I am looking to do a table top that will be 6/4 maple. What would be the best way to join them together? Biscut, spline along the whole length?
Its going to be roughly 60×60.
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Replies
wisky,
6/4 maple, 60" x 60". That's a big project. No offense, but since you're asking this question, I'm assuming you haven't done something of this magnitude before?
There is absolutely no need to do anything to "enhance" the long grain joints of the planks of your table. There is nothing stronger than a properly-prepared glue joint of long grain to long grain.
The most important thing you can do is freshly joint the wood surfaces before glue up. Immediately before glue up is ideal. The longer the boards wait after jointing, the weaker the ultimate wood to glue adhesion. Use a (power) joiner or joiner plane (jointer for purists). Glue up within 24 hours. Don't touch the joint surfaces with sandpaper.
Second, the joints must be true along their length. A subtle variation is to make "sprung joints" where there is a very slight concavity along the length of the boards so that the ends of the boards touch first as the clamps apply pressure.
Third is to evenly and adequately spread glue on the joint surfaces.
Fourth is to use enough clamps along the length of the glue up and to apply pressure adequately and evenly.
Neither biscuits nor dowels nor splines will add to the strength of the joint. Excessive use of dowels and biscuits could weaken the joint by decreasing gluing area.
A spline would not decrease gluing area and it would aid in alignment, but the amount of effort involved to get the splines right would not be worth it.
However, it WOULD be worthwhile to use a minimum number of dowels or biscuits as alignment aids. My personal preference is to use dowels as I think they can be placed with greatest precision and take up the least space in the glue area. I would use 5 evenly-spaced dowels in the length of each glue joint as that would be adequate to ensure alignment.
Alignment aids will greatly reduce the anxiety of the glue up process. Without dowels, multiple cauls on both sides of the slab are a necessity to align the boards and keep the assembly flat. I would use cauls even with dowels in there. And I would glue up the 60 inch width in at least 2 if not 3 sections. A 60 inch width is huge and a real challenge to clamp up and keep flat.
Your joints either must be absolutely square to the surface of the boards, or you must be familiar with jointing the board pairs so that any tiny deviation from square in the board on one side of a joint is perfectly mirrored and compensated by the opposite deviation from square in the matching board. This happens "automatically" on a joiner who's fence is not perfectly square to the table (a very common condition) if the boards are fed through for edge jointing, one face "in," against the fence, the other face "out."
You also need to give consideration to whether the slab is glued up so that the grain alternates from board to board, resulting in a wavy effect, viewed from the end, as seasonal moisture shrinks and swells the wood, or glue the grain direction all the same, so that the entire slab arches in unison with moisture change. This decision affects how the table is secured to its support. Either way works. It's a personal preference, but requires planning of the hold-down design. I prefer the second technique.
Good luck.
Rich
Edited 8/20/2008 8:47 pm ET by Rich14
Using a fresh,quality wood glue and a proper clamp set-up is the most important technique. Biscuits will suffice, as will dowels. Just about the only advantage of using either is getting an even and flush joint.
I recommend that you find either a book or detailed article on the subject. Gluing tabletops is very similar to gluing panels.
Woodchuck1954
A "Legend" in his own mind.
wisky,
That's a big table, have you figured out where to do it (ie. a flat 60x60 space)? I suspect your going to need cauls to keep everything flat and square relative to itself.
wiskytango ,
As has been stated the long grain joints are really strong , one thing that can make them stronger is more glue surface . I have used a glue knife joint shaper set on thicker stock like you are using . Stickley and other furniture and table makers used the glue joint extensively to join solid tops and other glue ups such as chair seats and and panels to name a few .
The knives I have run one board up and the other down . I will tell you once you get it set for the exact thickness you are using it is easy , but imho the most difficult set up to get perfect .
How you going to surface that monster ?
I also agree with BG that is a big big top , it may move an inch in 60 , what do you think ?
may the wood lords be with you
dusty
Dusty,
Were you referring to this kind of cutter?
Not brand, just kind.ThanksBB
http://www.lagunatools.com/browseproducts/Glue-joint-cutter--model-110-.HTML
BB , No , that is a different one , sorry I haven't got a picture of the joint but it goes straight then sort of like two angled T & Gs then flat and repeats sort of . Lousy verbal description .
you have seen it a million times but never noticed it .
d
BB , here is a look at what I am talking about , this particular set is a small and I also have a larger set for a thicker stock .
The thing I like about this joint is even if there was a failure you will not look through a crack in the table top .
A picture is worth a lot of words
d
Edited 8/21/2008 11:34 am ET by oldusty
D,Gotcha. Do you run them on two different shapers or just change them out?
