compression set which remains after the cycle returns to 4, progressively loosening the joint. Glue or surface fiber will eventually succumb, but the M/T will still bear load in design direction, and if pegged, should not withdraw. |
#57
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On Mon, 23 May 2005 20:56:02 -0400, "mike hide"
wrote: Again read the first post in this thread by Stoutman ,not the one you choose to suit your purposes. Is this the post to which you refer?: :"stoutman" wrote in message .com... : This has probably been asked before, but... : I recently started watching David Marks on DIY. I have yet to see him cut a "real" tenon. Always loose tenons using a multi router. : Why is this? Is there an advantage to loose tenons that I am unaware of? Does he just like to show off his multi router? Are they just easier to make? : I use to only watch Nahmmy and I have learned 90% of what I know from him. Nahmmy "rarely" made loose tenons. : Confused... I read it...again. I was not concerned with the author but with the subject, loose tenons. I assure you I do know what a tenon is and exactly what a loose tenon is by general woodworking standards. Well, there it is. The subject says loose tenons, the first paragraph says loose tenons. The second paragraph says loose tenons. The third paragraph says loose tenons. It seems pretty clear that the subject was loose tenons. Not the fit of conventional, integral mortise and tenons, but loose tenons as a joinery technique. By general woodworking standards. A huge clue that it was indeed a loose (or floating, as someone else called it) tenon thread was the mention (twice) of the multi router. Your assumption that I am unknowledgable about " Loose Tenons" as defined by Marks has absolutely no basis ,you have no idea what I do or not know. Your words say otherwise. For example, you said you don't even know who Marks is ("[e]ven though I have never seen David Mark's program let alone ever heard of him"). Therefore, one can only conclude that you are unknowledgable about loose tenons as defined by Marks, by definition. And that's what the subject was and you were off the subject. Even David and CW thought so. As a matter of fact you would appear to be a nasty little know-it-all yourself., Being that it is surprizing you bother with mister Marks or the subject matter as it all has to be old hat to you. Ah, ad hominem attack. That'll prove your case -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 |
#58
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On Tue, 24 May 2005 00:20:28 -0500, the inscrutable Patriarch
spake: Dan wrote in 1: On Mon 23 May 2005 08:37:15p, (John) wrote in news:17300- : Mike may not know (probably) what a "loose" tenon is, but he sure knows how to back pedal. Hm? Oh. I think you're looking for the Loose Tenon Definition subthread further down. This is the Drawbored Tenon subthread, which has degraded to the Square Pins vs Chamfered Pins in Drawbored Tenons subthread. Sorry. When do we degrade to wiring for 220? ;-) Tenons got 'lektricity now? Well I'll be. P.S: Clams got legs! - The only reason I would take up exercising is || http://diversify.com so that I could hear heavy breathing again. || Programmed Websites |
#59
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Joinery That Held Together for Thousands of Years
vs A / C I grew up in the tropics, the place formerly known as the Panama Canal Zone (sounds sort of like the artist formerly known as Prince), where the temperature ranged from maybe 78 degrees up to perhaps 94 degrees. The humidity stayed in the 90 to 100 percent range because the Isthmus is only 50 miles wide with a lot of water on both sides (we only had two seasons, Dry Season and Rainy Seasno. ..Dry Season usually was on a Thursday). I grew up with solid wood, (teak, mahogany, rosewood, cedar etc.) often carved, furniture from India and China - all done with traditional joinery, and some quite complicated and all done with hand tools. Even the delicate stuff hung together well UNTIL air conditioning became available. Within 2 years the joinery started opening up on the more delicate stuff and a drop lid desk with drawers had the lid warp and split, stretches get loose, drawers get loose etc. The range of change in relative humidity and the resulting change in % MC was just too great for the joinery, given that it was probably made with a %MC of 14 - 18 and in an A/C environment was probably down to 4%. For some reason, some of the Chinese furniture, the ones with triple mitered corners, frame and panel with mitered frames held up despite the AC. So, I'm guessing that it's not wood expansion that I need to accomodate, but rather wood shrinkage - at least for "house furniture" (as opposed to "just shop furniture"). Guess I'll shoot for Spit Tight rather than Snug or CTSBTF (Cut To Size, Beat To Fit). Oh, BTW - if you're going to use half blind dovetails for a wall hanging tool cabinet, DO NOT put the pins on the sides and the tails on the top and bottom - especially not the bottom! Nails, even finishing nails, detract from the dovetails - just a little bit. Interesting discussion. charlie b |
#60
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"John" wrote in message
Mike may not know (probably) what a "loose" tenon is, but he sure knows how to back pedal. In case there is any doubt in most of you newbie's minds about whether Mike Hide knows of what he speaks, there is NO doubt that most of you are not even worthy of carrying the man's sandpaper. Take a look, weep, and be humbled in the presence of someone who _really_ does know what he is talking about. http://members.tripod.com/mikehide2 -- www.e-woodshop.net Last update: 5/14/05 |
#61
