How can I bond ABS (plastic) to NRL (rubber)?

[Nick WheelerParticipant @nickwheeler]

How about using a wider rubber strip that's attached further into the case, rather than along the edge? Then it won't be as susceptible to peeling off.

[Dave SParticipant @daves59043]

If the adhesive technical team don’t have a suggestion that is a good clue that you have the wrong materials (or design – but since the design is secret I’ll go with materials).

If you have to use ABS because you already made those parts then find a flexible alternative that you can stick.

Peel is a problem for glues. Most adhesive structures avoid it, or use mechanical fixings to prevent the peeling starting.

Assumkng you 3D printed in ABS the it’s only cost to get 3D prints in a more suitable plastic. Sometime you have to let go of the money already spent to actually make progress toward the end goal. (Easy for me to say, I have no financial or emotional investment in your thingy)

[John Smith 47Participant @johnsmith47]

Posted by Nicholas Wheeler 1 on 21/01/2022 19:04:22:

How about using a wider rubber strip that's attached further into the case, rather than along the edge? Then it won't be as susceptible to peeling off.

Sorry I don't quite understand your point.

The whole problem peeling is that rather than the whole area taking all of the forces – i.e. tension/compression/sheer etc forces – at the same time, depending on what is being done to the lid in any one moment, all of the tension is felt at the very each of where the soft material is bonded.

e.g. In my image, if a force was being applied vertically DOWN

The result would be that only a very thin strip of material – i.e. a strip that is nearest to the hinge – absorbs all over force.

This is ultimately because one material – the rubber in this case – is SO much more flexible that the rest of the structure. And exactly because of this flexibility of the soft rubber, it doesn't any significant difference how far away from the hinge the rubber extends.

Sorry hard to put into words, but I don't think I'm trying to say anything non-obvious.

@Dave – you just have to trust me when I say that it's too late to change the design. If you really want to know, the 3D parts were 3D printed at a best-in-class high resolution and then vac-formed into a strong, high quality ABS. It is specialist work that (obviously) I outsourced and it cost a LOT of money. Well into 4 figs. There is certainly no budget to re do it.
To get clear, this is primarily just a proof of principle prototype/model, and the ultimate product would almost certainly be completely re-designed by licensees, presumably using an over-moulded rubber design. The idea isn't to solve ALL of the manufacturing problems. At this point we need something that says "there is a hinge HERE… and it behaves roughly like THIS…"

For the real injection-moulded/over-moulded product there will be many and various workarounds, but for this prototype I just need… a good strong bond between the rubber and the ABS!

From everything I have heard, I am quite certain a very much better bond than we are currently getting is technically possible. But its a deeply technical subject and getting access to the correct experts has been proving tricky.

[SillyOldDufferModerator @sillyoldduffer]

Posted by John Smith 47 on 21/01/2022 18:58:57:

Posted by Dave S on 21/01/2022 08:22:37:

…

…

Sadly all of the glues were complete FAILS. i.e. None of them were able to resist even pretty weak peeling forces and they have basically failed to bond well enough.

…

If all else fails I could try superglue again, but it's it instantly screws up the NRL rubber's finish. And so small accidents would be irrecoverable….

Thing is Superglue is your best bet because it sticks ABS and NRL.

Objections seem to be personal as much as technical:

to be honest I've always rather hated CA, because:
– the fumes rather sting the eyes,
– it requires a good fit (i.e. not good at filling in any gaps) and
– it's such a nightmare to clean up any spillage – particularly if it gets on the your skin!

These can all be fixed with proper technique:

• fumes – improve ventilation and wear goggles
• fit & spillage – ensure there are no gaps or spillage by holding the parts securely in a folding jig. Or, accept hand-methods won't be perfect in a prototype. Note it's very common in engineering to hide messy details behind some sort of cosmetic facade. If you can't make it, fake it!

Peeling can be prevented by adding mechanical support such as staples.