They look easy to sharpen.It looks like the Laguna one is a run and flip.BB
Dusty has a pair of "F" joint cutters-Delta used to make those. You run a pair set up in the shaper to cut the joint and merely flip the boards. They can be used in slotted collars or safety heads which prevent them from flying out-but cutters for those had a hole for the retaining bolt. They are in fact cheap and easy to sharpen as long as they are done equally.
One can also get a router cutter that does the same thing- it is carbide and costs more, but very convenient for small runs/ small production shop.
Various manufacturers have their own configuration and nomenclatures eg shaper glue joint sets that comprise two or more parts.
I show you some here- a router cutter, a three knife F joint set similar to what Dusty has, but meant to run in a 3 wing safety head and a three cutter carbide tipped set to be used in a heftyish shaper.The ones Delta made were very convenient and easy to use and could be used happily in their little shaper-the model 43-110 if I recall correctly.
If one needed to make a production run of say ten or more of those 5 foot square tops then the three piece carbide tipped set would be the ticket.
But for just one top , as mentioned, properly done butted joints are the answer and I would do it in two halves-quite straight forward and there should be no difficulty with alignment as long as the boards are straight and well set up in decent sash clamps such as the Record T bar type, on a nice working surface.Philip MarcouEdited 8/23/2008 2:59 am by philip
Edited 8/23/2008 3:01 am by philip
Hi Mook ,
Thank you for doing such a great job of showing and explaining the glue joint cutters and such . The router version if tall enough seems like a good one to have .
Most of my old cutters and knives are for the old style collars , they only have set screws for keeping the set up not for holding in the cutters . Keeps one on his toes so to speak .
cheers dusty
Hi John , You run one board face up and the mating other face down , same machine same set up .
Many old time factories and shops have used the glue joint in one form or another extensively for many years . There are always many ways to do the same thing , I was sharing a method that is imho really skookem !
dusty, the trout slayer
Old Slayer"You run one board face up and the mating other face down , same machine same set up." That's what I assumed. It's all good.But more importantly, as far as slaying, would that be on the middle Rogue for late, late,late springers and early winter steelies or would that be on the upper Rogue for the bows?
Heard it's pretty good upstream of Lost Creek Reservoir.Maybe plank em reeeel slow on some 6/4 cedar* on some alder* coals.
Maple does give them a sweet taste though.The chinooks are starting to jump up here. Just crossing the bars. We get some rains soon and they will be runnin. Three big rainstorms and they will be up ten miles.Gotta love fall on the rivers here.S'pose this should go to cafe.BB*gotta talk wood you know!
dusty,Using such cutters in a small shop, especially for one-offs or a limited number of projects is really over-kill. It's nice if you have the equipment, but hard to justify the expense if you don't. And cutting the profile properly on a shaper requires very careful setup, and very careful, controlled (slow) feeding.Don't get me wrong, I like such joints but . . .The profile does increase the glue area, but the increase in strength over simply edge jointing the boards is small and doesn't give any advantage over the plain-edge-joined slab, as any stress strong enough to break it will just result in failure of the wood fibers, not the glue joints.The real advantage of cutting such a profile is as an alignment aid in a high-production shop where time is money and many slabs have to be assembled and glued. Such a profile is the ultimate alignment assurance. The boards literally can't go anywhere but into the correct mating positions. It allows very rapid, very accurate glue up.But then everything else about the scale of the job must match. The volume must be high. A high-speed, power-fed shaper is a must to accurately cut the profile, fast. Glue-up stations must be manned by workers who can handle boards quickly, or automated to apply glue and clamp in rapid sequence.If the shop has enough slabs to produce, wood goes in one end and money comes out the other.Rich
Rich , you are making a mountain out of a mole hill , they sell the darn thing in a router bit for gosh sakes , special stations are not needed . The OP asked for opinions on best and better ways to join boards and such , I merely gave my experienced opinion . A standard speed shaper or router will work fine .
Your statement was double talk , first you said the joint offered no more then you said it was the ultimate .
Show me and teach us all a better way .
regards dusty
Dusty,I said the joint was overkill for a one-off. It is.Yeah, I know the cutter is offered as a router bit. And we all know that routers are the ultimate woodworking tool and can do anything and everything.If you want to joint 60+" long, 6/4 maple boards for 2 thirty-inch-wide glue-ups with a router with such a bit, be my guest. Let me know how well the whole thing fits together.For a one-off, the point of diminishing returns falls off a cliff after properly jointing the boards on a joiner.And, yes, that glue joint (correctly done with large, robust cutters on a shaper, with a power feeder) is the ultimate way of providing alignment during high-volume production runs. And that use (alignment in high volume operations) is what brought it into existence. Not glue line strength concerns.Rich
A glue up like that is fairly routine for my shop, but it can be daunting the first time around, especially if you're working alone.
Everything that Rich said is right on. Study his post.