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charlie b wrote:
Interesting discussion. And the diagram on your web site is one of the best I've ever seen. I'v bookmarked the site. Thanks. |
#62
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"George" george@least wrote in message ... "Dan" wrote in message ... On Mon 23 May 2005 05:18:59p, "George" george@least wrote in : Principle is well-known. Round peg in round hole splits. Square edge, breaks fiber to make passage. Yah but, but, I thought the whole idea was to apply pressure on the mortised board so the whole thing stayed together better. If you deliberately whack the pin in so a piece of it actually breaks off, then you basically got nothing but a pinned mortise, not a drawbored one. No. The idea is to get the shoulders of the tenon to register against the face of the mortised board and keep them there. When you don't have clamps, or the clamps would be too large, as in house framing, you draw bore. You really need to learn some woodworking, and it will involve some thinking. If you drive a round peg into an undersized round hole it will split the piece. Force is applied evenly around the peg, finds the weakest place - along the grain - to gain room. With a traditional square or whittled peg, the force on the edges pushes fibers aside or even severs them to make room without splitting. |
#63
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"Swingman" wrote in message ... "John" wrote in message Mike may not know (probably) what a "loose" tenon is, but he sure knows how to back pedal. In case there is any doubt in most of you newbie's minds about whether Mike Hide knows of what he speaks, there is NO doubt that most of you are not even worthy of carrying the man's sandpaper. Take a look, weep, and be humbled in the presence of someone who _really_ does know what he is talking about. http://members.tripod.com/mikehide2 -- www.e-woodshop.net Last update: 5/14/05 Thanks for the kind words, at times like this it is good to have a bribable brother who does not have the same last name ...mjh |
#64
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"George" george@least wrote in message ... "Dan" wrote in message ... On Mon 23 May 2005 05:18:59p, "George" george@least wrote in : Principle is well-known. Round peg in round hole splits. Square edge, breaks fiber to make passage. Yah but, but, I thought the whole idea was to apply pressure on the mortised board so the whole thing stayed together better. If you deliberately whack the pin in so a piece of it actually breaks off, then you basically got nothing but a pinned mortise, not a drawbored one. No. The idea is to get the shoulders of the tenon to register against the face of the mortised board and keep them there. When you don't have clamps, or the clamps would be too large, as in house framing, you draw bore. You really need to learn some woodworking, and it will involve some thinking. If you drive a round peg into an undersized round hole it will split the piece. Force is applied evenly around the peg, finds the weakest place - along the grain - to gain room. With a traditional square or whittled peg, the force on the edges pushes fibers aside or even severs them to make room without splitting. It is even better if the square pin is the same width as the hole diameter then there is no chance of splitting. I have chairs made in the 1730s that have pegged tenons and they are as tight now as the day they were made .the offset between the motice and tenon hole is about 1/32" to 1/16"...mjh |
#65
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"Patriarch" wrote in message . 97.136... Dan wrote in : On Mon 23 May 2005 08:37:15p, (John) wrote in news:17300- : Mike may not know (probably) what a "loose" tenon is, but he sure knows how to back pedal. Hm? Oh. I think you're looking for the Loose Tenon Definition subthread further down. This is the Drawbored Tenon subthread, which has degraded to the Square Pins vs Chamfered Pins in Drawbored Tenons subthread. Sorry. When do we degrade to wiring for 220? ;-) Right after kickback safety and sawstops. -- -Mike- |
#66
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"George" george@least wrote in message ... "Mike Marlow" wrote in message ... This is where all of the discussion here about wood swelling with moisture etc., goes a little astray. First off - yes it does swell with moisture, I am aware. The rates that we see published for wood expansion and moisture absorbtion are for raw, unsecured wood. They do not apply to sealed wood and they do not apply to wood that is secured as in a mortice and tenon. You are incorrect. The fibers will expand and contract when the moisture gets to them, and at the same rate, less compression set. You may slow the arrival with occlusive finishes, but wood loves water and will find a way. This does not make sense George. Wood fibers that are constrained can only absorb water to the point that they equal the force placed on them by the joint. At that point they effectively reach their saturation level. Wood does not continue to obsorb moisture until it reaches the point that its moisture content is equal to the surrounding air, it absorbs it to a maximum it can hold and that maximum is limited by the cell's ability to contain that moisture. Constrain those cells and they are capable of holding less moisture. Like I said, look at how many mortice and tenon joints have held up for decades and longer without showing effects of changes in humidity. Look at wood that is nailed in place. The wood does not move between the nails, it moves where it extends beyond the nails. It moves where it is unconstrained. If you could wring out a piece of wood what