Let’s talk multi-material printing on desktop 3D printers. There are a lot of problems when printing in more than one color. The easiest way to do this is simply to add another extruder and hotend to a printer, but this reduces the build volume, adds more mass to the part of the printer that doesn’t need any more mass, and making sure each nozzle is at the correct Z-height is difficult. The best solution for multi-material printing is some sort of mixing hotend that only squirts plastic from one nozzle, fed by a Bowden system.
The basic idea behind this multi-material upgrade is a four-way Y-shaped filament path. Each color of filament is loaded into a separate extruder, and when the material is changed the currently ‘active’ filament is retracted out of the heater block to just before where the filament paths cross. After the filament is swapped in the hotend, the remainder of the previous color of filament is squirted out onto a small (3x5cm) tower.
Because this is an upgrade to the i3 mk2, Prusa needed a way to add three additional stepper motors to the build without having to replace the printer’s electronics board. He’s doing this with an SSR-based multiplexer that allows one stepper motor output and a few GPIOs to control four motors.
If you have an i3 mk2, a four- material upgrade for your printer will be available for $249 USD in a few months. That means a full color, four-extruder i3 mk 2 costs less than $1000 USD, a price no other multi-material printer can touch.
You can check out [Prusa’s] video of the multi-material upgrade below. The printer and the man will be touring the US for Maker Faire and Open Hardware Summit, and you can bet we’re going to get some video of this multi-material printer in action.
3D printers have become incredibly cheap, you can get a fully workable unit for $200 – even without throwing your money down a crowdfunded abyss. Looking at the folks who still buy kits or even build their own 3D printer from scratch, investing far more than those $200 and so many hours of work into a machine you can buy for cheap, the question “Why the heck would you do that?” may justifiably arise.
The answer is simple: DIY 3D printers done right are rugged workhorses. They work every single time, they never break, and even if: they are an inexhaustible source of spare parts for themselves. They have exactly the quality and functionality you build them to have. No clutter and nothing’s missing. However, the term DIY 3D printer, in its current commonly accepted use, actually means: the first and the last 3D printer someone ever built, which often ends in the amazing disappointment machine.
This post is dedicated to unlocking the full potential in all of these builds, and to turning almost any combination of threaded rods and plywood into a workshop-grade piece of equipment.
Josef Prusa’s designs have always been trustworthy. He has a talent for scouring the body of work out there in the RepRap community, finding the most valuable innovations, and then blending them together along with some innovations of his own into something greater than the sum of its parts. So, it’s not hard to say, that once a feature shows up in one of his printers, it is the direction that printers are going. With the latest version of the often imitated Prusa i3 design, we can see what’s next.
The Hackaday Overlords (or Hackaday family) are running a series of AMAs on SupplyFX. What is SupplyFX? It’s a social network for EEs. Who’s in the first AMA? [Brady Forrest], the guy who runs Highway1, a Bay Area hardware accelerator. They’re the accelerator responsible for the lustworthy Keyboardio, and the startup that is purely mechanical and has shipped zero lines of code, CoolChip. If you want to talk about hardware startups, [Brady] is your man. The AMA is tomorrow, May 16th, at 13:00 Pacific.
Makerbot is dead, or at least they will be soon. Whatever. Nothing of value was lost. Lulzbot, on the other hand, is going gangbusters. They saw eight hundred percent growth over the last two years. and $15M in revenue in 2015. They did this all with open source hardware and software, and using 3D printing in a manufacturing context. They’re the jewel of the Open Hardware movement, and a shining example of what Free Software can do.
The current generation of software defined radios started with the ubiquitous TV tuner dongles, and quickly graduated to the HackRF. You can only get so much bandwidth out of a USB 2.0 socket, and the newest and bestest SDR is the LimeSDR. They’re about halfway through their crowdfunding campaign (and halfway funded), and have finally changed out the USB A connector to a USB micro B connector. Good choice.