I would use some 5 biscuits along the glue line, just to help with the alignment. Dowels are extremely difficult to get exactly right, and a spline is OK but really too much unnecessary fuss. You can also do a "dry run" to see how the clamping will proceed. If you do the glue up in intermediate stages be sure not to harm your jointed edges with the clamps; running half a tabletop over the jointer is no fun.
And if you ever considered getting a stroke sander, here's your excuse.
David Ring
http://www.touchwood.co.il/?id=1&lang=e
One tip not mentioned above is to do a glue-up like this in stages, and to do it with boards that are as wide as possible. For maple, that generally means a minimum width of 12", and 18" is better. You can, of course, do it with 6" wide boards, but the result will look like a sheet of slip-matched plywood.
If you're working with 12" wide boards, I'd do this in 4 stages - 3 12" pairs of boards glued together, and final glue-up of the 3 pairs glued together.
And, though I realize your customer may have married the project to those dimensions, 5 feet wide is about the absolute maximum width recommended for a table-top. The reason is that the average person's reach across a table is limited, and therefore tables generally don't go much over 48" wide. Chris Becksvoort wrote an excellent article about choosing table top dimensions a few years ago in FWW.
If you use biscuits don't register the cut from your work bench, but register it from each piece (flip down the angle to 90 degrees and lie on top of the piece to be cut. I have done this many times and it never comes out perfect, so count on sanding or whatever to get the top flat after glue up, as ther isn't any give to boards that thick. My wood supplier has the equipment to do this and all he does is glue the joint (oversized thickness) and plane to thickness.
Thanks All for the info,
Rich
Thanks for the info, as far as my skill level, I am not a complete newbie, I have done some large tops in the past the biggest ones where 8/4 cherry 20 inch by 66 inch long with excellent results. I dig that this one is lots bigger though, but at some point everyone has to do something just a bit outside what there envelop or you never grow. In the past I have used biscuits to help with the alignment I was just wondering if they where necessary or if a spline would be better, again just looking for all your opinions.
I guess I am looking for more of a validation that my approach is correct. And also this will actually be split in two half's so each one would be 60x30, still big but not quite as BIG.
I do plan on doing it in stages if for no more reason to ease the stress and allow myself to pay a bit more attention to each joint.
Someone mentioned that the wood might expand up to an inch? Does that sound reasonable to everyone? Seems like a lot to me.
Thanks again for all the input its greatly appreciated, Attached is a pick of my other big tops.
Expansion and contraction will vary considerably depending on the species of wood and how it is milled, but 1" is certainly possible.
Jim
It's not clear whether the table design is a construction of two separate 30" wide slabs or if you mean that you're going to glue up 2 such slabs then join them together.Im any case, the glue-up station including the clamping cauls top and bottom (either double convex cauls or one flat, the other convex) and a table big enough and stiff enough to deal with the clamping pressures, the clamps for both the cauls and across the width of the slab(s) is going to be a much bigger assembly/construction than the slab itself. If it isn't, you are not going to be able to control the forces involved and the result will be a warped or poorly-glued construction.Shops that do this kind of thing all the time have such set-ups as "standard" equipment. If this is a one-off you'll need to decide how much you want to invest in constructing the assembly station. Not to scare you off, but there's a lot to be said about buying the whole thing glued up from a company that specializes in just this kind of thing. (I know, I know . . . you want to stretch your abilities. No need to explain the reasons)Wood shrinks and expands with seasonal humidity changes. It's not unusual for RH in a heated house in the midwest or northeast in the winter to hover near 10%. That same house could have RH of 60% or greater in July and August.Using a calculator such as that found athttp://www.woodbin.com/calcs/shrinkulator.htmor other sites, for that much change in RH, the dimensional change across a maple table top of 60" could be as much as 1.6" for flat sawn wood (tangential movement). Even quarter sawn wood (radial movement) could show a 0.5" to 0.75" change.The movement would actually be about 1/2 of those figures, as the table would have to come into complete equilibrium with the environment for those conditions to achieve those extremes of dimension change. And that would take many months or years at the RH extremes.Rich
The construction would be two 30x60 for a total of 60x60 when they are set together so they can expand into a larger table if necessary. So the glue up although still larger would not be one solid 60x60.
So each 30" x 60" half has a width of 60"? You will be clamping across 60"?Or is the width 30", anticipating that the longer, "expanded" table will have the grain direction running in the short dimension of the assembled piece?The challenges of assembly and glue up increase rapidly as the dimension increases. If the clue up distance is 30", that's fairly straight-forward, whatever the length.Rich
Rich
This should explain what i am looking for better then me trying to ex[plain.
well if i put in the attachment it would.
Another satisfied user of Sketchup.OK, the glue up is 30". Piece of cake.
Ha satisfied I dont know about that I have been monkeying around with this ting all day, But i am learning. Thanks for all the advice. I pretty much know what i am doing but its nice to get other ideas and hear others bring up possible issues one might have before hand.
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