Table top glue up

[jeff phillips]

So i have all of the boards to make up the top of my table all cleaned and squared up. It is now time for the glue up. My question is will i be better off gluing the whole top up at once, or glue it up in sub assemblies? The top consists of seven boards varying in width from 5.5" to 7", for a final width of about 42".

[Sean Hughto]

The only benefit of doing it all at once is that it's faster. The downside is that it is much riskier in that most glues don't have a very long set up time, so you don't have a lot of time to get everything on 7 boards clamped up and edges aligned etc. A beginner is likely to have more clean up work after a gang glue up. If you do one or two seams at a time, you can concentrate on perfecting the joint and pressure so that clean up with a plane or sandpaper of the panel is much less.

[Jim Barrett]

With the correct glue press there is no reason why you could not glue up this assembly in one pass. You can do it with all kinds of clamps...pipe, bessy, etc or you could take a look at the Plano Vertical Glue Press that I have for sale :)
Let me tell you it makes gluing up large panels much less stressful...
But back to your original question...it really depends on how comfortable you are. Don't know what clamps you are using but do a few dry runs to get the feel on how everything will go. Don't forget once you put that glue on the edge things get a bit slippery.
Jim

[Jamie Buxton]

I glue up panels like that in the following way...

I clamp a board on edge, directly underneath a lamp on the ceiling. When I place the next board on top, any misalignment is made obvious from the shadows. I put glue on the edge, put the upper board on, and put a spring clamp on each end, just bridging the joint. The spring clamps keep the upper board from falling off when you're fiddling with it. Then I put a pipe clamp at one end of the joint, and then more pipe clamps along the joint. As I put each clamp on, I tweak the upper board to get exact alignment. I can push and pull at the unclamped end to adjust the board position at the clamp I'm applying.

I pretty consistently get alignment good enough that I flatten any misalignment with nothing more than a card scraper.

Oh yeah... I glue up just one board at a time. My joints are tight and clean, and the glue sets up well enough in a half hour that I can put the next board on. I could probably drop to fifteen minutes even.

[jeff phillips]

I'm doing the glue up with bessy paralell clamps. I was leaning towards doing it in sub assemblies, but wasn't sure if there was any significant advantage in doing it all at once. You guys have confirmed my suspicions that there really are no big advantages.

[Frank Drew]

I'm doing the glue up with bessy paralell clamps. I was leaning towards doing it in sub assemblies, but wasn't sure if there was any significant advantage in doing it all at once. You guys have confirmed my suspicions that there really are no big advantages.

Jeff,

In addition to saving time, doing it all in one go, if practical, saves you having to rejoint the edges that might get dented, marred, bruised, whatever, by the clamps during the first glue ups.

This is also an argument for using fewer, wider boards in a tabletop -- the results usually looks better and it's less work (fewer glue joints). The ideal, IMO, is using a few wide boards all from the same tree.

[Derek Cohen]

What glue are you using?

I tend to go for Titebond III here. It has a little more open time.

I prepare everything carefully before hand. The boards are jointed and ready to be glued together. The Besseys have blue tape along the runners to prevent glue adhering. I have a plastic-headed mallet to hand to tap edges flat. There are extra clamps to hand as well as scrap I can use as cauls. There are clean wet rags on hand.

I place all the boards on the Besseys, in the correct order. Then run glue along one edge at a time, just enough not to create too much to wipe away. Push them together, at the marks, and lightly tighten the clamps. Tap down any edges that project. Add cauls, tighten a little, tighten the Besseys, tighten the cauls. Wipe away excess glue.

Go have a beer.

Regards from Perth

Derek

[Greg Becker]

I will also be gluing up a large table top from 8/4 cherry when I get back from Kabul at the end of the month. I'll be gluing 3 boards to equal 42" wide and plan to glue two together first then add the third on a second setup as the wood is pretty heavy.

I am wondering about using biscuits just to help align the boards when first clamping them (using an antique Stanly # -300259 biscuit plane of course!:D)

I realize that the bisquits will not provide any structural strength increase but I would think that they would help a little in the slipping and sliding stage of putting the boards together before I am able to tighten the clamps.

Opinions? I've never glued anything this large before -- or so important.

Thanks
Greg

[Jamie Buxton]

..I am wondering about using biscuits just to help align the boards when first clamping them ..

Using the procedure I outlined above, I find biscuits just get in the way. I'm aligning the board edges to better than .01 accuracy, and my biscuit joiner isn't that accurate. (I've never figured out why my biscuit joiner isn't that accurate. It should be, but it clearly isn't.)

