Laminating a hardwood worktop [completed]

[Boz62]

I'm planning to make a new workbench using 40mm thick beech kitchen worktop. I intend to laminate two layers :shock:.

I usually use Evostick blue PVA. The largest lamination I've done with it has been a medium sized router table top, and that was a bit of a panic. The new work top will be 1500x620 and each layer is 25Kg so it won't be fast to spread the glue, move the halves together and clamp. So I'm looking for a longer open time and a thinner consistency (easier to spread evenly).

I'm comfortable with PVA, but am prepared to look at other types. Ideas so far include; Titebond Extend, Titebond Liquid Hide Glue and Cascamite.

Any thoughts?

Boz

 

[OPJ]

Normally I'd recommend 'cascamite', as this doesn't creep in time like ordinary PVA. You can mix it your own consistency but I still think you might find it too thick... There are also bound to be other glues available on the market with longer open times.

I've used a couple of the Titebond glues and they do seem to be 'runnier' than ordinary PVA. I was also going to such Titebond Extend wood glue, although I've not used this one myself. I'd be inclined to leave the Hide Glue alone this time - you'd have to leave to cure for most of a day and it really is best for 'reversible' furniture repairs in restoration.

 

[Derek Willis.]

There is nothing wrong with using PVA, the only drawback is, as you have said, the open time, this is due to porosity of the timber, so prime both pieces with a diluted coat of PVA first and allow to dry, by doing this the PVA adhesive you eventually use will stay open for a long time.
Derek.

 

[MIGNAL]

Cascamite but applied with a roller. I've mixed Cascamite quite thin, applied to both mating surfaces and it's always resulted in a very good bond.
Fish Glue is another option but I don't know of a source in the UK. Again it's quite thick but if applied with a Roller it shouldn't be a problem. I use the stuff for caul veneering.

 

[Boz62]

Thanks for the comments.

I hadn't thought of "pre-sealing" for PVA Derek, think I'll try it on some scraps to get a feel for it.

I've seen comments that Cascamite sets "glass hard". As I'm going to be finishing the edges, drilling dog holes and routing a cutout for the front-vice, all through the glue-line, is it best avoided? Does it have to be applied to both faces, Mignal, or was that because you were using it thin?

Thanks,

Boz

 

[MIGNAL]

Applied on both surfaces because of the consistency. The problem with mixing it thin is that the glue will soak into the surface and probably create a starved joint. Applying the glue to both surfaces avoids that problem.
I wouldn't worry about the glass hard glue. it should be a very,very thin glue line. Think about how much glue is used in plywood, that doesn't stop people making things out of the stuff.

 

[woodbloke]

Cascamite (or urea formaldehyde) should be applied thin (it should drip evenly off the end of the mixing stick) and if applied with a roller as has been suggested will enable you to cover the gluing area pretty quickly before it starts to go 'off' - Rob

 

[yetloh]

I agree that cascamite applied with a roller will be just fine. I don't think you need to worry about cutting through the glue line; if you have a good close joint the glue layer will be very thin indeed and it certainly won't bother a TCT router cutter.

I am very sceptical about the idea of pre-sealing with pave. I have always understood the PVA will not stick to a layer of PVA which has already set - the reason why it is unwise to repair a pva glued joint with pva - but maybe that is an old wives tale, I haven't tried it.

Jim

 

[moz]

Another vote for Cascamite. I've tried all types of PVA for laminations and they all creep to some extent leading to ridges. Try not to let squeeze-out set 'glass hard' as you describe it. It's all too easy to tear chunks of wood out when cleaning it up, i.e. clean as much off with a sharp chisel as possible when rubbery.

John

 

[OPJ]

Excellent point on removing excess cascamite before it's cured - this stuff really does dry as hard and as sharp as glass; I even managed to cut myself on it a few weeks ago! :? Chisels are good but, if it's a good one, you'll need to clean it off later. I've started using the blunt ends of card scrapers, which you don't ever use anyway. :wink: Small, cheap rulers are good too.

 

[Boz62]

Thankyou for your responses. Sorry for the delay in reporting back, I have had a hiatus due to a dodgy back, but have now restarted the project, so here are the results of the lamination.

I ordered a 3.0m x 0.62m x 40mm hardwood beech worktop from Worktop Express. Thanks to mikepooley for pointing them out. It arrived when requested, and well packed:


It came with an "A side", clean, unmarked and finished to 150g, and a "B side" probably 80g ish and with a couple of light scrapes, both at one end. On unwrapping, it was cupped to a max of 0.5mm across it's width and as far as I could tell it was flat lengthways. The ends weren't cut quite square; the 3.0m sides were 1mm different in length.

