Major glue-up trauma

[PerranOak]

I've just glued-up a box:

300mmx150mmx150mm, 9mm thick walnut
through dovetails all round and inset base
pretty standard design

It takes ages to put glue (Tightbond III) on every surface so by the end most of the glue was dry-looking. It seemed to stick a bit as I assembled it so I thwacked it with a dead-blow hammer.

Yes, the walnut split. Right through on one corner, ene-to-end (but not right through) on one side. You could say I panicked.

At the root of this is that I fear the glue will dry and I'll not get a proper joint when the glueing takes so long.

What do people do? Boxes have been made this way for centuries. Are people REALLY quick? Does glue actually take ages to dry?

Advice would be most welcome, thank you.

PS
How do I cover-up the splits(!)?

 

[ondablade]

Seems to me PO that as ever it's about the balance between time to get the work done, and speed of the adhesive - with the risk of a delay caused by e.g. fit problems, missing kit being the big imponderable.

As in if it's an assembly step you've done before/are confident of then you can use a faster adhesive. If in doubt use something slower.

The various Titebonds are characterised by differing open times and water resistance - i think there's a slower one that gives about 15min, but some are as low as 5min. One of the old reliables like Evo Stik Resin W so far as i can recall was quite quite a bit slower - maybe 20 - 25min. It's going to depend on the conditions too.

I too find myself under pressure for time on even simple joints. The rush to faster adhesives can't help everybody, but i suppose if you need an assembly dry enough to work on by tomorrow morning the adhesive has to be fast enough to achieve this too.

Getting really well set up - fast and appropriate spreading methods, right glue placement and amount, clean up method to hand (wet rag), a worked out clamping plan, and fits verified as far as possible in advance etc. - has to be important. It's so easy to dab some glue on, and only then realise that you haven't got it figured out.

One that catches me sometimes is the tendency for parts to slide on each other when the clamps are tightened - avoiding issues like this can entail going right back to design choices.

Others have to be calmness, and a readiness to recognise that there is usually an 'abort' point. It's not desirable, but most glue ups have a point where if it's not going well it's better to separate and clean up everything - the trick is to stay calm enough to recogise when this point is reached. Some don't - you better get it right first time. e.g. with adhesives that may discolour your wood like epoxy or polyurethane.

Not much help to you I know, but there's no magic i know of....

 

[AndyT]

PO, when you say it takes ages to put the glue on every surface - I take it you don't mean on all 8 ends before you start assembly?

What I would do is glue one corner, knock it together, then glue the third piece onto the first, insert the bottom (possibly not glued, depending on the design) then the last piece. It's the last one where you need to be quick, as you have to do two corners at once.

And of course, make sure you're working the right way of the dovetails so you can slide the last bit in!

Sorry if I'm stating the obvious, but wasn't sure what you meant. Bad news about the split though.

One other thought - I sometimes use using Titebond Liquid Hide Glue - no stated open time, but it's much longer than PVA or PU.

 

[PerranOak]

ondablade, it is helpful, helpful to know I'm not the only one who gets stressed! The Titebond I have says 20mins open time but It was like contact adhesive by the time I came to fix it.

You are right about the calmness idea. Also, it's true I didn't have the clamp right in front of me. If I had, maybe I'd have closed the joints with them rather than the hammer!

I wonder, do you use (I don't know whay they're called) strips of wood with "teeth" for clamping to put pressure only on the tails?

AndyT, my Ma always said, "Never be afraid to state the bleedin' obvious." Now I see why. No, I glue absolutely all surfaces first! I assumed that this was the way in case, say, one corner sets up then you "crack it" by doing the next one.

Don't tell me everyone does it corner by corner! :shock:

 

[Paul Chapman]

I find that with glue-ups you really need a method.

1. Clear enough space

2. Work out how you are going to do it (some things are better glued up in one go, others are better done in sections)

3. Get everything that you will need

4. Set all your cramps, etc., to the correct lengths and have the right wooden blocks

5. Do a trial, dry glue-up (ie no glue) - that will ensure that you do have everything you need, that it is going to work, that you know in which order you are going to do everything and you know how long it's going to take

6. Keep in mind that some jobs actually need two people - both of whom know what they are doing

7. When you are sure you are ready and you know what you are going to do, start glueing

That's how I try to do it and it usually works.

