What adhesive – that shrinks when it sets – do you recommend for melamine laminate sheets?

[Robert ButlerParticipant @robertbutler92161]

Posted by Hopper on 01/04/2022 22:23:22:

Posted by Donald MacDonald 1 on 01/04/2022 15:20:49:Hopper – And no, as I have already said, I will not JUST be using it under a cutting mat. Please stop over-thinking your answer and just attempt to answer the question. If you have nothing of value to add please then please don't!

Perhaps you should try stating your problem clearly in the first place instead of — once again — drip feeding often contradictory information as members spend their time coming up with solutions for your partially described problems that never seem to be up to your exacting standards

You can't hope to do precision — certainly not to the standard you aspire to — work on a folding table. A length of 4" x 2" timber wall studding cut up and screwed together will make a stout table frame an four legs for your MDF boards and cost about the same as one or maybe two cups of skinny soy latte coffee. Could be made with hinged legs for folding up. Or hinged off the wall with two outrigger legs. A bit of lateral thinking should solve most of your problems.

And being rude to those spending their time trying to help you is probably not the way forward, either on the forum or in life.

Hopper, Hear! Hear! well said!

Robert Butler

[Grindstone CowboyParticipant @grindstonecowboy]

+1 for ^^^^^

Rob

[CirclipParticipant @circlip]

C'mon guys, don't you like to rise to a challenge? Took more than 20 replies to find out the thickness (sic) of the material we were trying to bond. Dentistry springs to mind.

Regards Ian.

[Donald MacDonald 1Participant @donaldmacdonald1]

To be fair my original question was simply:
"What adhesive that shrinks as it sets would you recommend to bond two large sheets of melamine covered boards (AKA laminate) together?"

There was me thinking that this would be nice simple question!

Well it turns out that I nobody is aware of any shrinking glues for melamine… other than wood glue, which I think we can agree  would probably never set.  Ok fine, I'll just have to abandon the shrinking requirement. 

But mysteriously I find myself sucked into a detailed analysis of my workshop… my project, why do I need such precision, why can't I use screws not glues, is really melamine, why melamine, my approach, my lifestyle, and if I ignore anyone's suggestion then offense is taken.

Any then it's why didn't you tell us about: your workshop, your project, your need for precision, why you don't want screws, whether it really is melamine, why you want melamine, what kind of table you have, why you bought that particular table, why you live where you do… etc etc at the start?

I mean I'm grateful for all the suggestions… but where will this process stop? Will it be the name of my cat and my inside leg measurements next?

Don

 

Edited By Donald MacDonald 1 on 03/04/2022 13:01:21

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Donald MacDonald 1 on 31/03/2022 00:10:40:

Yes I am bonding 2 large 100cm x 100cm sheets of Melamine Faced MDF. I am wanting to create a rigid work surface that is as flat as possible. Most of the time it will be used on a table but under a cutting mats.

[…]

Any further recommendations?

J

.

As you haven't acknowledged my previous post, I will try again:

Use the thinnest sheets of Melamine Faced MDF that you can get, and use them to sandwich a suitable core material.

Do some Google-based research and you may get to understand why this is a good idea.

MichaelG.

[Donald MacDonald 1Participant @donaldmacdonald1]

Posted by Michael Gilligan on 03/04/2022 12:50:01:

Posted by Donald MacDonald 1 on 31/03/2022 00:10:40:

Yes I am bonding 2 large 100cm x 100cm sheets of Melamine Faced MDF. I am wanting to create a rigid work surface that is as flat as possible. Most of the time it will be used on a table but under a cutting mats.

[…]

Any further recommendations?

J

.

As you haven't acknowledged my previous post, I will try again:

Use the thinnest sheets of Melamine Faced MDF that you can get, and use them to sandwich a suitable core material.

Do some Google-based research and you may get to understand why this is a good idea.

MichaelG.

Apologies, Michael. Yes, that sounds like a good idea. Maybe a layer of plywood or MDF that would absorb the solvent/water and thereby form a bond.

