How to shop for a 3-D printer

[Shaula]

To get it to print like that you would probably use a filament with a graded colour - like this one https://www.amazon.co.uk/Zi-Rui-Fila.../dp/B07GTH4666 . You don't get to control the colour there, it just changes slowly as you go through the print. So it can only vary vertically, not horzontally. And it changes based on the volume of filament used so small things won't have much of a gradient.

If you wanted to accurately control the colour, rather than just have a gradient, then yes, you would need a different printer. I think there are only a couple of hobbyist ones that do full colour printing (that I've seen advertised). Otherwise you are limited to the number of spools/extruders the machine has (which is one for that model, so yes, only one material at a time there). So most of what you said was right - but there is the option of a graded filament.

Can't help you on kits I am afraid, I just bought assembled.

[Delvo]

OK, I've pretty much settled on which printer to get, so at this point I'm really just picking up stray details I've noticed along the way...

Some printing materials are gluable, but the descriptions always specify to use an "acrylic" glue. I remember from building a plastic model ages ago that there was a particular kind of glue at art supply stores for gluing plastics, called "cement" at the time. Is that the same stuff? I also have a container of "superglue" right here and see that "acryl" is part of the name of its active ingredient. Is superglue an acrylic glue?

I've noticed that the only context in which people seem to talk about the possibility of a printing material (other than PVA) absorbing moisture is while it's still a filament. Once it's been printed, nobody seems to be concerned with having the object in a humid climate or letting rain hit it or even letting water sit touching it for a long time (like in a printed plant pot). And they'll deliberately dunk it for a while at least once just to get rid of attached PVA. So it seems as if the printing process prevents subsequent water problems by putting the plastic in a state that doesn't absorb water anymore. Is that right? (Otherwise maybe people are just figuring they can just print a new one whenever the old one gets ruined by humidity.) (The light-fixture project I mentioned before is in a bathroom that gets foggy during showers.)

Also, what is the purpose of heating the platform that the object sits on while it's still being printed? Some manufacturers' websites show that thing's temperature for each model in a way that's easier to spot than nozzle temperature, and one YouTube review said the printer he was reviewing was limited to 80° so it can't print ABS. Why not? And what other cutoffs apply to other materials? Is there a list of what minimum platform & nozzle temperatures are needed for which materials?

* * *

(The one I'm almost certainly going to get is an Ender-5 Pro by Creality. My main point of hesitation about it was that it has one nozzle & extruder and I really wanted a dual system of some kind, but the ones that come that way from the start are more expensive by a wide margin, even wider if we eliminate Creality's CR-X based on frustrated reviews of it even by people who are happy with other Creality products like Ender-5 Pro. I have some stuff in mind that ideally calls for dual extrusion, but there are other workarounds for those, like accepting breaking off same-material supports, learning to paint, and/or even just not ever making one or two specific items that can't be done any other way. But I also discovered along the way that, instead of adding hundreds of dollars to the price just for that one feature, I can get a separate 2-in-1-out or mixing hot-end to replace the original one with, for under $25.)

[cjameshuff]

I've noticed that the only context in which people seem to talk about the possibility of a printing material (other than PVA) absorbing moisture is while it's still a filament. Once it's been printed, nobody seems to be concerned with having the object in a humid climate or letting rain hit it or even letting water sit touching it for a long time (like in a printed plant pot). And they'll deliberately dunk it for a while at least once just to get rid of attached PVA. So it seems as if the printing process prevents subsequent water problems by putting the plastic in a state that doesn't absorb water anymore. Is that right? (Otherwise maybe people are just figuring they can just print a new one whenever the old one gets ruined by humidity.) (The light-fixture project I mentioned before is in a bathroom that gets foggy during showers.)

It's mainly an issue for the filament because printing involves melting it at temperatures well above the boiling point of water, obviously not conditions you can use the printed objects at. Some plastics do also swell noticeably when they absorb moisture.

Also, what is the purpose of heating the platform that the object sits on while it's still being printed? Some manufacturers' websites show that thing's temperature for each model in a way that's easier to spot than nozzle temperature, and one YouTube review said the printer he was reviewing was limited to 80° so it can't print ABS. Why not? And what other cutoffs apply to other materials? Is there a list of what minimum platform & nozzle temperatures are needed for which materials?

Bed heating is mainly to prevent the part from warping. ABS is particularly bad because of its high thermal coefficient of expansion.

[Shaula]

Some printing materials are gluable, but the descriptions always specify to use an "acrylic" glue. I remember from building a plastic model ages ago that there was a particular kind of glue at art supply stores for gluing plastics, called "cement" at the time. Is that the same stuff? I also have a container of "superglue" right here and see that "acryl" is part of the name of its active ingredient. Is superglue an acrylic glue?

No, superglue is not an acrylic glue. It does work (really quite well) on most printed materials but it is a different mechanism of action. Superglue is a rapid setting polymerisation of a cyanoacrylate whereas acrylic glues (or plastic cements) rely on solvents to soften the plastic and 'weld' the pieces together. I use both - superglue is a bit more brittle a join but fast whereas the plastic cements tend to need to be clamped or held lest they slip but tend to give a more flexible, stronger bond when used properly. I don't know which alternative plastics the plastic cement works on though - I've only used PLA.

I've noticed that the only context in which people seem to talk about the possibility of a printing material (other than PVA) absorbing moisture is while it's still a filament. Once it's been printed, nobody seems to be concerned with having the object in a humid climate or letting rain hit it or even letting water sit touching it for a long time (like in a printed plant pot). And they'll deliberately dunk it for a while at least once just to get rid of attached PVA. So it seems as if the printing process prevents subsequent water problems by putting the plastic in a state that doesn't absorb water anymore. Is that right? (Otherwise maybe people are just figuring they can just print a new one whenever the old one gets ruined by humidity.) (The light-fixture project I mentioned before is in a bathroom that gets foggy during showers.)

Water ingress can accelerate the biodegredation of the plastic. There is a whole community who care about this in the form of 3D printers for fish tanks. ABS is bad as it poisons fish, PLA is biodegradable so has to be carefully treated lest it fall apart after a length of time (I have seen claims of months)

And I hope you enjoy your Ender! Good luck with it, I found 3D printing a bit of an adventure at first but very rewarding in the longer term.