Sunday, December 15, 2013

3D Printing December 13

Here are some things I've learned about my Replicator 2 since it arrived. I hadn't had time to work with it since the first day, so I set aside time after school Friday, and invited any of my Calculus students who cared to help explore.

Sticking issues (or, more properly, non-sticking issues)
The day I unpacked my Rep2 (with my 3rd period calculus class) we attempted each of the designs pre-installed on the included SD card. Bracelet -- success. Linked chain -- fail. Mr. Jaws -- success. Comb -- fail. Nut and bolt -- success. The failures were the result of the build becoming unstuck from the build plate mid-process, effectively ruining things.

My hypothesis was that I hadn't fine-tuned the build plate level well enough, so perhaps the extruder nozzle was knocking into builds, causing my issues with comb and chain. Friday I tried the chain once more, and had similar failure. So I went through the utility menus to re-level the build plate. My first time, I had 25 students clustered around me asking questions, so perhaps I got distracted. I was alone Friday, and so could focus well on how much friction there was between my sheet of paper (leveling gauge) and the extruder nozzle.

I tried the chain again, and it worked fine. Leveling seems to have been the issue.

Students loved watching the build process. It took about 20 minutes each to print the bracelet and Mr. Jaws, and I had some students staring at the motion of the print head for the entire time. Since I had just introduced the concept of a definite integral to them, I was hoping they would make the connection to the notion of accumulating infinitessimally thin layers to build the area under a curve. I had to raffle off the builds (using pseudo-random number generator in my TI-Nspire, tying it to statistics lessons). I had as much male as female interest in the bracelet.

Two students spent considerable time examining the packing materials, and were fascinated to realize some of it had been 3D printed. We talked a bit about recursion.

My last build Friday was the lid to a "bunny box" that I found on thingiverse.  Successful, but, man, when I started I didn't realize how long it would take.

File formats
Due to computer issues, I haven't installed makerware on my laptop. It's just too finicky lately, and I don't want to introduce another variable into its operation until I figure out what's wrong.  I'll have to install on my home computer to try to explore designing or modifying on my own.

So, I've limited myself to things I can download. I've noticed that most of the designs on thingiverse are in .stl format, whereas my Rep2 only understands .s3g format. Maybe that's a big d'oh to everyone else, but it took some research to understand why I couldn't print the things I was downloading. Now I know the limit my search to the proper file format, until I download and install software to convert for me.

Build time
The display on my Rep2 is friendly enough to tell me what percent of the build is done. But as I was building the box lid (see above) I was dismayed to see that, after almost an hour, it said I was only 20% complete. Yikes!

Less than 30 minutes later the build was done. So now I know that % complete calculation doesn't refer to the build. I'm guessing it refers to the final build height.

I opened the door to my room while building, and had windows open, but there was still a distinct aroma of melting plastic and I was coughing. I wonder about the health effects of volatiles from melting PLA.

Thursday, December 12, 2013

Team Effort. Maybe Not.

Perhaps I'm overreacting. But I don't like the way my school's guidance department is treating me.

I teach Advanced Placement Calculus BC. I have 25 students. We are an urban district, and though I have some strong students, I also have a number who struggle. Not all students are getting stellar grades in the course.

I offer tutoring three days a week. I stay at school until 6 PM to make sure I'm available even to students who may have other meetings or team practices. About 25% of my students take advantage of tutoring.

Our Guidance office has also decided to make tutoring available to my students. They did not offer me the job. They did not offer me the job (they say) because they know I'm busy. I'm busy because I'm tutoring my students. Their plan is to take my students out of my tutoring sessions to go to another tutor.

This other tutor is not a teacher at our school. They have not offered the position to any teacher at our school. They say they have not offered the position to any teacher at our school because they don't think any teacher at our school is qualified to tutor AP Calculus BC.

They say they must have 100% participation of my students if they are to offer tutoring. I suggested that they would save resources by getting 100% participation to the tutoring I already offer. If they do get 100% participation, I will have no students to tutor, so I'll be available to tutor for them.

I've suggested that, if they insist they must use this other tutor, it would be polite if they offered the tutoring on days I'm not already tutoring. They could choose a day when they know I'm doing something other than tutoring. That way they could more credibly pretend the job was not offered to me because I'm not available.

I feel they are trying to undermine the respect my students have for me.

