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Tabletop glue up questions

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Forum topic by Neophyte74 posted 09-29-2019 01:16 AM 911 views 0 times favorited 31 replies Add to Favorites Watch
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Neophyte74

17 posts in 128 days


09-29-2019 01:16 AM

Topic tags/keywords: glue

I’ve purchased a bunch of Sapele and paid to have it jointed and planned. I’m preparing to do my fist glue up. The hair pin leg table I’m building will be 6.5 feet long and 40 inches wide. The tabletop I am gluing up will have 6 boards – 4 six inch wide boards and 2 eight inch wide boards. I built a temporary work table out of dimensional lumber that is 8 feet by 4 feet and I have a collection of clamps. I also have boards to use as cauls. I’m using Titebond III glue. Here are my glue related questions:
1) once I glue up the boards and apply the clamps, how long do I wait before removing the clamps? 2) how do I determine when the clamps are tight enough and how do I avoid clamps that are too tight or too lose. 3) how many of the 8 boards should I glue up at one time? 4) what else should I do to ensure success. Thanks in advance for any advice the glue up portion of this project is a little intimidating for me but I’m excited about the challenge of learning a new woodworking skill


31 replies so far

View Manitario's profile

Manitario

2795 posts in 3487 days


#1 posted 09-29-2019 02:01 AM

Just because you paid someone to joint and plane the wood doesn’t mean that it will be flat and true. I joint and plane my wood but always need to do some fine tuning with my hand planes before glue-up.
1) I leave the clamps on overnight.
2)I tighten my clamps until I can’t tighten anymore by hand.
3)As many as you can flatten after glue-up, ie. I will only glue-up as many boards as I can fit in my 20” planer after glue-up. If you are going to flatten by hand or by sander after glue-up, then it doesn’t matter how many boards you glue up at a time.
4)Cauls across the width of the glue-up to try and keep it flat

-- Sometimes the creative process requires foul language. -- Charles Neil

View diverlloyd's profile

diverlloyd

3759 posts in 2462 days


#2 posted 09-29-2019 02:27 AM

Doing #2 above will get you in trouble depending on your clamps and hand strength. Over tightening will cause bows and more work for you. Tighten enough to get a bit of glue squeeze out out.

Stumpy nubs did a video on a counter top glue up https://youtu.be/D_dja9U1Sq4 see if it has any info that will help.
Also dry fit everything together first and see how well you can get it to fit up. You don’t have to glue the whole top up at once,you can do it in stages if you are more comfortable that way. Do two or three boards at once so you can get the hang of it and see if you can do anything better on the next small glue up. If you mess up it’s easier to go back one step then it is to cut a part a bunch of glue joints.

View anthm27's profile

anthm27

1599 posts in 1715 days


#3 posted 09-29-2019 03:23 AM

personally I would dowel your boards.
This serves to have the positioning of your boards work done before you even open a glue bottle. It will make your glue up a lot easier and more accurate and help with general flatness.

EDIT an example on a small scale can be seen on one of my projects here.

-- Hand Skills provide freedom.

View Rich's profile

Rich

5137 posts in 1194 days


#4 posted 09-29-2019 04:34 AM

Do not tighten the clamps as tight as you can because it’s possible to squeeze out the glue and leave the joint starved. Just pull the joint together. Big +1 on cauls. Dowels or biscuits might ensure even joints, but they will not ensure a flat surface. Even better, build a torsion box surface for your glue ups. Done right, they are dead flat.

Forget the Titebond III. It’s often mistakenly assumed it’s stronger because it’s one higher, but in fact, its intent is for use in outdoor environments. It has an odd greyish-brown color that can make joints stand out. Titebond II is all you need—and it costs less. Now if they ever come out with Titebond XI, go for it, because hey, it’s eleven (Spinal Tap reference).

There’s probably more to cover, but I’ll leave it at that for now.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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therealSteveN

4618 posts in 1179 days


#5 posted 09-29-2019 04:53 AM

Might I suggest you buy a few pieces of the “select” pine sold at most BORGs, and do a practice glue up before committing your Sapele to a less than good outcome. If you can get a satisfactory joint from them, move ahead. If not keep tweaking. It is the stuff that has absolutely no knots, clean crisp edges, and if they are straight you can glue up satisfactorily without prep. Most places just call it select, but it is Radiata pine. To look for likely pieces lay them side to side on the floor until you have as much as you would for your table top. I say the floor, because it will help let you see any that are twisted, cupped, bowed, or otherwise not so straight.

