Printing parts with inserts

With my first printer due to arrive within the next couple hours, my brain has been running non-stop thinking of things to print, projects to prototype, and ways to improve the properties of the printed parts to make them more functional. That being the case and realizing the limitations of plastic from a structural perspective, has anyone attempted to print a part that contains threaded or structural inserts? As an example, the typical point and shoot camera has a plastic body but often has a 1/4-20 thread at the bottom for use with a tripod. That thread is not molded into the plastic but rather is a metal insert that the case is molded around. I'm curious if a print could be stopped or paused partway through to allow inserts to be placed into the partially printed model, then the print would be resumed (or a "2nd" part is printed without removing the first one and without moving the build platform) such that when it's finished the metal insert becomes fully encased in the plastic part. While this wouldn't necessarily result in printed parts that would be suited for more stressful environments, I could see this sort of work flow being useful for printing functional prototypes of mechanical devices. Another possible application would be a structural framework inserted into the part. The plastic surrounding it is used solely for cosmetic purposes while the metal frame serves to give the part the necessary strength for whatever it's being used for.

I guess it depends on the exact printer your getting. Which one is it?

But I guess in theory, any object that sticks up above the current layer being printed would possibly/probably interfere with the extruder head. Unless you're inserting a flat piece of material, I can't picture anything in my head (ie bolt, threaded tube, etc), that wouldn't have anything sticking above that layer.

If you're trying to insert a nut or threaded tube, I would design your part with the opening, then use a die to put some aggressive threads on one end of your tube, screw it into the part after coating it with epoxy or the like. That should hold fine, and with the right epoxy, would increase the strength of the plastic around it.

As to a skeleton, if it's just cosmetic, build your skeleton, and then glue the skin to it. But to be honest, you should be able to design an internal structure to hold most of the stress. If the plastic, with the right design, can't hold the stress, you shouldn't be using it. When I was learning to Tig weld, I was giving a 1" wide, 48" long strip of titanium, .015" thick. Literally paper thin. My instructions were to build a structure that can hold a 150 pound (82kg) weight. I wasn't allowed ot bend the material, just weld flat parts together. So I made a truss bridge. Held 2 of the weights. Point is, even extremely weak materials, when designed correctly, can do amazing things.

I made a mic holder for a friend of mine, used a similar design for the boom arm (truss design). It may be only 6mm thick, but against the truss, using ABS plastic, I can't bend it. The other direction though, it bends more than a drunk politician.


But I've been there. With my printer arriving soon, I was designing all sorts of stuff to build.

Good luck!

It is not worth the effort and it will end up time consuming most of the time because you have to design specifically. Further, FDM printed objects is a complete joke when it comes to mechanic properties, because you will always have internal stress from temperature gradient when cooldown. Not to mention layers do not "fuse" together properly which drastically decrease the material strength.

My printer arrived yesterday and is humming along today making a cute desk statue for my Mrs. (who's less than thrilled with me buying a printer but oh well). I bought a Creator Pro off amazon. As far as designing for inserts, that's no big deal for me. I'm a mechanical engineer and spend my days designing in CAD. The thought would be to insert a nut, bolt, etc. into the part by means of designing a cavity into which the fastener would fit. To your point Marm, the print would have to be paused after the very last layer of the cavity was printed, before the first layer covering the cavity was laid down. This would prevent the extruder from contacting the insert.

As for designing to handle the expected stress, that's fine when you have unlimited space for your structure (as in your case of the truss bridge). When the need for strength also comes with specific locations and size constraints, the combination of material and design doesn't always work out so the need for further support is still there. Gluing the cosmetic skin on is certainly an option but having a fully integrated component is that much nicer overall.

Just design it in two parts that key together, with a cavity in between them that you can insert your bolt or whatever into. Then glue the two parts together and you're done.

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Originally Posted by soofle616

My printer arrived yesterday and is humming along today making a cute desk statue for my Mrs. (who's less than thrilled with me buying a printer but oh well). I bought a Creator Pro off amazon. As far as designing for inserts, that's no big deal for me. I'm a mechanical engineer and spend my days designing in CAD. The thought would be to insert a nut, bolt, etc. into the part by means of designing a cavity into which the fastener would fit. To your point Marm, the print would have to be paused after the very last layer of the cavity was printed, before the first layer covering the cavity was laid down. This would prevent the extruder from contacting the insert.

As for designing to handle the expected stress, that's fine when you have unlimited space for your structure (as in your case of the truss bridge). When the need for strength also comes with specific locations and size constraints, the combination of material and design doesn't always work out so the need for further support is still there. Gluing the cosmetic skin on is certainly an option but having a fully integrated component is that much nicer overall.

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The Flashforge is a good starter machine. I might mention a small thing I found with tolerances between the different printing programs you can use. I mainly swapped between Replicator G and Makerware to print things, depending on what it was. Makerware slices faster but it will not give you (or It did not give me) precise measurements on the Flashforge. Makerware wasn't designed for a flashforge, so this probably has something to do with it, but it's worth noting.

I would print the identical part from Replicator G and the same on Makerware.

RepG would have the exact metrics, whereas Makerwares output was always slightly smaller, I don't know the precise difference but I print in makerware with things scaled up 100.9% and that seems to match the metrics of ReplicatorG. I only mention it because it sounds like you want to do some fine work, and that is possible on the FF, but it might take some tinkering as you will need to most definitely be printing at 0.1mm layer height for threaded items that small.

You can use heated inserts. Just make a hole in your print, and then use a soldering iron to heat the insert while pressing it in.

This is not a problem. I have done it at work multiple times, and it works great if you can afford the extra diameter. In fact most external printing vendors will put inserts into your parts if want (helicoil or threaded). Just squeeze some epoxy onto the external threads and thread it in.

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Originally Posted by soofle616

My printer arrived yesterday and is humming along today making a cute desk statue for my Mrs. (who's less than thrilled with me buying a printer but oh well).

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Lol, I'm in the same boat soon (Hopefully monday)

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Originally Posted by Bassna

Lol, I'm in the same boat soon (Hopefully monday)

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I assume you mean the less than thrilled Mrs.? Mine got over it. She gives me a hard time about it here and there but ultimately she knows it was my money and my decision. I sold one of my bikes, used half the proceeds to get the freebie hottub we picked up a couple weeks ago going for her, and the other half for my printer. She was fine with me spending money on the tub, not so fine with the printer. When I called her on that little dichotomy she quieted down pretty quick.