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April 5, 2009

Behind the Scenes: Using ZCorp


Here's the first in a series of articles I plan to write about 3D Printing. The problem with most 3D Printing literature is that they're full of marketing crap that don't tell you the truth about the machine. Building Ownage, I've spent most of my adult life (haha don't worry.. I'm not that old) working with these machines so I'm happy to pass along what I know.  I hope the guild of printing magicians don't come after me because of this!  Trade secrets!

Today I'm gonna tell you about ZCorp. ZCorp produces the Z310, Z450, Z510, and Z650 3D Printers. These are 3D Printers as opposed to Rapid Prototyping Machines. What is the difference? The running joke answer to this question is, "Oh about $100,000." Truthfully, the difference between an RP machine and a 3D Printer is not that big. 3D printing describes machines like Stratasys FDM, ZCorp, and Objet that use a printhead similar to an inkjet printer. Because it uses inkjet technology, these machines are much cheaper than RP machines like SLA and SLS. In the future I will describe each of these in detail.

When it comes to ZCorp, the basic process is that the machine has two buckets of powder next to each other inside the machine. One bucket holds the finished print. The other bucket holds extra powder. ZCorp machines use a starch (flour) based powder that the printhead glues together on each pass while depositing a drop a color on the outside layers. ZCorp is one of two 3D printers that can print in color (the other being the Objet Connex500). But the ZCorp machines are the only machines that "kinda" prints in full color. The machine prints about 1 inches high an hour. When the print is done, it needs to sit in the machine for a few hours while the machine adds heat to bake the glue that holds the model together. After that, because the model is EXTREMELY fragile, you'll need to manually harden the model by dropping/spraying super glue over the entire surface of the model. This is extremely boring and time consuming.

The main benefits with ZCorp are that it prints fast, cheap, and in color. The material is the cheapest coming in at $2 a cubic inch.

I have a lot of complaints with ZCorp. It's really not that bad when you print big things. But it SUCKS at tiny details because the entire surface of the model is bumpy like sand. This is of course a side effect of using powder as the print material. But if you're printing rock or stone-type figures, it might actually be a good thing!

The post-processing with the ZCorp machine is the most time consuming of all machines I have used over the last 6 years. The standard method is what I stated above, to cover the model with CyanoAcrylate (superglue) and harden the model. The problem with superglue is that often times you don't get uniform curing. CyanoAcrylate reacts with water moisture in the air to cause a chemical reaction and bond. Many times if the super glue is applied too thick, and there is too much water (humidity) in the air, the glue will frost and turn your model white. This is called frosting or blooming. You'll see this on a lot of figureprints.com models. It also affects how the models look in photos. With any form of lighting or flash, the models will look washed-out and terrible.

ZCorp sells an additional way to post-process figures. It's a bucket of liquid wax that you can drop the models into. It's a lot easier to do it this way.

A lot of people ask me, "How does Offload Studios post process their ZCorp models?" Offloadstudios.com is famous for doing the best work using the ZCorp machine. I'm impressed with the surface finish they do with ZCorp. Makes me want to play with ZCorp more. But Offload says their methods are proprietary trade secrets. Haha, I wouldn't want to mess things up for them. But If you gave me 30 seconds with an Offload printed piece, a saw, and some smelling I could tell you exactly what they do. Aside from that, I can only guess based on experience and pictures. For larger pieces, it looks as if they do some surfacing to smooth out the plastery finish that ZCorp has. Because superglue does not sand well, my guess is that they use a sandable, clear resin such as a thinned down, polyurethane glue or epoxy. Or maybe they just use the wax bath. I believe it might be possible to put the model into a pressurized tank full of the resin or wax of your choice. This will quickly infiltrate the model and make it super strong. It's important to use a resin that cures fast and does not have to bubble and de-gas. Then they probably finish it off with a coat of clear, self-leveling protective lacquer. And some sanding. I'd have to smell it or taste it to really know.

Another issue with ZCorp is that the old machines (the 310, 450, and 510) all have problems printing pure black and pure white colors. They turn out grey-ish and yellow-ish respectively. The new 650 machine probably uses a dedicated white and black ink cartridge to solve this problem (like a sub-dye printer).  Also, while ZCorp markets the machines as clean, office-friendly products.  In reality, prolonged use causes a layer of white flour dust to cover every piece of furniture in your room.

So there you have it. ZCorp. The Good, The Bad, and The Ugly.

Really, I like ZCorp.  I like playing with it.  But it's going to be killed by Objet full color printing in 5 years. More about that story soon =D.

Filed under  //   rp   secrets  

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April 3, 2009

The real cost of Rapid Prototyping

When the raw cost of rapid prototyping plastic is $0.50 cubic cm or about $10 a cubic inch, a common question lately is why must a model be so expensive. A typical model is about 10 cubic inches, so why do people need to pay more than $100.

The answer I like to give is this. If you went out a bought a ferrari (typically the same cost of a mid-range 3d printer), and started a business renting it out, would it make sense for people to use it and only pay for gas?

Here's an example

ZCorp 350 Printer $50,000 + $10,000 (for tax and 1 year maintenance package). Material cost = $3 a cubic inch (also accounts for glue used in post-processing). If you charged $10 a cubic inch to print, it would take you 60,000/($10-$3) = 8571 cubic inches to make back the cost. Or if using the 10 cubic inch per model reference, you'd have to print 850 models, or about 2 a day. Two orders a day is a lot! And if you wanted to pay rent, electricity, time and labor for fixing files for printing. Let's say that comes out to about $2500 a month for salary (ur making $30,000 salary a year, minimum wage!). If you're doing 2 models a day or 60 models a month, that means each model would need to add $2500/60 = $42 flat fee on top of the base $10 a cubic inch.  A model that's 10 cubic inches would now cost a user $142 base price.  Assuming you run your printer out of an office that doesn't charge you rent.

Objet Eden 350 Printer $150,000 (after tax and maintenance). Material cost is 50 cents a cubic cm or $10 a cubic inch. If you charge $40 a cubic inch that Shapeways.com does. You make $30 a cubic inch per model. On the 10 cubic inch model you make $300 on the total model cost of $400. To make back the cost of the machine (not including salaries, rent, etc), it would take Shapeways 500 figure type models. Or roughly 1.5 models a day. I'm not aware of anyone that does 1.5 figure type models a day. Maybe little jewelry and rings. But not character prints.  Add in your salary and rent and you're looking at minimum $500 for a character print just to cover costs.  (Now imagine you need to paint it)

I know of some companies that charge $100 a cubic inch for Rapid Prototyping work. Your model that you would pay $200 on Ownage might cost you $1000-2000. ouch!

So if you want to get into the Rapid Prototyping business, start saving those pennies! =D


Update: Ownage is charging users about $200 for a 10 cubic inch print in plastic and painted.  So we're doing real $400-1000 production models for ZCorp price.

Figureprints.com stays in business because their ZCorp figures are 4 inches tall (about 3-5 cubic inches including base).  And they charge $139.99 for it.  It works out about right.

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