How Stable Is The Plastic Used In 3D Printing?

[oldcarfan]

I've recently bought a few smaller 3D pieces, but I'm looking at getting some bodies. I know it's still fairly new technology, but has anyone found any issues with larger printed pieces? Does it look like it will have any long term issues? A couple of resin bodies I bought 15 years ago show a slight twist and I was wondering if this might do the same.

 

[yh70]

17 hours ago, oldcarfan said:

I've recently bought a few smaller 3D pieces, but I'm looking at getting some bodies. I know it's still fairly new technology, but has anyone found any issues with larger printed pieces? Does it look like it will have any long term issues? A couple of resin bodies I bought 15 years ago show a slight twist and I was wondering if this might do the same.

 

i have been buying 3D parts & body's since they started printed them. as far as long term issues its way to early in the game to tell it they will be issues in years to come..

[Rick L]

3D models are printed by FDM (fused deposition modeling) or SLA (stereo lithography). Most FDM parts are printed with styrene and are fairly stable. All SLA  parts are formed by a UV sensitive resin, are hygroscopic and expand over time. Don’t confuse the SLA resin parts with your cast resin  body parts that are molded with a two part polymer. These are also fairly stable but can warp if not properly stored over time. Like sitting in a box jammed with other parts.

[espo]

I have found some parts to be a little more on the brittle side than the normal kit plastic. As Rick L points out there are more than one type of materials being used and I really don't know which resin was used on the parts I had. I think like anything else there will be a learning curve for both the producers of 3D parts and the consumer. The big advantage is that for a reasonable price you can get parts to build something that you wouldn't otherwise be able to based on the kits available. 

[Ace-Garageguy]

As yh70 said above, it's way too early in the game to have identified the long term issues.

Consider that these materials were developed for rapid prototyping, not specifically for production. Prototypes don't have to last forever.

Also consider the now-well-known issues with tire melt, some tires literally crumbling, old acetate bodies shrinking and warping and crumbling as well, some styrene kit plastics becoming brittle and crumbly...it becomes apparent that many problems with material degradation only come to light years or even decades after the parts were made, and artificial aging cycles simply do NOT duplicate the effects of time.

And remember that many commercial products made from a wide variety of plastic resins deteriorate to the point of sticky, gooey uselessness over time, even if stored sealed in the original packaging.

The facts that SLA resin is UV-sensitive by design, and is hygroscopic, both would hint at instability over the long run.

EDIT: From my own experience, it appears that acetate bodies that have been painted both inside and out survive much better than those that haven't. It might be a good idea to paint the insides of SLA bodies as well.

Edited September 27, 2023 by Ace-Garageguy

[jaftygas]

5 hours ago, Ace-Garageguy said:

As yh70 said above, it's way too early in the game to have identified the long term issues.

Consider that these materials were developed for rapid prototyping, not specifically for production. Prototypes don't have to last forever.

Also consider the now-well-known issues with tire melt, some tires literally crumbling, old acetate bodies shrinking and warping and crumbling as well, some styrene kit plastics becoming brittle and crumbly...it becomes apparent that many problems with material degradation only come to light many years or even decades after the parts were made, and artificial aging cycles simply do NOT duplicate the effects of time.

And remember that many commercial products made from a wide variety of plastic resins deteriorate to the point of sticky, gooey uselessness over time, even if stored sealed in the original packaging.

The facts that SLA resin is UV-sensitive by design, and is hygroscopic, both would hint at instability over the long run.

EDIT: From my own experience, it appears that acetate bodies that have been painted both inside and out survive much better than those that haven't. It might be a good idea to paint the insides of SLA bodies as well.

That is for sure Ace, you have a very practical mind. It is the obvious stuff we as humans seem to overlook. 

[MeatMan]

Resin tech is changing rapidly, so the resin used in the past is not the same as what is being put out today.
I took a course in 3D printing before I put down the money for a printer, and learned resins developed today are made for for longer life.
I had a body printed over a year ago and its still white, and still in as-printed condition. It was printed in standard resin. But yes, I'd say the jury is still out on how long it will last.

