PLA Welding: Join PLA like a boss

by maurerpe, published

PLA Welding: Join PLA like a boss by maurerpe May 24, 2012


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Cyanoacrylate super glues do not work on PLA. Epoxies are a hassle, take a long time to set, and not as strong as the rest of your printed part. Hot air tools melt too much material, make good joints very difficult to acheive, and cannot fill gaps.

For a strong, long lasting joint weld pieces together with a soldering iron using this rod as filler material.


Run your extruder as high as it will go and move the bed out of the way (position over a dump location). Extrude 5 or 6 inches (12-15 cm) of filament (this is ussually called "purge" on your host software, you will only need to purge a few mm of 3 mm filiment to get the desired length of extruded filament. Blow on the filament to cool it (if you don't have a fan) and pull it off of the extruder. Repeat a dozen or so times.

The next time you need to join PLA, find an old cheap soldering iron or a worn out tip for your good one. I used a cheap radio shack verion on "high" (40W) with a blunt damaged tip that can no longer be used for soldering. Place a piece of rod along the joint. Run over the joint with the soldering iron melting the rod and a small amount of both pieces to be be joined. For joints with large gaps, repeat with more filler rod.

This method forms joints as strong or stronger than the printed part, fills gaps, and gives great control over how much material is melted.

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excellent idea mate :) will try for sure

If you own a 3D pen, you can just use the same filament as your model, and let the heated extruder provide the melt and extrude filament to finish the weld.

Genius, thanks for sharing!

I have glued PLA using this glue. It comes with an activator to help bonding the parts together.

My tip for gluing PLA: Use DICHLORMETHANUM. I use it to glue polystyrene and even PMMA). Maybe hard to get at the phamacy, but if you say it is for modelling or 3D printing they will sell it. Use it with a small brush. It desolves the PLA and evaporates quickly. Only use in a well ventilated room!!! Ideal for small surfaces like edges and small parts.

Good old Elmer's glue will also create a strong bond with PLA. I've been using the scrap raft material from my prints, but this is a much more elegant solution.

Or "friction weld" it ... put a short piece of PLA in a Dremel tool and use that to weld the parts together.

Works like a charm, and Extremely strong.

This is a good idea but cyanoacrylates work great on PLA. The bonds I get are stronger than the part. But, you have to use a thick CA designed for porous parts since these FDM parts are very porous and water then CA's just soak in too quickly to make the bond. Try something like this: http://www.mercuryadhesives.com/products.htmhttp://www.mercuryadhesives.co... M300M or M1100G depending on the porosity. I bond PLA structural parts with the M1100G all the time.

Works with ABS too. I've been doing so without extruded filament "solder".

What a great idea. I love it.

I just broke off a piece from a 5 hour print, and remembered seeing this some time back.

It saved my print 8-)

Thank you for sharing!

Your welcome. Glad I was able to help save your print. Post a picture if you get a chance.

I've had good sucess gluing PLA with a plastic cement called Sigment, used in the guitar world for appling plastic binding, available from http://stewmac.comstewmac.com

After crashing my bukobot glider a few too many times, I can't tell you how much I like this technique. It's extremely effective!

Hot glue works very well too!


I usually welded by setting the tip of my 3mm transparent or black PLA on fire and let it drop into the gap which's to weld. It creeps deeper into the gaps but often too deep to places where you don't want it. Your method seems to lead to cleaner (more positional control
amp; no discoloration of transp. PLA) weaker (line connection) but less brittle (good melt of surroundings) connections.

Btw: self detatching PLA droplets are well beyond 250°C => keep away from skin.


fake tar finish

Used this technique last night and work really well. thanks

If you do this at work people will think something is on fire. Ask me how I know O:-)

yea sure, blame it on the PLA you stoner.