In fact maybe I could use shrinking wood glue after all

Given how large & heavy the MDF melamine sheets are (which like I say, are 18mm thick and which I have already bought, btw), who thick do you think the MDF/plywood sandwiching layer would have to be at a minimum as it is already fairly heavy….

Don

Edited By Donald MacDonald 1 on 03/04/2022 13:08:33

[SillyOldDufferModerator @sillyoldduffer]

Posted by Donald MacDonald 1 on 03/04/2022 12:27:31:

…

There was me thinking that this would be nice simple question!

But mysteriously I find myself sucked into a detailed analysis of my workshop… my project, why do I need such precision, why can't I use screws not glues, is really melamine, why melamine, my approach, my lifestyle, and if I ignore anyone's suggestion then offense is taken.

…

 

Not mysterious at all! Have a think about how your 'nice simple' question is interpreted by an experienced engineer.

"What adhesive that shrinks as it sets would you recommend to bond two large sheets of melamine covered boards (AKA laminate) together?"

The question screams 'wrong approach' for practical and theoretical reasons. Unusual for anyone to want to glue melamine laminate boards together, and unusual in this context to need a glue that shrinks as it sets. Although there might be a legitimate reason, it's unlikely. The question starts off key and a strong suspicion important detail is missing.

And so it proves. Later, we're told 'I am wanting to create a rigid work surface that is as flat as possible.' which can't be achieved by gluing two sheets of Melamine together, whether the glue shrinks or not. The underlying way it's imagined the solution will solve the 'rigid work surface' requirement is badly flawed. (Michael's ribs are a much better bet, conventional engineering, and not difficult to make.)

Confusions and red-herrings are best avoided by starting with the Requirement, because it avoids getting deep into a design only to discover it's an expensive way of producing a bad solution. (Happens a lot in engineering!)

No-one cares about inside leg measurements and lifestyle, but it's important to members on the receiving end that questions communicate clearly what the questioner is trying to achieve, ideally without hidden pre-conceptions and definitely not with important details sprung as surprises later.

Don't be disheartened – design is the hardest part of engineering. We're only trying to help, and questioners tuning into what answerers need to know makes it much easier to do a good job.

Dave

 

Edited By SillyOldDuffer on 03/04/2022 14:01:42

[BazParticipant @baz89810]

Don what is wrong with telling us a bit about what you are doing, if you really don’t want to tell us anything about what you are doing maybe you shouldn’t ask for our help, after all is what you are doing such a secret, anyone would think you are doing work that you intend patenting.

[pgk pgkParticipant @pgkpgk17461]

As an off-topic;ish thought does the glue really matter? If one placed the two boards together with any gap-filler (say water) and applied an air-tight edging then air pressure/vacuum would hold those boards together? Indeed, the thinnest layer of any thin bonding agent that can occupy any gaps would be the best?
I'm minded of the time I built some fitted wardrobes into an old house with lathe and horsehair plaster walls with a tendency to crumble. I glued a 12 foot length of 1/2 in baton to the wall with PVA and held with a few of pins until it set and was able to suspend my 110kg by the fingertips from it just by the sheer area.

pgk

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Donald MacDonald 1 on 03/04/2022 13:08:20:

Given how large & heavy the MDF melamine sheets are (which like I say, are 18mm thick and which I have already bought, btw), who thick do you think the MDF/plywood sandwiching layer would have to be at a minimum as it is already fairly heavy….

Don

Edited By Donald MacDonald 1 on 03/04/2022 13:08:33

.

Please read my earlier post more carefully

I suggested using foam or honeycomb as the filling for the sandwich … Originally they used endgrain Balsa Wood … it only needs to be stiff in compression.

MichaelG.

[MichaelRParticipant @michaelr]

Forget about the glue, why not use magnets to hold the two sheets together you can get Neodymium magnets in all shapes and sizes suitable for recessing into the joint face of your boards and give a firm joint.

MichaelR

[JasonBModerator @jasonb]

Ah but what glue to stick the magnets in place

Couple of pictures to come of a destructive test, need a mug of tea first

[MichaelRParticipant @michaelr]

Ha Ha Jason that's the the Question, maybe a bit of double sided adhesive tape or?