I admit I do a good job of preparing the planks. They are flat and square, and the edges are straight. So when I'm gluing up the panel, I'm not trying to bend the boards into alignment.

[Frank Drew]

Greg,

The biscuits aren't necessary but probably would help with alignment; with only three boards I'd glue them all up at once, for the reasons I outlined in my answer above. If they close up nicely in a dry run they'll come together fine with glue if you move right along. If you had a helper it would be easy-peasy.

Jamie's on-edge method would work fine for smaller stock, but I'd be reluctant to try it gluing up your table-length 2x14s :eek:.

[David Keller NC]

Greg - In my experience (I'm ashamed to admit that I was a "biscuit joiner" 10 to 20 years ago. :D), biscuits do not help you with the horizontal alignment of the boards, at least not much. The reason is that most biscuit slot cutters overdo the slots so that the biscuits go in easily. That means as much as 1/4" or more of "slop" in the slip-matching of a panel glue-up.

What they can do, though, is help you with the vertical alignment. For most large panel glue-ups, the challenge is getting all of your wood prepped and 4-squared and then getting it all glued up before humidity changes introduce bow in the length of the individual boards.

Without panel clamps, the tendency is to have mis-alignment of as much as 1/4" in the vertical height in certain spots of the edges of the boards. 1/4" might not sound like much, but that's a boatload of handplane work to re-flatten the assembly after it dries.

Besides biscuits, there's a good alternative to minimizing these edge alignment issues. Specifically, build yourself 3 or 4 panel clamps. These are simply lengths of 2" thick, 3"-4" wide lumber that you've carefully jointed on one edge, then drilled through the ends and assembled with threaded rods and nuts/washers. In use, you slip the boards to be edge-joined into these clamps, tighten them down lightly, use besseys/pipe clamps to apply the force necessary to push the board edges together, then cinch the panel clamps down all the way.

The result is usually no more than a 32nd of a inch mis-alignment between the edges of the boards, and usually not even that.

[Jamie Buxton]

...Jamie's on-edge method would work fine for smaller stock, but I'd be reluctant to try it gluing up your table-length 2x14s :eek:...

Nope, it works just fine on anything. You do have to have a way of securing a board on edge, but if you're going to be building a table from 2x14 planks, you better have some serious clamping anyhow.

[Greg Becker]

Greg - In my experience (I'm ashamed to admit that I was a "biscuit joiner" 10 to 20 years ago. :D), biscuits do not help you with the horizontal alignment of the boards, at least not much. The reason is that most biscuit slot cutters overdo the slots so that the biscuits go in easily. That means as much as 1/4" or more of "slop" in the slip-matching of a panel glue-up.

What they can do, though, is help you with the vertical alignment. For most large panel glue-ups, the challenge is getting all of your wood prepped and 4-squared and then getting it all glued up before humidity changes introduce bow in the length of the individual boards.

Without panel clamps, the tendency is to have mis-alignment of as much as 1/4" in the vertical height in certain spots of the edges of the boards. 1/4" might not sound like much, but that's a boatload of handplane work to re-flatten the assembly after it dries.

Besides biscuits, there's a good alternative to minimizing these edge alignment issues. Specifically, build yourself 3 or 4 panel clamps. These are simply lengths of 2" thick, 3"-4" wide lumber that you've carefully jointed on one edge, then drilled through the ends and assembled with threaded rods and nuts/washers. In use, you slip the boards to be edge-joined into these clamps, tighten them down lightly, use besseys/pipe clamps to apply the force necessary to push the board edges together, then cinch the panel clamps down all the way.

The result is usually no more than a 32nd of a inch mis-alignment between the edges of the boards, and usually not even that.

Thanks for the advice, and sorry it has taken me this long to get back on this post - I've been in Kabul (still here for a couple more days) and too busy (and worn out) to be able to look at the website.

The panel clamps you suggest sound great, but would they work with boards that are not the exact same thickness? I had asked previously on "Neanderthal" how to hand plane all my boards to the exact same thickness. I was told to stop thinking in machinery terms (running all the boards through a thickness planer), get the pretty side flat, glue up the boards, then plane the back side enough to get it to sit flat on the leg assembly.

My boards are close to the same thickness (at least they were when I saw them a month ago - my workshop is humidity controlled and my wife has been checking the hygro every couple days) but they are sufficiently different that placing up and down pressure (like I understand the panel clamps to do) would cause them to "average out" the thickness.

