Homebrew stereolithographic 3D printer

I've been interested in hobbyist 3D printers for quite a while. A friend of mine, Jeff Keegan has an exquisite blog about his several-year hobby of building RepRap-style printers. He has donated a printer to the Boston Museum of Science. I took a stab at starting a RepRap-style printer years ago, but my level of dedication was not equal to the task.

A RepRap-style printer (technically, a fused-deposition-modeling printer) works by squeezing molten plastic out of a hot nozzle onto the workpiece, where the plastic cools, forming the next vertical layer. One FDM printer can create some of the parts for another FDM printer, or to replace its own parts when they get worn. This was the idea behind the RepRap project, that partially self-reproducing printers could be very cheap.

Stereolithograhic 3D printers operate on a different principle, using ultraviolet light to cure resin. The video above illustrates this process.

The past few weeks I have been spending way too much time trying to figure out how to build a stereolithographic printer of my own. I looked at a lot of things other people have done and started doodling some ideas. A few times I made or purchased parts for a particular approach and later realized that it wouldn't work for some reason. But after a lot of tinkering, I finally produced the octahedron on the right.

My printer is pretty crude and is due for a lot of improvements in the days ahead. I had ordered a stepper motor controller board that didn't work, so I needed to manually rotate the threaded rod that lowers the workpiece into the resin bath.

Hopefully this picture isn't too confusing. A lot of this is stuff from the hardware store: a bucket, a lot of plywood, nuts and bolts, a piece of aluminum screen, a threaded rod, two straight rods. That black shape at the top held in place with a bungee cord is a pretty standard conference-room projector. When the thing is printing, the projector aims down into the bucket, which holds a quantity of resin floating on a much larger quantity of salt water. The ultraviolet light from the pattern projected onto the resin cures it in a particular shape, forming one layer of the product, and then the threaded rot rotates, moving the product down by one layer-height.

Currently I'm using a layer-height of 1/40th of an inch, which turns out to be quite visible to the naked eye, so I want to go down to something more like 1/100th of an inch.

I plan to post plans and software on Github and Instructables to enable anybody to build one of these printers for just a few hundred dollars. Most of the cost ($350) is the projector. I'd like to do the RepRap thing of using lots of pieces made by an identical printer, which would involve some redesign.

Cool new 3D printers

I don't want to fall into the habit of only blogging once per year about MakerFaire. So this post is actually about a crop of cool new 3D printers, and I'll probably see a few of them there, but it's not about MakerFaire proper. These all fall in the $1500 to $2500 price range.

First up is Makerbot's Replicator 2. There is some controversy around this one, because it's a mix of open source technology under the GPL, and some new technology that's very likely not open source, which allows for a much higher print quality. The open source 3D printer advocates are concerned that it violates the GNU General Public License. The open source technology is primarily the work of Adrian Bowyer who started the RepRap project, and he's given (unenthusiastic) permission to Makerbot to use it.

One of the RepRap enthusiasts is my friend Jeff, who will have a table at MakerFaire this year to show off the printer that has occupied two or three years of his nights and weekends. I like Jeff and I think he'll probably not be too happy with Makerbot's decision to include closed-source technology. But the step up in quality for the price is pretty appealing for a non-GPL-purist like myself. I don't worry about running GPL software on closed-source laptops, after all.

Second is the FORM1 from some Media Lab folks. I don't know much about these folks or their history, but the Media Lab has been at the cutting edge of high-end 3D printing for a couple of decades now, so they've probably got something pretty interesting. I think their raw material is a liquid rather than the long plastic spaghetti sticks used by most other affordable machines (based on one photo on their Kickstarter page). This is the most expensive of the lot, price currently listing as $2500.

Third is the UP!Plus from 3D Printing Systems. Their output doesn't look as nice as the Replicator 2 or the FORM1, but they are at the more affordable end.

What's cool about all these printers and some other new ones is that the user friendliness and quality of output are improving rapidly in recent years. Before long, these things will be popping up in homes, dorm rooms, high schools, and the local mall.

Makerfaire NYC 2012 is this weekend, and I'll be there to checkout 3D printers, microcontroller boards, art installations, and whatever else is around, and I'll blog about what I see.

MakerFaire NYC 2011

I went to MakerFaire at the NY Hall of Science, Queens, NY on September 17th and 18th, and took plenty of photos. Like last year, the location was the site of the 1964 World's Fair. Even though I grew up pretty close to New York, I didn't get to see the World's Fair as a child, so I'm glad to have these opportunities to see what's left of it.

As was true last year, there were lots of 3D printers and CNC milling machines. My impression this year was that a much larger percentage of them were hobbyist efforts rather than high-end commercial projects. I think that's a good thing. There seems to me to be a maturing of the 3D printer hobbyist effort in general, and the gradual emergence of more small businesses like Bre Pettis's Makerbot. The hard technical challenges (the big one being getting the extruder nozzle to work just right) have pretty much been identified now.

As I looked at some of the products, which have been improving in resolution, it occurred to me that an interesting approach would be, instead of going with increasingly fine nozzles, to use a coarse nozzle to place a slightly oversized drop of plastic, let that drop cool and harden, and then bring in a milling tool to shape it. This would mean moving back and forth frequently between the extruder nozzle and the milling tool, so it would need some tinkering and might not end up being an improvement.

There were lots of other tools, things on display, and cool stuff to see. I was really impressed with an elegant (if low-res) volumetric display called Lumarca. Essentially the guy uses a projector to project colors onto lengths of monofilament fishing line in the viewing volume, and by carefully controlling the projected image, he individually controls what colors appear along each length of monofilament.

There were a few interesting vehicles, like motorized skateboards and a Segway clone. Those were fun.

One thing I found interesting was that in addition to the expected Arduino stuff (which has the full weight of O'Reilly Publishing behind it), there were a good number of boards with more advanced microcontrollers, particularly ARM Cortex-M3 controllers. This interests me because with their larger address spaces and fuller feature sets, ARM processors can run Linux OSes or Python interpreters or other big pieces of code  beyond the itty-bitty programs that will fit on an Arduino. Teho Labs had a nice line of Cortex M3 boards. They shared space with Dangerous Prototypes who were showing off their Web Platform board.

I did get pretty tired and sore walking around so much, and needed some Advil. But it was definitely worthwhile. Maybe I'll have some project next year so that I can have a booth of my own.http://www.arm.com/products/processors/cortex-m/cortex-m3.php

Brilliant RepRap video (thanks to Emeka Okafor)

I've moved this posting over to my new Fabber blog.

3D printer in a knick-knack store

I've moved this posting over to my new Fabber blog.