The ESP8266 is quickly becoming the go-to device for when you want a cheap way to put a sensor on the Internet. The only problem is programming it. No problem – here’s a bunch of Lua scripts that do 90% of everything. Need to read a PIR sensor? Light up a few LEDs? Put the data from a temperature and humidity on the Internet? There you have it.
The Vintage Computer Festival West is back on this year. We’ve gone to VCF East in New Jersey for a few years now, and had a few occasional outings to the southeast and midwest Vintage Computer Festivals over the years. This is the first time the west coast has had a Vintage Computer Festival in several years. It’s in Mountain View, on August 6th and 7th. Yes, that’s the same weekend as DEF CON.
E3D, makers of fine hot ends and 3D printer paraphernalia, have released a new kind of filament. It’s called Edge, it’s based on PET, and it prints as easily as PLA, with better mechanical properties than ABS. A few sample prints made from Edge were at this year’s Midwest RepRap Festival, and the Edge’s bridging ability is crazy. You need a heated bed for Edge and it’s sensitive to moisture, but it has some very interesting properties that can be cleverly exploited.
In other filament news, Colorfabb released a filament to print clear parts. Yes, that’s very weird. Clear parts require 100% infill, meaning it will use a lot of filament. It’s still very advanced wizardry, and I’m very interested in seeing the first print of a sanded and polished convex lens.
Holy Crap it’s the 3D printing edition of the links post.[Prusa] just released the latest version of the i3. It’s now bigger: 250x210x200mm build volume. The heated bed – [Prusa] was one of the first to experiment with PCB heated beds – is now vastly improved when looking at it through a FLIR. The Mk. 42 heated bed doesn’t have a hot center or cool corners. PEI sheet removes the need for blue painters tape, glass, aqua net, or glue sticks. The printer has self-test capabilities. The mechanics of the printer, especially the Z axis, are improved. [Prusa] will be selling this as a kit for ~19000 Czech Crowns or $699 USD, but he’s RepRap to the core. Buy a spool and start printing your next printer.
After years of cutting my hands on the exposed threads of my Prusa Mendel i2, it was time for a long overdue upgrade. I didn’t want to just buy a new printer because it’s no fun. So, I decided to buy a new frame for my printer. I settled on the P3Steel, a laser cut steel version of the Prusa i3. It doesn’t suffer from the potential squaring problems of the vanilla i3 and the steel makes it less wobbly than the acrylic or wood framed printers of similar designs.
I expected a huge increase in reliability and print quality from my new frame. I wanted less time fiddling with it and more time printing. My biggest hope was that switching to the M5 threaded screw instead of the M8 the i2 used would boost my z-layer accuracy. I got my old printer working just long enough to print out the parts for my new one, and gleefully assembled my new printer.
I didn’t wait until all the electronics were nicely mounted. No. It was time. I fired it up. I was expecting the squarest, quietest, and most accurate print with breathtakingly aligned z-layers. I did not get any of that. There was a definite and visible ripple all along my print. My first inclination was that I was over-extruding. Certainly my shiny new mechanics could not be at fault. Plus, I built this printer, and I am a good printer builder who knows what he’s doing. Over-extruding looks very much like a problem with the Z-axis. So, I tuned my extrusion until it was perfect.
Only a few days ago, a significant proportion of the Hackaday crew was leaving Goshen, Indiana after the fourth annual Midwest RepRap Festival. We go to a lot of events every year, and even when you include DEF CON, security conferences, ham swap meets, and Maker Faires, MRRF is still one of the best. The event itself is an odd mix of people rallying under a banner of open source hardware and dorks dorking around with 3D printer. It’s very casual, but you’re guaranteed to learn something from the hundreds of attendees.
Hundreds of people made the trek out to Goshen this year, and a lot of them brought a 3D printer. Most of these printers aren’t the kind you can buy at a Home Depot or from Amazon. These are customized machines that push the envelope of what consumer 3D printing technology. If you want to know what 3D printing will be like in two or three years, you only need to come to MRRF. It’s an incubator of great ideas, and a peek at what the future of 3D printing holds.