Would I not be better off just letting gravity line them up by placing them face down on top of my row of clamps?

Thanks

[Darius Ferlas]

Greg,

First, I do my glue-ups piece by piece, not the whole top at once.
Then, even though I always try to make all boards the exact same thickness, the alignment may be an issue. I address that by concentrating on the flatness of the good side only. That helps me minimize scraping, planing and sanding.

For the glue-up I use two sets of clamps. One holds the boards' edges together, the other keeps them aligned for flatness. This second set are F-clamps with 5 inch reach. Since I use boards that are no more than 5" wide (limitations of my jointer) I can clamp a flat piece of wood (painted so it doesn't get glued) over the top of the two glued edges. That keeps the top perfectly flat.

Since I only glue up one board at a time my F-clamps have always enough capacity to reach over the join line. At time, I will use two F-clamps for the same spot, one for each of the two glued boards. With each added board, I also make sure I keep the entire glue-ip flat across the grain. Again, additional clamps came ion handy as I clamp down the extreme edges of the whole thing.

My glue-up process looks fairly ridiculous, much like a hedgehog. They also take more time since I can go one board width every 30 minutes or so, but this works for me and me results are just fine.

[Will Blick]

Darius, your method is interesting..... as you mention, time consuming, but requires less stuff....

But if the boards are NOT of equal thickness, how does the F clamp keep the good side flat?

[Darius Ferlas]

But if the boards are NOT of equal thickness, how does the F clamp keep the good side flat?

Will, let me clarify. The boards may, or may not be of equal thickness, and/or the difference in thickness may not be consistent. Also, there may (and does) occur) perceived difference in thickness when the boards will slightly loose their flatness along the length (humidity, storage etc are the factors), but each in a manner inconsistent with that of the other boards. The effect is that a board, say on a span of 30 inches will bow by 1/32", but the next board glued to it will not. One clamp will take care of it as both boards are really flat.

If the boards maintained its flatness between the time they are planed and glued up that would be ideal, but frequently this won't be the case.

At times the boards may be of different thickness indeed. For those cases I use clamps in configuration shown as "C" on the attached image.

Some legend to the attached graphics.

The whitish patterned pieces are perfectly flat pieces of painted oak, 1" by 2 1/2" by 12" stood on their edges.

A- clamps at the ends not that critical as for their alignment since the ends will get trimmed, unless the flatness is way out (1/32 or more). In such case there may be a need for clamp configuration C.
B - at these points the boards are of the same thickness
C - here the boards are of slightly different thickness

Any points between the clamping points appear flat. If not then another pair of F-clamps is added.

The tolerances I am addressing with my (to the best of my knowledge) method are not great but this virtually eliminated any issues I was experiencing with dowels, where a slight difference in the two boards' thicknesses was cut in half, but it was still there waiting for a plane, scraper and sand paper.

The second photograph shows a slight taste of what I do. I don't have a photo of an actual full glue-up using this method. This is also not the same scenario but the yellow circle shows a little better how I go about glue-ups..

[Paul Johnstone]

So i have all of the boards to make up the top of my table all cleaned and squared up. It is now time for the glue up. My question is will i be better off gluing the whole top up at once, or glue it up in sub assemblies? The top consists of seven boards varying in width from 5.5" to 7", for a final width of about 42".

It's a lot easier and less stressful to do it two or three boards at a time.
It takes a little longer, but there's a lot less pieces to line up.
I think that's the best way if you are using Besseys. IMO, you are less likely to make a mistake this way.

[Will Blick]

Interesting... but gosh, time consuming....

I would suggest the following....

If your boards are NOT the same thickness along their length, use either a biscuit or dowel.... these will keep the flat faces, FLAT... assuming the cut is made from the same distance from the flat surface on all boards. This will allow you to clamp more boards at once... (assuming you want to do that)

But regardless, as you keep adding a board, at best you can assure is that that last board is close to the same plane as the previous boards. But you have no assurance of the flatness of the entire finished top, which can go astray. I have battled this through the years myself....

The simple solution for me was, I plane to the same thickness.... but even then, I need STRAIGHT clamping cross members going perpendicular to the glue line, as your sketch shows... I have 4ft pieces of solid alum., so I can clamp down hard....this is similar to what the panel clamp systems do, but my method takes up less space... You can even use some strong angle iron.

Next, I use the edge clamp bars, only a few bucks at Harbor fright ...they assure the edges remain on the same plane.... with this method, no joinery requried. Before I used the heavy duty cross members, I wasted a lot of time making the entire top dead flat after glue up.... PITA.....