Is this endeavour solving a prototype or a production problem? A prototype only needs to work well enough to prove the concept. And does a hinge really require this level of attention? Details are usually best left to the Production Engineer. He'll do them cheaper and better. Unlikely there's any need here for the Inventor to get lost in a maze of glues, materials, primers and solvents.

Dave

Edited By SillyOldDuffer on 21/01/2022 20:52:23

[John Smith 47Participant @johnsmith47]

I seem to have lost my previous reply.

Dave, you may well be right…

However suffice-it to say, no I am not going to use superglue/CA, not just yet at least. There are multiple reasons for this, not least of which is that I have to accept that too much skill is required! And TBH, my parts are too valuable for me to work on with such an unforgiving material. My product designer who is extremely experience with CA found it extremely difficult to get a strong, absolutely dead-flat bond when applying the stuff in our configuration.

So I am going to try various other more forgiving adhesives first… Some of which are now on order… and most of which also allow any small spillages to be wiped clean (e.g. using Isopropanol) without damaging the rubber surface, as well as allowing small amounts of repositioning to get the rubber into exactly the right places, and the judicious use of small rollers to help level out the adhesive and create a dead-flat top surface to the rubber. 

I am also waiting to hear back from the likes of 3M who were talking about better primers & adhesive delivery via transfer tapes.

> Is this endeavour solving a prototype or a production problem?
Both. Albeit primarily the former for sure, it is also de-risking some of the key production issues.

> Does a hinge really require this level of attention?
Yes. The ergonomic nuances are of central importance.

We are very nearly there with this prototype round. We just need what is primarily a proof of principle and broad feasibilities. You are of course correct that in many ways the exact materials that we model with don't matter in the slightest, but we need to prove roughly what could be done, with roughly what materials and for roughly what price. And for example the exact behaviour of the hinge is critical!

SILICONE RUBBER
If all else fails, I shall do some out-right fakery with hidden mechanical stuff (e.g. I have my eye on some ultra-fine nylon threads favoured by the best magicians!)… but first I am also going to experiment with silicone rubber instead of NRL, as some suppliers were adamant that some of the adhesives in question, being made from silicone rubbers, would bond "very much" more strongly to silicone rubber than to NRL.

My slight problem with going silicone is that I have been unable to find anyone who can supply black, silicone rubber that is 40° shore or less, that is also 0.8mm thick. I have some 1.0mm stuff from Silex…

https://silex.co.uk/shop/sheeting/solid-sheet/general-purpose-sheet-40-shore/

…but at 1.0mm thick it is a bit too rigid for us… and also sticks out too much, creating some unwanted ridges that one can definitely feel albeit not really see.

Can anyone recommend an suitable alternative supplier of rubber latex sheet?

J

 

Edited By John Smith 47 on 22/01/2022 01:51:12

[Michael GilliganParticipant @michaelgilligan61133]

John,

I don’t mean to pry; but feel obliged to ask a serious question :

Given that this new product appears to be intended for handling …

Are you sure that Latex is an appropriate material to use ?

Latex Allergy is unpleasant and can be life-threatening.

[ Hopefully you have already considered the risks, ]

MichaelG

[Ebenezer GoodParticipant @ebenezergood76202]

Have you tried CT1? It sticks just about anything to anything!

I've forgotten how to upload photos on here but a Google search will soon find it, it says it sticks ABS in the blurb…

[AdrianRParticipant @adrianr18614]

Depending on your materials you may be able to use UV setting glue.

Have you looked at hot melt adhesive film? Maybe there is one that will bond ABS and Rubber.

Maybe it would be worth designing a jig for assembly so you don't need the assembly time.

Perhaps if the front side of the hinge joint rubber was pressed tightly to the ABS with a knife-edge, it would create a seal. Then the CA could be applied from the rear.

[HowiParticipant @howi]

Why are we trying to solve someones commercial product problems.

Having spent a lot (?) of money so far, why go cheap skate now, talk to adhesive manufacturers and get the right product for the job.

Don't you just hate it when someone comes on here for advice, only to Poo Poo (Black adder 4) every idea thrown at them.

