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.

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

Multimachine

Multimachine, built by Pat Delany of Palestine, Texas, is an inspiring project. It is...

a humanitarian, open source machine tool project for developing countries... The MultiMachine all-purpose machine tool can be built by a semi-skilled mechanic with just common hand tools. For machine construction, electricity can be replaced with "elbow grease" and the necessary material can come from discarded vehicle parts. What can the MultiMachine be used for in developing countries?
AGRICULTURE...
WATER SUPPLIES...
FOOD SUPPLIES: Building steel-rolling-and-bending machines for making fuel efficient cook stoves and other cooking equipment...
TRANSPORTATION...
EDUCATION...
JOB CREATION...

The project is open source and thoroughly documented. It uses commonly available pieces. It seeks explicitly to address the needs of the developing world. It recognizes the work people did in this area (1, 2) in years past. Cool stuff. We have all kinds of Industrial Revolution era mill buildings in the greater Boston area and this would fit right in.

Frostbot, the work of Brian Schmalz, is another food fabber. It's designed to frost cookies. The CNC mechanism is from Fireball CNC. Brian's other tinkerings include a cool USB bit-whacking board available at Sparkfun.

Penny wise, pound foolish

I got the idea that I should try to design and build my own electronics. I've done electronics design before, including microcontrollers and FPGAs and the like, but I have little experience with power electronics. That, and I'm impatient. The upshot is that after wasting about three weeks and a few hundred dollars in trying to control stepper motors, I'm not much further ahead. Here is the affordable pre-packaged solution (which had been recommended by the guy who sold me the mechanics) which I should have used from the start:

• Xylotex three-axis controller with power supply
  $205 plus shipping
• Xylotex four-axis controller with power supply
  $235 plus shipping
• Xylotex FAQ

So I'll plan to pick up a 3-axis controller and run it with LinuxCNC. Apparently TurboCNC is also very popular but I'm not about to run DOS on any machine that could be running Linux.

The mechanics cost about $300 including shipping. The steppers cost $75 (I got them from RRRF). This stepper controller will run maybe $225 with shipping, so the whole thing is $600. That's reasonable. Obviously it doesn't include waste.

I'm thinking it would be fun to fool with Python code that generates G code and sends it to the CNC. I could develop a repertoire of programmatically defined shapes.

RepRap replicates, and Will gets a New Toy

On the left is Adrian Bowyer, the University of Bath professor who started the RepRap project. On the right is Vik Olliver, the most active RepRap builder on the planet. The two machines marked "parent" and "child" are RepRap 3D printers with the interesting relationship that the "child" was mostly built by the "parent". This is a HUGE STEP toward Bowyer's vision wherein RepRaps make more RepRaps and humans benefit. This will do for physical goods what the GPL and Linux and Apache have done for software.

My own news is, at least locally, equally exciting. My CNC mill has finally arrived! And I also got an Arduino controller. I've got my stepper motors from RRRF, and a Harbor Freight router is on the way. It's going to take time to put everything together, and of course there's very little spare time in the life of a modern adult.

Once the CNC mill is up and running, I plan to work on a scheme for swapping out the router and swapping in an extruder for thermoplastic. By that time the RepRap guys will be doing even better than they're doing today, so I will benefit from their stuff. Maybe I'll end up making an actual RepRap before I'm through.

Affordable CNC gadgets

CNC has existed as a hobbyist pursuit much longer than 3D printers have been. I finally broke down and purchased one of these on eBay. It will take a couple weeks to arrive, and the one I got did not include stepper motors, couplers, or motor drive electronics. Those are things I'd enjoy doing myself anyway, so no problem.

I like this project which is along similar lines.

For my own gadget, I need to order stepper motors, think about couplers, and start planning how the electronics will go together. I'm thinking about being lazy and using the parallel port.

RepRap replicates 100%

This story in Computerworld is a couple weeks old, and I should be working harder to keep up. Vik Olliver, a RepRap hacker in New Zealand (and probably the hardest-working RepRap hacker in the world), has now fabricated all the parts of the RepRap except the Z flag, which can be cut out of the side of a beer can. This includes only the parts that it makes sense to print on a RepRap, so it doesn't include stepper motors, nuts and bolts, pieces of metal and wood (e.g. threaded rods). But it's an important step.

I myself am still drooling a bit over some of the hobbyist CNC stuff. There's a guy in New Mexico who sells these things on eBay. He sells aluminum ones (like this) and ones made of MDF, which I believe is a sort of particle board. Many low-end CNC machines are in the $2000 to $5000 ballpark, whereas he sells these in the $300 to $600 ballpark. It should be pretty easy to swap out that orange router and swap in an extruder.