[Steve Dallas]

So i have all of the boards to make up the top of my table all cleaned and squared up. It is now time for the glue up. My question is will i be better off gluing the whole top up at once, or glue it up in sub assemblies? The top consists of seven boards varying in width from 5.5" to 7", for a final width of about 42".

Assuming you haven't screwed up by planing the individual boards to finished thickness or close to it (the hugest of huge screwups by the way) there's no reason not to do the thing in one fell swoop and then process the top from there.

This is where you claim your insurance provided by being a hand tool woodworker - you don't have to worry about the table top being too large to joint and plane on a machine. Take the tool to the job.

[Russell Sansom]

Will mentioned dowels...I've always had good success with splines. I used dowels years ago but the requirement to register them perfectly to the face and perfectly ALONG the joint was always too much for me.
Splines fit tightly and one has to work quickly so they don't swell and fail to go home, or go home and split the board. Even a 3/16" spline will work quite well in a thinnish table top.

Oh yeah...I'm a one-board-at-a-timer mostly, but not always. Sometimes all at once feels right using a one-up clamping jig, depending on the size of the puzzle and the mass involved.
In the very specialized case of a harpsichord soundboard which is, say, 40" long, 34" wide, and sub 1/8" thick, I go for perfection on two boards at a time, then work my way up to larger sub-units. This gives me the time for reflection that I find I need to avoid mistakes no matter how well I prepare ahead.

[David Keller NC]

The panel clamps you suggest sound great, but would they work with boards that are not the exact same thickness? I had asked previously on "Neanderthal" how to hand plane all my boards to the exact same thickness. I was told to stop thinking in machinery terms (running all the boards through a thickness planer), get the pretty side flat, glue up the boards, then plane the back side enough to get it to sit flat on the leg assembly.

My boards are close to the same thickness (at least they were when I saw them a month ago - my workshop is humidity controlled and my wife has been checking the hygro every couple days) but they are sufficiently different that placing up and down pressure (like I understand the panel clamps to do) would cause them to "average out" the thickness.

Would I not be better off just letting gravity line them up by placing them face down on top of my row of clamps?

Thanks

I think you will find that gravity won't do the job here, at least if your tabletop is of any reasonable length. The reason is that you're likely to find that the boards have bowed or twisted a bit somewhere along their length, but not in other places. So you can use panel clamps to force out a bit of that uneveness (within limits), and I find that the glued-up panel tends to keep those imperfectiosn from re-appearing (i.e., there's less wood to remove to get the whole table top flat than there would be to make every board flat along its length).

Generally speaking, I also hand-process boards, so mine are never perfectly the same thickness, nor machine-flat and straight. However, they are within about 1/32nd of an inch, and the panel clamps ensure that's the maximum amount of wood you'll need to take off of the top to make it flat. On the occasions that I've had where the boards weren't within 1/32nd, and further planing wasn't possible or desirable, I just inserted a couple of very thin hardwood shims underneath the glue-up to ensure that the top surface was close to perfect and would require the least amount of planing.

The process of making 3 or 4 panel clamps is pretty easy, and it's pretty cheap, so I'd suggest you might want to spend a morning making a couple and see what you think. I wouldn't be without mine.

The supplies needed are some 2-3" thick hardwood (go cheap - I use utility maple because it's hard and strong and about $3/b.f. around here), about 6 feet of 1/2" all-thread rod (from any hardware store or the Borg), corresponding flat "fender" washers and nuts, a hacksaw, a triangular file, a 9/16" drill bit, and a 1-1/4" forstner bit, or other means of drilling a 1-1/4" hole.

Simply saw the wood into strips about 4" wide, about 36"- 48" long (or longer if you need them to be that way, but not too long - that cuts down on their effectiveness and makes them a pain to use), turn the stips on edge, hand plane a slight crown in both halves, drill them through on each end with a 9/16" bit, counter-sink 1-1/4" holes on one side only (that will be the "bench" side - the countersink allows the clamps to be self-standing), hacksaw the all-thread to an appropriate length, file the threads buggered up from the hacksaw with the triangular file so that the nuts will thread onto them easily, WAX the HECK out of the surfaces that will bear on the glued up panel, assemble them and put them to work.

[Frank Drew]

Darius,

With regards to your glue up protocol... does the name Rube Goldberg ring a bell? :D

[One other thing, you say you're limited to 5" boards due to your jointer; does that mean you've got a 6" jointer? If so, you needn't limit yourself to such narrow stock; a 6" jointer can effectively face plane boards up to almost 12".]

