We Couldn’t Resist this CNC Batik Bot

Batik is an ancient form of dyeing textiles in which hot wax is applied to a piece of cloth in some design. When the cloth is submerged in a dye bath, the parts covered with wax resist the pigment. After dyeing, the wax is either boiled or scraped away to reveal the design.

[Eugenia Morpurgo] has created a portable, open-source batik bot that rolls along the floor and draws with wax, CNC-style, on a potentially infinite expanse of cloth. The hardware should be familiar: an Arduino Mega and a RAMPS 1.4 board driving NEMA 17 steppers up and down extruded aluminium.

Traditionally, batik wax is applied with a canting, a pen-like object that holds a small amount of hot wax and distributes it through a small opening. The batik bot’s pen combines parts from an electric canting tool with the thermistor, heater block, and heater cartridge from an E3D V6 hot end. [Eugenia] built the Z-axis from scrap and re-used the mechanical endstops from an old plotter. Check out the GitHub for step-by-step instructions with a ton of clear pictures and the project’s site for even more pictures and information. Oh, and don’t resist the chance to see it in action after the break.

We love a good art bot around here, even if the work disappears with the tide.

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3D Printer Halts and Catches Fire — Analysis Finds a Surprising Culprit

Let’s build a robot that gets hot. Really hot — like three times hotter than McDonald’s coffee. Then make it move around. And let’s get the cost in at around $100. Sounds crazy? Not really, since that describes the cheap 3D printers we all have been buying. [John] found out the hard way that you really need to be careful with hot moving parts.

The short story is that [John’s] Anet A8 caught on fire — significantly caught on fire. Common wisdom says that cheap printers often don’t have connectors for the heated bed that can handle the current. There have been several well-publicized cases of those connectors melting, especially on early production models of several printers. However, this printer had an add-on heater with a relay, so that shouldn’t be the problem. Of course, a cheap power supply could do it, too, but the evidence pointed to it being none of those things.

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Thermistors and 3D Printing

I always find it interesting that 3D printers — at least the kind most of us have — are mostly open-loop devices. You tell the head to move four millimeters in the X direction and you assume that the stepper motors will make it so. Because of the mechanics, you can calculate that four millimeters is so many steps and direct the motor to take them. If something prevents that amount of travel you get a failed print. But there is one part of the printer that is part of a closed loop. It is very tiny, very important, but you don’t hear a whole lot about it. The thermistor.

The hot end and the heated bed will both have a temperature sensor that the firmware uses to keep temperatures at least in the ballpark. Depending on the controller it might just do on-and-off “bang-bang” control or it might do something as sophisticated as PID control. But either way, you set the desired temperature and the controller uses feedback from the thermistor to try to keep it there.

If you print with high-temperature materials you might have a thermocouple in your hot end, but most machines use a thermistor. These are usually good to about 300 °C. What got me thinking about this was the installation of an E3D V6 clone hot end into my oldest printer which had a five-year-old hot end in it. I had accumulated a variety of clone parts and had no idea what kind of thermistor was in the heat block I was using.

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MIT Is Building a Better 3D Printer

Traditional desktop 3D printing technology has effectively hit a wall. The line between a $200 and a $1000 printer is blurrier now than ever before, and there’s a fairly prevalent argument in the community that you’d be better off upgrading two cheap printers and pocketing the change than buying a single high-end printer if the final results are going to be so similar.

The reason for this is simple: physics. Current printers have essentially hit the limits of how fast the gantry can move, how fast plastic filament can pushed through the extruder, and how fast that plastic can be melted. To move forward, we’re going to need to come up with something altogether different. Recently a team from MIT has taken the first steps down that path by unveiling a fundamental rethinking of 3D printing that specifically addresses the issues currently holding all our machines back, with a claimed 10-fold increase in performance over traditional printing methods.

MIT’s revolutionary laser-assisted hot end.

As anyone who’s pushed their 3D printer a bit too hard can tell you, the first thing that usually happens is the extruder begins to slip and grind the filament down. As the filament is ground down it starts depositing plastic on the hobbed gear, further reducing grip in the extruder and ultimately leading to under-extrusion or a complete print failure. To address this issue, MIT’s printer completely does away with the “pinch wheel” extruder design and replaces it with a screw mechanism that pulls special threaded filament down into the hot end. The vastly increased surface area between the filament and the extruder allows for much higher extrusion pressure.

