Review: Printrbot Assembled Simple Metal

Hackaday is getting back into the swing of doing reviews, and with that comes reviews of the tool du jour, 3D printers. I have some reservations about reviewing a 3D printer; they’re a new technology, and what may be standard today could be hopelessly outdated in a few months time. Remember geared extruders? The new hotness is, apparently, direct drive extruders.

This is a review of the Printrbot Assembled Simple Metal. If you need any evidence that reviews of 3D printers have a shelf life, you only need to look at the Getting Started guides for this printer. When I bought my Simple Metal, the Printrbot recommended software stack was Slic3r and Repetier-Host. Barely three months later, Cura is now the Printrbot recommended software stack. If you think a simple change in software is inconsequential, check out these prints:

prusa parts
Prusa i3 X-carriages. Left sliced by Slic3r, right sliced by Cura

The print on the left was sliced with Slic3r. The print on the right was sliced with Cura. Notice the small teeth that grip the timing belt on each of these prints. With the Cura-sliced print, everything is fine. The Slic3r-sliced print is a complete failure, not of the machine, but the recommended software for the machine.

Therefore, if the goal of writing a review is to have a definitive opinion of a piece of equipment, a number of questions must be addressed. Since most 3D printing software is open source, should software be included in the review? Is the value proposition of a 3D printer simply a function of price to build volume (this seems to be the standard metric now), or are there intangibles? Should the review cover the quality of prints out of the box, or should the review only focus on print quality after dozens of hours of tweaking? I simply don’t know the answers to these questions, and I suspect you couldn’t get any two people to agree on the answers to these questions.

With that said, I feel I have used this printer enough to make a judgment call as to if this printer was a good buy.

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3D Printing Different Colors with a Single Extruder

Let’s be honest, multi-extruder 3D printers don’t work the greatest — even MakerBot decided to get rid of the feature in their latest line of printers. So what are you going to do when you want to print a multi-colored object with your trusty single extruder? Pause the print like a savage and exchange the filament? No, no, it’s much easier than that — well, you’re still going to have to switch the filament.

[Jan Henrik] has put together a simple script in OpenScad to split up 3D files into layers in order to facilitate printing in multiple colors (or even materials). You load in the file, tell it the print height you want to do, export, convert to G-Code, print, rinse, repeat. In between the layers you have time to purge the extruder, remove any excess skirt or support material, and then hit print again. Quite a bit easier than hitting pause and jogging the extruder out of the way (while avoiding plastic dribble coming out of your extruder!).

Meanwhile if your prints get interrupted — or fail a lot — you might be interested in this project by a group of MIT researchers. It’s an add-on for 3D printers that uses a laser scanner to evaluate how much of the part was printed, allowing you to restart a print that failed!

Modern Tools From Old Table Saws

Somehow or another, the modern hackerspace isn’t centered around table saws, drill presses, band saws, lathes, or mills. The 3D printer and laser cutter are the tools of the future. No one has yet figured out how to build a 3D printer or laser cutter out of several hundred pounds of cast iron, so until then [Chad] will lead the charge modifying old table saws into these modern machine tools.

The build logs for the laser engraver and 3D printer are pic heavy and text lean, but there’s enough detail to make a few educated guesses. Both of these machines use Craftsman table saws from the early to mid 1950s for the chassis. Inside each chassis, the rails, belts, and shafts that make up a Cartesian bot are installed, and the electronics are tucked gently inside.

There’s a lot of creativity in this build; the electronics for the 3D printer are tucked away in the shell of the old motor. For the laser cutter, the focus adjustment is the same knob that used to lock the blade at an angle.

While this may look like a waste of two beautiful tools, keep in mind these are equivalent to contractor saws you can pick up at Home Depot for $500 today. They’re not professional cabinet saws, they just look really pretty. They’re still a solid piece of metal, though, and refurbishing the frames into useful tools is probably the best thing you could do with them.

Thanks [Frankie] for the tip.

