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keith-hobley

Gluing PLA Plastic

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Having now been printing with my UM2 for the last three months, l’m ready to start my latest project which is a working clock mechanism. The plans for this are from Brian Law’s clock number 7 (http://www.woodenclocks.co.uk) originally intended to be cut from wood. Having printed some of the parts l now need to glue some together. Trying to google suitable glues l’ve found a number of people having problems tracking down something to glue PLA plastic together. Talking to the technical department of Loctite their advice was to use Loctite 401, and although slightly expensive; £21.00 for 20g it sticks like the proverbial pig to a blanket. Just 3 or 4 drops, push together for about 30 seconds and its done. I’ve tried pulling, pushing and hitting with a hammer but its still rock solid.

Highly recommended.

 

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Hi Keith,

What a great subject and interesting print that must be. I have seen his website before. I tried using some loctite glue a couple of days ago ( cant remember the number sry ) but the glue "burnt" the surface of the PLA and left horrible white marks. I guess I could of been more careful. Does the glue you use do the same?

Great bit of info. Thanks! Do post images of your clock when its done :)

 

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Good subject to post Keith. Some years ago I used a 2-part epoxy for gluing resin based 1:43 car models and Colourfabb tech support confirmed it would be a good glue for PLA. In a rush though I got some Revell Contacta Professional from my local toyshop.

It does not display the issue you noted but I cannot really say how strong the joints are; they seem OK but I have not yet attacked the assembly with a hammer :)

 

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Hi Guys,

I also use cyanoacrylate glue and it works extremely well, it glues the PLA and sometimes the fingers too.

If you don't apply too much glue, it dries only in 5 seconds (can be a disadvantage for some collages), but for me this is a plus.

 

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Hi everybody – thanks for all the feedback.

Skint: I've tried an experiment with the Loctite 401 by leaving some on the surface of the plastic and it doesn't seem to burn the surface as you found with your glue.

The other benefit I've found over a two part epoxy is that the Loctite is straight from the container and you don’t need to mix (l always seem to not mix enough or over compensate and waste some.

 

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As an RC modeler I also use cyanoacrylate (CA) glue. I use it for almost everything I need to glue. I really like the thin instant variety which every hobby store should have on the shelf. It is like water and penetrates well. If you have a joint that needs extra strength, pack ordinary baking soda around the joint then add a few drops of CA. You must use thin CA or it won't go into the baking soda. It sets up instantly, adheres to almost everything and is so hard it takes a power tool to sand it. Watch out for white vapors that exist from time to time. If you get that smoke in your eyes they will hate you for a few minutes.

 

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I'll add to this so that I've at least contributed something in my first week of printing with the UM2 instead of only asking questions.

I have found that the same type of glue used for PLEXIGLASS (acrylic) works on PLA. It dissolves the PLA, the same may regular modeling glue does with polystyrene kits, thereby essentially fusing the parts together. Cyano and epoxy are great, but you can't really beat "welding" together parts for a trong bond.

 

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Superglue is great in many respects but it does not handle vibrations or physical shocks well. And while it is super-strong in vetical stress situations (lifting a car) it has very poor abilities to handle shear stress (sideways). You can't really get a better bond than actually fusing the parts together. (I'm not knocking your preferred method of assembly, just pointing out the inherit weakness in the material. I use superglue for lots of things too.)

Yes, the acrylic glue can also be used to smooth out things. I successfully made a paste for filling gaps by mixing the glue (which is rather thin) with shredded PLA, just like you would with ABS and acetone. (Small warning though- you do need fairly good ventilation because it smells just as strongly as contact cement.)

 

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I tried some kind of CA glue for PLA which I use normally for fletching arrow vanes. Its from a supplier called G5. It is blue and become transparent when dry.

The benefit is that it seems to stay flexible and absorbs vibrations instead of shaking into parts.

Beside this, ordinary CA from Lochtite or epoxy are great for PLA...

Just my 2 cents

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If you are gluing large parts you can use heat or you can weld by putting some filament in a dremel and spin welding it into cracks. But this only works for welding large easy-to-get to corners.

From reading above, it sounds like not all "super glue" brands are the same. Also of course it will work better if you rough up the surface first or if it is porous.

 

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A customer (sorry man, I've forgotten your name) told me that Acrifix 116 works great on PLA. I haven't personally tried it though.

I haven't had any luck with "super glue" personally. I'm convinced the only thing it is good at is sticking to fingers (which I guess isn't so strange considering its use as a quick suture).

 

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I use this stuff:

$_12.JPG

You can get it on ebay easily enough. It chemically welds the surfaces together. I use it to bond the body parts together for my RC speed car and so far none of the joints have let go upto 133mph :)

 

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