[Carmak]

My company bought a 250k Stratus Systems SLA in the mid 90's not long after I started. The resin was a semi transparent clear with an amber tint (the only resin available at the time). I have pieces from that era that look like the day they were printed and are not brittle at all.

We have had our current 30K resin bed printer a year or so and some of the parts printed on it this year have become brittle already. I know that once a SLA part is cured it typically do not age well in daylight.

I agree with other that IN GENERAL FDM parts are more stable over time than SLA part but specific SLA materials could be as stable as FDM. 

[Ace-Garageguy]

29 minutes ago, Carmak said:

We have had our current 30K resin bed printer a year or so and some of the parts printed on it this year have become brittle already. I know that once a SLA part is cured it typically do not age well in daylight.

Here's the problem. Think about it.

Most "plastics" intended for consumer markets have "UV inhibitor" additives so they don't deteriorate so fast in daylight.

SLA resins generally DEPEND ON UV TO CURE, so you can't really add a UV inhibitor, now can you?

Maybe, just maybe, an SLA resin that cures when exposed to a very narrow part of the bandwidth of UV light could be developed, and UV additives that DON'T block the part of UV needed to cure, but DO block other parts of the UV spectrum that accelerate aging in daylight, could be developed for it. Sounds kinda tricky.

There are other possible solutions, but until the problem is thoroughly and reliably sorted by somebody getting paid to do it, painting your 3D parts to protect them from UV is probably your best bet.

[Carmak]

1 hour ago, Ace-Garageguy said:

Here's the problem. Think about it.

Most "plastics" intended for consumer markets have "UV inhibitor" additives so they don't deteriorate so fast in daylight.

SLA resins generally DEPEND ON UV TO CURE, so you can't really add a UV inhibitor, now can you?

Maybe, just maybe, an SLA resin that cures when exposed to a very narrow part of the bandwidth of UV light could be developed, and UV additives that DON'T block the part of UV needed to cure, but DO block other parts of the UV spectrum that accelerate aging in daylight, could be developed for it. Sounds kinda tricky.

There are other possible solutions, but until the problem is thoroughly and reliably sorted by somebody getting paid to do it, painting your 3D parts to protect them from UV is probably your best bet.

Bill,

In general, I fell we are on the same page here.

There was something "special" about that old school amber SLA resin that after 20 year it did not degrade in UV.

Aside from UV damage I am also concerned about stability of SLA resins. If UV is the only issue, then a good primer solves the problem  

[jaftygas]

On 9/26/2023 at 5:07 PM, MeatMan said:

Resin tech is changing rapidly, so the resin used in the past is not the same as what is being put out today.
I took a course in 3D printing before I put down the money for a printer, and learned resins developed today are made for for longer life.
I had a body printed over a year ago and its still white, and still in as-printed condition. It was printed in standard resin. But yes, I'd say the jury is still out on how long it will last.

Where did you take a course in 3D printing? I’m very interested in learning this, so that I can start using mine.

[Ace-Garageguy]

For what it's worth, I've already noticed some deterioration of printed parts.

One case in point is a Hilborn injection manifold. Beautiful part, still in it's original package (purchased so I'd have it if needed some time in the future), and it's warped to the point that it may not be usable.

I don't know if the part can be corrected with the old hot-water treatment useful on resin and styrene, but it's annoying as all get-out to have paid for a not-cheap part, and see it become useless.

EDIT: I came across it last night while looking for something else.

It's definitely not more than 2 years old.

Edited October 3, 2023 by Ace-Garageguy

[MeatMan]

On 9/28/2023 at 4:30 PM, jaftygas said:

Where did you take a course in 3D printing? I’m very interested in learning this, so that I can start using mine.

I don't see the one I took but here is the hub.   https://www.coursera.org/courses?query=3d printing

[jaftygas]

8 hours ago, MeatMan said:

I don't see the one I took but here is the hub.   https://www.coursera.org/courses?query=3d printing

Hey thanks Dennis. 

[stitchdup]

On 10/1/2023 at 4:32 PM, Ace-Garageguy said:

For what it's worth, I've already noticed some deterioration of printed parts.