Wrapping Up The Last Midwest RepRap Festival

The Midwest RepRap Festival is over – forever. This was the last one. Apparently enough people complained that Goshen, Indiana wasn’t in the midwest. The number of Dairy Queens I passed contradicts this, but whatever. Next year, there’s going to be a different con in Goshen. Same content, different name. If you have a suggestion, you know where to put it.

I promised the world’s largest 3D printed trash can, and I gave you the world’s largest 3D printed trash can. This gigantic orange vase was printed on the PartDaddy, SeeMeCNC’s 18-foot tall delta printer a few months ago at the NYC Maker Faire. I have been using this as a trash can in my basement since then, making me one of the only people who have their trash can on Wikipedia.

A failed print on Saturday morning

Speaking of the PartDaddy, this is what a fail looks like. The first PartDaddy print was a Groot, a 13-hour long print job. It was left running overnight, but it ran out of PLA pellets sometime around 4 in the morning. If you’re wondering what the black band is around the Groot’s face is, here’s the breakdown:

The PartDaddy sucks PLA pellets up from a trash can (that’s not 3D printed), and dispenses it into a hopper above the print head. This hopper was 3D printed on the PartDaddy, and there is still a little bit of colarant dust in there. When the PLA pellets run out, that dust is embedded in the extrusion. When you realize that masterbatch is only about 5% of the finished plastic, it doesn’t take much black dust to discolor a print.

Yes, this is a print fail that could have been fixed by having an all-night bash. A few other people left their printers running overnight including [The Great Fredini] and his Scan-A-Rama. This was a Rostock Max that had something wonky happen with the Bowden. There was filament everywhere.

How about some Star Wars droids? An R2 from the Droid Builder’s Club was there, but there was also the beginnings of a completely 3D printed Roger. While we’re on the subject of plastic robots that will fall apart at a moment’s notice, there was a K’NEX 3D printer. Yes, it’s made almost entirely out of K’NEX, and it did work at one time. Those orange parts sitting next to it? Those came out of the K’NEX printer.  If you’re looking for the definitive RepStrap, there ‘ya go.



For the last few months, metal filaments – PLA with tiny particles of copper, brass, bronze, iron, or aluminum have been available. MRRF was the first place where you could see them all together. A few things of note: these filaments are heavy – the printed objects actually feel like they’re made out of metal. They’re actually metal, too: the iron-based filaments had a tiny bit of red corrosion, and the Lincoln death mask above was treated with acetic acid. These filaments are also expensive, around $100 for 1kg. Still, if you want to print something that will be around in 100 years, this is what you should get.

The most beautiful printer ever

MRRF should have had a contest for the best looking 3D printer at the show. A beautiful delta from Detroit Rock City would have won:


DSC_0075That white hexagon in the center is a ceramic PCB that I’m told cost an ungodly amount of money. Underneath the ceramic build plate, there’s a few Peltiers between the bed and the large copper heat sink. The heat sink is connected to the three risers by heat pipes, making the entire printer one gigantic heat sink. Why would anyone make such an amazing art deco printer? For this.

Because you can use Peltiers to heat and cool a bed, a little bit of GCode at the end of a print will cool the bed to below room temperature. If you do your design right, this means the print will just fall over when it’s done. When the print bed is cooling, you can actually hear the bond between the bed and print cracking. It’s beautiful, it’s cool, and I’m told this printer will make its way to soon.

There you go, the best and coolest from the last Midwest RepRap Festival ever. There will never be another one. It only needs a better name, and [John] at SeeMeCNC is great at coming up with names. Just ask what VIP is a backronym of.

I told you there would be a T-shirt cannon. That’s 300 PSI shop air.

Adding Recycling Codes To 3D Prints

Every little plastic bauble you interact with has some sort of recycling code on it somewhere. Now that we’re producing plastic 3D printed parts at home, it would be a good idea to agree on how to recycle all those parts, and [Joshua Pearce]’s lab at Michigan Tech has the answer; since we’re printing these objects, we can just print the recycling code right in the object.

