I’m making a corner ( L ) shaped table top for a computer desk using solid lumber.
5′ long in one direction, 6′ long in the other, 22″ deep, + / – 1 3/4″ thick.
My plan is to ” join” the 2 sides of the top together at the corners. Essentially creating a miter joint roughly 30″ long.
How to hold this joint together??
I’m thinking
A) several loose tenons say 4″ wide, 1/2″ thick with epoxy and pocket screws from underneath
B) Dowels instead of loose tenons, epoxy and pocket screws.
c) Just make a long spline and stop short of the edges?
I’m wide open for ideas on this one.
I scored some really nice soft maple over the weekend and don’t want to mess it up.
Thanks, Bill
Replies
Consider making it a half lap miter joint. I'd make sure there was some structural element under it to support the table top over the length of the joint. I don't like metal fastners, but I'd consider using the support almost as a batten, and judiciously place some screws in slotted holes.
Frank
Biscardi,
Cool Idea!
Never did one before but shouldn't be to tough, the pieces are kind of big so I'd likely cut the laps with a router. lots of glue surface thats for shore.
I'm not a big fan on metal fasteners either, but some times you gotta do what you gotta do.
Bill
43Bill,
My Momma used to say to me when she saw I was about to make a poor decision, "Son, you're cruisin' for a bruisin'."
Bill, you're cruisin for a bruisin. While you can certainly fit and join a 30" long miter joint in solid wood, unless you can totally eliminate future changes in humidity in its surroundings, or totally encapsulate it, you will have problems the next time the weather changes.
How much will a 22" wide maple panel move from summer to winter? I'll guess somewhere in the range of 1/4" to 3/8". If your miter was not held together at all, it would develop a wide crack in it, on the inside of the L in the winter, outside of it in the summer. Hold it together in such a way that the joint cannot open, the top will likely buckle when it tries to swell, or develop compression-set, then develop splits along the grain when it shrinks, and cannot. There is no way that I know of to make a miter and allow for movement, and keep the joint closed. The angle of the joint changes with the width of the panel, causing either the points or the heels of the joint to separate, as panels grow wider or narrower.
A better way to make up such a top is with a substrate that will not move, mdf or plywood, veneered with a maple veneer. If you are committed to solid wood, you can work fast, spline that miter, and coat it with two or three layers of epoxy before it can develop any internal stresses. And keep your fingers crossed. Alternatively, use some kind of butt joint at the corner of your L, so that each leg of it can come and go independantly of the other.
Ray
Ray, I think you're saying the joined mitre could go from this when new...
View Image
... to look like either one or both of these images after a change in moisture content?
View Image
The diagonal of the square assemblies are 450 mm long (~17-3/4") . Put another way, each mitre from the outside corner to the centre point is 225 mm (8-7/8").
The wood is European steamed beech, a well known big mover, but here it's rift cut which exhibits lesser change in dimension across the plank width than tangentially cut stuff. Slainte.Richard Jones Furniture
Alas Richard,
Your photos failed to load on my machine. But, I bet one of 'em is of a failed miter joint.
Thanks,
Ray
I can't explain the lack of pictures at your end Ray. But yes they show how the mitres can open at either end after construction, depending on if the wood dries or gets wetter.
Perhaps you need a digital computer as compared to that old black and white analogue thing that you feed with coal, ha, ha. Slainte.Richard Jones Furniture
Richard, that was a great example to show what will happen. I wish I could explain why there is such a disconnect.
Richard,
You're right about the obsolescence of my machine. But mine is one made for the rural community, so is powered by a cow walking in a circle. Coal power e d o n e s w e...git up, Bessie!...r e f or the city folk. I saw a piece of coal once, tho. It was at Christmas, and oddly, had your name and address on its label...
cheers,
Ray, cow-puncher
I saw a piece of coal once
Hell.. as kids we picked them up walking along the RR tracks with a waggon all the time. Some really big chunks sometimes.... I think mom gave them to folks that needed them? OK, so I have no idea what she did with them...
At Christmas I never received a lump of coal.. Sometimes nothing. But my brother and I were happy children. I'd bet our mom would be arrested (these days) for what she let us do.
We had FUN!
I do not get along with my mother.. We never did but.. Somehow I still love her alot...
Our allowed freedom taught us much more that any book learning. I LOVE books anyway...
Just send the coal back then Ray if you have no use for it on your Bessie powered machine, ha, ha. Perhaps that should have been yeee-ha, not ha, ha. Slainte.Richard Jones Furniture
Richard,
I've heard of sending coal to Newcastle...
Ray
Just address it to Leeds instead... it is near to Newcastle.
