physical size, resolution, and file size

I've been out of touch for a little bit as I took on a pretty big project that's completely unrelated to jewelry. If you read my bio, you might have seen that I have a background in construction (of all things!). I've been in the middle of a major remodel of my parents' house, getting it ready to go on the market. If you can imagine, popcorn ceiling removal, paint, a new multi-level deck, and a total re-do of four bathrooms, including moving walls. If you've ever watched that show Fixer Upper, it's kinda like that...except for unlike the show, it doesn't happen over the course of an hour.

And some cool trivia...the software used on Fixer Upper is something called SketchUp—a program that I started out with trying to use for jewelry before I found ZBrush. There are some significant differences between SketchUp and ZBrush...for example, SketchUp is an example of a "parametric" CAD program, one which allows the user to input dimensions and create true measurements. In one of my new tutorials, I show how to use ZBrush to mimic that ability

Anyway, as I've become so dependent on my computer and CAD to do anything technical, I had to put the house in SketchUp to determine things like tile patterns, lighting, and which walls to remove.

But with all of that kind of work, I realized that I'm missing the heck out of ZBrush!

kathouse-sketchup.png

So last week I took my studio microphone and set up on a folding table in my bedroom. Then I recorded a series of tutorials that I should have out here shortly. I've got some new topics, and also some content for my upcoming course. This small pendant is one of the designs I came up with, and even as I write, this little piece is on my printer with Formlabs' new Castable Wax Resin.

But while working on that project, I realized that while I do cover working with size in some of my tutorials, I don't know that I've ever took the time to explain exactly how I achieve correct sizing.

 

size matters

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xyz-size-zbrush.png

Yup, size can be a big issue when working with ZBrush. While I don't have a formal answer why, I'm guessing that it's ecause the program was designed to make things that were abstract—things that lived in a virtual world. So for that reason, size is relative in ZBrush, and measured in plain ol' units. Here you can see the Size sub-palette under the Geometry palette on the right-side of the interface.

The pendant on the stage (only the pendant, not the chain), is a minuscule amount smaller than 25.4 units. Well, if you count this as 25.4 millimeters, this equals one inch across. You can also see the Z Size is 1.61 units, so approximately 1.61 mm thick, which is a nice thickness for a pendant. And likewise, the height is 16.7 mm.

When I first started working with ZBrush, I saw a tutorial that suggested calibrating something called the Transpose Line tool. I struggled with this, and every time I thought I had the size correct, something would change and everything would be off. I couldn't reliably gauge bezel cups or stone settings...or even thicknesses. This also became an issue with the amount that a design or text was raised off or inset into the surface. So finding a way to make this work was really important.

Someone also asked me on YouTube if I used a plugin called "ScaleMaster." The answer is no. I have also tried RingMaster, another plugin, which is nice, but I also had some problems with that. However, I DO use RingMaster to insert gemstones because the models contain minimal polygons, meaning they don't slow ZBrush down.

getting started with a correctly sized model

simplebrush-zbrush.png

So here's the process I use:

  1. From the right-hand side of the stage, click on the yellow "S" that represents the SimpleBrush tool.
  2. Choose the Cylinder3D from the list.
  3. Click and drag a cylinder on the stage. It doesn't matter how large you make it...it comes into ZBrush at an XYZSize of "2" units.
  4. Immediately press the "T" key to switch to the Edit mode.
  5. Press the Make PolyMesh3D button toward the top under the Tool palette.
  6. Look under the Geometry palette on the right-hand side of the window for the Size sub-palette.
  7. Enter "10" in the XYZSize box and hit return to accept the new size.
  8. The primitive is probably taking up the whole window, so click somewhere on the stage to deselect the number in the XYZSize. 
  9. Now press the "F" key to fill the stage with the current object.

And there you have an object on the stage.  It's pretty faceted, and not smooth, but we'll deal with that next.

smoothing the primitive

I have a special technique that I've developed to get a smooth object as soon as possible in the workflow. In the beginning, I thought simply performing a DynaMesh operation would smooth it, and I went back and forth between DynaMesh and Polish Features, but with results that weren't efficient or acceptable. So here's how I smooth things out.