Despite tuning my extruder steps perfectly, and getting good results instantly on larger prints. I was still having a ton of trouble with smaller parts. PLA is the favored printing material for its low odor, low warping, and decent material properties. It also has many downside, but it’s biggest, for the end user, lies in its large glass transition temperature range. Like all thermoplastics, it shrinks when it cools, but because of this large range, it stays expanded and, getting deep into my reserve of technical terms, bendy for a long time. If you don’t cool it, the plastic will pile up in its expanded state and deform.
I am working on a project that needs a tiny part, pictured above. The part on the left is what I was getting with my current cooling set-up and temperature settings. It had very little semblance with the CAD file that brought it into this world.
The bond between layers in a 3d print occurs when the plastic has freshly left the nozzle at its melting point. Almost immediately after that, the plastic crosses from the liquid state into a glass state, and like pressing two pieces of glass together, no further bonding occurs. This means that in order to get a strong bond between the print layers, the plastic has to have enough thermal mass to melt the plastic below it. Allowing the polymer chains to get cozy and hold hands. Nozzle geometry can help some, by providing a heat source to press and melt the two layer together, but for the most part, the fusing is done by the liquid plastic. This is why large diameter nozzles produce stronger parts.
What I’m getting at is that I like to run my nozzle temperature a little hotter than is exactly needed or even sensible. This tends to produce a better bond and sometimes helps prevent jamming (with a good extruder design). It also reduces accuracy and adds gloopiness. So, my first attempt to fix the problem was to perhaps consider the possibility that I was not 100% right in running my nozzle so hot, and I dropped the temperature as low as I could push it. This produced a more dimensionally accurate part, but a extraordinarily weak one. I experimented with a range of temperatures, but found that all but the lowest produced goopy parts.
After confirming that I could not get a significant return on quality by fine tuning my temperature, I reduced the speed of the nozzle by a large percentage. By reducing the speed I was able to produce the middle of the three printed parts shown in the opening image. Moving the nozzle very slowly gave the ambient air and my old cooling fan plenty of time to cool the part. However, what was previously a five minute part now took twenty minutes to print. A larger part would be a nightmare.
So, if I can’t adjust the temperature to get what I want, and I can adjust the speed; this tells me I just need to cool the part better. The glass state of the plastic is useless to me for two reasons. One, as stated before, no bonding occurs. Two, while the plastic remains expanded and bendy, the new layer being put down is being put down in the wrong place. When the plastic shrinks to its final dimension is when I want to place the next layer. Time to solve this the traditional way: overkill.
A while back my friend gifted me a little squirrel cage fan he had used with success on his 3d printer. Inspired by this, I had also scrounged a 12v, 1.7A fan from a broken Power Mac G5 power supply. When it spins up I have to be careful that it doesn’t throw itself off the table.
I printed out mounts for the fans. The big one got attached to the Z axis, and the little one rides behind the extruder. I fired up the gcode from before and started to print, only to find that my nozzle stopped extruding mid way. What? I soon discovered I had so much cooling that my nozzle was dropping below the 160C cold extrusion cut-off point and the firmware was stopping it from damaging itself. My heated bed also could no longer maintain a temperature higher than 59C. At this point I felt I was onto something.
I wrapped my extruder in fiberglass insulation and kapton tape, confidently turned the nozzle temperature up, set the speed to full, and clicked print. With the addition of the overkill cooling I was able to get the part shown to the right in my three example prints. This was full speed and achieved full bond. Not bad! Thus concludes this chapter in my adventures with cooling. I was really impressed by the results. Next I want to try cooling ABS as it prints. Some have reported horrible results, others pretty good ones, I’m interested. I also wonder about cooling the plastic with a liquid at a temperature just below the glass state as it is deposited. Thoughts?