Nice work on the repro chairs by the way, in another thread. Slainte.Richard Jones Furniture
Thanks Richard, for the kind words.
Ray
Richard,
This is probably a dumb question but I've never shyed away from asking them. :-)
Why is it that mitres seem to separate unevenly at the joint? Is it because moisture is absorbed unevenly by the endgrain? If one were to seal the endgrain of mitres and pin/secure them so they won't separate, couldn't the wood then be free to expand/contract elsewhere and not effect the joint?
Confounded mitre joints will be my undoing I suppose. I really like to use them whenever I can but they don't seem to want to cooperate.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Bob,The wood moves at the weakest point in the construction and that's the endgrain miter joint.Imagine a picture frame. If the joints COULD be made to be absolutely continuous, fused joints (which they can't), therefore constrained from opening at either end of the miter, the legs of the frame would have to bow inward and outward from perfectly straight with moisture changes.There is no other way for the geometry to respond as the width of the legs changes.Rich
Rich,
OK, I'll buy the legs bowing as they often do depending on moisture......... and I can live with that.
How's about a few words on stock selection? Would quarter-sawn be the right choice? If the majority of expansion/contraction is along the length of the pieces then I would expect to see..... oh never mind, I just realized the answer to that one. DOH!
Can one minimize the negative effects by proper stock selection?
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Bob,"Can one minimize the negative effects by proper stock selection?"Sure, always. That's called engineering, or design.In picture frame construction it's possible to design so that tangential movement, which is almost always much greater than radial movement occurs in the front to back dimension. In other words, use "quarter-sawn" stock. The tangential movement will then have no effect on the miter joint and only the lesser radial movement needs accommodation.In the OP's case, this is not possible. But that design violates so many good design principles. Solid wood, almost 2 inches thick, 22 inches wide, and a miter joint? Without redesign, all the suggestions (including mine) fall into the "brute force" method of construction.Rich
It looks like you've got an answer that makes sense from Rich14, but mitres open because of cross grain movement in each of the two intersecting members.
Shrinkage due to moisture loss leads to open inside corners... and I'll leave you to work out the result from moisture gain and wood expansion. Try taking a close look at the snaps I included in my first post, somewhere like post 8 to 12-- I don't remember exactly. Those pictures may help you get your head around it all, if you haven't done so already. Slainte.Richard Jones Furniture
Richard... I still have that old Heath Kit Analog puter.. I' have put in writing it has to be burnt up with my ashes!
What a wonderful toy at the time!
Ray,
You're right in that this joint, as proposed, would suffer from wood movement. However, I think it would work all right if the outside edges of the two sections of the "L" were not confined.
The problem, as you alluded to, is that the wood will shrink. The shrinkage will pull the edges of the assembly in such a way that it will make the formerly 90 degree angle of the glued-up desktop less than 90 degrees. However, if the desktop isn't fastened in such a way that restricts movement, the dimensions should be able to change back and forth with no ill effects on the joint.
If such movement is built into the design of the piece, I'd be surprised if making the joint as proposed wouldn't work.
A spline, biscuits, floating tenons, or even battens fastened along the underside of the joint would help to keep the top surfaces aligned, and would also provide more glue area to reinforce the joint.
ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon
Zolton,
Hmmm,
You might be onto something there. I wonder how much a 1/4" change in the width of each of those panels translates to at the end of a 6' run of top? I'd guess 3/4" or so out of square.
Ray
Ray,
I have enjoyed this thread thoroughly. You spiced it up pretty good. But the more I think about this issue of the long miter, the more I think that everyone who has responded so far has missed an important point. Ray, you have repaired as much Chippendale and Queen Anne furniture as anyone has. Ever come across any splits???????Sure, lots of them, right? But they are still very nice pieces, even with the splits that occurred for any number of reasons. WHAT IS WRONG WITH A PIECE OF FURNITURE HAVING SOME SPLITS? It adds to the character of the piece.
It brings people together by giving them something to talk about.
It gives the person who made the piece tangible evidence that there is room for improvement in his skill set. IT IT A MOTIVATOR.IT is possible that if this piece of furniture is built as designed, it could start a NEW FURNITURE DESIGN MOVEMENT. And sometimes it is good to have a movement. The OP could be the new Thomas Chippendale or the new Ralph Sheraton, or the new Bill Federal We could see a new movement in which furniture is designed to split. The bigger and nicer the splits, the more prestigious the piece. Multiple splits would be worth even more. Each piece could come with a "design sheet" which predicts where and when the piece will split. You can get your money back if the splits don't occur.Splits are not inherently a bad thing. They have gotten bad press in the past. We have not had a new paradigm in furniture design for a long time. NOW IS THE TIME. Stop to think. The whole Bonsai movement is based on constraining growth. There are millions of Bonsai afficianados out there. Why not build furniture which constrains wood movement and then CELEBRATE the splits.It is time to be more creative in furniture design. I believe the OP is onto something and should roll with it. Laissez les bon temps rouler!