You will have a better feel for how much glue you use, clamp pressure, cleaning up squeeze out, seeing if you feel the need for cauls, or other positioning aids. It is an added cost, but could end up saving a lot of money if you mess up the first glue up, on expensive wood.

You can talk and read all you want before hand, but until you have them glued up, and are trying to clamp them, you won’t know, but after you will tank me for mentioning this.

-- Think safe, be safe

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Aj2

2650 posts in 2402 days


#6 posted 09-29-2019 04:57 AM

I’m a over gluer and over clamper.

-- Aj

View Rich's profile

Rich

5137 posts in 1194 days


#7 posted 09-29-2019 05:03 AM


Might I suggest you buy a few pieces of the “select” pine sold at most BORGs, and do a practice glue up before committing your Sapele to a less than good outcome.

- therealSteveN

A brilliant suggestion. It’s not like you have to do a full-size model, but practice makes perfect. Any cheap hardwood, even poplar, will help you get a feel for what you’re attempting. And, if you fail, better that than expensive sapele.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View 4wood's profile

4wood

42 posts in 558 days


#8 posted 09-29-2019 02:53 PM

Call Titebond and see what they suggest for Sapele. I glued up a bunch of 12” x 40” stair treads a while ago . I called Titebond and they suggested Titebond III and also wiping the surface with denatured alcohol or acetone to remove any oil that may be present. I always use splines for alignment. As suggested above try a small mock up first. Before you apply any glue to the Sapele make sure you set it up completely in the clamps dry and make any corrections that need to be done. If possible take a straight edge and check form corner to corner in an X pattern to see if your setup is flat. The number of boards that you are able to glue up at one time may be determined by the number of people helping you. If you are doing this alone you don’t have a very long open time and the glue may tend to dry too much before you have a chance to get all of the clamps tightened up. I would suggest someone to help if possible or doing only one or two glue joints on the first try. I only apply glue to one surface.

As far as clamping time this may be determined by you shop conditions. Temperature, humidity and how well your joints fit together when you did the dry fit. When you talk to Titebond ask them about the clamping time. I believe the information on the bottle may say that 20 minuets may be enough in some situations. I usually keep my clamped for two hours before adding other boards. This is in the South Florida environment. I have a set of old I beam bar clamps and I do not apply a tremendous amount of pressure. Different types of clamps apply a different amount of pressure. You should have glue squeeze out. Here is a link to a discussion about clamping. http://www.woodweb.com/knowledge_base/Gluing_and_clamping_pressure.html
The replies from Gene Wengert are from an expert. https://www.woodworkingnetwork.com/author-works/genewengert

View tynewman's profile

tynewman

117 posts in 317 days


#9 posted 09-29-2019 04:20 PM

A lot of good suggestions. Definitely a dry fit (before doweling, biscuits or splines), pre-joining doesn’t mean perfectly square and you may end up flipping or turning the board to get a better fit. Splines are easy, cut a groove with a router, just don’t go all the way to the end. Definitely cauls, and enough pressure to close the gap. I like the color of titebond III on darker woods, the light glue is more noticeable. And, if you don’t have a planer or sander, glue all at once.

-- Ty

View Rich's profile

Rich

5137 posts in 1194 days


#10 posted 09-29-2019 05:22 PM

Since part of the discussion is around glue, consider the Titebond II with fluorescent dye. On a somewhat porous wood like sapele, it and a $10 UV flashlight will allow you to see any traces of glue before they bite you in the butt at finishing time. I did a blog post about it last year and use it exclusively when I use PVA glue. Hide glue is another good option since it also fluoresces and is very friendly with finishes.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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Geraldsh

11 posts in 814 days


#11 posted 09-29-2019 06:25 PM

Woodworking is my hobby. Since I retired from the real world I have more time than money and more opinions than facts.

If this was my first big project I would number the boards 1-6 then glue one seam at a time thus allowing plenty of time to get the two boards perfectly aligned and evenly clamped. Probably in the order of 1 to 2, 3 to 4, 5 to 6 then 1/2 to 3/4 and 1/2/3/4 to 5/6 or if I felt confident enough after the first two glue- ups, I may do 1/2 to 3/4 to 5/6 all at once.

