3D printed intake manifolds?

[Northern]

PETG is a semi-garbage material to print with lol

True, basically I only use it because I can use it with zero mods to the printer. I've got settings dialed in to deal with the stringing/dripping (mostly lower speed/temp fiddling/Z hop), main issue now is that my CR-10S has their common hot end thermocouple issue (seems to be a matter of reflowing solder on the connector, but wiggling the connector works and I'm lazy).

[nando]

Lost PLA casting. You can also 3D print bucks for mold making or even molds depending on the geometry and use them to form Carbon Fiber fairly easily. FDM is borderline useless for any direct use parts in an engine bay except in specific low load use cases and with limited materials.



PETG is a semi-garbage material to print with lol

You can print with Nylon... Build a drybox, get an all metal hotend and hardened steel nozzle, put the printer in a cabinet. The only reason I don't print with Nylon instead of PETG is that I don't really need the durability and heat handling. I print some interior parts, little brackets, RC airplane and drone parts. PETG is stringy and prone to oozing and blobs but it's fine for most of what I do. I use PLA when I can because PETG is a pain to print. Recently I printed a ring squaring tool and a ring grinder attachment for my dremel in PETG. They came out a bit hairy.

PETG absorbs moisture as well. Not quite as bad as nylon, which I think can absorb up to 20% of it's volume, but you definitely want to keep PETG in a dry box and use a dehumidifier before you print with it. The stringing and blobs is definitely because of moisture absorption. I've done lots of nice prints with PETG but you have to keep it dry.

[varg]

I'm aware. I store all of my filament in a sealed box with containers of color indicating silica gel. The stuff has always made blobs and horribly stringy prints even out of the box for me. That was back when the printer had a stock hot-end and was bowden feed. Nowadays it's a direct drive with an all metal hot running freshly dried filament and it's still a mess. I added retraction distance until I hit the limit of the manufacturer's recommendation for the hot end and it helped some but I printed a cylindrical attachment for my dremel just last night and it was filled with fine stringing. About an hour ago I heard a bad sound from the printer, a sizeable blob had detached from the nozzle and was getting run over by the cooling fan duct. Had to cut the blob off with the flush wirecutters I keep on the printer for that reason. People I've known who print always seemed to have issues with TPU, which I printed (slowly) from a bowden feed and had zero issues with, ever. PETG has been nothing but trouble. I wonder if I've received bad material and it just takes me so long to go through it because it sucks and I rarely use it.

[nando]

yeah could be bad quality material. I don't use a lot of PETG, because it's not really that much better than PLA and is definitely harder to use, but I've gone through a couple spools that printed fine without issue on my stock Ender 3.

[AexD]

Its an interesting thought because the plastic intakes i assume are moulded in ABS, i know you can ABS+ that you bake in the oven after printing to further heat treat it.

Personally i would be using some variant of Nylon - or colourfabb offer an engineering grade filament called colourfabb HT, its specifically designed for applications like this although it is expensive, continuous service temp of 100c: https://colorfabb.com/ht-dark-gray

I have a fairly nice DIY Printer with chamber that is capable of printing Nylon & HT etc.

I print ABS everything, its much nicer to print than PLA and worlds ahead of PETG, has a higher volumetric flow rate too so i can use the full print speed of 150mm/s on my printer.

[varg]

Plastic intake manifolds are almost exclusively glass reinforced Nylon. The problem with 3D printing is the layer adhesion, not so much the material itself. Though glass reinforced nylon would be a good bit stronger than printed nylon even if the printed piece was isotropic.

[AexD]

Plastic intake manifolds are almost exclusively glass reinforced Nylon. The problem with 3D printing is the layer adhesion, not so much the material itself. Though glass reinforced nylon would be a good bit stronger than printed nylon even if the printed piece was isotropic.

Interesting to know thanks, somewhere along the way someone told me ABS but Nylon makes much more sense.

