ABS Plastics Repair?

Not an urgent requirement- ie I don't have a current repair to do but it it is something that comes up from time to time.
To be blunt, I've never found a sure fire way to glue/repair ABS. In particular, the kind of thing you find in car interiors when you get a crack etc. or the fixing 'lugs' break off. I've tried various things, some have worked to an extent but I've never found one I'm confident will 'always' work.
I've tried: 'welding' with an old soldering iron, acetone, various adhesives, epoxy, super glue, Gorilla Glue, no more nails.
JB Weld seems to be the better of the epoxies I've tried. No More Nails worked rather well fixing some 'lugs' where I could form some 'webs' and get a good bonding area.
'Welding' (with and without a filler, some scrap plastic) is very hit and miss. It is hopeless if you can't hide it and getting a good, deep, weld isn't easy.
I've seen references to using ABS slurry- ABS dissolved in acetone in varying concentrations (thin and running to a paste) but I've not tried it yet.
The type of things I'm most likely to want to repair are: electronic item cases- the 'posts' where thread inserts go etc, cases for same, may be car interior parts etc., general domestic items.
So, what do others use- assuming they've found something that works!
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On 26/02/2018 11:45, Brian Reay wrote:

If it isn't load bearing, is small opaque and you just want a cosmetic repair then the stuff sold as Sugru will do as a filler and sticks fine. Worth waiting until it is on an Amazon cut price deal though.

Epoxy has worked for me on some load bearing repairs (and clear epoxy on light clusters with a bit of organic solvent based dye added).

Nigh on impossible.

Tends to initiate stress corrosion cracking and looks a mess where the solvent attacks the outer surface. Polystyrene model kit cement will sometimes do a good enough job if it isn't too critical. You can get problems with the plastic softening and marking if it was clear.
The trick is letting the glue part dry and soften the two edges before squeezing them together. If you get lucky it binds together fairly well.
Methylene chloride based acrylic solvent glues do not work well on ABS.

Mostly slow cure epoxy unless I think something else would do well enough.
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On 26/02/18 12:00, Martin Brown wrote:

I've heard of Sugru but never tried it. I've used various two part 'putties' but not for this type of thing.

Hmm, interesting. I've never tried to repair a light cluster.
However, the dye idea could be used elsewhere. So, what kind of dye do you recommend?

That is my experience. At best it is good to 'tack' things for holding while other methods 'set' etc.

Slow cure expoxies always seem to give better results in my experience. The problem is, there seem to go through a 'softening' phase after application (I assume due to the reaction) so the joint needs to be clamped / held. Then leave be for a good 24 hrs.
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On 26/02/2018 12:16, Brian Reay wrote:

I got a mixed pack to make an Amazon order up to free delivery when it was on a cut price deal. I wasn't expecting much but I was pleasantly surprised that it aced the first job I used it on - damaged doorseals.
I have since used it to mend such unlikely things as a rubberised case for screwdriver bits that a mouse nibbled the corners off.

I have access to real dyes, but the stuff sold for decorative glass painting should be OK if you allow the solvent to evaporate. Check a small batch behaves. If you were unlucky there might be a side reaction that messes up the glue curing. Carbon black and TiO2 white pigments are also handy for making epoxy repairs nearly invisible. Otherwise the clear/straw colour in a crack stands out as a dark line on pottery.
You can find such dyes on eBay but I hesitate to specify names since some are carcinogenic and all of them are capable of making an enormous mess if mishandled even slightly. Imagine biro ink as a fine dust.
There are better glue formulations for pottery repairs that are white.

It goes through a phase of running like water before it thickens again - good because it gives any air bubbles a way to escape. You have to clamp it rigid for at least 6 hours and preferably 24. The thinnest layer that wets out completely makes for the strongest joint. Magic stuff epoxy.
I find 5 minute epoxy a PITA to work with - it goes off too quickly, end up full of air as a result and is nothing like as strong.
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Not a lot works as you say, since the posts for screws need a good bit of resistance to forces and normally the holes either go too big or the post splits. Even when a brass insert is in there, like on some shaver cutter assemblies the plastic splits as if its just far too brittle. Epoxy seems the only fix and it looks awful if its not hidden inside something. Brian
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On 26/02/18 12:05, Brian Gaff wrote:

Certainly any repair needs to be handled with care but, sometimes, the equipment just won't hold together unless something it done.
I've filled and redrilled screw holes which don't have inserts with some success.
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On 26/02/18 12:20, Brian Reay wrote:

I've had some success with car body filler/polyester resins.
It's a lot easier to use than epoxy and though it doesn't bond 100%, if the surface is rough enough it grips quite well
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On 26/02/2018 15:54, The Natural Philosopher wrote:

Horses for courses, car body filler is brilliant for some jobs (and much cheaper) but epoxy is usually my first port of call for small repairs because of more reliable grip. Often useful to improve the "flow" by warming it slightly (flow is sometimes a disadvantage, in that case build a temporary plasticine dam). If the repair is "exposed" then CBF may be better because it is easy to shape after curing, but provided nothing is missing, epoxy can usually be used to repair cracked plastic by gluing the "crack" and adding a strengthening fillet on the concealed back side.
Epoxy can be made to behave a bit more like CBF by adding inert filler. Also, JB Weld (or other metal filled types) are very strong.
OTOH CBF is brilliant for repairing cracked or badly scratched wood, or regions lost to rot after curing the root problem.
Both are essentials in the workshop IMHO. Also, I'm using the glue gun (another favourite of TNP) a bit more since Lidl had a big, cheap pack of sticks of EVA.
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On 28/02/18 22:18, newshound wrote:

Ought to do a wiki entry on adhesives.
Its a huge subject and one I have a lot of experience in from building model planes.
I will make just one point here and now. Epoxy is almost useles in the form it is sold and in the way it is used by the majority of DIYers. Exp[oxy putties and mortars work, but te alraldidte tyoe of thng should never have nbeen sold.
To make epoxy really work as it should you need 100% accurate mixing of exact quantites, heat and clamping. No one avheives this. I get OK results with accurate mixig and heat..but even then the boind strength to wood is less than e.g. PVA because it doesn't soak in - it just tears the top off the wood.
However stoving 5 minute epoxy in a hot oven is the bees knees for invisible china and pottery repairs. The epoxy goes transparent and is virtually invisible
If you don't stove, it falls apart in hot water. amd the epoxy looks like solidified snot.
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On Thu, 1 Mar 2018 08:38:04 +0000, The Natural Philosopher

Great. That will be extensive then (not).

What a load of BS.

You obviously didn't use the right glue on your keyboard keys!

Nope.

Nope (although not being 'cold' helps speed up the curing process).

And no.

Because no one needs to.

So Epoxy would be 'unsuitable' for that application then, nothing to do with if providing a weak bond.

Or just mixing it as instructed and putting the parts together. How strong does a glued repair on china or pottery need to be FFS!

No, 'some epoxy's' are transparent and remain so when cured.

So again, it can be down to the suitability of the application, rather than the epoxy itself.
Cheers, T i m
p.s. I crashed my high wing RC trainer aircraft (it didn't want to do an inverted loop and the wings folded up) and the fuselage hit the deck like a bomb, pushing the engine and bulkhead back up the fuselage.
One pack of 5 min epoxy, some splints and tape ... 10 mins it was flying again and continued to do so till I gave it away.
I can cite probably hundreds of other examples where I have used all sorts of epoxy's to great success and without jumping though any extra hoops.
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On 01/03/2018 10:26, T i m wrote:

People mix them incorrectly.
If the two parts are transparent then they should be transparent when mixed. What people do is energetically mix the two products resulting in the mix turning milky with too much trapped air. This is not ideal for bonding, especially with the fast 5 minute epoxies - you are effectively bonding with an epoxy foam.
Heating the mix can make it more runny releasing most of the trapped air but its probably better not to trap the air in the mix in the first place.
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On Thursday, 1 March 2018 08:38:08 UTC, The Natural Philosopher wrote:

h

d

that could go in the wiki if you're happy with that. And it can be edited f rom there.
NT
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On 26/02/2018 11:45, Brian Reay wrote:

I've never had any lasting success attempting to 'glue' two broken pieces together without using an additional piece of a similar material as a patch or support structure.

One method that I've tried, and has worked, is to take the patch material and soak it in acetone so the surface of the patch becomes a slurry and the patch becomes more flexible. Apply this and mold it into place - and then leave for at least 12 hours to fully harden.

The method above is only suitable for an semi invisible repair if you can get behind a crack or break.
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On 26/02/2018 11:45, Brian Reay wrote:

Maybe doesn't help with the decorative aspect, but have you tried "friction welding" abs? There are some YouTube videos about it which show varying levels of success.
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Trouble is there are so many different types of plastic around. Solvent weld - for PVC drainpipes - is always worth a try on a flexible plastic.
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On Monday, February 26, 2018 at 1:53:08 PM UTC, Dave Plowman (News) wrote:

I have repaired motorbike mudguards with a big soldering iron and stainless steel mesh which gets pushed into the plastic. As strong as the original.
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wrote:

Google "plastic hot stapler".
Stainless steel wiggly wire, heated resistively, and pushed into the (thermoplastic) plastic.
Thomas Prufer
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On 27/02/2018 09:44, Thomas Prufer wrote:

In industry, some larger plastic services pipes are welded in situ by having couplings which contain a heating element that is powered up externally to do the job. Can't recall whether this is ABS, PVC, or possibly both; but very quick, reliable and robust.
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On Mon, 26 Feb 2018 10:36:46 -0800 (PST), misterroy
Quite,
Someone asked be about re-paining a motorcycle (plastic) front mudguard and I noticed it has a poorly repaired crack across it. I suggested he first repair the crack (reinforce with fibreglass underneath / weld / mesh etc) and he went and got it repainted without.
And of course it's now cracked across the previous crack and so 'spoiling' the paint job he had paid for. ;-(
Cheers, T i m
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On Monday, February 26, 2018 at 11:45:16 AM UTC, Brian Reay wrote:

ABS pipe is/was used in building services, mostly for chilled water. It was joined by solvent welding, using the appropriate pipe cleaner and solvent cement which was smeared onto the fitting. You can get the solvent at plumbers merchants.
You can get a solvent for UPVC and 'multi-purpose' solvents, but if you use those on ABS the joints are weaker and won't take any pressure. OK for rain water down pipe, maybe.
ABS becomes brittle on exposure to sunlight/UV. A part that has cracked may be knackered and will just crack again. Pipes always had to be insulated or pasinted to protect them from UV.
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