I have done the spline trick and like it for alignment if you don’t have a flat surface to work from. It doesn’t take much in misalignment to result in lots of sanding. That said; sanding might tire you out but it won’t kill you :) don’t be afraid to try and have fun.

View Neophyte74's profile

Neophyte74

17 posts in 128 days


#12 posted 09-29-2019 06:34 PM

Question: is it essential to get rid of all glue that squeezes out of the joint before it dries or can you scrape it off when it is dry? I am concerned because the cauls will cover part of the joint and I’m unsure how I will get to the extra glue that is under the cauls

View Rich's profile

Rich

5137 posts in 1194 days


#13 posted 09-29-2019 06:54 PM


Question: is it essential to get rid of all glue that squeezes out of the joint before it dries or can you scrape it off when it is dry? I am concerned because the cauls will cover part of the joint and I’m unsure how I will get to the extra glue that is under the cauls

- Neophyte74

It’ll stay wet under the cauls. I do find it easiest to wait until the squeezed out bead is just about completely translucent and then scrape it off. That way you don’t get wet glue smearing around, but it’s not so hard you can’t scrape it. I use a chisel plane, but any thin bladed tool will work.

You can take the cauls off before it gets to that stage and the wet glue under the cauls will dry enough to scrape as well.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View anthm27's profile

anthm27

1599 posts in 1715 days


#14 posted 09-29-2019 11:15 PM



Question: is it essential to get rid of all glue that squeezes out of the joint before it dries or can you scrape it off when it is dry? I am concerned because the cauls will cover part of the joint and I’m unsure how I will get to the extra glue that is under the cauls

- Neophyte74

With a very wet rag , Wipe as much glue off the project as you can while you can and when you can, I then tend to dry where I have wiped with a nice clean dry towel or rag. you will however get the dry glue off later though. If you use dowels have them pre glued into the boards so whilst doing your main glue up you dont have to fluff about with loose dowels, have them pre set. I wrap my steel clamps in glad wrap cling film so as the steel doesnt stain the workpiece, also your cauls wrapped in glad wrap then they wont stick to your project when the glue oozes out.
Rehearse what you are going to do over and over, have everything at your fingertips.

-- Hand Skills provide freedom.

View Robert's profile

Robert

3600 posts in 2085 days


#15 posted 09-30-2019 01:42 PM

I always allow 24 hrs in clamps, but depending on shop temp, it can be shorter.

Clamping pressure is subjective. I don’t think you can overclamp, but extreme clamping pressure it not necessary.

On a top that wide I recommend gluing up in at 2-3 sections.

There are a couple ways to handle squeeze out, wipe off right way or allow to rubberize and peel off with a putty knife or blade. Personally I don’t like to let the glue dry as scraping dry glue on can result in tear out in certain woods.

Be sure to put packing tape on the cauls.

My only other tip I can think of is be sure you keep your panel stored so it receives equal air flow on both sides both during and especially after clamping. The worst thing you can do is lay a panel flat down on table for a few days,which will usually result in some kind of warping or cupping.

Proper jointing and alignment are the two keys to a successful panel glue up. If you’re starting out with nice, straight, perfectly jointed boards, that makes it a lot easier.

I can’t emphasize how important perfect jointing is. Straight and 90°. Don’t trust the place that jointed them. Check every edge at several points along the board. I alternate faces against the fence on the jointer this way complimentary angles cancel out any minor discerpancy off 90.

Along those lines, often you’re not dealing with “perfect” boards. Sometimes there is a bow, IOW after jointing, the board moves. Minor gaps can be clamped out, especially in the middle of a board. However, gaps on the ends are bad and need to be rejointed.

Getting the boards flush is the most stressful part. Alignment aids will help (dowels, Dominoes, biscuits, etc). Personally, I can usually bring every thing in with some incremental clamping pressure and a judicious strike from a rubber mallet.

That said, IMO one of the keys to a good panel glue up is to keep it thick as long as possible. Planing to final thickness prior to glue up really creates a lot of pressure to get it perfect.

Of course this assumes you have the ability to joint and plane something 12” or wider.

Hope this helps!

-- Everything is a prototype thats why its one of a kind!!

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