What’s a good glue to use for PLA?
Thanks,
Steven
This is often highly recommended.
I haven’t used it myself though.
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Have a look at this thread: There ain’t no glue for PLA - MakerWorld - Bambu Lab Community Forum
Classic CA seems to work for most applications.
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This is the is the hidden part of the iceberg of cost behind of 3D Printing that they don’t tell you about in the brochure. 
It’s the hidden cost of scamming the customer who doesn’t know better.
Beware of products claiming to be purpose-made for 3D printing. They are often everyday items relabeled, with their chemical composition obscured to appear as specialized glue.
There is a topic which touches upon various types of glue vs cement.
Understanding the difference between glue and cement can help you choose what’s best for you. Glue forms a chemical bond relying on its own strength, like crazy glue. Cement creates a weld by chemically melting materials together, making the bond stronger than the surrounding material, similar to metal welding uses heat. Plumbers as an example use cement, not glue, for joining PVC pipes. The provided link above offers more details.
If you use crazy glue, it works best on two smooth surfaces. Print on a smooth plate with the intended bonding surfaces facing the plate for optimal results.
Plastic Glue Vs Acrylic Cement Properties
| Property | Plastic Glue | Acrylic Cement |
|---|---|---|
| Bonding Strength | Moderate to High | Very High |
| Drying Time | Varies (minutes to hours) | Fast (seconds to minutes) |
| Flexibility | Moderate | Low |
| Clarity | Clear | Clear |
| Application Method | Brush or nozzle | Applicator needle |
| Chemical Resistance | Moderate | High |
| Usage | General plastic bonding | Acrylic and Plexiglas bonding |
If it were me, I wouldn’t use glue, especially anything marketed specifically for 3D printing. These products often cost 30% - 70% more just for the label. For example, compare the chemical composition of white 3D printing glue sticks to Elmer’s or other classroom glue sticks. They are chemically identical and even come in the same tube and packaging from the same factory, but the 3D printing version can cost up to 200% more. Why 200% more? Purely to convince the buyer that if it costs more, surely it must be the best, right? It’s all part of the scam.
While it might be appealing to select a product that uses terms like “Specially formulated” or “Nano Polymer Technology”, I learned by reading labels and requesting MSDS from that manufacturer that anytime you see these terms, assume you are being scammed. Also, the prettier the package the greater the con.
You can pay $10/oz for something with dubious results in a pretty box, or choose an ugly package for $3/oz. The choice is yours.
This is the material I use. It is a 5oz tube. It is very runny so it is best applied using either a small disposable brush or you can use even a cotton swap. I actually printed up some shallow ink wells for this purpose and just squeeze an amount into the well and then spread it using the cotton swab. That gives you a lot more control than squeezing it our of a tube.
Note that there are other “Plastic Cement” on the market that likely work equally well. Old style model cement like Testors used to have these solvents but because of inhalant abuse, it was reformulated and no longer qualifies as a cement.
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I’m pretty sure SCIGRIP is a repackaged Weld-On 16. In my past I used it a lot for welding acrylic parts together. It doesn’t work (for me) on PLA. But, then again, I say the same thing about CA and I’m apparently the only one in the world for whom it does not work.
You’re so right about packaging. Take the most expensive perfume. Try to sell it in milk jugs for $10/gallon. It would gather dust sitting on a shelf.
You are not alone. For me too, CA fails every time. No use at all for PLA.
Wow! Thank you all for the wealth of information! I will report back with my results.
Just keep in mind that bonding surfaces should be clean (especially important if you have used a glue stick for bed adhesion). You can also give them a mild sand (80 to 120 grit) but need to remove the dust.
PLA is my main filament and while I prefer to design with locking pins, dove tail joints and such sometime there is no way around glue…
PLA does not even allow silicone caulk to stick properly, so gluing it should be no problem
Jokes aside though I had a long learning curve with PLA and like it or not I do prefer superglue, the dirt cheap kind in those 2ml throw away things…
Thing with superglue is that you either have to cheat or make sure you create a sealed and air-FREE seal.
The stuff just won’t cure at all if there is still air present.
PLA makes this even harder with layer lines and such…
IF you can sand those mating surfaces flat and smooth to form a flat and gap free fit…
If not then read on please…
Superglue can creep a very long way if it won’t cure along the way…
You can get activator pens for superglue, Loctite even sells them as a bundle.
And while this can work well if both surfaces are treated it still is hard to get those layer gaps to work out.
The glue will set fully within a day or so if the joint hold initially.