Cheers :wink:

Paul

 

[p111dom]

I have to say that I find the glue up the most stressful stage for just this reason. Despite doing pretty much all that is suggested above, it's still amazing that every time I'm doing this critical stage the phone rings, someone knocks at the door or my wife says that dinners ready and expects me to drop everything that instant. STRESS! :twisted:

 

[moz]

Bad luck, it happens to everybody. It could be that your joints were a tad too tight. More likely the end pins were too small - they easily split if there isn't enough material to withstand the inevitable spreading. Also, try inserting all the joints dry, just very slightly, to start them off then apply glue to all surfaces before finally knocking/clamping them up. I find it's much less panicky this way.

John

 

[mailee]

Oh thank god for that, I thought it was just me who finds the phone rings or the wife calls when gluing up. I usually ignore both and leave the ear defenders on. :lol:

 

[scholar]

I hate working to any deadline which is why I hate glue-ups full stop!

I have not used Titebond III as far as I recall, but my preferred glue for any "complex" glue-up is Cascamite - it has a longer open time than any other glue I have used and also goes on quicker (with a brush).

For really big glue-ups like panelled doors with all those mortises and twin tenons etc, I call in reinforcements in the shape of SWMBO who I must say is quite a dab hand now I have trained her!

cheers

 

[9fingers]

On dovetail glue ups I use masking tape on the inside surfaces up to each corner. This means you can be a little less careful in applying the glue and hence quicker.

Bob

 

[Sgian Dubh]

...my preferred glue for any "complex" glue-up is Cascamite - it has a longer open time than any other glue I have used and also goes on quicker (with a brush).

The Cascamite version of the ureae formaldehyde glues has on open time of about 10 minutes at ~20°C. At the same temperature this is a little longer than than typical or 'average' PVA or aliphatic emulsions, bearing in mind that manufacturers make some that have 'extended' open times and others have 'quick-setting' properties.

If you are ever looking for glues with longer open times, again at the same temperature, many polyurethane glues will fit the bill, although you need to check what's written on the container. A typical open time is twenty minutes for this glue type.

Liquid hide glue has, at about 20°C, has an open time of roughly 15- 20 minutes.

Some of the slow set epoxy resins have open times that are longer still, eg up to about two hours.

Most adhesives have shorter open times and quicker cure times with increased temperature. For example, urea formaldehyde in the form of Cascamite, will cure in less than two minutes when used for veneering in a heated hydraulic press where the temperature of the platens is raised to 60°C. Slainte.

 

[wobblycogs]

I do all my glue ups (not that I've done that many) one joint at a time. If it's at all complex I get LOML to help either passing me the next piece or spreading glue.

Dry fitting is a must in my book, especially for dovetails, I tend to half fit the joint rather than fully knock it home when dry. I find that is a good compromise between just blind fitting at glue up time and ending up with a loose joint because of compressed fibres.

The single most important thing I've done to reduce stress at glue up is to make a plan of how the parts will go together. I don't write it down but I lay the parts out and go through in my head the order I'll fit the bits together.

When there is a screw up and something isn't quite square I find that the joint can normally be persuaded to move a little as long as the glue hasn't fully set. I'm sure the joint isn't as as strong then as it could be but I've never had a problem.

 

[jlawrence]

I think it's just about being careful and planning how you're going to do the glue up. Sometimes you need to do one joint at a time, sometimes you can do all corners at once.
Just plan it out and make sure you've got everything to hand when you start - there's nothing worse than having to search for that clamp which has chosen this moment to get buried in a pile of shavings.

 

[MIGNAL]

The other Glue alternative is Fish Glue. Better than Liquid Hide and gives a similar open time. It's not readily available in the UK although Kremer Pigmente stock it, as do Lee Valley.
Hopefully, sometime soon someone in the UK will.