  1. Look for a button labeled Divide from the Geometry palette. 
  2. Make sure that the Smt button is turned on (this will smooth your primitive).
  3. Click the Divide button twice.
  4. Look above the Divide button for another button labeled Del Lower. This will delete the two lower-resolution subdivisions that you just created.

That should give you a nice, smooth primitive. 

So what happened? Each time that you use the Divide command, ZBrush takes each rectangular polygon and divides it into four polygons. Then when you divide again, it divides each one of those resulting polygons into four more polygons. If you have the Smt button activated, it takes the opportunity to smooth out your model.

You can see the underlying geometry of your model by using the Draw PolyFrame (Shift - F) button to the right of the stage, toward the bottom of the vertical row of buttons.

Subdivisions are wonderful if you're roughing out a shape, then switching back and forth between lower resolution subdivisions and higher resolution subdivisions. Adding material with a brush like the ClayBuildup brush works faster when working with a low resolution. But finer details are better applied with the higher resolution. I'll address this in a tutorial later.

Take a look at the example below...look at the pixillation of the cylinder and the number of ActivePoints. Each time that the cylinder is divided, it QUADRUPLES the number of ActivePoints. This has implications with regard to file size...our strategy is to get a smooth resolution while still keeping the file size down. 

So keep this in mind, and I'll write a little more later...then we'll talk about how working in actual size relates to your DynaMesh resolution. and how you can work more efficiently and on lower-end hardware.

Heck, I can even run ZBrush on my 2012 MacBook Pro! And you know what that means? I can sit in a café in the Caribbean and design jewelry. SWEET!

zbrush bezel tutorial

Hey guys! Late last night I added another video to my YouTube channel to show you how to create a bezel setting that you can reuse in other jewelry projects. The nice thing about this tutorial is that we work in actual size! With a lot of trial and error, I have figured out how to get accurate sizing with ZBrush when when printing to my Formlabs Form 2 printer. 

I am casting pieces with a vacuum casting setup (KayaCast), then setting the stones using a Foredom hammer handpiece attachment. This particular size of bezel is a little thicker than using fine silver bezel wire in traditional fabricated pieces. But I like the thicker look, so I use this setting quite a bit. I'll be adding another bezel tutorial that uses ZModeler to create a thinner bezel, or you can just substitute a Cylinder3D in this tutorial instead of the Ring3D and adjust the diameter to give thinner walls. You should be able to repurpose the skills in this tutorial easily.

Here is a list of resources for this exercise (NOTE: these are downloads, not links to pages):

Place the materials into the ZStartup/Materials folder which is found in your ZBrush folder. However, Pixologic recommends having no more than 25 materials loaded simultaneously because it can affect performance. 

Whew! Lots of fun. Although a big test of my editing skills as I tried to spare you all with my repetitive use of the word, "so!" I'll try to be better about that.

Sooo... (haha!) Kat, tell me about this tutorial. Why did you make something so basic yet take almost a half-hour to tell me about it?

There are a couple really important concepts in this video. First, you're not just making a bezel. This is a great opportunity to understand the hows and whys of ZBrush. Sure, we all just take for granted that we use this cool little technology called DynaMesh to "redistribute" the polygons on our model, but how in the world do you know how to choose the RIGHT resolution? It was a mystery to me.

A lot of tutorials on the internet just pick a number. That wasn't good enough for me as a geek. HOW do I pick that number? It ends up that there's a balance between finding a resolution that's the absolute minimum without losing detail. Another important concept is that the larger your model is, the LOWER the DynaMesh resolution...for the most part. At least with how I use ZBrush for jewelry.

What About Size?

And this project is a great opportunity to talk about size...as you know, size matters. No, really. All primitives are loaded into ZBrush at a size of "2." What are the units? There ARE NONE. It's just two. But as a jewelry artist, I can imagine that I'm working on a piece of jewelry that's 2mm. Too small for most jewelry, but a starting place.

In this video, I start with a Sphere3D and change it to a "5" to represent a 5mm cabochon, then cut it in half with the Gizmo 3D tool (found in the "Move" mode). A really cool new feature, by the way. Just grab the little rectangle and drag up or down (or side to side!) while holding the Ctrl key on a PC or Command on a Mac. Jump to that part of the video by clicking here.

