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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3D Printing Has Evolved Two Filament Standards

We’re far beyond the heyday of the RepRap project, and the Hackaday tip line isn’t seeing multiple Kickstarters for 3D printers every week. In a way, this is a bit of a loss. The rapid evolution of the low-cost 3D printer seen in the first half of this decade will never be matched, and from now on we’ll only see incremental improvements instead of the revolutionary steps taken by the first Prusa, the first Printrbot, and even the Makerbot Replicator.

This doesn’t mean everything is standardized. There’s still enough room for arguing over deltas versus Cartesians, beds moving on the Y axis versus moving along the Z, and a host of other details that make the current crop of printers so diverse. One of these small arguments is especially interesting: the diameter of the filament. Today, you can get any type of plastic you want, in any color, in two sizes: 1.75 and 3mm. If you think about it, it’s bizarre. Why on Earth would filament manufacturers, hot end fabricators, and even printer manufacturers decide to support two different varieties of the same consumable? The answer is a mix of a historical choice, engineering tradeoffs, and an absolutely arbitrary consequence of what 3D printers actually do.

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A Different Kind of Plastic Shredder for 3D Filament Making

Haven’t you heard? You can make your own 3D filament nowadays from plastic granules (10X cheaper than filament), or even by recycling old plastic! Except if you’re recycling plastic you will have to shred it first…

[David Watkins] came up with a different way of shredding plastic. Typically we’ve seen shrunken versions of giant metal shredders used to dice up plastic into granules that can be melted down and then extruded back into filament. These work with a series of sharp toothed gears that kind of look like a stack of circular saw blades put together inside of a housing.

But that can be rather pricey. [David’s] method is super cheap, and you can do it at home with minimal tools, and maybe $10 or less worth of parts?

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Hackaday Prize Entry: Welding Plastic Filament

There are a lot of neat toys and accessories that rely on 3D printing filament. The 3Doodler is a 3D printing pen, or pretty much an extruder in a battery-powered portable package. You can make your own filament with a Filastruder, and of course 3D printers themselves use up a lot of filament. [Bodet]’s project for this year’s Hackaday Prize gives those tiny scraps of leftover filament a new life by welding filament together.

The EasyWelder [Bodet] is designing looks a little bit like a tiny hair straightener; it has a temperature control, a power switch, and two tips that grip 1.7 or 3mm diameter filament and weld them together. It works with ABS, PLA, HIPS, Nylon, NinjaFlex, and just about every other filament you can throw at a printer. By welding a few different colors of filament together, you can create objects with different colors or mechanical properties. It’s not as good as dual extrusion, but it does make good use of those tiny bits of filament left on a mostly used spool.

Since the EasyWelder can weld NinjaFlex and other flexible filaments, it’s also possible to weld NinjaFlex to itself. What does that mean? Custom sized O-rings, of course. You can see a video of that below.


The 2015 Hackaday Prize is sponsored by:

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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!

Making T-Glase Crystal Clear

There are 3D printing filaments out there with a lot of interesting properties. Whether it’s the sanded-down MDF feel you get from Laywood, the stretchy and squishy but somehow indestructible feel of Ninjaflex, or just regular ‘ol PLA, there’s a filament out there for just about any use. Even optically clear printed objects. Yes, you can now do some post-processing on printed parts to make T-glase crystal clear.

The big advance allowing translucent parts to be made clear is a new product from Smooth-On that’s meant to be a protective and smoothing coating for 3D printed objects. With PLA, ABS, and powder printed parts, this coating turns objects shiny and smooth. Strangely – and I don’t think anyone planned this – it also has the same index of refraction as T-glase. This means coating an object printed with T-glase will render the layers invisible, smooth out the tiny bumps in the print, and turn a single-walled object clear.

There is a special technique to making clear objects with T-glase. The walls of the print must be a single layer. You’ll also want a perfect layer height on your print – you’re looking for cylindrical layers, not a nozzle that squirts out to the side.

The coating for the pictures above was applied on a makeshift lathe built out of an electric drill and a sanding pad. This gave the coating a nice, even layer until it dried. After a few tests, it was determined lenses could be printed with this technique. It might not be good enough for 3D printed eyeglasses, but it’s more than sufficient for creating windows for a model, portholes for an underwater ROV, or anything else where you want nothing but light inside an enclosure.

Custom Filaments With A Filastruder

A while ago, when 3D printing was the new hotness, a few people looked around and said, ‘our printers are open source, why can’t we just build the machines that make our 3D printing filament?’ There was a $40,000 prize for the first person to build an open source filament extruder, resulting in a few filament fabrication machines being released into the wild. [Rupin] over in the Mumbi hackerspace has one of these filament extruders – a Filastruder – and decided to take a look at what it could do.

The experimentations began with a few kilograms of ABS pellets he found at the market, with bags of red, blue, green, and white masterbatch pellets showing up at the Hackerspace. Experimenting with these pellets, [Rupin] was able to create some very nice looking filament that printed well and changed color over the course of a print.

There were a limitations of the process, though: the filastruder has a long melt zone, so colors will invariably mix. If you’re thinking about doing a red to blue transition with filament created on a Filastruder, you’ll end up with a filament with a little bit of red, a little bit of blue, and a lot of a weird purple color. The time to create this filament is also incredibly long; over the course of two days, [Rupin] was able to make about half a kilo of filament.

Still, the results look fantastic, and now that [Rupin] has a source for masterbatch and ABS pellets, he’s able to have a steady supply of custom color filament at the hackerspace.