Michaelr

[JasonBModerator @jasonb]

As I mentioned the other day a Cyano glue would be up to the job. Easy to run a series of straight beads, a little positioning time, no need for one surface to be porous.I use it quite a bit to stick trims to MFMDF and the odd bit of MFMDF to itself.

So yesterday while the CNC was doing its thing I ripped a couple of 50mm wide strips from an offcut of 18mm MFMDF, ran two beads of mitre adhesive about 300mm long and pushed the two bits together, did not bother to clamp or spray any activator on one surface..

Today I stuck one end in the bench vice and pulled the other, MDF just snapped. Then took a chisel to the joint and did get it apart. Looking at it the melamine film has been ripped off of one board, wider where I pushed the joint together in the middle and just bead width at the ends. I'd say its fit for the job in hand.

[Ramon WilsonParticipant @ramonwilson3]

Posted by Donald MacDonald 1 on 03/04/2022 12:27:31:

To be fair my original question was simply:
"What adhesive that shrinks as it sets would you recommend to bond two large sheets of melamine covered boards (AKA laminate) together?"

There was me thinking that this would be nice simple question!

Well it turns out that I nobody is aware of any shrinking glues for melamine… other than wood glue, which I think we can agree would probably never set. Ok fine, I'll just have to abandon the shrinking requirement.

But mysteriously I find myself sucked into a detailed analysis of my workshop… my project, why do I need such precision, why can't I use screws not glues, is really melamine, why melamine, my approach, my lifestyle, and if I ignore anyone's suggestion then offense is taken.

Any then it's why didn't you tell us about: your workshop, your project, your need for precision, why you don't want screws, whether it really is melamine, why you want melamine, what kind of table you have, why you bought that particular table, why you live where you do… etc etc at the start?

I mean I'm grateful for all the suggestions… but where will this process stop? Will it be the name of my cat and my inside leg measurements next?

Don

Edited By Donald MacDonald 1 on 03/04/2022 13:01:21

If we take the potential need of personal details out of the question I think it fair to say you've now had your money's worth

You asked – To be fair my original question was simply:
"What adhesive that shrinks as it sets would you recommend to bond two large sheets of melamine covered boards (AKA laminate) together?"

And many of us have taken time to provide opinions to that question – most no doubt based on personal experiences – and none of which appears to have given you the answer you seek.

Something tells me that you have not stopped to even consider that possibility so may I offer you one last piece of help.

Listen to all – decide what suits you best – and go and do it. The choice you make is yours alone – if it works it's fine you can congratulate yourself but if it doesn't you can't blame anyone.

Personally speaking I really can't help thinking about Horses and Water

Tug

[Mike PooleParticipant @mikepoole82104]

I spent my working life solving problems on control systems. Gathering information on the precise nature of the fault was an essential start to the process. The more information that is gathered the clearer the problem becomes and the solution will emerge. Once the nature of the problem is identified then testing to eliminate possible causes can take place. I was fortunate that people would feel they could tell me that if they had cocked something up it would stay between us and we could then put it right. Too much information is more useful than too little but your cats name and your inside leg are probably not relevant to this problem. You haves posed some questions that have some very difficult to meet parameters and in real life people accept that an ideal solution may not exist and a work around process may be the best possible outcome. I spent some time on your ruler problem as did a number of others and the result was that not all your requirements could be met but a variety of work arounds were proposed.

Mike

[Donald MacDonald 1Participant @donaldmacdonald1]

To get clear, I'm sorry if offends anyone that I still have not actually done the bonding, but my 2 sheets are deply buried under projects.

MichaelG – Noted. My main problem is that I would need to go and buy some A0 material and get it cut to size. It would also add unwanted weight onto 2 already slightly heavy boards. I'm assumging honeybomb wont offer enough tentile strength to resist any pre-existing warping. What do you think is the thinnest material (e.g. MDF/plywood) that I could get away with that would absorb enough moisture to allow a wood glue to set?

MichaelR – Magnets won't bond over nice large surface area (to help flatting any warping), will require the melamine to be drilled into. Ultimate flatness is the primary goal here not ease of shifting the A0 MDF sheets.