Making a Smooth Foundation—"the great divide"

 "Smt" is activated here

"Smt" is activated here

I also mention in the video something I use quite a bit...the Divide a couple times and use Del Lower process. This gives the surface a smooth appearance, and should be done first before using DynaMesh to get a nice foundation. I use this process in other ways, but if I ever see "faceting," the process is to Divide 2-3x (watch your ActivePoint count) with the Smt button activated. That is the smooth function. If you Divide without it, you'll have a finer mesh, but the faceting remains. Just check the Polyframe (Shift-F) to see what's going on under the hood. You can always undo. To see it in action, click this link.

If you'd like to see this technique in a little more depth, check out this video on Subdivisions and Hotkeys.

Using a Transpose Line and SelectRect to Measure

At the very end of the video, I come back to share a little more information about how to "section" the model using the SelectRect tool and take a thickness measurement using the Transpose Line. I didn't understand the beauty of the SelectRect function until about six months ago, as I struggled a little to understand the difference between "ClipRect," "SelectRect," "TrimRect," and "SliceRect." I'll explain them all in upcoming videos, but for right now, the SelectRect tool will allow you to temporarily hide part of your model. There are other variations...you could change the Stroke to a circle, or even a curve for more control. But I usually only use SelectRect for this operation.

Keep in mind that you need to enable the Double button in the Display Preferences palette to be able to view the inside of the model and measure it.

Switching to the Move mode (press "W"), you now have a choice between the Gizmo 3D and the traditional Transpose Line. I use the Gizmo quite a bit to eliminate parts of models by using Command/Ctrl (Mac/PC). In this tutorial I think I do that three times. But the Transpose Line for me is more often used to measure.

Flower Ring.jpg

What's Next?

Next up on the agenda is the Flower Signet Ring, based on the signet ring included with ZBrush. We'll create an accurately-sized signet ring from scratch because it's a great example of using DynaMesh Boolean operations, and explore axial and radial symmetry to finish the ring and add a 7-petal flower to the top. The icing on the cake is adding the bezel we just created. When it's done, I'll add a link here! Stay tuned, and happy ZBrushing!

more huichol, please!

Yes, it's time for another Huichol beading project!

This time we're going to learn how to create a simple Huichol-style flower earring or pendant. You'll need some Preciosa beads like the ones found in my other Huichol tutorial here, in several colors. The tutorial is done in shades of yellow, orange and pink, with a little green loop at the top. (The flower shown here is just a placeholder).

Just a reminder, the tutorial and images are copyrighted. If you are interested in using them for a club or class, please contact me for permission.

You can follow along with my colors, or use the worksheet to design your own. Click here to download a PDF version that can be easily printed.

Click this link to start learning how to create these pretty and easy little earrings!

an experimental earring from a kaleidoscope program

mandala-3.jpg

I'm just putting this experimental earring up here because I think it turned out pretty cool! Created in the new ZBrush Core.

I used a kaleidoscope drawing program that I found on the internet to make the basic design, used the Gaussian Blur tool in Photoshop to blur the jagged edges, then Unsharp Mask to bring it back into focus. The design was then brought into ZBrush as an alpha mask, turned into a polygroup, isolated, then extracted. The resulting mesh was then Dynameshed so it could be sculpted, then divided (using Subdivisions and the Divide function) to give a finer mesh for sculpting.

DISCLAIMER: I wouldn't say that this is my best design work, but it was more of an experiment...so carry on.

Rendered image from ZBrush

I used the Helix tool in ZBrush to create the coil on the drop, added some jump rings, then brought in a Cube primitive and Dynameshed it so I could draw a mask and create the darker supports that would recess into the background after a patina was applied. The original supports were straight. The curls add a nice touch that mirrors the swirls on the main design.

By the way...using the MRGB function in ZBrush, you can "paint" different areas to mimic the patination applied during finishing. Just choose a material, and change the color to a darker gray. This behaves a little differently than using the "dirty" silver MatCap material, and results in a more dramatic presentation of the finished piece.

UPDATE: When this earring was printed and cast, it was too thick and too heavy. Thanks to the technology, I was able to shrink the thickness, enhance the scrolls, and reprint. The great thing about having a printer on your workbench is being able to make adjustments and test techniques. 