The US system of plastic recycling codes is particularly ill-suited for identifying what kind of plastic the object in question is made of; there are only seven codes, while China’s system of plastic identification uses 140 identification codes. This system for labeling 3D printed parts borrows heavily from the Chinese system, assigning ABS as ‘9’, PLA as ’92’, and HIPS as ‘108’.

With agreed upon recycling codes, the only thing left to do is to label every print with the correct recycling code. That’s an easy task with a few OpenSCAD scripts – the paper shows off a wrench made out of HIPS labeled with the correct code, and an ABS drill bit handle sporting a number nine. 3D printing opens up a few interesting manufacturing techniques, and the research team shows this off with a PLA vase with a recycle code lithophane embedded in the first few layers.

3D Printering: Induction Heating

Every filament-based 3D printer you’ll find today heats plastic with resistive heaters – either heater cartridges or big ‘ol power resistors. It’s efficient, but that will only get you so far. Given these heaters can suck down only so many Watts, they can only heat up so fast. That’s a problem, and if you’re trying to make a fast printer, it’s also a limitation.

Instead of dumping 12 or 24 VDC into a resistive heater, induction heaters passes high-frequency AC through a wire that’s inductively coupled to a core. It’s also very efficient, but it’s also very fast. No high-temperature insulation is required, and if it’s designed right, there’s less thermal mass. All great properties for fast heating of plastic.

A few years ago, [SB] over on the RepRap blog designed an induction heater for a Master’s project. The hot end was a normal brass nozzle attached to a mild steel sleeve. A laminated core was attached to the hot end, and an induction coil wrapped around the core. It worked, but there wasn’t any real progress for turning this into a proper nozzle and hot end. It was, after all, just a project.

Finally, after several years, people are squirting plastic out of an induction heated nozzle. [Z], or [Bulent Unalmis], posted a project to the RepRap forums where he is extruding plastic that has been heated with an induction heater. It’s a direct drive system, and mechanically, it’s a simpler system than the fancy hot ends we’re using now.

Electronically, it’s much more complex. While the electronics for a resistive heater are just a beefy power supply and a MOSFET, [Z] is using 160 kHz AC at 30 V. That’s a much more difficult circuit to stuff on a printer controller board.

This could be viewed as just a way of getting around the common 24V limitation of common controller boards; shove more power into a resistor, and it’s going to heat faster. This may not be the answer to hot ends that heat up quicker, but at the very least it’s a very neat project, and something we’d like to see more of.

You can see [Z]’s video demo of his inductive hot end below. Thanks [Matt] for the tip.

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New RepRap With Integrated Case, Oddly Called Case-Rap

The great thing about RepRaps are that there are so many to choose from! No matter what features or design intent you could want, there is probably a RepRap for that. Even so, there has been a recent addition to the RepRap family. Creator [jlguil] calls it the Case-Rap, and for good reason, the frame of the printer folds up into a suitcase.

The Case-Rap is inspired by the Mendel90 which tries to improve on the original Mendel by replacing the threaded rods for a more rigid sheet material frame with bracing to keep the X, Y and Z axes perpendicular to each other. The Case-Rap goes a little further with the design to have the frame also perform double duty as a travel case.

Check out the video after the break, the printer is actually built in 2 complete separate assemblies. The X and Z axes are mounted in a 4-sided wooded frame. The Y axis and the electronics are mounted on a 2-sided wooden frame. When the frame pieces are latched together in one orientation, they conceal the printer inside a suitcase-sized box. The latch positions were thoughtfully placed so the frame pieces could also be latched together in ‘printer mode’. Setting up and breaking down the printer takes all of 30 seconds.

You may think a super portable printer has to be small… but you’d be wrong. The Case-Rap has a commendable 8x8x8 inch print area. According to [jlguil], the total DIY cost comes in around 350$ CAD, which is not too bad for a 3D printer, and pretty good for one that is unique, portable and capable.

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