MelMeasure your output in smiles per board foot.
Mel,
There's certainly nothing wrong with furniture that is full of splits, if that is the builder's intention. I didn't get the impression that was the poster's intent.
There's nothing wrong with furniture that is full of nails and falling apart, either. That kind of furniture gets me lots of work, when its owners want it to be something different from what it has become.
Ray
Ray,
Interesting photo, that Eggleston chest.Here's to woodworking practices that will bring you more business. Perhaps we need to insidiously introduce such practices, because of that very practical benefit. :-)I am aware of what the OP was interested in. But I have never seen a thread that wasn't worth "hijacking". Some people see that word in its perjorative sense. But sometimes one needs to turn a question around to see it in a better light. That is another way of seeing "hijacking". It is like when you kid says to you, "Dad, when I go to college, I want to study either Drama or Art History." and you reply "Why not electrical engineering or medicine?" There are times when hijacking a thread (ie giving it a nudge in a different direction) is the best thing you can do for them. Besides, the OP had already gotten a lot of feedback in the direction he was looking for. Those paths are now fully explored. NOW IT IS TIME FOR THE WOODWORKING EQUIVALENT OF THE TWILIGHT ZONE. Enjoy,
Mel SerlingMeasure your output in smiles per board foot.
Geez Mel, you're off into philosophy with that post -- and not just esthetics! There's even a touch of semiotics in there somewhere, as in, "That's not a piece of furntiure, that's a crack waiting for the right time to happen!"
I have to disagree just a bit. Everything is subject to detirioration over time, but when we're desiging a practical piece of furniture, ought'nt we do so with the knowledge that we've done so in the best possible manner to prevent premature failure? Oh cripes! Now I've introduced epistomology and ethics. Dang! Once you start down this road, there's no end to it. Verne
If a tree falls in the forest, and no one is there to cut it up and make something with it . . . what a waste!<!----><!----><!---->
Verne,
As always, I really enjoyed your post. I have never thought of myself as a semiotic. All of the "right and proper" responses had already been made to the OP by some excellent woodworkers. There was nothing for me to add, and yet I felt the urge to write, so I just had some fun. Every once in a while, when I do that, someone actually takes me seriously. Now that is a mistake. There is a very serious issue on Knots. That is: how can you tell which advice is good and which is not? I posted a question the other day on the Clifton 450 multiplane. You should read the responses. Finally Larry Williams posted a message which hit the nail on the head. But that is only my conclusion. How can one tell which of many different responses is the most useful?That is both a philosophical and a real question.Have fun.
Mel the SemioticMeasure your output in smiles per board foot.
"how can you tell which advice is good and which is not?"
That is easy. I am of course infallible. I know that because I say so, ha, ha-- ha, ha, ha.
Nurse! can I have this big white suit with the tied up arms removed now please? Slainte.Richard Jones Furniture
Richard,
You must have too much time on your hands if you are reading my attempts at humor. After a few years on Knots, I have come to know those who actually provide excellent information which is based on learning and practice, and who is just yakking away. You and Ray and Larry and some of the other professionals always give excellent advice. There are some amateurs, such as Samson, who always give excellent advice. I like the place. I learn a great deal here. (( OF course, I also enjoy adding a bit of humor to the stew. Don't tell anyone.))My interest in "how a reader can tell which advice is the good stuff" started long ago when I wrote to Adam Cherubini saying that the newbie who asked the question would not be able to understand his response. Adam was displeased with me, to say the least. We exchanged a few private emails and he calmed down. But I believe I was correct in trying to see the problem that the OP through the OPs eyes (not that that is easy). As Mom used to say, if a person doesn't know he is lost, it is hard to convince him to come out of the woods. Of course, she said that in Italian, so I may not have translated it exactly. Have fun.
MelMeasure your output in smiles per board foot.
My interest in "how a reader can tell which advice is the good stuff"
Sent it my way and I will try to do it 'MY Way"...
I would say any advice is good in here.. Ok, some judgement called for but if you try to see it from their point of view, it just may work!
Mel.. I always listen to your advice and I KNOW you are from another planet!
Why I love your posts..
Will George,
I don't do miter joints very often. I guess it is just not my style. I bumped into this thread and just had some fun. Ray and some others brought truth and justice to the thread. My job is humor and confusion. Remember the first law of management: People who are confused are easier to lead." Have fun.