This post is not the only one recently.

[Gordon TarlingParticipant @gordontarling37126]

Give this a try – if it doesn't work, I don't know what will!

G.

[noel shelleyParticipant @noelshelley55608]

CT 1 ! It comes in many colours ! Noel.

[John Doe 2Participant @johndoe2]

Aha ! With his photo of the hinge on this thread, we now know why John 47 is asking on another thread how to make those very thin metal strips with an angle on one edge ! One can be seen here as part of a hinge seating mechanism or somesuch.

Edited By John Doe 2 on 23/01/2022 15:08:39

[John Smith 47Participant @johnsmith47]

Posted by Michael Gilligan on 22/01/2022 07:19:48:

John,

I don’t mean to pry; but feel obliged to ask a serious question :

Given that this new product appears to be intended for handling …

Are you sure that Latex is an appropriate material to use ?

Latex Allergy is unpleasant and can be life-threatening.

[ Hopefully you have already considered the risks, ]

MichaelG

 

Fair question. No, it is emphatically NOT the material we would use for a product, because the life expectancy isn't long enough. This is purely for proof of principle.

For the real product the plan would probably be to use a silicone rubber. But ironically I was put off modelling with it because everyone said it was harder to glue!

Yes I have been talking to manufacturers of the leading brands of glue (see above)

@John Doe 2 – I wish I could tell you folks all about my designs but it would me a public disclosure and everything would not longer be patentable.

J

PS  'All Purpose Welder Contact Adhesive' ordered – thanks!

Edited By John Smith 47 on 23/01/2022 15:33:02

[John Smith 47Participant @johnsmith47]

Posted by noel shelley on 22/01/2022 11:24:59:

CT 1 ! It comes in many colours ! Noel.

Which type of CT1? There seem to be many completely different types of adhesive…

**LINK**

https://www.ct1.com/our-products/

[Robert ButlerParticipant @robertbutler92161]

Of relevance, there only appears to be Superfast in 20 or 50ml packs but I am happy to stand corrected!

Robert Butler

[Pete WhiteParticipant @petewhite15172]

Posted by Howi on 22/01/2022 09:57:44:

Why are we trying to solve someones commercial product problems.

Having spent a lot (?) of money so far, why go cheap skate now, talk to adhesive manufacturers and get the right product for the job.

Don't you just hate it when someone comes on here for advice, only to Poo Poo (Black adder 4) every idea thrown at them.

This post is not the only one recently.

I did wonder this myself, but I suppose its because everyone on here is always keen to help wherever they can.

I am not really sure about how I could recommend a bonding agent without knowledge of the intended use though?

Sorry about the joined quote and reply system is having a bad day, was getting a red outline on the reply page ?

Edited By Pete White on 24/01/2022 09:53:09

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Pete White on 24/01/2022 09:46:03:

Posted by Howi on 22/01/2022 09:57:44:

Why are we trying to solve someones commercial product problems.

Having spent a lot (?) of money so far, why go cheap skate now, talk to adhesive manufacturers and get the right product for the job.

Don't you just hate it when someone comes on here for advice, only to Poo Poo (Black adder 4) every idea thrown at them.

This post is not the only one recently.

I did wonder this myself, but I suppose its because everyone on here is always keen to help wherever they can.

I am not really sure about how I could recommend a bonding agent without knowledge of the intended use though?

.

I know these things happen, Pete … But it would be helpful to your readers if you could separate your ‘reply’ from the text that you are quoting.

As for whether the content of John’s posts is acceptable … Neil has already determined.

MichaeG.

.

Edit: I’ve just seen your edit, Pete 

Edited By Michael Gilligan on 24/01/2022 10:01:52

[Pete WhiteParticipant @petewhite15172]

It got worse when I tried to edit, never had it before but I could not get my my reply below the vertical lines??

There was a red boarder present, I did finally get my reply below the vertical lines but it still didn't work out. Don't know what was happening?

As we used to say "the boss is not always right, but he is always the boss", lol

Sorry for barging the thread .