The models with supports added, ready to print. This version was too thick and too heavy.

MoI — moment of inspiration CAD software

types of CAD modeling

After taking an online course on jewelry in ZBrush, I was a little frustrated that the instructor was going back and forth between ZBrush ($795) and another piece of "parametric CAD" software that was more expensive. I had a few early attempts to stretch SketchUp's capabilities to make basic forms for ZBrush that worked okay, but since then I've learned more about ZBrush's ZModeler functionality for hard surface modeling.

Simple flower made in virtual "clay" in ZBrush

So you say, "Kat, you're using that crazy terminology again, and I have no idea what you're talking about." Let me explain.

ZBrush gives you the ability for more freeform modeling. Imagine sculpting with a ball of clay in real life...you can push and pull the material into organic shapes, creating a model in a very realistic way but in a new medium. The flower shown here is a very basic example of this type of freeform modeling in ZBrush. However, the flower was originally created in ZModeler as a hard-surface model, then sculptural details added with other more freeform brushes.

The ZModeler mode in ZBrush is great for creating hard-surface models...this would be like modeling a starfighter...you might start with basic shape and push and pull surfaces to make something more mechanical looking. Here's a fascinating time-lapse video of "Alex O" modeling a war helmet in ZBrush with ZModeler. In jewelry design, I might use the ZModeler functionality to create a square frame for a pendant, then an inner medallion, then switch over to soft sculpting to create the design. When creating a base for 3D printing, I also use the ZModeler functionality. Here's another great video from Alex O that shows him using ZModeler to make a geometric ring.

However, something like SketchUp (SketchUp Make, FREE download) is a little more rigid. I can create a box, then push and pull geometric shapes. But if I were making a box that I wanted to be exactly 20 cm, I have a precision built in to the program that can make that happen. That is a characteristic of a "parametric" 3D modeling program. That makes SketchUp...like AutoCAD, Fusion360 (cloud-based, FREE for hobbyists), Solidworks, and similar software...perfect for creating technical drawings and product designs. For example, I used SketchUp to design my jewelry workbench.

moment of inspiration (MoI)

I had some issues with creating printable models in SketchUp, so I started looking around for another "technical" drawing solution that wouldn't break the bank. Enter Moment of Inspiration, also known as MoI. MoI is $295, works on both Mac and PC, and has a 30-day trial.

At first I was a little skeptical. The interface was pretty basic, and definitely wasn't written to take advantage of the Mac interface I'm using. But then again, neither is ZBrush. After a couple of YouTube videos I was up and running, and I was able to figure out the rest on my own. 

So what is MoI good for? Probably almost any kind of technical modeling you might want to do except freeform "clay" type modeling. You could take a freeform "extruded" shape and "subtract" a sphere from it. Combining different "primitive" shapes, such as cubes, cylinders, and spheres, you can make pretty complex models that export well. Turning on a "grid snap" or "object snap" helps line things up. Then you can export these items easily, bringing them into the PreForm or other "slicing" software that prepares the file for 3D printing.

Some rubber mold frames made in MoI

I jokingly say that the second phase of having access to a 3D printer is when you start making your own tools. I purchased some frames for making rubber molds from Rio Grande, but they were too wide to fit in a nifty little spring clamp that holds the split mold together while filling with hot wax. Additionally, trying to estimate the amount of two-part "RTV" (room temperature vulcanizing) mold material usually resulted in wasted material...and at $56 a container, it's too expensive to do that! So my "improved" version has markings on the side to indicate centimeters, and a handy spreadsheet calculates the exact volume and weight of RTV needed. Remember the ability to measure in a parametric modeling program? Because MoI works that way, my one centimeter marks are accurate when printed. In ZBrush, that would be more difficult.

And because I'm a dork, I added www.katkramer.com and my logo to the side...and it was backwards, so when the rubber mold is made, my website address doesn't read correctly. Oh well, there's always version 2.

So in a nutshell, MoI is a nice little program, and the models created are accurate in size. It is a nice alternative to more expensive programs for making basic models to bring into ZBrush.