[Darius Ferlas]

Darius,

With regards to your glue up protocol... does the name Rube Goldberg ring a bell? :D
I was asked a question and I provided a response. This works for me and it works great. I don't care about the comparison with Goldberg. I am happy I'm not compared with Sisyphus, even though my finishing skills bring me pretty close to him.

If I had the funds I'd be doing glue-ups at a push of a button. But then... perhaps not. For me it's a hobby after all, so I take as much pleasure in the result as I take in the process.

hope this helps.

[jeff phillips]

Well the glue up is complete. I ended up gluing up three assemblies, two with two boards each, and one with three. I referenced the top faces against the bars on my paralell clamps so i had a fairly solid reference surface to keep them flat. Once out of the clamps i planed out any slight misalignment on the top face and then glued the three assemblies together at once.

Those last two joints didn't come out great as far as alignment goes, but they werent too bad either. It wasnt a big deal to correct it, as i left the boards about 1/8 oversize in thickness to give me wiggle room for just such a problem. I ended up at just about my target thickness of 1-1/2" when finished.

I planed the top and bottom flat last weekend. I have a slightly convex top, but its not noticable unless a straightedge is put to it. The true test was when i put plates on it, and there was no wobble, they sat very solid.

[Roger Benton]

Jeff, FWIW,
i glue up large panels like table tops in sections. start with the stock 1/8" thicker than finished size. my planer is 15", so for a 42" table top i would glue up three sections at <15" each, run them through the planer, then glue the three sections up. shop made curved cauls handle the two joints in the middle of the panel. works well for me.

[Derek Cohen]

Glue ups should not be so difficult. Let me add a couple of points to my original post.

Firstly, the boards I use are often not the same thickness. This is not important for tabletops - unless you use the underneath as much as the top! :)

What is important is that the top side is coplanar/flat. So I assemble the boards on the Besseys with the top sides facing down.

Secondly, biscuits and dowels are quite unnecessary. They made it all overcomplicated and fiddly. Butt joints and glue will last a century.

After adding and spreading the glue, I give the adjoining boards a rub together. This causes them to suck together. No more is needed.

Lastly, I use more clamps that seem necessary. This is not so that the boards are pulled together, but rather than I can remove one to swap away glue without disturbing the alignment.

Here is a recently-built table. It required very little flattening after the glue dried.

http://www.inthewoodshop.com/Furniture/AShakerTableforMothersDay_html_m63b86ce8.jpg

Yet a look underneath will reveal that only the outer boards were of equal thickness ...

http://www.inthewoodshop.com/Furniture/AShakerTableforMothersDay_html_73b8d1c5.jpg

Reference: http://www.inthewoodshop.com/Furniture/AShakerTableforMothersDay.html

Regards from Perth

Derek

[Greg Becker]

I think you will find that gravity won't do the job here, ...

.....the hacksaw with the triangular file so that the nuts will thread onto them easily, WAX the HECK out of the surfaces that will bear on the glued up panel, assemble them and put them to work.

That's a very good explanation - thank you. I can't wait to get home (for lots of reasons ) see how my boards are doing, then put the panel clamps to work.

[Will Blick]

> file the threads buggered up from the hacksaw with the triangular file so that the nuts will thread onto them easily,


Or even better, place a few nuts below the cut point, after hacking the threads, twist the nuts off, it will re-thread the burred threads.... worse case, you waste the cost of a few nuts.

[Greg Becker]

I think you will find that gravity won't do the job here, at least if your tabletop is of any reasonable length. The reason is that you're likely to find that the boards have bowed or twisted a bit somewhere along their length, but not in other places. So you can use panel clamps to force out a bit of that uneveness (within limits), ...

......thread onto them easily, WAX the HECK out of the surfaces that will bear on the glued up panel, assemble them and put them to work.

I have taken your advice and put together some panel clamps. I took it a step further and put them together in a frame to support the rest of my clamps at the right level.

I used southern yellow pine as it is very available and cheap here and has good structural strength. I have coated the contact surfaces with painters tape which has then been covered with as much paraffin wax as I could apply.

Altogether I will be using 12 pipe clamps and 5 K-Body clamps as well as the 3 panel clamps. The pipe and K-Bodies will provide about 13,500 psi which is about half as much force as the 30,000 psi "Fine Woodworking" recommends. I have a hard time believing that I will not have enough clamping force. My joints are 72" x 1.75" and are Cherry which according to their guide requires 250psi.

Any thoughts????