I think colofabb HT is still a good candidate for an adapter piece, especially if you make use of some kind of PTFE / Thermal Spacer between the head.

[nando]

Plastic intake manifolds are almost exclusively glass reinforced Nylon. The problem with 3D printing is the layer adhesion, not so much the material itself. Though glass reinforced nylon would be a good bit stronger than printed nylon even if the printed piece was isotropic.

the successful engine parts I know of that were DIY printed used carbon fiber/nylon filament. still pretty tough to print with and expensive, but doable.

[varg]

Of course it's doable, it's just only practical in limited usage cases. Regardless of the filament you use, anything 3D printed by FFF/FDM is highly anisotropic in strength because of layer bonding, as well as flexibility and impact resistance. We're all familiar with how it behaves; if you load it in anything other than its preferred direction the strength difference is typically a factor of two or greater depending on the material. Powdered salt immersion re-melting is feasible for some parts and can reduce the anisotropy significantly but it does reduce ductility. PETG can nearly reach isotropy in ideal parts with salt re-melting. If you can make a part which you know will see very favorable loading and use a material which will handle the heat you can easily use 3D printing to make an automotive part, but if it sees unexpected loading it will probably fail in short order. Keep in mind that the strongest prints are typically at small layer heights, so large parts where strength is required take a super long time.

I've printed multiple PETG and TPU (I don't use ABS because of the smell, my printer is in my usually unoccupied front room) specimens which I have tested in my engine bay for heat tolerance, mostly to see if PETG brackets and TPU grommets are feasible. Both are, even left in my engine bay for years neither specimen just fell apart and the TPU specimen retained its flexibility. Custom TPU grommets are now something I have used multiple times and I have 3D printed cup holders, interior brackets, hose and harness constraints. The grommets don't self-seal like rubber, but you can use sealing tape or RTV sealant. Most of my printed parts have been RC airplane, multirotor and helicopter parts. I've successfully used 3D printed PLA tail rotor blades on my 450 sized RC heli. 3D printed RC airplanes are a novelty. They're crap, they're so fragile it makes balsa look durable and are much harder to repair, of those I have seen crash, very few were repairable.

[AexD]

Of course it's doable, it's just only practical in limited usage cases. Regardless of the filament you use, anything 3D printed by FFF/FDM is highly anisotropic in strength because of layer bonding, as well as flexibility and impact resistance. We're all familiar with how it behaves; if you load it in anything other than its preferred direction the strength difference is typically a factor of two or greater depending on the material. Powdered salt immersion re-melting is feasible for some parts and can reduce the anisotropy significantly but it does reduce ductility. PETG can nearly reach isotropy in ideal parts with salt re-melting. If you can make a part which you know will see very favorable loading and use a material which will handle the heat you can easily use 3D printing to make an automotive part, but if it sees unexpected loading it will probably fail in short order. Keep in mind that the strongest prints are typically at small layer heights, so large parts where strength is required take a super long time.

I've printed multiple PETG and TPU (I don't use ABS because of the smell, my printer is in my usually unoccupied front room) specimens which I have tested in my engine bay for heat tolerance, mostly to see if PETG brackets and TPU grommets are feasible. Both are, even left in my engine bay for years neither specimen just fell apart and the TPU specimen retained its flexibility. Custom TPU grommets are now something I have used multiple times and I have 3D printed cup holders, interior brackets, hose and harness constraints. The grommets don't self-seal like rubber, but you can use sealing tape or RTV sealant. Most of my printed parts have been RC airplane, multirotor and helicopter parts. I've successfully used 3D printed PLA tail rotor blades on my 450 sized RC heli. 3D printed RC airplanes are a novelty. They're crap, they're so fragile it makes balsa look durable and are much harder to repair, of those I have seen crash, very few were repairable.

Haha yep I had a phase of building some 3d printed quad Copters, even when printed in carbon nylon they rare survived a crash without fatal damage. Whereas a true carbon frame can sustain multiple crashes and carry on.