Three-Dimensional Printing: Z406

ITG has two identical 3D printers for solid object creation. The one shown above is in the VMIL on the fourth floor of Beckman Institute. The printers are available for all University students, faculty, and staff. The ITG only charges its users for materials costs. The printers have lots of uses, like protoyping, scientific modeling (like a rat's visual cortex or chemical structure), architecture models, and much more.

How they work: The printers build each model layer by layer, starting at the base. For each iteration, a thin layer of powder is spread over the entire building area. Then, a print head similar to that of an inkjet printer prints a layer of binder onto the powder plane. The colorful binder bonds with the powder to create a solid layer of your object. You can think of the complete model as a stack of 2D images that were printed onto the powder. When the process is finally finished with the top layer, the model will be completely enclosed in a matrix of powder that will be removed during the excavation process.

Click on the Image Above to View a Time Lapse Video of the Printing Process

 

The printing process: First, you must acquire a 3D model. You can create one using Maya, Rhino, Inventor, AutoCAD, ProE, and other software. The model file must be converted to a suitable format. These include .zbd, .stl, .bld, .ply, .zcp, .sfx, .zec, and .wrl. You will need to review the model with a VMIL consultant to make sure that printing the model is feasible (for example, you can't print something with paper thin walls). Only ITG staff may send prints to the printer, so you will need to contact someone to help you print your model. That person will open the model using the software "ZPrint" where it can be resized and positioned before it is sent to the printer. Next, the printer prints the model. Printing can take less than an hour for very small parts up to many hours for large ones. After the print completion, the powder matrix is scooped and vacuumed away to reveal the model. We call this process excavation. After the model is removed from the printer, it is blasted with a fine stream of air in the depowdering station. This process removes more loose powder, especially powder in holes or crevices. Finally the model is infiltrated with wax, epoxy, cyanoacrylate, or an elastomer. This provides neccessary structural integrity for the model; without infiltration the model is very easily chipped, scratched, and cracked.

Features:

Models may be printed in Monochrome (clear binder) or Full Color (RGB) .

Models may have interlocking parts such as chains.

Thin models can be infiltrated with an elastomer or pva glue to make flexible parts

Maximum Build Volume: 8" x 10" x 8 "

Layer Thickness: User-selectable at the time of printing: 0.003"- 0.010"

Build Speed: Monochrome: 6 layers/minute Color: 2 layers/minute

Resolution: 300 x 300 dpi

 

Starch or Plaster? Typically, one of the printers is filled with starch and the other plaster (see chart below for medium comparison)

Plaster	Starch
Solids or flexible shapes	Solids or flexible shapes
May be infiltrated with wax, cyanoacrylate, epoxy, or polyvinyl acetate glues (for flexibility)	May be infiltrated with wax, cyanoacrylate, epoxy, or elastomer (for flexibility)
Stays fresh and ready for printing in the build volume	Gets sticky if exposed to the air for too long. Starch left in the build volume shouldn’t be used for printing. Refresh the starch by doing 1 or 2 new spreads.
Spreads easily	Does not spread easily (small tears on surface sometimes appear)
Can be excavated at one’s leisure	Must be excavated within 30min of print
Used with ZB56 Binder	Used with ZB51 Binder
Example: Polynomial and Gum Stick	Example: Squeeze Bottle

 

Flexible Plaster Models
Infiltrate Testing is underway to produce plaster models with flexibilty. Testing will also focus on utlizing infiltrates that can reduce the overall cost of models (i.e. basic craft glues). Preliminary results have produced flexible models with various degrees of strengh. The flexibile models are produced by using polyvinyl acetate glues to infiltrate the parts after printing. The current limit to producing flexible parts is a model thickness of 1/16". Polyvinyl Acetate Glue = Basic White Glue (i.e. Elmer's, Sobo, Tacky Glue)

 

Infiltrate Options
There are various options availabe for infiltrating the finished parts from the 3D Printer. Typically plaster parts are infiltrated with wax, cyanoacrylate, or a polyurethene mixture. Each infiltrate has its advantages and disadvantages and are selected by the user. To facilitate this process we have divised a small diagram illustrating which infiltrate will best suit user needs.
Wax	Drying Time: 30-60min Strength Level: Low Monochrome Finish: Waxy Film Color Finish: Waxy Film
Cyanoacrylate	Drying Time: 1-2 hours Strength Level: High Monochrome Finish: Clear Color Finish: Slightly Dulls Color **Can Leave White Spots on Part**
Polyurethene mixture	Drying Time: 24 hours Strength Level: High Monochrome Finish: Light Yellow Tint Color Finish: Slightly Dulls Color
Polyvinyl Acetate Glue	Drying Time: 24 hours Strength Level: Moderate Monochrome Finish: Clear/White Film Color Finish: Clear/White Film **Can Impart Flexibility to Part**

 

reset log.zbd: used to reset the pixel count in the job log before printing a part.

Download and print from the ZPrint software.