I want to take this time to thank a youtube subscriber for asking me about prong design, and wondering why his prongs don’t appear to print correctly on his 3d printer.  This is a common problem, and it has to do with three factors.  These three factors include; the size of the prong, both width and height, the location of the prongs on your design, and most important, the particular settings you use with the resin you are printing the item.  

Let’s try and cover these in a bit more detail.

Properly Sized Prongs!

When speaking in terms of the size of a prong, it should be rather proportionate to the size of the gemstone you are setting into the prong(s).  If we combine the CAD design with 3d printing, we not only have to take into consideration, the gemstone size, but the printing process of the design.  During such a process, we will incur a shrinkage rate depending on the resin you use, between 2% and 8% under typical and reliable settings!

Along with this article, I’ve also produced a video tutorial to go along with it.  The video follows this section, and covers all three topics.

Now, lets get back to the size of a prong.  

As mentioned, it is important that the size of the prong be large enough to hold the gem in place, with consideration to wear, future repair, and durability.  This is a flaw I see many times whenever I order a stock piece from a vendor.  Most of the time, I feel that the prongs are slightly smaller then they should be, and when setting stones in these mountings, I run into situations where it is difficult to push the prong over the gemstone to the point I’m happy with its expected lifetime.

So, looking at the photo above, we see the same ring, with two different size prongs.  The Ring on the Right, has a prong that was designed to be .7mm wide, the Ring on the Left, has a prong width of 1.2mm.  If you look at them closely, you can see that the Ring on the Left has a much more durable and proportionate size of prong to fit the stones we are setting.

The ring was designed to be a size 6, and the proportions of the stones and prongs also must fall into your design proportions.  As in the three examples, you can see that both the standard resin (grey) and the castable resin (dark green) show this factor.

The photo above shows the three prints, one each with the proper size prong proportions, and the third, with prongs that are much too small for the ring design.

In addition, we Must factor in the rate of shrinkage during 3d printing, especially with castable or waxy resins.  Normally, I would import my model into the printer’s slicer, and increase its size by approximately 2%.  This almost always covers the loss in size due to printing.  However, you should always run a test on your printer, and especially with the specific resin you use, as they always vary, and in some cases, the resin, even from the same manufacturer, may print differently.

Now, lets cover the last important factor regarding the size of the prong you design.  Casting!  YES!  It is true, after you’ve had burnout in your furnace, and the model leaves a void in your investment, you will have to deal with errors in the casting.  Sometimes, the molten gold, silver or other material you use, doesn’t quite find its way to each space left in the investment material, and you may get sections of your casting that have errors, (little places where the metal didn’t flow well).  If you have a slightly larger prong, or one that protrudes higher from the surface, you won’t have to deal with the possible loss of a complete prong that may ruin your casting.  It is much easier to file down a large prong then it is to add material and shape it correctly after casting!

Watch the video here!

Prong Location

The location of the prong, or prongs you design into your profit making jewelry, is important too.  You have to take into consideration that prongs, for better or worse, greatly affect the visual look of your design, and in some cases, can be over-bearing.  The location of your prong must not match the look you are seeking, but more important, create an item which will stand up to long term use, abuse, and future repair.

As you can see, in the photo above, the look I was going for was to create a prong that allows the gemstones to stand out, but limits the number of prongs that may take away from the gemstone(s) you are setting.  

While there are many factors to consider when creating your perfect design, such as metal color, gemstone color, shape and size, is that the part of the ring, usually the prongs, that hold the stone in pace, must not detract from the beauty of the stone.  There are many other factors, and I could write a book about these, but common sense and appealing visual styles will stand for themselves.

To give you an idea of why I drew up this ring the way I did, let me explain.  First, in my mind, I imagined that I’m setting three stones, the center stone will be a .75 ct Diamond.  The two side stones will be .50 ct each, blue sapphires.  The next factor that I imagine, is the color of the ring.  With that combination of stones, and to make a ring that will appeal to more potential buyers, I would cast this in white gold, or for that discerning client, platinum.

