Zbrush negative molds.

Slash

I'm working on a project where zbrush models are gonna be cast in silicone. The suggested workflow is that we print the negatives for the mold directly. My question then is this; How would i go about making a set of digital negatives from a zbrush model? Basically a digital mold. If anyone has experience with this I'd be very happy if you'd share with me!

And if this sounds weird to you, feel free to suggest alternate workflows. But as far as we can tell we'd be better off printing the mold directly instead of printing the model, then making a mold from that.. Skipping a step seemed to be a logical choice.

Thanks for you time!

pior

That sounds extremely unpractical... especially since the print material is likely going to be porous and will need touchups (very hard to perform on a negative shape)

Good luck and post pictures - mold making techniques depends a lot on the scale and nature of the objects being cast.

Jesse Moody

while it could be done in zbrush (saw a demo of it on some site) i would rather print the object or cut it up into it's pieces to avoid undercuts and problems with making molds and go that route.

I have made molds for everything from statues, mini busts to smaller objects. The less undercuts and stuff like that the better in the long run.

ceebee

I think the easiest way would be to sculpt what you want to have molded, and then use the new boolean/remesh features in ZBrush in 3.5r3

divi

http://www.pixologic.com/docs/index.php/Geert_Melis

?

Neox

now look how horrible the negative form looks, especially on the head, all details got lost :X

Neo_God

I see the logic used by whoever suggested that work flow, however I agree with the others.

Cost-wise it's kinda silly, because instead of getting a single print made of the model you'll be getting at the very least 2 prints made for the mold parts. I don't know the rates of who you wanted to use for printing or the scale of your model, but I'm pretty confident that it would cost less if you were to make the mold physically.

What is it that you are trying to mold (pics of model or concept)? At the very least some of the folks here may have the ability to direct you in a proper direction as far as molding it.

CheeseOnToast

I think the easiest way would be to sculpt what you want to have molded, and then use the new boolean/remesh features in ZBrush in 3.5r3

This would be fine if you didn't need to do some extensive cleanup after remeshing. In its current form it would make a horrible mold.

I'd leave the mold-making to some proper software designed for the job, rather than trying to hack it in Zbrush.

Disco Stu

Also wouldnt you need to mold the mold as the print material will break when you fill it?

Slash

Thank you guys, you bring some exellent food for thought to the table! The finished casts will be around 1/7 size humanoids. The models aren't made yet, since the process of molding and the pitfalls/shortcuts will impact the level of detail we're trying to achieve. There will be a stop motion armature inside the finished puppets, so I think we have to cast everything in one solid chunk.

Pior: The material being potentially porous is a pitfall we should look out for. Thanks for bringing that up. But wouldn't the same problem apply in reverse when making the mold?

Cheeseontoast: Would you recommend a specific piece of software, or are you talking generally?

Disco Stu: I'm not sure i understand what you mean. Its been a long day of work, so my brain is going a little slow.. :P

Jesse Moody: I'd love to pick your brain about some more specific stuff, if you won't mind. I'll send you a PM once I've looked up more resources. I think having someone who've actually gone through the process giving me some pointers would be really cool if there's something thats unclear.

I'll post pics of the process once we get around to that. I'm sure documenting the prep work and the process could be interesting for people to see.

Sorry if I'm asking stuff that google could tell me, I'm currently working on site, and the internet is so shitty that crawling through lots of google results is a PITA. I am of course doing my own research, its just a tedious process.. :P If anyone know of good resources for this kind of stuff I'd be most grateful if you'd share.

Again, thanks for your time!

CheeseOnToast

I'm working on a little side project at the moment (www.warheadsthegame.com). One of the guys on team has a lot of experience of making rubber molds for white metal miniatures, so I can hit him up for specifics if that would be any use to you. I don't know how similar the processes are for silicone models though. Drop me a PM if you like, and I'll put you in touch with him.

pior

On porous stuff/surface quality : one thing to keep in mind is that 3d prints always require some sort of post processing. Highest quality stuff only requires a light priming (check out Tamiyas fine surface primer spray cans), medium quality prints ask for serious wetsanding and priming, and lowest quality stuff requires filler putty, sanding and priming. Dont trust pictures of prints with that famous slight translucent look. It is misleading since the print problems go unnoticed because of the SSS effect. Judge prints only after priming.