First task was to cut the worktop into halves:


This resulted in two 26Kg lumps of worktop. I would recommend anyone else to now get on with gluing them together, straight away. I didn't . I was hoping the cupping would improve with time (sitting stickered in the end of the living room), but, of course, it got worse. By the time I got round to gluing it a week later, it was at 1.1mm max, with no sign of stopping moving. Of course, the cupping was such that the good A side would end up inside being glued :evil:. Luckily one half of the B side was clean and unmarked, so I refinished the new "outsides" with 180g Abranet (first time I've used this with the Camvac - wonderful ).

I'd decided to ignore the majority of advice above and use Titebond Extend PVA glue. The main reason was that Cascamite felt too far out of my comfort zone - mixing it was another new variable I could do without when I would already have my hands full with clamps. I was also a little worried at how much harder it would be cleaning up squeeze-out.

I did a dry run first to get my clamping sorted. I in effect "folded" the two halves onto each other book style, compared to their original orientations in the worktop. The 1.1mm cupping each side pulled together, and the centre "self clamped", leaving the good face 0.2mm max concave:


Timing came out as follows:
Spreading glue - pouring it out of the bottle and spreading with a wide spatula - 5min.
Moving the top onto the bottom and positioning clamps - 10min.
Tightening clamps progressively and dealing with the squeeze-out while also monitoring the flatness - 5 min.

So that was my 20 min assembly time all gone! In practice, the glue stopped oozing at about the 30min mark. I ended up using 2/3 of a 16floz bottle. Temperature was 16C and humidity 70%. Sadly I could only tighten the clamps enough to get it flat to 0.5mm concave. It was then left for 24 hours. I will say at this point that I think this size, two 26Kg halves, 1.5mx0.62m each, is about the most I would like to do single handed. Much more than this and glue spreading, moving into position and clamping would be better with two sets of hands.

After unclamping I immediately gave each face a first coat of finish, to minimize any more movement due to humidity:


After another 24 hour pause, I was delighted to find that the face had settled down to a concave top 0.3mm max depth across it's width and very slightly convex along it's length, 0.1mm max height . These measured by straight edge (two different ones checked against each other, < 0.05mm between them) and feeler gauge.

Here is a cleaned up edge shows a nice clean glue line:


Gratuitous shavings shot :


So far I'm very happy with how my large lump of timber has come together. It cost about the same as if I'd bought sawn beech, but has saved me the planing and flattening for which I am not equipped. The downside is those ugly joints on the edges, and that it looks like a kitchen worktop. Only time will tell how stable it will be in the long term, and if the PVA will creep with the stressed tops. All I've got to do now is get my act together and try to convert it into a workbench :wink:.

Boz

 

[Boz62]

And for completeness sake, here is the setup for squaring and flattening the ends. A variation of the planing method that LN and OPJ used on the faces of their workbenches:


The wood guides are scrap so I happily cut into them to stop tearout. I didn't use the dust extractor since it was all at shoulder height and I didn't want the drag of the hose. I hate using the router at the best of times :evil:. Took a while as I only had a 1/2" cutter, but gave an adequate finish and just needs some sandpaper now.

That completes the basic worktop prep. I'll do any workbench posts in a separate thread.

Boz

 

[StevieB]

Very nice! Not a bad price either looking at the website you got the worktop from. They also do a 4M length - was there any reason you only went for 3M? That has given me some food for thought as I am idly (still!) thinking of a workbench and you top looks a good design. How do you plan to fit a vice to it?

Steve.

 

[Boz62]

Thankyou! My workshop is quite small and 1.5m is as long as I can fit in, so a 3m length was ideal for me. Oh my, a 4m one will be heavy - 70Kg!

I won't be having an end vice, due to length issues again, but will dog-hole it and use a Veritas Wonder Dog. For the front vice I've got a 9" Quick Release to fit. I bought these last year before the prices went up 8). I'll be recessing the QR vice so the front of the back jaw ends up flush with the existing front edge of the slab. I want the jaws easily replaceable since I do tend to be hard on them . It will mean hacking out the front-left corner of the slab, but I think it will be worth the effort in the long run.

Boz

Edit: Just to note that the WIP for the bench which this slab went on to make is here.