MichaelR – No, the problem with adhesive tape is that never sets. Over time, any bowing of the material would re-establish itself. Ultimately, I just want to bond melamine to melamine.

So back to my question ideally I really I just want a glue that sets to bond Melamine to melamine.

It would be nice if the glue shrank at least slightly as this would help pull the 2 surfaces together. (In fact best of all would be if the glue shrank to zero thickness and just bondind the two sides together!). But I am happy to drop the shrinking requirement if necessary.

Jason – Much though I hate CA, I concede that CA may well be the best way forward. It would certainly save me the bother of finding and cutting third sheet to fit between other two, that would be required for say wood glue.
Good to see you got a good bond. And hopefully one could still get a good bond right in the middle of a square metre or so (?)

How importantd do you think using thin strips are? And how far apart do you think that they should be?

Thin strips will of course let help let the air out, help get an extremely thin layer of glue… plus in theory even let the additional moisture in the air diffuse back in (eventually).

That said, the problem with strips is that the melamine is such a thin/fragile layer it will need all the help that it can get to fight any bowing after the clamps have been removed. But I think if one ended up with strips of glue over c. 50% of the bonding surface area, that would be fine.

In your model I see that for much of the areas in question you seem to have acheived nice wide bonding strips… but that ends the bonding strips are very narrow. [And FWIW, this is exactly that sort of problem I personally always seem to get with CA!]

Nonetheless, CA may well be the way forwards. But I'll have a think. My boards won't be free to be bonded for at least another week in ay case.

I'm also still tempted by mixing up a load of Epoxy resin – at least I could guarantee it will set! On the down side even though it's so viscous that it would difficult to get it properly thin. So I guess that I would definitely still use strips though to let the air out and minimise the distance the the viscous glue would need to flow to… in order to overcome accidental lumps & bump in the application of the adhesive.

As well as applying the adhesive in strips, I would of also use a serated glue applicator to help apply the adhesive evenly, as well as to create micro-escape channels for the air to escape locally.

Don

[JasonBModerator @jasonb]

As I said applying the adhesive in long beads(strips) allows any air to escape which may prevent the boards being pressed together if it gets trapped. It is also quite easy to apply an even thickness bead each time, not so easy to spread a thick epoxy or contact adhesives. There is no need to use any form of spreader with the cyano as it is liquid enough to spread under clamping pressure.

I did not clamp the test pieces just gave the middle a push together and left it at that. I would suggest if your boards do have any bow in them you put them convex face to convex face. That way the middle will press itself together when you clamp around the edges. I doubt you have a press so have no way of clamping the middle if you have them concave to concave.

Remember that I also said edges will need to be sealed as that is where moisture will get into the MDF and make it swell.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Donald MacDonald 1 on 04/04/2022 12:52:46:

[…]

MichaelG – Noted. My main problem is that I would need to go and buy some A0 material and get it cut to size. It would also add unwanted weight onto 2 already slightly heavy boards. I'm assumging honeybomb wont offer enough tentile strength to resist any pre-existing warping.

.

Just forget I mentioned it, Don

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Michael Gilligan on 04/04/2022 13:09:55:

Posted by Donald MacDonald 1 on 04/04/2022 12:52:46:

[…]

…

Just forget I mentioned it, Don

MichaelG.

Feels as if Don has fixated on a particular answer and is unable to tune into other ideas! His reasons for rejecting Michael's suggestion show it hasn't been understood, sigh. However, I'll have one last go.

First, a single sheet of anything is bendy. (Try waving a sheet of paper)

Second, doubling the thickness of a sheet by gluing two together is still bendy, despite being twice as heavy:

A much better approach is to increase the effective thickness of the sheet by fitting deep ribs:

It's the increase in depth highlighted in dayglo green that makes the difference. Ribs, or even better a honeycomb, are lighter and stiffer than Don's two boards, use less glue, and there's nothing difficult about the construction.

My images shows nine open longitudinal ribs, which might be overkill, and stiffen end-to-end but not sideways. Michael's honeycomb fixes this, or alternatively a second sheet could be fixed underneath. If the top sheet only is loaded, then the lower sheet can be much lighter than the top – 3mm hardboard would do.