The next factor is of course, the prong position.  Here, of course, you see that I’ve placed four prongs, of good size (1.2 mm), and made them high enough for printing and casting.  When designing your item for 3d printing, you also have to take into account the finish work after casting.  I can use a diamond bit bur to cut the prongs, leaving them very strong after cutting, to still hold the gemstones for a long time.  After placing the stones into the settings, I still have a lot of material left to both cut them down, and use a cup bur or graver to push the prongs properly over the stones.  

The design above, shows a nicely proportionate and symmetric style.  One row of prongs, holds the stones into the cutouts created in the ring shank, allowing for more gemstone to be visible.  While the prongs are aligned around the circumference of this ring, I could have easily created two prongs for each stone, set laterally and given this a completely different look, but still creating a very durable and appealing look.

Hopefully, you understand now, the design style of prong placement and how important it factors into the items you create, whether for yourself or your customers.

3d Printer Settings, Important Factors

So, I’m hoping you made it this far, because this is where I finally answer the most important question from my YouTube Subscriber.  What printer settings should you use…

I’m going to keep this as simple as possible, because of course, settings are going to be slightly different depending on both the 3D printer and the type of Resin you are using to print your design after you’ve created it.

In the video above, you will see the settings I used in the ChituBox Slicer (version 1.5).  This slicer comes with many different sla/dlp/lcd printers using a UV projector.  

The nuts and bolts of this process is important to understand because different Printers have different power outputs for the UV lamps.  For this instance, I’m going to stick with the Elegoo Mars and the Anycubic Photon.  These printers are practically identical, use the same lcd display, and almost identical UV Projection.  For a reference, the power output on the Anycubic Photon and the Elegoo Mars is approximately 25 watts from the UV lamp.  Keep that in mind if you are using a more powerful UV printer.  The more output wattage, the quicker you can print your design.

Now, lets go through the settings for the printers…

Elegoo Mars, Anycubic Photon Standard Resin

With the setting above, the print time should be approximately 3 & 1/2 hours.  Make sure to have the antialiasing turned on to about 4, although I see little difference in the prints no matter this setting, and your design should print well.  






I printed two rings, with each of the three prints…  one was printed vertically, and the second printed at a 45 degree angle, and there is little difference with the standard resin.  I also printed these with “thick” supports, and only used the recommended supports from the ChituBox slicer.  I did not add any additional as it seemed to put the correct supports in the proper places with default settings.


Elegoo Mars, Anycubic Photon with Castable Waxy Resin

Using the settings above, the castable prints took approximately 8 & 1/2 hours.  The castable resin prints, like printed with slightly more shrinkage as expected. This is caused mostly because of the wax content of the castable resin.

Additionally, the same file was used, with one ring vertical and the second at a 45 degree angle.

The results were perfect on both resins, and you should get the same results.  

Gem sizes vary from 0.2ct to 3ct. 70-80 pieces per...
Gemstone :- Green Moissanite Carat Weight :- 2.20 Ct. Measurement...
Gemstone :- Green Moissanite Carat Weight :- 1.50 Ct. Measurement...
Immaculate palm stone, AAA grade lapis lazuli used to make...
Lets sum this up

Hopfully, your results are the same as mine.  Practice with several different styles and sizes.  Don’t be afraid to try different design styles as you will eventually find those that work for you, your 3d printer and your customers.

Keep in mind that the size of prongs should be proportional to the item you are designing and the gemstones you intend to set.  Placement of a prong will change the look of an item dramatically, so again, practice.

The settings you use on your Elegoo Mars or Photon will vary according to the resins you use.  I prototype in Grey Resin because customers seem to be able to visualize finished items with the grey designs.  Castable resins typically come in Green, Dark Green and Yellow.  Remember what I’ve covered in the past, Darker resins require longer layer curing times, so keep that in mind with setting up your Elegoo Mars or Photon.  

Longer prongs, help to compensate for errors in design and casting, remember that also, to cover those little flaws that crop up now and then.

Most of all, practice safety.  It really doesn’t matter whether you are using standard resin, castable resin or water washable resins.  They are all toxic.  While I’m blessed to have skin that seems not to react to the resins, many people get chemical burns which can cause other problems.  Gloves, masks, cleaning supplies, these are things you should always have on hand.  Click here, for a list of recommended items to keep around your printer.


Good Luck, and let me know if these things help you in your designs!

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