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3D print grow lines

Hello I’m new here and a jeweler fresh out of school for about a year and I just landed a good job as a bench jeweler. A huge issue I’ve been having is removing the grow lines from the 3D printer on all the casting. Currently I am working on some earrings that have a very small pavé area and I have no idea how to clean the seats and take the lines out as they are very small. Any information would help a ton. Thanks.

A problem I encounter too.

Printing the model at a different angle will often remove the lines or force them to appear in an easier to clean area. If you have a laser welder you can polish down in the recesses with a weak wide beam.

I never tried using the laser to polish large areas, which is what is required to remove what I call a fingerprint pattern that is created on every surface of the CAD CAM castings being given to me to complete.
I will give it a try though.

Using the laser is an interesting idea…however, I don’t have one…I wonder if the low tech way would be using various silicone polishing wheels, points, etc. in a Foredom or similar handpiece. These lines, which seem to occur in most 3D printed resins (by report) are a problem in finishing any jewelry cast from these models. Apparently there are some formulas with more wax in them that do not have this problem…but perhaps this requires a more expensive printer?? Interested in comments on this. Are there some ways to work on the resin model before casting that will remove the lines?

Another expensive way to deal with these lines is to mill a wax to cast from your computer design, but this is, well, expensive and more labor intensive than 3D printing.

I do not know if you guys are overthinking things a tad.
Of course if it is one off, no problem you can do most all.
If it is high volume production, then angles, dipping into hot wax and so on have to be considered.
I’m not in the realm of “production” so I plan to use lacquer and polish until smooth before casting.
Then there should not be any lines.

You will of course have to consider, what will cost more labor, polishing first or after.


Welcome to Ganoskin!

I am not sure what material you are printing with but I have worked with castable wax resin and high temp resins so far.
I just use 1000 grit sanding stick (clean paper) and sand them prior to investing or molding. Wear a mask to protect yourself from the debris.

Good luck


I am curious to know…what 3d printer is being used?


It is usually possible to sand out build lines on resin castings, if they aren’t too delicate. But if it’s not, the best thing to do is cast them, grind out any lines that show, then re-mold the finished casting and make wax duplicates, so that any future castings won’t have that problem.

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I do not often get to see the “waxes” printed from the CAD designs I am trying to complete, just the castings by a house or two in NYC that a friend passes on to me to finish and set for her.
Her designer is a very accomplished artist and friend from her homeland in Russia.
He is an accomplished wax carver, but he is quite new to CAD.
I believe he pushes things a bit to thin, because that is easy to do on a computer.
His designs are extremely fine, very thin, and I am told the resulting printed pattterns, in whatever material they are being printed in are far too fragile to do any prefinish work on.
Several of the actual castings handed me have been so thin that I cannot possibly remove the printed “fingerprint” texture from inside and outside of a shank, without removing far too much metal, resulting in failure.
The problem begins with thin designs, and is compounded by printer chatter of some sort.
The results can all too often be a miserable failure by the time the castings reach me.

I have been doing CAD,CAM, casting, clean up and setting for about 10 years. The lines you are talking about I refer to grow lines. They are produced at whatever the printer Z resolution is set to. In my case using a DPL printer that is 30 microns or 30 um. These grow lines are produced each time the printer produces a 30 micron slice. My printer will go to 20 um but that adds to print time and makes more grow lines. The print can be angled but there will still be lines just at a different angle. I have tried just about every thing available to mask with out success. When possible I will tool the print to clean up as much as possible. Another option as mentioned is to mill instead of print. If these are production pieces I would scale up in CAD
then cast and clean up, then make RTV mold. I am starting to see a lot a new pieces and semi mounts where you can see grow lines that were not cleaned up.

Hope this helps

Hi Craif
If you want to explore a growing blog, I might have “a few essays“ for you to look into! Just go to
Hoping you might find an essay that you need. Just ask the 54,850 jewellers in the 81 countries. No charge to access it.
If not, that could be another topic for me to write about!
Welcome onboard, we are a real fantastic group of helpful folks.

“Gerry, on my busy iPhone”

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Sometimes CAD designers without a lot of bench experience will make models that are not correct for production. I am attaching a link to Stullers guidlines for proper design.

If the link doesn’t work just Google " Stuller production standards. "

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thank you for your interesting post! and congratulations on your new career!

a few quick questions:

when you say “clean the seats”, do you mean the stone seats were “cut out” in the CAD model and then printed?

  • will they not just be “cleaned”’when you bur the seat to fit the stone?
  • i think cutting the pave seats is needed for the render to make the diamonds whiter…but not needed for the printed model…i guess it is a cost/ benefit analysis…does cutting the seats in the model save time? or improve quality?…

when you say “very small area of pave”, do you mean that the bead prongs and side walls were done in the CAD model and then printed?
-will you be setting these stones?
-i personally think this type of work might be better done in the stone setting phase, rather than in the CAD model stage.
-meaning just put pilot hole divots in the CAD model (or not) and do the drilling/ burring/ bright cutting/ bead raising in the actual metal casting…


Hi again,

i just wanted to mention something i was told by 3D CAD printing peoples that i occasionally use…

(I do not own 3D printers or do any printing…)

some printers print certain things better than others, so it might be helpful to find out what printer(s) are being used for each project…(ie: when it comes out good…or when it comes out bad…so you can gain knowledge)…and which printers you have access to…

how the model is oriented during printing can affect where the grow lines develop…so you could ask/ learn about that too

I believe the resolution of the printers will determine the size of the grow lines…?…so you could ask about that too…

just my musings


I’ll chime in here.

As has been stated, the lines are due to 2 particular aspects of 3d printing: layer height (for both wax and resin printers), and resolution (for DLP/LCD printers).

Generally speaking, the lines you see with the naked eye on a resin print aren’t actually the layer lines. At 30 micron, those lines are just over 1/1000 of an inch. They can been seen fairly easily under magnification. These lines are actually really easy to get rid of through carefully calibrating the printer settings, and tuning it for each resin you use.
The other lines, however, are a bit more difficult to remove. These are the lines that look like growth rings on a tree, and are evenly spaced, anywhere from .5mm to 1mm apart. They are caused by the printer trying to print a curved surface with stacked flat planes.
This can be somewhat remedied. You need to know the resolution of your screen, and the layer height being printed, then do a bit of trigonometry to find the ideal angle at which to orient your models. This changes with just about every printer (for example, one of ours has an ideal angle of 41.3 degrees at 30micron, and another has an ideal angle of approx 47 degrees).
Obviously, this would be super simple if all we were printing were boxes, but jewelry has a bit more going on. So my methodology is to analyze the piece, and orient it such that the most critical/hard to reach places end up right around that angle.

As far as removing them once they’re there: a laser works great, as well as just good old elbow grease and sandpaper. Also, if you have access to mass finishing equipment, it can do a pretty good job as well.

Hope this helps!

Wow, what a wonderful file of useful information. I’d suggest printing out all of those 9 pages.
So much to learn, don’t just scan the texts, but learn and then experiment each topic as best as you can.
Regards to everyone!

“Gerry, on my busy iPhone”

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