One case in point is a Hilborn injection manifold. Beautiful part, still in it's original package (purchased so I's have it if needed some time in the future), and it's warped to the point that it may not be usable.

I don't know if the part can be corrected with the old hot-water treatment useful on resin and styrene, but it's annoying as all get-out to have paid for a not-cheap part, and see it become useless.

EDIT: I came across it last night while looking for something else.

It's definitely not more than 2 years old.

the hot water trick still works, but you need to use water closer to boiling than we do with resin or plastic, and its has to be cooled immediately with cold water or it may go back to its original warped state. I find it works best to do it in smaller stages and one section at a time as the print goes floppy. I found this out when a set of door cards i printed for a 32 coupe were too flat to fit. I figured i had nothing to lose as i printed it myself so if it went wrong i could print more. I also placed the printed parts on a sponge before pouring water out the kettle over them. This keeps the heat more consistent on small parts and cools the parts quicker when the cold water goes on. I have noticed that thinner parts are more inclined to warp

[Repstock]

My problem has been spongy bodies. Some distort just by handling them. I've had to back bodies with styrene to help it keep it's shape. I've also noticed the resin will distort at lower temperatures than two-part resin. I'm amazed at the fidelity that can be had with 3D printing. Perhaps the next step is to improve the material used to print.

[stitchdup]

4 hours ago, Repstock said:

My problem has been spongy bodies. Some distort just by handling them. I've had to back bodies with styrene to help it keep it's shape. I've also noticed the resin will distort at lower temperatures than two-part resin. I'm amazed at the fidelity that can be had with 3D printing. Perhaps the next step is to improve the material used to print.

you could use some extra resin and a brush to thicken up the bodies. obviously you'd need a uv light but they can be had on amazon for less than a fiver. its just a case of building it up by brushing it on and using the light to cure it. its pretty quick to do to as its can be cured in less than a minute so if your going to be working with a lot of printed bodies its a convenient filler to have and there no compatibility issues as its the same product. you may have to do it over few days as overcuring the resin makes them brittle but leaving time between could avoid that.

[peteski]

FYI: Natural sunlight is an excellent (and free) source of wide-spectrum UV light. Of course it is not available 24 hours a day, and also depends on the weather conditions.   Best is direct outdoor exposure since some glass could filter out some UV rays.

Edited October 3, 2023 by peteski

[bobss396]

We did a lot of 3D printing at work. At first, mainly prototype parts before we had them machined up. Fits and tolerances were excellent. We later graduated to making assembly tooling as well, we found the parts we could use as-is with no further machining. Threaded holes, we bonded in threaded inserts. Some of the inserts like Dodge Serts we pressed in.

I buy a lot of 3D parts. My main gripe is that distributor holes and also those in master cylinders are often too small for even a .016" wire. I use a lot of braided lines that measure .020", good luck opening those holes even by .002-.004". In thin sections, the material is quite brittle.

It would be easy enough to design-in a larger hole for easier assembly and establish a glue-line. This shows that many parts makers are not the actual consumers.

[peteski]

6 hours ago, bobss396 said:

I buy a lot of 3D parts. My main gripe is that distributor holes and also those in master cylinders are often too small for even a .016" wire. I use a lot of braided lines that measure .020", good luck opening those holes even by .002-.004". In thin sections, the material is quite brittle.

Are we talking about 1:25 scale?  0.016" ignition wire would scale up to 0.4" in 1:1.  That's rather thick for spark plug wires. Maybe some specialized high-performance wires?

[bobss396]

On 10/4/2023 at 4:16 PM, peteski said:

Are we talking about 1:25 scale?  0.016" ignition wire would scale up to 0.4" in 1:1.  That's rather thick for spark plug wires. Maybe some specialized high-performance wires?

Most of my wire wrap stock is around .016-.018". I find it to be just right for me. I drill distributor holes to .020-.022" and the plug holes in the heads to around .026" since they get paint build up. Or I have to chase them after paint. Lately I have been drilling them even bigger, so I can slip the plug boot wires into the heads, gives the wires more support.