would happen? Just like a rag, it would lose its water due to the squeezing process. Cells and fibers under pressure cannot hold the same amount of moisture that cells and fibers not exposed to the same pressures can. Wring partially and you evacuate some of the water, wring more and you evacuate more until you reach the point that you evacuate all of the water that you can under the pressure that you're able to exert by wringing. Likewise with wood. Fit tight tenons and the increase in moisture will only swell the wood to the point where the pressure exerted on the mortise and the tenon does not exceed the cell's and the fiber's ability to hold water. The tighter the joint, the less this ability. Both the mortise and the tennon are going to expand from the increase in moisture, and both are going to contract by the absence of it. Looser joints will allow for more movement resultant from the changes but in either case, the wood is going to be constrained in its ability to absorb moisture by the pressure exerted on the joint, by the joint. Fit the joints tightly, and you create a joint that effectively reduce this movement to the point where it is negligable. There is too much joinery out there that does not open up gaps in dry weather and close up tightly under higher humidity to deny that the pressures exerted on wood does not affect movement from moisture. The reason M/T joints work loose is related to this reality. What went together "spit tight" at 12% MC is less so at 8 or 4. The joint may then be subject to racking strain, compressing some contact areas which will make the joint sloppy even when the MC returns to 12%. That's why the glue and pegs - to deny motion even when the tenon tries to become smaller in the mortise. This agress with what I said originally, and with what I elaborated on above. My point originally was that the pressure factors on the joint have as much or perhaps more to do with what these movements are than relative humidity does. I suggest that we find way more mortise and tenon joints that work loose from mechanical stresses (think of a dining room chair) than we do from wood movement related to moisture levels. That mechanical stress works the joint regardless of the moisture content. It's an entirely different issue. Works the other way, too, though more slowly. Joints made at 4%, if the don't split the wood getting to 12, begin to develop some compression set which remains after the cycle returns to 4, progressively loosening the joint. This is the point that I suggest is less of an issue in the real world than is often discussed. I suggest that within certain limits these conditions will not have the adverse affect on the joint that is often suggested. This of course, assumes that the joint is constructed reasonably correct in the first place. The joint has to enjoy mortises and tenons that are constructed of the proper proportions in the first place. That assumption allowed, the joint will not see moisture levels vary as much as a raw piece of wood will. The expansion and contraction within the joint will be much less than the tables attempt to indicate. This is why wood products of all sorts can be and are, shipped from all over the world to all over the world, and do not fall apart. These products are around us every day of our lives, everywhere we go. The proof of this is easy to see. My point does not suggest that moisture content is not a factor to be considered in woodworking and in joinery, rather it is that this one factor is too often spoken of in isolation and not considerate of other factors that play into the issues of wood joinery. Moisture tables are only part of the story, and like everything else, they need to be taken in a context. What I've tried to say in this conversation is that interactive joints such as a mortise and tenon are affected by factors other than just what is suggested in the moisture tables. -- -Mike- |
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"charlie b" wrote in message ... mike hide wrote: I meant exactly what I said. In the past ,and I have furniture to prove it Mand T joints had no glue ,they were secured by pegs anything but a perfect fit would ensure the structure would "rock" and secondly would soon fail...mjh If you double draw pegged them they wouldn't charlie b I am not familiar with the term "double draw pegged" What I refer to is the standard practice of chairmakers at the time was to bore a hole normal to the mortice insert the tenon and "spot" the hole center on the tenon .Then remove the tenon and bore it with the same drill a thirty second or so closer to the tenon shoulder, so when the peg [usually square] is inserted it draws the joint together tight....mjh |
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"Mike Marlow" wrote in message ... You are incorrect. The fibers will expand and contract when the moisture gets to them, and at the same rate, less compression set. You may slow the arrival with occlusive finishes, but wood loves water and will find a way. This does not make sense George. It does to wood technologists. RH correlates directly to moisture content. Wood fibers that are constrained can only absorb water to the point that they equal the force placed on them by the joint. At that point they effectively reach their saturation level. Wood does not continue to obsorb moisture until it reaches the point that its moisture content is equal to the surrounding air, it absorbs it to a maximum it can hold and that maximum is limited by the cell's ability to contain that moisture. Constrain those cells and they are capable of holding less moisture. Incorrect again. The fibers adsorb moisture at the molecular level, binding to the cellulose. There is a lot of air left inside any board, indeed, inside the cells themselves, which spaces are shrunken by the inexorable gathering of moisture, though they do compression set - they don't return to full expansion - which condition exacerbates the one caused by shrinkage of the fibers themselves once the wood begins to seek EMC with lower RH. Wonderful, well-documented stuff here http://www.fpl.fs.fed.us/documnts/fp.../fplgtr113.htm to read. Start with chapters 2 and 3. |
