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I want to print a model of an animal cell.

What I have so far: I managed to use different colors to print out the different parts of the cell.
My question is: what is the best way to connect plastic 3d printed parts?
Glue? Melted plastic? I need it to have a strong connection and not very visible when used well, and preferable dries fast.

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    $\begingroup$ What printing technology and material are you using? $\endgroup$ – Mark Jan 12 '16 at 20:29
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    $\begingroup$ I am voting to close this question as off-topic, since it is not specifically about 3D printing: as it is currently worded it is just a question about how to (generally) fasten objects, and the fact that they are 3D printed is secondary. At the very least the question should specify a 3D printing process and material so answers can focus on that. $\endgroup$ – Tom van der Zanden Jan 12 '16 at 20:40
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    $\begingroup$ @TomvanderZanden When prints are too large, they need to be printed in multiple pieces. To assemble them they must be connected. Even though this connecting not because of size, I think it is a valid question. $\endgroup$ – Eric Johnson Jan 12 '16 at 21:06
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    $\begingroup$ I disagree with closing this topic. The problem is very specific to 3D printing because of the materials that are being used that are specific to 3D printing. For example, where do you find PLA plastics commonly used other than in 3D printing? So what's the best way to connect PLA 3D printed parts together? If you have a combination of PLA objects and ABS objects, what do you do? These are not questions that would come up in a non-3D-printing forum. A person doing 3D-printing needs these techniques as part of their toolkit - choosing the right glue / cement / epoxy is extremely relevant. $\endgroup$ – Tony Hansen Jan 19 '16 at 4:29
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    $\begingroup$ I think it is on-topic, for the reasons @TonyHansen gives. However, "the best" makes it opinion-based and it might also be too broad. I suggest rewording it ("How to make a strong/durable connection") and specify the material used. $\endgroup$ – S.L. Barth - Reinstate Monica Jan 19 '16 at 16:19
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For ABS print, I recommend acetone. It is not a glue, but it will dissolve the plastic a bit and if you apply it to both connecting parts and push them together, they will stay connected after the acetone dries. However, it does not dry very fast and you have to be careful not to destroy the object.

For PLA I usually use regular super glue (Cyanoacrylate).

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    $\begingroup$ And you should always have proper ventilation when working with acetone. $\endgroup$ – Matt Clark Jan 12 '16 at 20:55
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For ABS I use a gel super glue (Loctite is my current favorite), it seems to slightly melt the ABS parts together and makes for a great bond. A slurry of old scrap ABS and acetone also works well, though I find that it will evaporate even if left in a closed mason jar over time. The small nozzle applicator and the fact it doesn't seem to evaporate makes super glue the better choice for me.

The gel super glue works "OK" for PLA but I've had parts fail after taking a small tumble. I just started using this acrylic cement for PLA. It cures very fast but seems to slightly melt the PLA in the same way the ABS options do.

For internal seams I like to put a bead of "high performance" hot glue over the seam. It's just a bit flexible and seems to do a good job taking drops.

Lastly I really like (but haven't mastered) friction welding parts together using a Dremel. Matt Griffin at MAKE Magazine did a great write up on the technique here.

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  • $\begingroup$ I second the friction welding suggestion. It creates very strong bonds. It takes a lot of practice though. Currently I limit my use to welds I can do that will end up hidden. $\endgroup$ – kareem Jan 13 '16 at 4:23
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After doing the processes that hroncok described, the edges of the print can be finished with a 3D printing pen. The pen extrudes filament as a regular print head does, but is hand held. The filament can be extruded on the previous gap between the two prints. It will melt between the two sides and can be finished to create a smooth connection point.

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