3D printed part opinion needed

For those that have not seen my build "Europa TCST" I am currently upgrading the rear roller bearings to tapered bearings and we printed some seal holders with PLA.... then someone asked if that is oil resistant so I have one soaking in gear oil to confirm that...then someone mentioned temperature... and I checked it in 140 and 170 degree water (supposedly normal wheel bearing temps) and it is somewhat pliable. It's not like if I hold it out it droops under it's own weight and the part is constrained by the upright, trailing arm mounting area and the brake backing plate. It just holds a "seal" to contain gear oil under no pressure. Should I print with a better material or am I over thinking it and just need to press on ?

I would use something that deals with temperature better--PETG is fairly good about not reacting with stuff and better with high temperatures, plus it's easy to print. But ideally I'd think those parts would be nylon.

Thanks Tom, we are looking at that or ABS...

Do these bearings have rubber seals that you are holding in place with the PLA part or is the PLA part your seal you are relying on to keep your grease in the bearing?

The printed part is holding the seal.

TurboFource said:

Thanks Tom, we are looking at that or ABS...

ABS reacts to hydrocarbons, so it probably isn't the greatest for something in close contact with seals that hold back grease.  I second Tom's recommendation of PETG at a minimum or nylon.

Nylon preferably a fiber reinforced nylon would be my recommendation. Service temp on nylon as with any thermoplastic will vary with the base resin however most glass fiber reinforced PA6 nylons will be stable at 100°C (212° F) for a long life, 150-180°C for short durations in some cases even.  The fiber reinforcement (glass or carbon) helps with creep over time and thermal resistance.

As for PETG and ABS, they are both great materials that are much easier to print than nylon but they fall short for this application.  80°C (176°F) is the glass transition temp of PETG at no load, it's service temp is actually lower than this at 70° C (158°F) per ATSM D648.  That's too close comfort in my book.  Normally I would recommend ABS for automotive uses and it should hold up to the grease just fine. However, if you ever clean this assembly with brake cleaner the acetone in the brake cleaner will dissolve the ABS part.

My son says we can print PA and I am using gear oil for it's higher rpm rating and service life.

In that use, PLA probably would warp and fall apart over time.

I use carbon-reinforced PETG for this kind of part and it's really nice.  Actually prints nicer than my regular PETG, which is a bonus.

+1 to at least PETG

I've pretty much switched to printing in PETG as-standard these days, unless I need something fancy.

If I can thread-jack a bit, anyone have recommendations on specific brands of fiber reinforced PETG / Nylon / Fiber reinforced Nylon? I've been wanting to experiment with them.

In reply to Nukem :

I've had good results with Sainsmart ePA carbon fiber. It's pretty cheap as far as nylon goes and is pretty stout stuff.  I've also had good results with PA6-GF30 from 3DXtech.  A lot of the 3D pewpew guys like Push Plastics for Nylons and PLA+ I have only ever used their ABS.

In reply to Nukem :

I've had great luck with Atomic carbon-filled PETG.  It's not cheap at $50/kg, but it's very consistent and prints beautifully.

TVR Scott said:

In reply to Nukem :

I've had great luck with Atomic carbon-filled PETG.  It's not cheap at $50/kg, but it's very consistent and prints beautifully.

Going to second this. I use it all day at work and it is surprisingly resilient to oil and chemical spills. 

Thanks all!

Now is your chance to buy an inexpensive lathe. 

You could probably turn those in a lathe faster than you can print them. 

Again from the thermal aspect alone, PETG is a poor choice for this application. 

To be completely honest I do not understand the fascination everyone has with PETG, not just here but the 3D printing community in general.  I've never been impressed with it's properties and I've actually found it to be harder to get dialed in than Nylon or ABS.  It's not commonly used in injection molding outside of water bottles so I really struggle with it's existence as an "engineering" filament in 3d printing.  If you want a part use PLA. If you want a part that can handle heat use ABS/ASA.  If you want a part that is chemical resistant and/or heat resistant use Nylon. Sorry, end rant.

In reply to Toyman! :

If I had a lathe I would be making them out of aluminum!!

The problem is that no melt printed plastic is suitable for high temps or else it couldn't be printed. You'll have to look at resin-based stuff, but I'd just stick with metal.  Just going off this site (https://all3dp.com/2/the-best-printing-temperature-for-different-filaments), PETG prints at 220F.  If someone tells me that "normal temp" for a bearing is up to 170F, then, knowing my car gets driving hard in North Carolina, I'll design for over 200F. But again, that's VERY close to the temperature at which this stuff flows out a nozzle. Even if it isn't liquid at 200F, it will be significantly weakened. 

As Tom said above, Nylon has a significantly higher nozzle temp at ~250F. But really, if your gut says lathed aluminum, go with lathed aluminum. 3D printing is great for stuff that can't be done with subtractive methods, but for flat-ish circles, it is rarely going to be the right choice. 

EDIT: misread the temps on that site as F and not C, so the margin isn't as tight as I thought. I'd still have it turned, but printing could still be useful for test fitting 

In reply to cyow5 :

The temps you quoted are correct, but actually Celsius. Still, you're not wrong: Plastics that can easily be 3D printed also have low melting points. 

RacetruckRon said:

Again from the thermal aspect alone, PETG is a poor choice for this application. 

To be completely honest I do not understand the fascination everyone has with PETG, not just here but the 3D printing community in general.  I've never been impressed with it's properties and I've actually found it to be harder to get dialed in than Nylon or ABS.  It's not commonly used in injection molding outside of water bottles so I really struggle with it's existence as an "engineering" filament in 3d printing.  If you want a part use PLA. If you want a part that can handle heat use ABS/ASA.  If you want a part that is chemical resistant and/or heat resistant use Nylon. Sorry, end rant.

I 100% agree (and print almost exclusively in ABS or carbon-reinforced Nylon), but PETG does have a place in the world since it can be printed easily on consumer printers. An Ender 3 will do PETG easily all day long, but struggles with ABS or Nylon. 

Tom Suddard said:

In reply to cyow5 :

The temps you quoted are correct, but actually Celsius. Still, you're not wrong: Plastics that can easily be 3D printed also have low melting points. 

I swear it said F on my computer! ;)

There is one huge, priceless advantage to 3D printing these parts, it involves my son helping on this project! Even if the results are not optimal, the time spent over the Christmas holidays figuring it out together will be optimal!

We are going to try to print with carbon fiber reinforced nylon....someone on another forum

mentioned there could be galvanic corrosion between the carbon and aluminum housing.

Is this a real concern ( I didn't think gear oil was an electrolyte?)?

Thanks for all the input!

Galvanic corrosion between carbon fiber and aluminum is a thing.  When I did aerospace composite work, we would always laminate in a layer of fiberglass anywhere something would bolt to a carbon part.  And the aluminum got plated.

Not sure about whether or not that would be a problem in this case.  Printing the part a little small and adding a little bit of epoxy adhesive would likely do the job.

They are glued in with high temp sealant