Is 3D printing being held back by an invalid patent?

190 points · K0balt · 27 days ago

Parts made using the FFM (FDM) process are stronger in some directions than in others. This is due to imperfect adhesion between printed layers. This directional or anisotropic structural strength is a significant limiting factor for the structural integrity of 3d printed parts made with the common FFM process.

A method to drastically reduce this effect is described in an expired Stratasys patent, US1997/5653925A. As of this writing, I have not seen this feature implemented in any of the common open-source slicers. I would have expected this now-public-domain knowledge to have made its way into the slicers we use since the patent expired in 2017.

With some investigation, I believe this may be because of the 2023 patent US2023/11813789B2, to my knowledge only implemented as a proprietary in-house product of a 3d printing service house which appears to make the same claims illustrated in the 1997 Stratasys patent.

I am not expertly versed in patent law, but this patent would seem to have been granted in error. The fact that the 2023 patent actually references the Stratasys patent from 1997* makes the issuance of this patent even more baffling. At any rate, this seems like a low-hanging opportunity for a significant improvement in print strength that could benefit millions of users.

*The 2023 patent references the 1997 Stratasys patent as “teaching a process for adjusting the deposition rate .. to provide a predetermined porosity rate” but neglects to mention that the core claim of the patent was the staggered bead heights claimed.

In referencing the 1997 patent the 2023 work also gives a single-digit error in the patent number, as well as other “minor” errors in other patent numbers referenced in the patent. These misleading references could have impeded the examiner’s role in determining the validity of the patent.

https://patentimages.storage.googleapis.com/08/f6/2b/d3d9964...

https://patentimages.storage.googleapis.com/ea/e7/3c/2b836c9...

Looking up the 2023 patent filer leads to this:

https://www.addmangroup.com/

42 comments
atrettel · 26 days ago
This comment is not legal advice. This comment is merely for educational purposes.

The quote that you have about the 1997 patent, namely "U.S. Pat. No. 5,659,925 teaches a process for adjusting the deposition rate..." is from the specification. That is written by either the inventors or more likely the attorneys filing the application. The specification is not legally enforceable or binding. It is supposed to disclose enough information to let somebody reproduce the claimed invention. As a matter of practice, the specification can say almost anything it wants, including non-enforceable things.

Only the claims are legally enforceable. I suggest taking a closer look at the claims and seeing if these are problematic for your application or not. You may want to consult an attorney if you have further questions.

You can look up the patent examiner's reasoning for allowing the application here:

https://patentcenter.uspto.gov/applications/17667081

Click on "Documents and Transactions" and look for "Notice of Allowance and Fees Due". Also look for the "Non-Final Rejection" for additional information from the examiner from an earlier version of the application.

I should note that it does not appear that the patent examiner considered the 1997 patent directly relevant because they did not cite it in any of the office actions or specifically the PTO-892 forms (search the documents page for 892 to see what I'm talking about). However, they likely did at least look at it since it is listed in the specification.

Again, if you have further questions, you really should consult an attorney. This is not a good forum for this kind of discussion, in my opinion.

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Meleagris · 26 days ago
bb88 · 26 days ago
The real problem is that patent system seems ripe for abuse. Even if the "invention" is not a valid patent, companies want to patent it anyway, as to force the other side to expend resources to prove it's not valid.

There's a couple Bambu Lab patents that probably should not have been granted with prior art in open source.

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manuel_w · 26 days ago
This post seems very well researched. It's great that OP has brought this up. If we could push further the state of the art in 3D printing, by simply no longer adhering to an (now proven to be invalid) patent, it's a no-brainer to do so.
dogma1138 · 26 days ago
Non linear slicing is also patent protected but there are some projects that modify slicers to do it.

I did some experiments with bricklaying using a macro in S3D and in all honesty it’s not worth it.

It doesn’t work all the time causes a lot of slicing edge cases on complex models and the cost in print time outweighs any strength gains.

For properly dried filament and a heated chamber the adhesion gains are within the margin of error.

I can also quite confidently say stratasys also currently does not implements it in GrabCAD* which is their slicers/CAM software and I’m not aware of any of their partner slicers/CAMs that do it either.

*There is a chance that they do it as a post processing step in their printers especially the super high end ones either globally or for select locations within the model but I’ve handled quite a few FDM prints on Stratasys machines and I’ve never actually seen it in a production model.