 

[JoinerySolutions]

PerranOak,
A lot of good advice posted.
Some of it comes under the 5 P's, Prior Preparation Prevents Poor Performance.
There is also Don't Panic. Take it steady and do not try to rush the task.
For my glue ups where they need to be in the clamps for a while I leave the job till nearly home time, not so late in the day that I am flagging but late enough that I will not need the clamps(or anyone else in the 'shop in some cases) later in the day.
The more you do something the easier and less stressed you will be at it.
Titebond do a dark glue version that may be of help in disguising the cracks with some judicially applied cramping. Cleaning off the excess glue prior to it drying will help prevent shadowing illuminating the join after finishing.

Rob.

 

[PerranOak]

Yes indeed! Thank you very much to everyone.

I'm glad that I'm not totally out-there when it comes to glue-stress. Still, I do need to heed ALL the advice as I have a panic-mode reserved for glue-ups(!)

 

[scholar]

...my preferred glue for any "complex" glue-up is Cascamite - it has a longer open time than any other glue I have used and also goes on quicker (with a brush).

The Cascamite version of the ureae formaldehyde glues has on open time of about 10 minutes at ~20°C. At the same temperature this is a little longer than than typical or 'average' PVA or aliphatic emulsions, bearing in mind that manufacturers make some that have 'extended' open times and others have 'quick-setting' properties.

If you are ever looking for glues with longer open times, again at the same temperature, many polyurethane glues will fit the bill, although you need to check what's written on the container. A typical open time is twenty minutes for this glue type.

Liquid hide glue has, at about 20°C, has an open time of roughly 15- 20 minutes.

Some of the slow set epoxy resins have open times that are longer still, eg up to about two hours.

Most adhesives have shorter open times and quicker cure times with increased temperature. For example, urea formaldehyde in the form of Cascamite, will cure in less than two minutes when used for veneering in a heated hydraulic press where the temperature of the platens is raised to 60°C. Slainte.

You make a very good point about the vital impact (helpful and unhelpful)of temperature on glue-up stress. As I have the luxury of a centrally heated workshop, I do always try to remember to turn the heating down before a big glue-up - it does give you so much more time.

I would, however, query the view that Cascamite only has an open time of 10 minutes at 20°C - I haven't measured it of course, but am sure that in practice it is longer than this and without question in like-for-like conditions, it is way longer than pva, which is my main alternative experience.

The Cascamite guidance on the tub only states an open time of 3hrs at 15°C. This technical sheet for some other brand which appears to be the same thing http://constructionchemicals.co.uk/acat ... mite09.pdf states a "Gel time guide" of 1-2 hours at 20°C.

But I'm not questioning the fundamental point that temperature is important.

Cheers

 

[moz]

Cascamite is supposed to have a long open time but I think this is often academic. Regardless of pot life or whatever you want to call it, I have found the water will begin to evaporate from thinly spread glue surfaces in a warm environment fairly quickly and you do have to get a move on. I think its the moisture evaporating and affecting the catalytic reaction that can make Cascamite so sensitive to temperature variation, not just the cure time.

John

 

[Ironballs]

Paul gave some good advice about the method, I try and do this each time, it doesn't eliminate stress and **** ups but it does reduce the chances. You should have seen the swearing and hammer twatting when I had to assemble the sides of my Stickley chair - 17 spindles with a tenon on each end, 2 rails, 2 legs and an arm rest. The spindles weren't perfect and some required glue injection with a hypodermic to cure a little bit of rattle

 

[scholar]

Cascamite is supposed to have a long open time but I think this is often academic. Regardless of pot life or whatever you want to call it, I have found the water will begin to evaporate from thinly spread glue surfaces in a warm environment fairly quickly and you do have to get a move on. I think its the moisture evaporating and affecting the catalytic reaction that can make Cascamite so sensitive to temperature variation, not just the cure time.

John

Good point and I agree.

I mix Cascamite by the weight method, but usually add an extra few drops of water which makes a great difference to the consistency and therefore the practical open time.

cheers