Nylon with Rostock Max hotend for automotive hose connectors

[milp]

Hi there,

I'm planning on constructing and printing hose connectors for diy projects regarding my car's cooling system. (Namely degassing hose connectors to redirect air bubbles back to the reservoir)

Since the absolute maximum range of temperatures in the cooling system should range between -20°C to 125°C with pressures going up to 2 bar I was considering either going on a limb and printing them in ABS in the hope that they will last under those extreme conditions or printing them in nylon filament (Taulman's probably).

Taulman's nylon filament's optimal extrusion temperature is between 140-150°C, so i was wondering if it's even safe trying to print this with the stock Rostock Max v2 Hotend? It says that 245°C should never be exceeded since that would melt the peek section (whatever part that is?) of the hotend. But does that also mean that 245°C is a safe working temperature when printing things?

Another thing: I would also need some hard-to-get-by special connectors for the fuel tank, does anyone know whether ABS, PLA or Nylon are Gasoline resistant?

I'm glad for any constructive input.

[Jimustanguitar]

Sounds like you're building a Pike's Peak racer or something where you plan on taxing the cooling system... What' the project?

[milp]

Sounds like you're building a Pike's Peak racer or something where you plan on taxing the cooling system... What' the project?

Eeh not quite I'm converting a small citycar into a one man survival car for travelling across europe. And for this i installed a park heater and converted it to a full-time heater (still usable as a park heater). That took quite some muddling around with the cooling system and now it's difficult as hell to bleed all the air out, so i just wanted to automate the process by installing a automated bleeding system that runs small tubes from high points in the cooling system back to the reservoir to 'auto-bleed' it.

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As much as I love talking about my car, some input on my questions would be really awesome

[Jimustanguitar]

Sounds like you're building a Pike's Peak racer or something where you plan on taxing the cooling system... What' the project?

Eeh not quite I'm converting a small citycar into a one man survival car for travelling across europe.

Ahh, just mountain racing in the Alps. I get it

[rpress]

ABS glass temperature is right around coolant temperature, so ABS is probably not the best choice as it will lose a lot of strength. Nylon's glass temperature is lower but the strength falls off much more gradually so I'd think this is a better choice.

In any case you're going to have a hard time making things water tight, although it is possible. I think drying the filament and printing slowly will help with this.

For printing nylon I use an E3D "all metal" hot end. I don't think it's recommended to print nylon with a PEEK hot end. PEEK is a type of plastic that is used in some hot ends to insulate the heat block, it's usually beige in color. At high temperatures the PEEK will break down.

ABS is not gas resistant. Nylon is rated as excellent for gas resistance.

[Captain Starfish]

The PEEK section is the plastic barrel that sits between your heater block and the heatsink section of your hot-end. Fine for low temp stuff but it's your enemy when you want to print high temps.

Nylon might be extrudable at 245º but I find the inter-layer bonding is rubbish until I get to around 260º. I now print ABS at 255º as well, for the same reason. Much better bonding between layers.

Even then I think you'll struggle to hold 2 bar. The porosity of the plastic etc means it's an uphill battle. With the appropriate use of superthin epoxies sucked through your part you might manage it but I'd never trust it.

I make a lot of ancilliary dive equipment with my printer but so far nothing in the loop or pressurised gas circuit because of this porosity. So if you DO manage to get it happening, please share - it would open up a whole new bunch of opportunities for a lot of people!

[milp]

Awesome, thanks for all the input!

So I'll wait with this project until I have enough money to afford both a spool of nylon and an E3D All Metal Hot end. Right now the budget is rather tight. Does an all metal hotend have any downsides compared to the stock peek hotend? Is there a reason they didn't include it in the first place?

I'd imagine that getting a part water tight would only be a matter of thick walls, slow print, very thin layer thickness (maybe?) and replacing the infill with solid mass and a high enough temperature?

In the meantime i might play around with an ABS part just to see how well it performs in terms of water tightness and pressure/temperature stability.

[Captain Starfish]

The E3D and other metal heads tend to be expensive (compared to the SeeMe ones) and it's just one of the areas SeeMeCNC have used to produce printers like these for a grand instead of twice that. The only downside I've really heard for the e3ds is that they have a propensity for jamming PLA.

Water tight (at pressure) does seem not come from thick walls, slow print, very thin layers etc unfortunately. Whilst you can print a vase that will hold water pretty easily, crank the pressure up to two bar and things go south very quickly. Best option I've seen so far is to print the vessel with a nice wide infill pattern and then inject the guts with silicone or something.

[Nylocke]

If you're filling it couldn't you go the ABS route? The ABS may deflect a little but, but the filler should act as a "frame" of sorts right?

[Captain Starfish]

Abs will get soft at the top of the application's temp range. You'd be better off in that case making a mould using ABS and then injecting glass filled epoxy or similar into the mould, allowing a cure then pulling it out of the mould.

Except ABS will probably go soft and distort from the heat generated during curing. Back to nylon (also makes it nice and flexy/easy to pull the part).

[jdurand]

For sealing stuff, you might look into vacuum impregnating* the parts with an epoxy, varnish, or other sealer.

* no, not sex in space. You submerge the item in a fluid and then pull a vacuum on it to make all the bubbles expand and come out. Then before it sets you let the pressure back in and the fluid is sucked/pushed into all the openings. This is commonly done with transformers to keep the windings from vibrating and shorting.

[Toysrme]

not sure if this is still a project for you, but I'd use nylon, 100% fill printed at very high temps and then epoxy seal it. be warned tho, epoxies are brittle and de-cures with heat so it could crack if deflected and it will soften as the temp rises. doesn't mean it will, but i would test first.

FWIW many radiators & heater cores are capped with GFP.