[JasonBModerator @jasonb]

I do feel the moans about commercial content are more due to peoples attitude towards John and his attituted to others.

There is one other and possibly a second active thread that are commercial. In the case of the one I know for sure the poster often asks for assistance and not once have I seen complaints about it being related to their business. So do members have double standards and only complain when it suits them?

[Andrew StewardParticipant @andrewsteward85018]

Fascinating to read how knowledgeable you all are on adhesives! I'm the technical director of an adhesive company. Unfortunately not for adhesives along these lines.

Natural Rubber is very hard to bond. Typically done with cyanoacrylate (which is why everyone keeps suggesting it) and not a lot else.

I believe you are going to need a primer. If you coat the natural rubber with a thin layer of cyanoacrylate and let it dry your question then becomes how do I bond cyanoacrylate to ABS, then the answer is use a two part epoxy and clamp it hard (use the loctite plastic bonder). Use an ultra thin superglue and that should give you a really neat coating. if you can coat the rubber before cutting to shape you would get a great coating. you wouldn't need to apply much of the epoxy, thinner the layer of the adhesive the better, you just want good coverage.

Any tape (and we supply the adhesive on tapes) will creep fail over time, whilst the unika tape is very strong, there is no real weight (stress) being applied on a worktop edge.

If you are actually planning on these two pieces of ABS being bent back and forth then you need something that dries hard.

Sanding / scratching the surface of the rubber / ABS will help greatly.

Just a heads up that there is a lot of marketing going on with adhesives. For example superglue for metal, is the same thing just a different tube as superglue for plastic and the same trick is played for "epoxy resin for X". You sell more when you make it very clear what it can be used for. That said… there are different types of epoxies, the curing system used can make a difference (this is clearly stated on the tube).

[John Smith 47Participant @johnsmith47]

Thank you for your input Andrew

With CA as a primer, even the smallest amount of the stuff seems to cause severe curling of a soft NLR, but I shall experiment further.

> Any tape (and we supply the adhesive on tapes) will creep fail over time
Do you mean "double-sided adhesive tape" or "transfer tape"… or both?

Truth to tell, I have literally just thrown the loctite plastic bonder out because even when properly mixed and fully set, it was so soft. It wasn't even fingernail proof!

My testing is now leaning towards using silicone rubber rather then NRL, because I am now being told that I should be able to get a "much" more decent bond to silicone than with NRL, if using a silicone based adhesive (+primer).

J

PS. By way of trying to not ignore anyone, re the moaning about anyone "commercial" being allowed to participate in this forum, to recap, it is NOT against the rules of this forum for commercial organisations to participate. What is not allowed if for them to promote their own products.

Edited By John Smith 47 on 24/01/2022 13:18:00

[Robert ButlerParticipant @robertbutler92161]

Posted by JasonB on 24/01/2022 10:36:09:

I do feel the moans about commercial content are more due to peoples attitude towards John and his attituted to others.

There is one other and possibly a second active thread that are commercial. In the case of the one I know for sure the poster often asks for assistance and not once have I seen complaints about it being related to their business. So do members have double standards and only complain when it suits them?

Jason, I think it has more to do with the nature of the question and following helpful advice the abrasive responses from the OP. The start point is always high precision but with limited machinery and budget the OP resorts to basic hand tools and methods suggested by forum members and poo-pooed earlier by the OP. He then wishes to measure a hand filed radius with precision, what is being measured and where on the component? To produce consistently accurate radii by hand is a skill few if any posses.

One thing which is clear is that if the OP had purchased the Unimat 3 with all the accessories for sale at reasonable cost and suggested by members of the forum and myself then a lot of the tasks laboriously undertaken could be completed with far greater accuracy and speed. The precision element stressed as of critical importance when originally posted.

I also feel the OP try's to stifle criticism by suggesting members use the ignore button, I have been tempted but find the posts very amusing.

The for profit element is of no concern to me.

Robert Butler

.