Regardless of quality, all these processes basically smooth the surface and seal it too. Now, all that would be pretty annoying to do on a reversed shape - the sanding especially would be painful or close to impossible.

Also, molds require quite a bit of trial and error to get them to 'flow' right (figuring out where the air bubbles will get trapped, where to place the sprues/chemneys for them to escape, and so on) If you have a good quality master print you can try different molding solutions and setups. If you print reverse you would get stuck with one specific seam line and it could be painful.

However it could work just fine for a simple enough design. For smooth art toys like the kidrobot Dunny / Sunny / Munny, I could imagine that reversed molds prints could work very well - if! you have previous molding experience and make your 3D mold juuuuust right hehe. I'd say play with molding/casting a little beforehand, you'll understand those challenges much more. Now I want to do reversed prints myself too hehe, just for the sake of trying it out!!

To test out your print designs I recommend Shapeways.com. Quite cheap, fast international delivery and good service. Then once you get a design up and running, switch to the highest quality print services like protodemon and others ...

Keep us posted!

Slash

Cheese: Thanks, I'll get back to you on that!

Pior: Getting some cheap prints done for testing is an exellent idea! If I'm not mistaken the guy I'm working for is gonna be using ownage.com for the final stuff, and if i know him right he won't settle for anything less than the highest quality. I don't know if getting cheap prints for testing has crossed his mind.


Thanks again for your input, this is really helpful!

Mark Dygert

I don't really see the advantage. Classically several negative and positive molds are made working up to a material that can withstand the pressures the mold will come under for the given process, like Disco Stu said.

There's a good chance that the material you print with, will really suck as a negative mold. Which means you'll have to use your negative mold to make a stronger positive mold so you can make a stronger final negative. Which means you're actually adding steps by printing a negative first.

When I was working in R&D for a water ski/snow board company we made as many as 7 molds before we got the final mold. But it really depends on what the negative will be used for. But that was to take a concept to a final aluminum mold.

You also need to account for holding the molds together and the pressure that involves. It really helps to have a mechanism designed into your negative mold to hold the two pieces together with evenly distributed force. Any slippage or weak pressure, translates to the material spreading and leaving horrible steams that have to be cleaned up. When it spreads, it actually can leave a gap in detail so its really important that the two pieces fit together really well and they be held together with a lot of force.

The chances of you getting a good fit between two pieces that are printed at different times is going to be messy.

You also need to make sure your final cast doesn't stick to the mold. You an easily destroy detail and damage the negative when you're trying to get the final cast out, This is another reason you want a tough negative mold.

Also know that molds don't last forever, so having a good strong well defined positive allows you to make more negative molds when they start to wear out. It's probably cheaper and faster to make a new negative than it is to print another negative.

I think you should do some research on mold making and cover all the angles before rushing off to the printers. Mold making is an art unto itself and its been going on for a long time.

Microneezia

This is a great idea, but I think for the purpose of making stop motion puppets you might find a couple things difficult.

Usually stopmo puppets are made of foam latex. this requires baking at 300 degrees. Im not sure your print material will withstand this baking process.

Also from what I know, puppet makers almost always build the armature first. Then sculpt on top of that armature in clay. This ensures joints are lining up. then when you mold the sculpture and release, you can be sure the armature fits well inside the empty mold before injecting latex and cooking. Fitting an armature to a pre-existing mold might prove difficult. Especially if you are using machined armatures. It will be easier if the armatures are wire. But if you are going to use a zbrush quality sculpt in latex, and the shoot is even a little long - you dont want that wire breaking during your shoot. im getting the machined armature feeling from this.

Im excited to see more on this project...