I’ve watched dozens of YT videos over the years where makers proclaim various adhesives as ‘just great’ for PLA and other filaments. People have different standards for what constitutes a good bond. Almost everyone says super glue is the answer. Some who say CA doesn’t work swear that Weld-On 16 will do it when nothing else will. I’ve tried both of those any many more and none of them work for me. If I can pull it apart without doing any real harm to either piece, it wasn’t bonded. I used to build acrylic (AKA Plexiglas) cabinets for hospitals. Weld-On 3 applied with a syringe would literally weld the pieces together. Within 10 minutes you couldn’t pull it apart without breaking one of them, but not at the weld.
There’s some value in a material that resists sticking to anything. Where would we be without Teflon? Add PLA to the list. At least-- that’s my story and I’m sticking to it (pun intended).
Gloop is the best in the business
In general, I find the best way to use superglue is with an activator. With printed plastics, I like using the more viscous super glue, as it fills the gaps where a more watery one just seeps into the gaps. That’s kind of been the key for me, to make it work well.
@BillByrd I’ve been using Gorilla Super Glue GEL XL for a while now. Takes a bit of time to set (30 secs or so and I use clamps) and you have to let it continue to harden for another hour or so. Works well with PLA for my needs.
You probably want something like plastic cement. @Olias mentioned it in the link below.
In the case of cement, you’re using a solvent-based material that will literally dissolve the two materials and weld them together.
Have you tied to pull it apart?
I’m a recent covert to the CA with activator, just love the stuff. The odd yellowing is meh but thats usually my fault for sending it a bit too wild. I’ve also discovered the bottle of acetone is better to be left uncapped and in reach when using said CA…
I have glued PLA prototypes together myself using standard superglue. And yes, it worked fantastically! - Here’s why: I tried to remove one of the attached PLA parts on a chassis made of PLA because I thought it should work. However, the chassis was broken off and the glue held. On closer inspection I realised that the adhesive had dissolved the PLA and bonded both parts in this way. With a different PLA mix or PLA+ there may be different results. Or it may be due to the adhesive used. I think I used superglue from Pattex back then (but it’s been a few years, so there’s a possibility of error). But perhaps the surface of your printed part was contaminated before gluing? However, I always make sure that I apply plenty of superglue to the contact surfaces when I use it on PLA. We know that 3D FDM printing is “not quite tight” and the glue seeps into the material quickly, so we use more (plenty of) glue before joining the parts, then I wait a few minutes or even much longer to make sure that the chemical reaction of the amount of glue used has finished safely.
I feel your pain and frustration…
But I am also an old fart how was already past the best before date when we used a threaded rod Prusa and 3mm filament…
Means I had to learn what it takes to not glue PLA together but to actually make this connection last.
And like it or not superglue IS the easiest and fastest option - but also the worst if you don’t know how to correctly use it.
PLA is a pain with superglue because you can only cure the stuff in the ABSENCE of air.
If the fit is not perfect or there is gaps between the layers because our filament won’t produce flat vertical surface it will fail more often than stick.
Leaving you frustrated, then swearing once the remaining glue on the model makes your finger stick.
My first secret is of course sanding the to be glued surfaces - preferably flat surface or nicely rounded ones.
Just to make the surface even, like removing those tiny bumps and leftovers or some over-extruded lines.
If the fit is loose it will be a bad fit, is it is snug and requires some pressure to mate it is best.
Not just because of how superglue works but mainly because you can apply the thing types onto the joined parts - it will creep inside if there is any tiny gap left.
Another trick that works on PETG and Nylon as well is the flame treatment.
A soft flame going over the mating surface breaks the bonds in the plastic that makes the surface inert.
Like that you even glue PETG parts with contact glue…
Of course not always can we get a perfect enough fit…
At least not for superglue…
Here we can cheat with a dirt cheap activator - baking powder…
Sprinkle it over the mating surface, push the together and remove the excess.
Repeat a few times and you shall be left with a perfectly smooth surface.
Put the two together, then apply the glue onto the joint - do not drip it onto any part that has the baking powder on it as it will go rock hard instantly!
This trick works especially well for joints you know might not be perfect after printing.
Just make them intentionally a bit too large to get a slightly loose fit and use baking powder and superglue to make it perfect once assembled.
If you have very tight, structural joints and won’t mind going outside to reduce the harm than on PLA MEK or Methy-Ethyl-Ketone works quite well.
You can find it in the plumbing department as PVC primer for gluing PVC pipes together.
Apply the stinky stuff with a soft brush and rather thin, just wetting the surface.
Wait until the surface appears visually dry and apply again.
Check with a toothpick or such if the surface shows signs of softening - it should already slightly show after just two applications.
While still appearing wet, or after applying another quick layer get the tow parts together and secure them in this position for at least half an hour.
If the joint feels cooler than the rest wait a bit longer, same if can still smell the MEK.
A warm environment helps to evaporate the MEK.
PLEASE use this stuff only in well ventilated areas, only if there is no other option and use nitrile gloves!
If you see that the MEK discolours the gloves of affects their surface change them before they fail.
CA (superglue) works fine on pLA, it’s just the glue is cured by moisture and PLA is very dry. Use acceleratant or a mist of water, it’ll be fine. CA is not particularly strong however.
Almost anything will work if you clamp it and leave it a few hours.
Clear Gorilla Glue creates a strong invisible bond for me. It’s kind of like epoxy without having to mix parts together. It does take an hour to dry, so I usually clamp the parts together.
Look at tradional modelmaking channels who are using 3d printing to assist them. For example fauxhammer (mainly SLA resin) or kathy millat (FDM) if you speak english. they are printing and gluing and painting models all day, and can show you the techniques needed. They are usng just regular glues.
What’s the acetone for for?
I’ve tried over and over. But, maybe I’ll try again. Thanks for responding.
I’ll give it a try. I love your Navy jets!
PLA glue huh? I wonder if it’s just CA. I’ll look into it. Thanks
Once you glue your fingers either together or to something else, you will fully understand why having acetone easily reachable is important.
I wish I knew this a month ago 
Now I’m not gonna tell you what happened a month ago, but you can probably imagine.
Was it similar to the time I ate REALLY spicy chicken wings and then didn’t wash my hands before taking a leak?