 

finally casting...the mandala pendants

UPDATE, December 2017: Looking back at this post, there are so many things that are wrong! Anyway, a good exploration of what works and what doesn't, and modifying a design to cast and finish more easily. The main change I eventually made to this pendant is to attach the design to a backplate, so the design is simply raised from a background. With a patina, the design is similar but much easier to cast and finish. I have since scrapped this design and melted them all down. So maybe they'll be collector's items some day! Anyway, carry on...

Well, it's finally time. What better time to start casting holiday gifts than a week before Christmas?

It's been an interesting journey. It started back in Denver after I got the casting setup...I remember that my first attempt at casting with a perforated flask, I ran out of acetylene at 1 a.m. and didn't have a way to heat enough metal to cast. The second attempt, I realized that my acetylene/ambient air torch couldn't heat enough metal hot enough to cast. After switching to my old Smith Little Torch (acetylene/oxygen) with a "bud tip," I was able to get the metal melted, but never cast before we suddenly moved back to Texas.

Fast forward over a year. Since then I've taken the wax-working class with Kate Wolf, learned ZBrush, and explored printing in 3D on the Formlabs Form 2. I've printed a lot of things, but the missing link was casting them into metal jewelry.

So I was ready to go! Treed up some models, was burning them out, and my kiln fell victim to the outdoor sprinkler. Since I work late at night usually, I didn't realize that the sprinkler was scheduled to water the lawn that night. The kiln was sitting on a little window in the outdoor kitchen burning out my first 3D model flask, and a poorly aimed sprinkler doused the kiln and killed it. I awoke to an error message and a flask that hadn't completed burnout. I was crushed.

So what do you do when your Paragon SC2 kiln has been watered? Let it sit for a few days and let it dry out. Since this kiln has a metal cabinet, I removed the back and aimed the fan on the inside. Sure enough, about four days later I had the guts to turn it back on. It worked.

Next, I was ready to cast the 3D prints. I prepared the trees, the flask, and tried casting again. I was still having difficulty getting the metal heated correctly. About that time I was helping my parents downsize their house, and my dad gave me a little present...the Kerr Electro-Melt that I needed to get the metal to the right temperature for casting. Something I've learned through research—not in practice—is that metal can be porous if overheated. When melting with a torch, you don't really know how hot the metal is. Any casting I've done in the past was on a very small scale, and I probably just got lucky!

 Incomplete casting

Incomplete casting

So I was ready to cast, and treed up some nine models. This time when I cast, I heated the sterling silver to about 1740°F (Kerr recommends going 100°F above the melting temperature of the metal, and silver is about 1640°F). I used the Formlabs castable resin burnout schedule, which clocks in at about 14 hours, landing on a 900°F casting temperature with a 3.5"x4" perforated flask. The result was not good!

But why?

After consulting Creative Side Jewelry Academy here in Austin, and the Formlabs forum, I found that it could be either the metal was not hot enough, or the flask was not hot enough. I found in another article that the flask can drop about 100°F in one minute in a vacuum caster, so it suggested making your flask temperature 100°F hotter. Also, filigree designs require a slightly hotter flask. The girl at Creative Side asked if I cast close to 1100°F, and I remember casting at or near that temperature in the past. Participants in the forum suggested between 900°F, or 950°F for filigree. Then the suggestion that every casting situation is different and these numbers are just guidelines, so it requires experimentation. 

So I set off to cast again. This time, I used two 2"x2.5" flasks, a 2.5"x2.5" flask, and a 2.5"x3" flask, each with three models, rather than trying to cast a tree with ten models (or more?). I also tried adding a forked sprue coming into the bezel on the back, and another configuration with four sprues coming to the back of the frame. On that one I also added two small sprues coming into the back of the bezel. The sprues on the back of the frame are very easy to clean up, but when I 3D printed this one, the different support configuration distorted the frame on the bottom.

I also conquered my fear of cleaning up the jewelry! I learned from the forum that I should try tumbling the pendants for longer (these were polished about 40 minutes on a rotary tumbler), and silicone wheels work well for cleaning up raw castings. So far I hadn't had much luck with them. So I busted out the kit and it worked!  I also tried these little wheels made with 3M micron finishing papers, and they worked well for grinding down the sprues from the back and finishing the back of the frame. And something surprising...the back of the pendant with a patina is as pretty as the back...so it's reversible. I'll have to play around more with that.

However, they were still usable, and became Christmas gifts!