An improved extruder doesn’t do any good if you can’t melt the incoming plastic fast enough to keep up with it, and to that end MIT has pulled out the really big guns. Between the extruder and traditional heater block, the filament passes through a gold-lined optical cavity where it is blasted with a pulse modulated 50 W laser. By closely matching the laser wavelength to the optical properties of the plastic, the beam is able to penetrate the filament and evenly bring it up to nearly the melting point. All without physically touching the filament and incurring frictional losses.

There are still technical challenges to face, but this research may well represent the shape of things to come for high-end printers. In other words, don’t expect a drop-in laser hot end replacement for your $200 printer anytime soon; the line is about to get blurry again.

Speeding up 3D printing is a popular topic lately, and for good reason. While 3D printing is still a long way off from challenging traditional manufacturing in most cases, it’s an outstanding tool for use during development and prototyping. The faster you can print, the faster you can iterate your design.

Thanks to [Maave] for the tip.

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Mini Delta Gets a Hot End Upgrade

3D printers are now cheaper than ever and Monoprice is at the absolute forefront of that trend. However, some of their printers struggle with flexible filaments, which is no fun if you’ve discovered you have a taste for the material properties of Ninjaflex and its ilk. Fear not, however — the community once again has a solution, in the form of a hot end adapter for the Monoprice Mini Delta.

The Mini Delta is a fantastic low-cost entry into 3D printing but its hot end has a break in the Bowden between the extruder and nozzle. This can lead to flexible filaments not being properly guided through the hot end and a general failure to print. This adapter allows the fitting of the popular E3D V6 hot end, and is similar to modifications out there for other Monoprice printers.

Overall, 3D printing has long benefited from the efforts of the community to bring both incremental improvements and major leaps forward to the technology. We look forward to seeing more hacks on the Monoprice range!

Converting a 3D Printer from 3mm to 1.75mm

A few weeks ago, I published a post discussing the filament diameters common in 3d printing. For no reason whatsoever, consumer 3D printers have settled on two different sizes of filament. Yes, there are differences, but those differences are just a function of engineering tradeoffs and historical choices. [Thomas], YouTube’s 3D printing guru, took this post as a challenge: what does it take to convert a printer to accept different sizes of filament? Not much, actually.

The printer [Thomas] is changing out to accept 1.75mm is the Lulzbot Mini, one of the most popular printers that would ever need this modification. The only required materials is a new hot end suitable for 1.75mm filament, a 4mm drill, and a few wrenches and allen keys. It would be a smart idea to get a hot end that uses the same thermistor as the old one, but that’s not a deal-breaker as the problem can be fixed in the firmware.

Disassembly was easy enough, and after mounting the PTFE tubing, cutting the old wires, soldering in the new hot end, thermistor, and fan, [Thomas] had everything set up and ready to go.

It should be noted that changing a 3mm hot end to 1.75mm doesn’t really do anything. Just about every filament is available in both sizes, although it may not be convenient to buy 3mm filament locally. It would be a good idea to change out the hot end so can standardize your workshop or hackerspace on a single diameter of filament.

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Cheap Hot End Modification Allows Easy Future Repairs

We’ve seen a lot of experimenting with 3D printers over the years, and that is a good thing. However, [Tyler] has had a bad experience with experimenting. He has a Printrbot Simple Metal and decided to try nylon weed wacker line. Since he wanted to get straight to printing, he skipped the apparently important step of drying the trimmer line before printing. This experimentation ended in several clogged nozzles. Removing and cleaning the nozzle several times put undo stress on the Ubis hot end wires and they broke. Things were not going well.

In an effort to make his printer more repairable, [Tyler] ordered up an aluminum RepRap heater block, heating resistor and thermistor. The heater block was tapped with standard M6 threads but the Ubis was 1/4 inch. This was remedied by drilling and tapping the M6 hole to 1/4-20.

Now for the nozzles, [Tyler] bought a handful of cheap brass acorn nuts. He drilled a hole for the molten plastic to exit the nozzle, then used a Dremel to grind the acorn nut’s dome into a cone. He reports it only took him about 5 minutes per nozzle.

It looks like [Tyler] got back to printing with a little creative thinking. Unfortunately, the Ubis and J-Head hot ends are not interchangeable. A couple of other ex-Ubis users have made J-Head adapters for their Printrbots.