3D Printer Tutorial
We have the Dimension BST 768 3D printer. It takes ABS plastic and a support material, and lays out layers of each to make a 3D model. The printer supports models of up to 8x8x12 inches. Depending on the amount of support material required for the built, a 5 cm X 5 cm X 5 cm can take about 1 hour to build. The ABS plastic come in a variety of colors (white, blue, yellow, black, red, green, gray).
BST stands for breakaway support technology, where you can simply break off or chisel away the support material from the ABS model. There are printers that use a soluble support technology, where the support material can be removed by dipping the model in a support removal solution.
The printer is in CSE 505. Please ask permission (and for the password) before using the printer.
Making a 3D Model
A 3D model can be made using one of a variety of CAD software tools. Rhinoceros (also called RhinoCAD) and SolidWorks are two popular examples. Both allow you to built 3D models and save the model as a stereo lithography file (.STL). The software that talks to the 3D printer is called CatlystEX and takes in STL files.
CatalysEX is installed on the PC that is connected to the 3D printer. SolidWorks is also available on that machine. You can also download a fully functioning trial version of RhinoCad from their website.
Catalyst's GUI tabs:
- General: used to look at the model to import it see how it looks. You can also set the STL scale size and fill types here. The fill types control how solid parts are filled in. "Sparse" will make up internal structure, whereas "Solid" will make a truly solid part. Use what seems right, and doesn't waste material.
- Orientation: Here you can reorient your model to get it to print using the least support material. Also note that pieces are the least strong vertically, so if you're really looking for strength in a narrow spot, orient accordingly.
- Pack: Here you can pack many objects into one printing session, and also get estimates for amount of material and time used to print.
- Use File-> Open STL to import the .stl file, then use the "Process STL" button to convert that STL into a toolpath. A toolpath (saves as a .cmb) for this machine is the path it has to run the head around to create the model you want. After it does this, you may see an error, meaning that it didn't like your model and can't figure out how to print something you gave it. If this is the case, go back to your 3D software and make sure there are no gaps or problems in your model.
- Make sure you set the right STL units and the appropriate scale.
- Don't forget to add the model to the pack before printing. There's also the ability to pack many models into one printing session, and this same tab can tell us approximately how much time and material will be used. This is handy so that you can avoid running out mid-model.
- One very useful feature is the ability to look at exactly how a model will be printed. You'll see your model divided up into slices, with red being a slice of your actual model and blue being a slice of the support material. You can further look at individual slices and see how each slice will be filled in. This will tell you if there are going to be any gaps in places you may not expect them, and will give you a good idea of what may stick together from being too close. If you pay close attention to this, the only way that your model won't print as expected will be if the plastic doesn't go where the printer puts it.
- Before you print the model, make sure the machine is ready to print.
Getting the Printer Ready
CAUTION: The inside of the printer is very hot.
Check list for the printer:
- Is a black plastic tray in the printer?
- Is the tray locked in position?
- Is the tray free of all support material (to avoid scraping the print heads on it)?
- Is there enough material in the printer to print all of your model?
- Have you selected the proper fill types for what you are trying to make?
- Is the little head-cleaning bucket in back empty?
Starting the Print Job
You will have to select print on both the computer and the printer. After making sure the printer is ready, select print from the CatalyEX software. At the printer, start the job. You can cancel the print at the printer if there are any problems.
Removing the Support Material
You can break off the support material from the model. For tight spaces, you may need to use a knife or sharp end (be careful!).
You need to clean off the black plastic tray and re-load it, just in case the next person doesn't check. Use the putty knife to scrape any support material off of the tray. The tray should be completely smooth and free of excess material to ensure a proper build.
The plastic trays are actually single-use, but you can usually re-use them. It seems that after many many prints on a tray, the support material may fail to stick to the surface, and as the part is printed, the support material warps and bows upwards. If this happens, discard the tray and use a new one.
Things to Keep in Mind
- Walls are printed as 2 sides with zig-zag filler in between. If the wall is thinner than 1.5mm, then the printer gives up on putting in this filler, and you just get two walls. If you make the wall between 1.25 mm and 1.38 mm, however, the printer will print 2 walls and a third in the middle. At 1.25 mm it goes back to just two walls, with those walls getting a little "unstable" at .76 mm. Finally, at the thickness of .05mm on the model, the printer gives up entirely and prints nothing. For cylinders, you get a circle filled in with zig-zag patterning, then a hollow tube, and eventually just a dot. It's worth noting that you can get thinner dots than walls.
- You can print two walls 0.2 mm from one another without them "sticking" to one another. If you leave near-zero space between two parts in a model, and then print them, they will "stick" together, but can be pulled apart later. This seems to also apply for circular walls, regardless of orientation (for example, if you have an axle in a hole, 0.2 mm space should be enough.)