MelMeasure your output in smiles per board foot.
Remember the first law of management:
Law 1: Unless you are the CEO you still have a boss to contend with.
Law 2: If you are the CEO you still have bosses on the Board of Directors.
Law 3: If you are on the Board of Directors you still have the Share Holders.
Law 4: Unless you are God the 'real boss' is probably waiting for you to come home for dinner.
I was a Manager working for a VP (A Really nice woman IF you did what she wanted) for several years. Good money at the time but HATED IT! I went back to 'fixin' stuff.
"That is both a philosophical and a real question."
Actually, I'd say it's a real philosophical question, but then I'm pointy headed about some things. We could go way too far down the epistomological path here and end up nowhere. But the practical concern is valid -- how do you know you're getting good advice? I'm not up to dealing with that tonight, but I'll think on it.
Being taken too seriously by self or others is always a grave concern, especially if you're a habitual smart#%* like me. I'm really glad someone had the good sense to conjure up the " ;>) " business so that I have half a chance of letting folks know that I'm kidding.
Verne
If a tree falls in the forest, and no one is there to cut it up and make something with it . . . what a waste!<!----><!----><!---->
Verne,
Things are good.
I haven't scared my wife away.
My kids still take my woodwork if I don't charge them.
For ten hours a week, I make $8/hour at Woodcraft.
I have the time to do woodwork for many hours a day.
Tell me. How could life be better?
Hope things are good for you too, Brother Verne.
We may have splinter groups in woodworking, but we hang together.
MelMeasure your output in smiles per board foot.
Mel..
I was thinking about a LOOOOng miter. Wood expands more along it's width so I would expect different expansion ratio from the base ( as in wide ) to the point of the miter ( As in small width ).. Is this rocket science?
Bill,
I agree with Ray, except for the part where he encourages you that you might actually get away with quickly assembling a spline joint and coating the piece with epoxy.
You are designing a construction that will fail. In fact, you are designing a construction to DEMONSTRATE failure in solid wood joinery.
That miter will open and close at one corner (or both), and the gap will be significant, as seasons change. Period.
You are ignoring the reasons that alternatives to solid construction have been developed over the centuries to deal with wood movement.
Why are you considering epoxy glue? And why pocket screws AND splines/tenons/dowels?
If you insist on solid construction, you MUST accommodate wood movement. A long spline in the joint will behave exactly as an end cap to a breadboard design. The top will expand and contract in width, while the spline will not change dimension in that direction (its length) at all. If glued its entire length, it will split the top somewhere as the top moves. So it must be glued only for a few inches at the midpoint of the width of the top. That will leave the ends of the miter weak.
You could glue up the joint, with the spline unglued at its ends and use fasteners such as these across the joint at the ends to adjust for seasonal changes. Or you could leave the joint unglued (with a spline to keep it aligned) and use these fasteners alone (3 would probably do).
http://www.knapeandvogt.com/516_Tite_Joint_Fastener.html?page=details.476
http://www.constantines.com/browseproducts/Tite-Joint-Fasteners.HTML
http://www.mcfeelys.com/product/FSC-2600/Zipbolt
I suggest yellow wood glue, not epoxy. It will crack.
But I really suggest you completely rethink the design.
Rich
> You are designing a construction that will > fail. In fact, you are designing a construction > to DEMONSTRATE failure in solid wood joinery.
> That miter will open and close at one corner > (or both), and the gap will be significant, as > seasons change. Period.
Ummm... It depends. Because this is an "L" shape, the joint doesn't have to fail. If you were to use a butt joint, the two parts will expand and contract by approximately the same amount, so the length of the joint will remain the same -- It won't fail because of size changes. And as long as the two ends can move, it won't fail because of angle changes.
However, if the "L" were forcibly held at 90* (like when there are four pieces mitered together), it would fail like the pictures show. It's just like when a solid log dries -- it develops checks because of differential shrinkage while being forcibly held in the "log shape."
As has been stated, the angle of the "L" will change, but you'll never notice it. If it will be scribed to the wall, you might be able to see the ends/inside corner get a gap. As long as you're using one of the various techniques for mounting a solid top to the carcase, you should be fine.
I agree with Rich14 that splines, half lap or T&G would fail. Even with a 1/4" depth, these joints couple the length of one side to the width of the other side. While a butt joint could work, it may not survive the flexing incurred during install.
Well, now you can see why it's not normally done. It's possible, but it's fraught with danger. The only joint that won't fail is the weakest one, structurally. The butt holds them close together and keeps them level, and the batten keeps them flat (i.e., planar). Hmmmm... Isn't that what plywood really is? Really thin top layer, really thin splines, really thin battens. Except all glued together. ;)
HTH!/dev
Ouch!