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In article , Larry Jaques
says... On Sat, 21 May 2005 16:24:11 -0700, the inscrutable charlie b spake: stoutman wrote: This has probably been asked before, but... I recently started watching David Marks on DIY. I have yet to see him cut a "real" tenon. Always loose tenons using a multi router. Why is this? Is there an advantage to loose tenons that I am unaware of? Does he just like to show off his multi router? Are they just easier to make? I use to only watch Nahmmy and I have learned 90% of what I know from him. Nahmmy "rarely" made loose tenons. Confused... Several advantages in most situations to use loose tenon joinery. 1. The parts that would otherwise have tenons can be their actual length NOT their actual length PLUS the tenon lengths Two less chances to make a mistake Yeah, and two fewer chances, too. gd&r 2. With a piece of stock ripped to the desired tenon width and planed to the needed thickness you can cut off what you need on a chop saw or cross cut them on the table saw. If you blow it you're not out an entire tenoned part. Think of the wood you'd need if you blew the tenons on a bed rail. Ayup, and you can't just make the bed a bit shorter. Mattresses and box springs don't squish much in length. 3. You can make the loose tenons out of any wood you want and maybe scrap at that. Want the tenon really strong - try ebony! Wouldn't you want the same (or physically similar) wood so they had the same expansion/contraction rates? That's what I've always read. I've noticed that David Marks always seems to use the same wood for the tenons as the pieces he's joining. I wondered if that was the reason why, or if it was just because there was usually plenty of scrap available. But why else use something expensive for the tenons since they don't show? Is there another reason or is it for stability? (He also always veneers both sides of his base stock, and has explicitly said that's for stability, but often uses a different (nice, but cheaper) wood for the side that doesn't show.) - The only reason I would take up exercising is || http://diversify.com so that I could hear heavy breathing again. || Programmed Websites -- John |
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John Santos wrote:
.... I've noticed that David Marks always seems to use the same wood for the tenons as the pieces he's joining. I wondered if that was the reason why, or if it was just because there was usually plenty of scrap available. But why else use something expensive for the tenons since they don't show? Is there another reason or is it for stability? .... I would expect he does it for all the above reasons. It certainly is "safer" to use the same material from the standpoint of reliability. The amount of material used is insignificant in terms of saved cost. Plus, he may (probably is?) like many of the rest of us--whether it shows to anybody else or not isn't material--he knows what the interior is. A similar case is wiring inside a wall--many make it as neat as they can "just because" even though it all gets covered over and the electrons don't care... |
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On Fri, 27 May 2005 10:29:10 GMT, the inscrutable John Santos
spake: I said: Wouldn't you want the same (or physically similar) wood so they had the same expansion/contraction rates? That's what I've always read. I've noticed that David Marks always seems to use the same wood for the tenons as the pieces he's joining. I wondered if that was the reason why, or if it was just because there was usually plenty of scrap available. But why else use something expensive for the tenons since they don't show? Is there another reason or is it for stability? Stability, but there's always scrap which can be used from each project. By using the same wood in the same grain direction, he keeps from having any trouble with different expansion rates. His loose tenons don't explode the wood they're in during the humid seasons. (He also always veneers both sides of his base stock, and has explicitly said that's for stability, but often uses a different (nice, but cheaper) wood for the side that doesn't show.) Right. It lessens cupping. -- REMEMBER: First you pillage, then you burn. --- http://diversify.com Full Service Website Development |
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Duane Bozarth wrote in news:42972420.7B6094D2
@swko.dot.net: snip A similar case is wiring inside a wall--many make it as neat as they can "just because" even though it all gets covered over and the electrons don't care... And another thread devolves into an electrical wiring discussion... ;-) |
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Patriarch wrote:
Duane Bozarth wrote in news:42972420.7B6094D2 @swko.dot.net: snip A similar case is wiring inside a wall--many make it as neat as they can "just because" even though it all gets covered over and the electrons don't care... And another thread devolves into an electrical wiring discussion... ;-) Oh, you're now saying the electrons do care??? |
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In article , David
wrote: We're talking Fuji apples vs McIntosh apples. Versus Apple's Macintosh. ;-) Kevin |