Before we go deeper into cheating with superglue: What about other glue on PLA ?
Right, why do I ask, you obviously already tried everything available it failed all the time.
Do you know that you CAN make most glues stick to PLA after giving it a flame treatment?
Same for Nylon by the way.
Prepare the surfaces as you would with other things, meaning sand flat, clean up and such.
Then use a soft flame from a lighter or blow torch to go over the surface.
Start fast and with a bit of distance until you get a hang on things.
You will see the plastic surface change appearance.
NOT the melting, I mean when the flame changes the shine of the sanded plastic.
A slight change is great, mostly shiny is still fine, a glossy finish means you overcooked.
After that even shoe glue, contact glue or PVA wood glue works, the later though requires a long time to dry…
Back to those toxic and fast glues…
If you create your own models then don’t create a really tight fitting joint if you know you will glue it.
For flat parts to be glued prefer to print that side down on the bed.
You can give your parts a light dusting with baking powder (baking soda).
Use a soft and fine brush to apply and to remove excess.
A slight tapping also helps.
Superglue cures instantly on contact with baking soda.
Means you join the parts first and then apply a drop or two of glue to the joint.
If it has a gap left use very little glue, wait a minute, fill the gap with baking soda and add another drop of glue.
Do NOT overfill a gap as it can be hard to sand this cured stuff down, it is always best to wipe excess baking powder off before applying the glue to a joint.
Tough case: Gluing two large surface with layer lines…
Let’s say that for whatever reason you need to glue to 10cm squares together.
And it has to be a good bond.
Put some 180 grit sandpaper onto a glass plate and sand off most of those layer lines.
Repeat with 200 and 400 grit until smooth and those gaps between the layers almost fully gone.
Put some (non residue) sticky tape or just paper circles in some spots of both surfaces.
Like the number 5 on a dice.
Dust the rest with baking powder on both surfaces.
Remove the coverings and add a generous amount of superglue in this powder free area.
You need to be reasonably quick here as the stuff spreads fast.
Align both pieces with the superglue one kept flat, press together and hold for a moment.
Ideally there should be some glue coming out of the sides.
Don’t worry if not as you can always drip some in.
Superglue and toilet paper…
Not ideal but a single layer of toilet or other tissue paper between two PLA surfaces if often enough to let the glue form an airtight seal so it can cure.
This works particular well with uneven surfaces where you might expect tiny gaps to appear.
It really helps to give the surfaces a light sanding and flame treatment prior.
Last one and only for those with the right PPE or willing to stay outside.
Methyl-Ethyl-Ketone, or MEK, PVC pipe primer DOES affect PLA badly.
Ok, not as badly as Methylene Chloride but that stuff is really nasty and no one should use this at home.
Anyway…
Those bottles from the plumbing isle in the hardware store usually come with a brush attached to the lid.
Do NOT open the bottle and just pull the lid up to check!!!
These things are intentionally designed to waste a lot of the MEK and to make the application inside pipes easy.
Lift it out carefully and let the thing drip out into the bottle.
Preferably wait with that until you want to test it on PLA.
That way you can use it once to make a big mess on the part before cutting it off and putting it in the bin once dried out.
As said, do not use MEK inside, it stinks, is not healthy and needs good ventilation.
For smaller joints I prefer to use cotton swabs - those little things we keep using to clean the ears and noses of our kids despite knowing better…
Get the cotton wet, let it drip off and then wipe it over the PLA test piece you have.
Try to wet the surface, meaning it should have some liquid left on it before it evaporates.
Repeat until you either notice the cotton takes the colour of the plastic or that the plastic starts to feel tacky.
Push together now quickly and secure the parts in place for at least two hours.
Once you can’t smell anything it might just mean the surfaces are sealed but not that all MEK is evaporated from the inside.
If you have some small and properly sealing glass jar you can also create a lot of fine PLA dust to create a MEK-PLA slurry mix.
This works great for joints with slight gaps or where the surface are not fully even.
Be aware that you shall use vinyl gloves and that they shall be disposed off once contaminated.
MEK will eat through them after a while and they tear quickly.
Best not to get it onto your skin…
If you need a really strong bond, especially for ill fitting part grab a bottle of the PVC glue as well.
Do as above to get the PLA soft, apply the glue QUICKLY and get the parts together quickly.
Have a cloth or such ready to take of any excess pooping out.
Try to not use excessive amounts of glue, a thin and even spread will do fine.
One joined things set quickly so have ready what you need to keep the parts secured until the glue is fully set - this can take 24 hours or longer depending on the temperature, ventilation and surface area joined.