Edited By Robert Butler on 24/01/2022 23:03:07

Edited By Robert Butler on 24/01/2022 23:03:31

[John Smith 47Participant @johnsmith47]

Tempting though it always is to descend into a war of words, I have shall ignore the all personal attack. I have learned to develop a thick skin, when people are being unreasonable… and fighting back with similar personal criticisms & comparable attacks back ever EVER helps.

But please try get your facts correct…

> He then wishes to measure a hand filed radius with precision,
Wrong. I have never wanted to measure with precision the radiuses that I have only hand filed. This is factually incorrect. What I have been measuring is the consistency of radiuses/radii on edges may or may not have involve a hand-file to do the grunt-work, but that have always then been either finished either with a deburring wheel or made with a precision diamond hone (possibly using with a modified honing guide), or both.

But nope, never just with a hand file.

Whilst we're here Robert, although:
a) my workspace is exceedingly tight and
b) although I had no immediate requirement for a lathe of any size and
c) although I also have basically no idea how to use a lathe and
d) although I don't really have the time to spend learning how to use one and
e) although it has a circular pillar (which is not ideal) and
d) although the Unimat 3 being an exceedingly old, and second hand product, so being a novice I would be extremely likely to buy a dud with shot bearings or some such problem…
…and probably not even know!
…However the point here, is that I have – many months ago in fact – already thanked you for the suggestion and have also – many months ago – eaten the humble pie of conceding that I should have bought that darned thing!

That said, the Unimat 3 would not help me ABS plastic to NRL rubber, so I'm technically we committing the crime of being in the incorrect thread.

Hey-ho.

But I am gratified to hear you are enjoying these threads… Me too

And I have learned a LOT about tools. And I am deeply grateful for that. Sadly my technical knowledge is so limited (or so I keep being told!), and the expertise around here is so high (mostly!) that there isn't much I can offer in the way of knowledge back.

J

PS At some point I may just use a new email address and start again. And hopefully people will go back to answering the questions I pose, let me make my own mistakes and stop trying to join do join dots about what my various private/IP protected projects involve.

[John Smith 47Participant @johnsmith47]

Back to this thread's question…

UPDATE

I have been doing quite a lot of testing of materials. I now have found a less watery and slightly less aggressive type of CA/Superglue called Powerflex made by Loctite, which goes no more like a gel which would definitely help reduce spillage…

Unfortunately, although the bond to rubber latex (NRL) is good/sometimes excellent – even a thin layer of the Powerflex causes swelling/warping of the latex, which then unavoidably seem to cause lumps & bumps in the outer surface of the RNL. See upper half of this photo:

In the lower half of the photo is my only real success so far, which is Elastosil E41 + NP2 primer, which combine to product a REMARKABLY good bond onto 1mm thick Silicone Rubber. In fact you may not really need to primer.

And crucially it forms it's bond in a very 'civilised' manner giving you time to wipe off excess (using IPA) and has a reasonable repositioning time – which can seriously help when model making.

Adhesive/glue FAILS include:
– Repair Extreme
– Dowsil 732
– Loctite Plastic Bonder
– BSI Epoxy 15min
– Collall All-purpose
– Zap Z-poxy
– B7000
– E6000
– Professional Welder
… } all of which TOTALLY failed the fingernail test (not even close!) when bonding each of NRL rubber and Silicone Rubber. That said, some of the glues claim to keep getting stronger for 48 hours so I may be being slightly premature…

Interestingly, almost all of them bond wonderfully well to my ABS plastic despite it's high-gloss finish. Ironically the one notable failure was Plastic Bonder!

I am delighted with Elastosil E41. My sight problem is that an extremely despite a soft shore hardness (of 40&deg my silicone rubber is nothing like as elastic a natural rubber latex. Latex can be stretched to a length of about x2, whereas the latex can easily do x3.

J

[Michael GilliganParticipant @michaelgilligan61133]

You might want to check that closing line, John … and correct it accordingly.

” Latex can be stretched to a length of about x2, whereas the latex can easily do x3. ”

MichaelG.

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