I was thinking a bit last night about how to drive those steppers, since the offerings on eBay don't include the drive electronics. Digikey sells a stepper motor sequencer chip, the L297, which would be used to drive some power MOSFETs. The L297 just needs an input to choose clockwise or counter-clockwise, and a clock pulse to advance a step in that direction, so you need six GPIO lines to control the three motors, and one more to turn on/off the router or squirt goop out of the extruder. There's some very good information on stepper motors and driver circuits here.

It occurs to me that I've never posted the Sourceforge download page for the RepRap design files. A shocking oversight, given that I want to see the project succeed and proliferate.

More service bureaus

In a couple of recent postings I have talked about the Ponoko laser-cutting service. Another very interesting online service bureau is Emachineshop.com which is a machine shop to which you send design files created with their downloadable CAD software. They have some examples of the things people have made. Just poking around their website really makes me drool a little bit. I can't believe I'm not doing something with this.

Big Blue Saw is a service bureau that does waterjet cutting of metal and plastic. They cut very thick pieces of metal, which surprises me, I didn't know you could do that.

A couple more: Fabjectory.com specializes primarily in making physical copies of avatars from games like SecondLife. FluidForms makes pretty flowing shapes for things like vases and pitchers. I haven't read about these yet, and as of this writing I don't know what technology they use, or what design software.

Broadening the definition of "fabber"

I want to broaden the scope of this blog a bit. The word "fabber" is generally accepted as synonymous with "3D printer" but a 3D printer has a lot in common with both CNC machines (routers for wood or milling machines for metal) and laser cutters. There are hobbyists building all of these. All of them make a 2D or 3D shape under computer control with relatively little human intervention, and minimal need for human skill.

How many of these gadgets could be self-replicative in the RepRap sense? For example, could one use a laser cutter (or a laser-cutting service like Ponoko) to cut out pieces and use those pieces to build another laser cutter, thereby driving down the cost of laser cutters? As with RepRap there will inevitably be complicated pieces that can't be made that way. CO₂ lasers are dangerous and expensive, so I don't think this could make the kind of impact in the developing world that RepRap hopes to make. A replicating CNC machine might be a better bet, as Dremel tools are much cheaper and safer than lasers.

That self-replicative idea does fascinate me a good deal. It will, over time, drive down the price of the self-replicating thing. That doesn't mean we'll enter a microeconomic paradise, but it promises at least to be interesting and possibly to raise the quality of life noticeably.

I've haven't blogged too much about commercial machines. I want to do more of that. I admire the hobbyists and their perseverance in the face of difficulties, but the technology appearing in commercial machines will gradually trickle down into the hobbyist arena as patents expire.

An XYZ platform for fabbing or CNC

I was watching an auction for a CNC XYZ table on eBay that went for $300, item number 200198037915. I would have bid on it if the Z travel hadn't been only 2 inches. It was built from plans from hobbycnc.com and didn't have stepper motors or the machining tool but was otherwise complete. I felt lust in my heart, but that itty bitty Z travel bugged me, so I thought about what could be done to increase it. Here's my general idea.



My hope is that the blue-hatched stage can be made to take either a Dremel tool for CNC milling, or an extruder for fabbing. The result might or might not be self-replicative in a RepRap sense but it would be a cool toy.

Interesting Russian project

Here's the website in Russian, and a Google translation to English (click on the "Constructor Kulibin" link). I found this referenced from MAKE Magazine. This is a very interesting project.
They have a great-looking XYZ stage built from a CNC kit. They lower a heating element onto powdered raw material, sintering the raw material as the CandyFab does, except their heating element is a length of nichrome wire instead of a jet of hot air. It gets hot enough to glow, and on the web page they mention that they can work with any powdered material with a melting temperature from 100 to 300 Celsius, including sugar, wax, "Plexi" (plexiglass?), and mixtures such as plastic and sand, plastic and metal powder, powdered paint and sugar powder. Like the CandyFab, each layer of fresh material is laid down on top of the previously worked layer (and I hope that process is automatic as it sounds tedious otherwise) and then you scribble a cross-section on the new layer with the heating element, and then it's time to put down another layer.

The nice thing to this kind of approach is that the unmelted/unfused material provides mechanical support for the built structure. You can build shapes that RepRap and Fab@Home can't make, such as bridges or inverted cones, because any bridge-like part that will go over empty space is built with stuff under it to support it.

This made me curious to start looking around at CNC kits, which could nicely jump-start any fabber project. The XYZ machinery for a fabber is called a "gantry" in CNC language, and there is a very active hobbyist CNC community. Here is a video for a CNC gantry kit that somebody was selling for $195 on eBay. The video itself is for sale ($20) so this is just a teaser.

Here's a few interesting CNC links.

• HobbyCNC.com: CNC router plans for $25
  
• ShopBotTools.com: a very nice gadget but too expensive
  
• MadVacCNC: a 4-foot-by-8-foot CNC table
  
• SolSylvia.com: more CNC router plans, I want this one