Dave

[JasonBModerator @jasonb]

Well there are difficulties for Don to construct that. He will need to be able to cut parallel strips of for the ribs, he will need to face the outer surfaces and he will need a flat surface to make it on.

Michael's Light weight solid core would be a bit easier but would quite likely need a 8×4 sheet of PU foam or other core material, having to buy two pieces of facing material and not make use of the two sheets of 18mm that he already has. Still needs a flat surface to build it up on and finding a suitable glue. Or you could just go out and buy Egger's Eurolite which has the cardboard honeycomb much like a cheap flat panel door but with Melamine faces but its a big sheet

[Sam Longley 1Participant @samlongley1]

I would just use Trespa & get on with life. There are a host of varieties & thicknesses. I have a fair quantity of 12mm Th & use it for all manner of things, including worktop for a couple of mobile benches. Main use is for jig making & small plastic parts.Also have made bits for club members yachts out of it.

[not done it yetParticipant @notdoneityet]

Posted by Sam Longley 1 on 04/04/2022 17:00:21:

I would just use Trespa & get on with life. There are a host of varieties & thicknesses. I have a fair quantity of 12mm Th & use it for all manner of things, including worktop for a couple of mobile benches. Main use is for jig making & small plastic parts.Also have made bits for club members yachts out of it.

I have come to my conclusion – in that he has two pieces of unsuitable material and is going (or determined) to try to make something useful from them. It may yet cost more than purchasing something more appropriate, that would easily suffice for the duty required. Four pages of wasted effort from members, later, and he will likely attempt what he thought of in the first place – that of using glue that he already has in dtovk.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 04/04/2022 16:00:40:

[…]

Feels as if Don has fixated on a particular answer and is unable to tune into other ideas! His reasons for rejecting Michael's suggestion show it hasn't been understood, sigh. However, I'll have one last go.

[…]

It's the increase in depth highlighted in dayglo green that makes the difference. Ribs, or even better a honeycomb, are lighter and stiffer than Don's two boards […]

.

Nice try, Dave … thanks for the moral support

Just to be clear : The accepted ‘optimum’ is to use a comparatively thin skin on each side of honeycomb, suitable foam, or whatever.

Interior doors, IKEA’s occasional tables, caravans, Aircraft floors, etc. etc. all use “sandwich panels”

The most substantial one we built was a 4 foot square header plate for a shaker … 1” Aluminium alloy plates with four layers of Ciba Geigy ‘F board’ between them, all bonded with Araldite 2002

… Those were the days !!

MichaelG.

.

Edit. __ These products are similar to ‘F Board’ and ‘M Board’

https://www.collinsaerospace.com/what-we-do/Business-Aviation/Cabin/Structures/Honeycomb-Panels/Aerobase

and here is IKEA’s bargain : 

https://www.ikea.com/gb/en/p/lack-side-table-white-30449908/

Edited By Michael Gilligan on 04/04/2022 17:50:43

[SillyOldDufferModerator @sillyoldduffer]

Posted by JasonB on 04/04/2022 16:35:19:

Well there are difficulties for Don to construct that. He will need to be able to cut parallel strips of for the ribs, he will need to face the outer surfaces and he will need a flat surface to make it on.

…

Hope not, I would make the ribs out of DIY Store Smooth Planed Pine, like wot B&Q sell. This stuff is 18x44mm deep, other sizes available.

Assembly, lay sheet flat on floor and glue thin edge of rib to it. Dowels from rib into the sheet would reduce the strain on the glue. Or instead of dowels: screws, or those rotate in hole cam wotsits that clamp onto a screw-in spigot. as found on self-assembly furniture:

I'd probably just glue the ribs unless the table had to take more than average table weight.

Glued, staple or pin the lower sheet of hardboard, if it's thought worth the bother.

I hope Don has room to lay his sheets flat somewhere, because gluing them without taking on a warp whilst they're leant on a wall or straddling a horse will be difficult.

Dave

Edited By SillyOldDuffer on 04/04/2022 18:33:55

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