My Assistant Principal is unhappy with the Guidance Office for taking this action. He has voiced his displeasure to the Guidance Office and to the Principal. The person who runs the tutoring program I work for is unhappy with the Guidance Office. The students have signed up to be in the program for the entire year, and he will not lightly release them from his program.

I don't think they can get 100% participation anyway, so, if they were speaking honestly, they will not be able to go ahead with the tutoring. But it has eroded my respect for the Guidance Office. I know longer am under any illusion that they are working WITH me for the students.

Tuesday, December 3, 2013

First Day with my 3D Printer

Thank you MakerBot, thank you DonorsChoose, thank you anyone who contributed to make this deal possible. Yesterday afternoon my Replicator 2 arrived.

MakerBot has announced a desire to have a 3D printer (one of theirs, of course) in each public school in America. They've partnered with to offer their printers for an incredibly low out-of-pocket cost to teachers. More details on that in my previous post 3D Printing. Funding isn't unlimited, so the first time they offered, I wasn't able to get it. Second round of funding I managed to get in. Now many teachers are waiting for a third round of funding. But that's a different story.

My printer, a MakerBot Replicator 2, was funded just under two weeks ago, and the actual printer arrived at my school Monday afternoon. I decided to set it up with my Calculus class today.

I brought the box up to my classroom and cleared enough space on my desk for the printer, which is roughly the size of a microwave oven. I unpacked the boxes, put the printer on my desk, and began working through the startup procedures in the user guide. I was not very far along when the period bell rang, and my students began filtering into the room.

I had mentioned the printer to them, and many immediately realized what that big black thing on my desk was. I was peppered with questions, which made it hard to continue setting up. I assigned tasks to students. Snake the power cord to the outlet. Work through the interface menus. Load the PLA filament (the "ink" the printer extrudes to do it's work). I really wanted to do it myself, but I also knew that my students would get a huge thrill out of helping.

Finally, set up, the question was what to print. I wanted to start small, since I don't know much about the machine. My students wanted to start big. The two most frequent requests were for Hello Kitty items, and Pokemon goods. They also read the news, and so there were a number of questions about printed guns. I brushed all suggestions aside (one benefit of being the teacher) and announced we would print one of the projects pre-loaded on the SD card that came with the Replicator. We looked through the items and decided on a flexible bracelet.

Go. It is so cool. The PLA filament feeds up from a spool hanging on the back, gets to the extruder, which melts it at 240 degrees C, and the gantry system maneuvers the extruder around to squirt out the design. We just started looking at Integrals, and I was really happy that all the students were watching us build up something from very very very thin layers (not really infinitessimally thin, but I think it was good enough to make the abstract idea concrete). It took about 20 minutes, but most of the students' eyes were glued to the printer for the entire process.

When done, I took the bracelet from the build plate and passed it around for students to inspect. It is amazing technology. I did a random number drawing (thank you TI-Nspire) to see who got to keep the bracelet. I had as many boys as girls interested in the bracelet.

Next we tried to print some chain links. This didn't go well. Partly through the build, the item separated from the build plate, which effectively ruined the job, so I cancelled.

Third we tried a fish-shaped fob called Mr. Jaws. This also took about 20 minutes, and we did another random number drawing to decide who kept it. I made an effort to lecture for a very short time, connecting yesterday's lesson about approximating the area under a function by drawing many thin rectangles. They weren't interested.  So I began a fourth print job. This one was a nut and bolt. I couldn't believe the threads would actually work.

The period bell rang, and the students left, but I could see it was one of the most interesting classes ever for them, even though we did very little formal learning.

The nut and bolt eventually finished printing. I removed them from the build plate, and broke off the thin plastic the forms at the beginning and end of print. Twisting them together I found that, though tight, the threads actually worked -- the Replicator had printed a useable nut/bolt combination. Playing with it through the day, it got better and better. I suppose it wore off rough places in the build.

Later in the day we tried to print a comb. This item, too, came loose from the build plate, and so was ruined.

So, the question going forward, is how to use this effectively in class. I need to learn how to design things on my own. I cannot rely solely on other people's postings on I need to figure out why some items come loose during printing, and prevent that from happening. Math for America is going to offer a PLT in 3D printing this spring, which I intend to sign up for. In the meantime, I suppose I'll have to find some online user groups and begin studying.