I can’t believe that it’s been two weeks since I started working with the 3D printer. The wind-up to school heading into the Christmas break has been unusually hectic and, while I’ve had some time working with the printer, I’ve, obviously, not reported back anything here. The work that I’ve done with the printer has begun the journey into the more technical side of the device and has resulted in a series of troubleshooting processes that seem to be part of the learning curve. If you are thinking of getting into this technology yourself or in your library, these are issues that you will no doubt also run into early on.
Likely, the first issue that you will run into will be in changing filament. This is not a hard process, but it can reveal other issues. The Replicator 2 has a set of on-board utilities that includes unloading and loading filament. These utilities heat the extruder (the jet that melts filament for printing) and turns the motor to move the filament through. In the unloading process, the filament is heated and the motor runs in reverse so that you can pull the filament out from the feed end. The loading process turns the motor in the normal operating direction to pull the filament into the extruder and pushes out any old filament still in the system. This is a pretty easy process, except when the old filament doesn’t get completely flushed out. When this happens, you might be able to pull the filament out by hand or you might have to remove the motor and clean it out from the inside. Before touching anything too close to the extruder, you might want to reflect on what 230 degrees Celsius might feel like on your fingers. I learned this lesson the hard way… While removing the motor sounds like it could be a particularly difficult task, it isn’t. I’m far from being a handyman and I was able to do it with minimal cursing. In fact, I’ve done it twice now and am fairly comfortable with the process. You might want to keep an old toothbrush or makeup brush around to get in and clean out the inner workings of the motor. Dried filament can get trapped in there and then the new filament doesn’t grip and feed through properly.
I’m still working through the concept of rafts and supports. As I mentioned in my first post on the subject, when you print an object with a large amount of surface area in contact with the build plate, it can be difficult to remove the object at the end of the print. It is important that there be a certain amount of sticking so that the object doesn’t shift in the printing process, but too much can make it had to separate the object from the build plate. One method of making removal of the object easier is through printing the object on a raft. A raft is a lattice pattern that is printed on the build plate and then the object is printed on the raft. Because there is less surface area in direct contact with the build plate, it is much easier to remove the object. You then simply pull the raft off of the bottom of the object. The trouble with rafts is that if the object’s bottom surface is not simply a large flat space, it can be difficult to remove the raft cleanly from the bottom of the object. You really have to think through the object and decide whether or not a raft is in your best interest. A tip for those of you in libraries: don’t throw out those old bookmarks – they are very useful for sliding under the object to separate it from the build plate!
Supports can also be used when printing objects that have overhanging areas. I printed a replica of the Statue of David. David’s elbow extends down and out from his torso. When an object is printed, it is layering plastic on top of other plastic and printing the entire object from the bottom up. When it gets to the elbow, there is nothing to hold it up until the rest of the arm is printed (and the arm is above the elbow). For this, we need to build a support to hold up the elbow until that connection with the rest of the body is made. Supports can be printed that are thin rods of filament that extend from the base of the printed object to the offending overhangs. They are thin enough to be easily removed, but thick enough to support some of the initial weight as the object is printed. They allow for the printing of more complex shapes, but like rafts can cause issues when removed if they don’t come off cleanly. When David was done, I was not happy with the texture of his elbow and think that either a healthy dose of sandpaper might be in order or I might try printing him on his back so that the supports are used in different places.
Through the printing of the Statue of David, I realized that the Makerware software that is free from Makerbot does not allow the control that I would be looking for for more advanced printing. It is fine for printing many objects off of Thingverse and was certainly good enough for my initial forays, but there is little customization that can be done. It is great if you don’t want to be thinking too much about how the object is printed and are happy letting decisions be made for you that affect the printed result. But my experience is that it doesn’t take long before you need a little more control. I quickly discovered ReplicatorG (or RepG as it’s called on the MakerBot Operators Google Group). This nifty little piece of software is an open source (free and customizable if you are into coding) program that allows much more control of the interface between the real world and your 3D printer. You can control many aspects of the way an object is rendered and finally printed and you can use the software as an interface for doing things like updating firmware and the like. This becomes very important if you are in any way unhappy with the way an object is being printed. As far as I understand things, and recognize that it is still early days, you have a digital representation of a 3D object that you’ve either created, modified or simply taken from a library of objects and that object needs to be analyzed and turned into a pattern of slices for it to be printed. A slice is a very fine layer that is printed, in sequence from bottom to top, to create the complete object. If you want to control the resolution of the object (how smooth the object is), how quickly it prints, or what kind of material you print with, you need to have some control over the parameters used in rendering the object. RepG allows you that control. I would highly recommend that you play with it to see if it would work well for your situation.
One would assume that, at some point, you or your students will need to build your own designs. Thingverse has a number of designs that are customizable through their Customizer web app and I’ve used this service with great success. But you are still limited to starting with designs that are generated by others and the parameters for customization are limited to what has been set for you. I’m now playing with SketchUp which used to be a free piece of software owned by Google. It is now a stand-alone company that offers a variety of options for their software for a variety of applications. They still have a limited free version and I am experimenting with that to see how much can be done to generate printable 3D objects. Educators can get a year’s subscription to the Pro version of SketchUp by verifying their school employment and I am also playing with that. Beyond that, one can get licenses as cheap $15 per copy per year for the pro version if that is truly necessary for student work and I am thinking that I may need to go that route in my school library. The idea with this software is that you can design any 3D object that you want and export it as an .obj file that can then be imported into Makerware of RepG software for building. Early days yet in this realm and I will be exploring this further over the coming weeks.
I have found a few sources for ready made objects. Some of the applications I have in mind include models for teaching. There is no need to spend a lot of time designing a 3D model of a brain, when there are many already out there. Also, there are times when starting with another design can speed the process in customizing your own. I have a student who is working on building a better bottle top. If I can start him out on an existing bottle and top, then he can focus on the customization element, not spending time on getting a thread that works to fasten the top to the bottle. Thingverse is Makerbot’s open library that I’ve mentioned a few times already, but beyond that, I have found the Sketchup/Trimble/Google 3D Warehouse has a ton of 3D images that can be used for 3D printing. Not all designs will work “off the shelf” but the library connects with such things as the building images from Google Earth and my Statue of David was sourced from there. I’ve also found GrabCad which is another free library of images contributed by users. Neither of these last two suggestions are intended to be immediately useable as Makerbot designs, but as starting points they present a huge array of opportunities.
As always, I’m on a journey of discovery here and if there are any experts who happen to stumble upon this post that can correct, illuminate or aid me, I’d be forever grateful!