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Heptane works surprisingly well as an “activator” for supergluing any plastic to any plastic. I’ve even superglued to pure teflon rod with it.
Without knowing any better, I used to buy it in these stingy little kits:
without any thought as to what it was, but to @Olias 's point above, heptane is identified by name right on the very cover of it (as you can see in the WARNING! text in the photo here). Once you know the name, you can buy it at a favorable price instead of $5 for just 0.14g of the stuff, which also tends to quickly evaporate when you uncap the pen.
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Thanks for the tip. I recently saw an episode of Adam Savage’s “tested” on YouTube where he speaks of CA accelerants. I’ve been wanting to try it out ever since.
Here’s the link to that episode.
Here’s the Amazon link to the product in case anyone’s interested. I can’t understand why the price is so over the top on Amazon.
https://www.amazon.com/s?k=681925
I know why this product is much cheaper at Home Depot.
I’ve used super glue with an accelerator. It works well.
Sometimes I will put glue on one part and accelerator on the other. You have to be fast when you put it together because it hardens immediately. Otherwise, if I need more time I put the glue on one of the parts, push and hold them together and get somebody to spray the accelerator on the edge where the parts join.
Just to be clear and hopefully avoid confusion by anyone, for AC113 3M describes Heptane as an “activator” for its instant adhesives (see screen shots
below) and for AC77 3M describes Heptane as "a cyanoacrylate primer that aids bonding to low surface energy plastic substrates. "(also see screen shot below):
FWIW, in this context my reading of the above is that an activator is an accelerator, but a primer is not an accelerator and does not speed anything up per se. Rather, a primer somehow prepares the plastic surface for bonding with the adhesive, and without the primer the adhesive would have no grab and would not stick to the plastic surface. When I was using Heptane, I was using it in this manner as a primer so that two pieces of plastic could be glued together. Without the heptane primer, the two pieces of plastic might not even weakly stick to each other from the gluing attempt and probably wouldn’t glue together at all.
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Heptane certainly works for the purpose but it is also on my list of chemicals I prefer NOT to use.
MEK is bad but Heptane is worse - just saying…
Use with caution and only in well ventilated areas.
Edit: Loctite 770 is the official primer in bigger bottles of 100ml
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I’ve had good results for PLA using super glue (cyanoacrylate adhesive) for smaller parts and joints. It sets pretty quickly and forms a strong bond. If you’re looking for something more versatile, epoxy adhesives designed for plastics also work well and provide a durable hold. It really depends on what you’re gluing and how much strength you need.
Name the names. Which ones, exactly?
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I’ve had some pretty good success with this stuff. It seems to slightly melt PLA when some pressure is applied to the parts being glued. Amazon.com
I think we should settle on TWO different demands…
- A quick setting glue with enough bond strength.
- A slow(er) setting glue that chemically welds the parts rather than just providing a surface bond.
For number 1 there really only is superglue and 2k epoxy, with the later often falling into the number 2 region due the chemical cocktail used.
And for most applications that might be all we ever need with PLA…
MIGHT…
Unless you add fillers like baking soda and such superglue stays rather brittle.
PLA on the other hand is a bit flexible, especially when a joined part is subjected to blunt trauma…
For parts the get a lot of flexing and/or mechanical stress superglue is about as bad as when you want to use parts submerged in water…
Solvent based glues or plain solvent welding of joints provides the strongest bond and most lasting bond.
Epoxy or stinky contact glue can be cheaper alternative.
Especially if you design the joints for the purpose - then you might even be able to use UV curing epoxy glue
I could start a new topic where we start to list our favourite glues/solvents for PLA and how to use them.
I edit the first post every now and then to keep the list up to date.
And if there is anything meaningful in a post that the users say helped them I could add a link in the first topic to the corresponding reply, like so:
Amazon product suggested by user
Loctite (and maybe others?) makes an “impact resistant” super glue that I’ve found helps quite a bit in overcoming the brittleness of regular, standard super glue, especially when gluing plastics with the heptane primer I mentioned earlier:
Something else I didn’t realize until too late is that the shelf life for superglue is only about 1 year from date of manufacture, even if you never before opened the container prior to applying it. The fresher the better. Since the manufacturing date usually isn’t stamped on it, about all you can do is buy it from a source that hopefully turns it over rapidly enough that you won’t be buying old stock.
If you have access to it, chloroform will bond PLA as acetone does with ABS.
It’s my to go solution for PLA.
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