You guy's make some strong points!
Let me try some answers…
1) The top would be able to float and move a little, not rigidly attach as Zolton suggested
Rich,
epoxy glue? To avoid glue creep and allow more working time, also stronger bond.
pocket screws? Strong mechanical closing / clamping pressure
splines/tenons/dowels? To add " Face Grain" glue surface
Or you could leave the joint unglued (with a spline to keep it aligned) and use these fasteners alone (3 would probably do).
Like making a bread board end?? Cool idea!
Ray,
Alternatively, use some kind of butt joint at the corner of your L, so that each leg of it can come and go independently of the other.
Care to elaborate on that idea??
Thanks to all, Bill
Bill,
"Alternatively, use some kind of butt joint at the corner of your L, so that each leg of it can come and go independently of the other.
Care to elaborate on that idea??"
Simply two rectangular tops, one butted to the other to form the L . You could vee groove the joint, and cut a similar groove perpendicular to it across the grain of the longer segment for appearance sake. Loose spline or similar for alignment if you want.
Ray
Ray
to all,
Looks like I'll be going with a loose spline and some draw bolts. Maybe even a "center board" for each end to die into, kind of like a bread board end, but in the center.
Thanks for all who replied and saved me a major headache!
Bill
I agree with Ray, except for the part where he encourages you that you might actually get away with quickly assembling a spline joint and coating the piece with epoxy.
I made some large table tops for a horse stable. Just the tops as there was already a steel support.
MDO with epoxy paint. The top had two 90 degree miters (As a 'U' shape). I used a half lap as another poster suggested and inserted a 1/4 inch plywood spline. Epoxied the joints. No failures. In fact no hint of a crack in the paint in 6 years use. Exposed as the horses are (but covered with a roof)..
I'm not sure the spline was needed, I just did it. The spline, as I recall, went into the MDO about one inch (Two inch wide spline). I 'think' the MDO was 3/4 inch 7 ply. Great stuff!
They could operate on a horse on that table if necessary!
Yes,But that was MDF, which is inherently stable. Not 22" wide 1-/3/4" thick solid lumber, which is at the other end of the stability spectrum.Rich
Bill,
Not to belittle any of the suggestions you've gotten, but having done more than a few of these joints I wouldn't go any other way except using "tite-joint" fasteners from underneath. Use dowels or biscuits or splines just to align the surfaces, and use 2 or 3 of the tighteners from underneath the desk top. You just tighten it up using a wrench, and also you assembly/disassemble the whole thing whenever you like. I know it's not FINE WOODWORKING but it's just to good a solution to turn your back on.
David Ring
http://www.touchwood.co.il/?id=1&lang=e
I'm with David. I'd avoid glue entirely, using only something to align the two sections, and then clamp them together. Eventually, the piece will need to be moved, so some sort of knock-down design will be better than a chainsaw. ;-)
So if I use draw bolts and a loose spline ( starting to sound pretty good )
I assume staining and finishing the 2 pieces separately, then join them once finished?
I'd join them temporarily in the shop, to sand flush and check that all's right. Then take it apart to finish and transport. Assemble on site.David Ring
http://www.touchwood.co.il/?id=1&lang=e
I have to agree with those who've tried to talk you into rethinking your design. Two very good reasons aside from the joint failure problem. Think about moving this piece around when the time comes -- you'll be dealing with a 5'X6' L shape with legs and a weak joint in the middle. Also, you've got quite a bit of work surface that might be really nice in a different configuration someday. I'd look for a design that is easy to move and easy to rearrange.
In any event, I believe the long miter is going to be a problem for you no matter how you approach it. If you're hard over on having the corner go together that way, why not build it in two separate pieces that just fit together without being connected? If keeping them together is a problem, a pair of straps screwed to the underside across the diagonal would hold them together and keep the tops even, but would allow everything to move without cracks and splits.
Verne
If a tree falls in the forest, and no one is there to cut it up and make something with it . . . what a waste!
I'm with David Ring on the underside fasteners. They work well, and you can undo them, as opposed to a glued joint (if you would move to a new location, how are you going to get a 5' by 6' desk through a door or up/down stairs?).
I would go with a stable substrate, like countertop particle board (much smoother than the big box junk and lighter than MDF), and cover that with wood veneer.
The fasteners are available online or any place that sells laminate countertops.
kreuzie
draw bolts and a spline is the way to go
and I would'nt hesitate to permanantly screw the pieces together where it matters, the outside edge
plan for everything else to move
This forum post is now archived. Commenting has been disabled