Keep Your Nozzle Hot and Your Prints Cool

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.

The old cooling fan on my trusty and thoroughly battered Prusa i2.
The old cooling fan on my trusty and thoroughly battered Prusa i2.

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.

I had a little cage fan my friend had given me, and a huge one from a Mac G5 powersupply lying around. This will do.
This will do.

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 should have added a rib to this bracket, this fan is heavy!
I should have added a rib to this bracket, this fan is heavy!

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?

Upgrading a 3D Printer with A Leadscrew

Consumer 3D printers have really opened up the floodgates to personal at home fabrication. Even the cheapest of 3D printers will yield functional parts — however the quality of the print varies quite a lot. One of the biggest downfalls to affordable 3D printers is the cost cutting of crucial parts, like the z-Axis. Almost all consumer 3D printers use standard threaded rod for the z-axis, which should really use a leadscrew instead.

Threaded rod is not designed for accurate positioning — it’s primarily designed to be a fastener. You can have issues with backlash, wobble, and they usually aren’t even perfectly straight — not to mention they gunk up easily with dirt and grime. In other words, you’ll never see a threaded rod on a commercial machine.

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Interview With A Printer

The Hackaday European tour continues, this time in Prague with Josef Průša (Google translate), core developer in the RepRap project, feature at all the Maker Faires and cons, and creator of his namesake, the Prusa Mendel and i3 printers.

[Prusa]’s involvement with the RepRap project started with a RepRap Mendel, the second iteration of RepRap hardware, but the first popular and easy to build version. [Jo] found the Mendel rather difficult to build, so he loaded OpenSCAD and started to design his own version of the hardware. This version became the de facto standard RepRap for a few years, with many inspired by and derivative printers making their way to hackerspaces and workshops around the world.

The first Prusa printer, derived from the RepRap Mendel.
The first Prusa printer, derived from the RepRap Mendel.

A few years ago, [Prusa] was one of the first to make a complete break with the traditional ‘threaded rod and nut’ construction of RepRaps with the introduction of the Prusa i3. This was the first model that had a metal plate as the frame, another feature that would be seen in dozens of other models. It’s not something that was without controversy, either; using a metal plate for the frame doesn’t allow for as much self-replication, something that’s a core value of the RepRap project. That didn’t matter to the community; the Prusa i3 or a similar design is the third most popular printer on 3Dhubs.

The first Prusa printer showing off its Makerbot heritage
The first Prusa printer showing off its Makerbot heritage

What’s the future of the Prusa name? There is an i4 in the works, and I’m pretty sure that’s all I can tell you. Someone already bought the Prusai4 domain, so there may be a name change.

In the interview below, [Prusa] goes over his involvement with the RepRap project, his business, what he considers to be the latest advances in 3D printing for the past year, what the worst things about the 3D printing scene is (it’s Kickstarter), the state of the RepRap project, and thoughts on SLS, DLP, and SLA printing technologies. Video below.

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Midwest RepRap Festival

midwest-reprap-meetup

Midwesterner’s should take note — here’s an event that’s happening somewhere other than New York or California! We jest, of course there are great events in the Midwestern states every year, like the Kanasas City or Detroit Maker Faires. This event puts focus on 3D printing. The Midwest RepRap Festival will be held in Elkhart, Indian March 15-17, 2013. Despite the name, the event is meant to encompass all things involved with any brand, make, or variety of 3D printing.

The owners of a local business called The Royal Phoenix have opened their doors for the weekend. Organizers have arranged for [Josef Prusa] and [Johnny R] to speak. There will also be build events (one session will show the build process of the MendelMax 2.0) so feel free to bring your own equipment for help with construction or getting it dialed in.

There is no registration fee, or tickets. But it would be best if you did fill out the questionnaire so they have some semblance of how many people might be coming.

[Prusa] interviews a whole bunch of RepRappers

prusa

Any time a media outlet or conference wants an expert on 3D printing there are two people to turn to. The most famous is [Bre Pettis] of MakerBot. The other is an awesome guy named [Prusa], designer of the most popular RepRap and possibly the most popular 3D printer of all time. He’s been putting his fame to use by interviewing all the big names in 3D printing and putting them all up on his YouTube account.

First up is [Kliment], RepRap core dev and creator of the Sprinter firmware and Pronterface host.

[Ruben Lubbes], RepRap community guru, tells [Prusa] about his collection of RepRap parts from famous RepRappers. It sound like a quite interesting collection that’s probably very valuable from a historical perspective. Who knows, in a few years it could be as interesting as [Gutenberg]’s first printing press or [Tim Berners-Lee]’s NEXT cube.

Next up is [Tonokip]. He developed the original Tonokip firmware, the firmware that all major RepRap firmwares are based on.

[Prusa] also interviewed [Jordan Miller] a.k.a. [jmil] of the Philly hackerspace Hive76 and the University of Pennsylvania. He made his name in the RepRap community for 3D bio printing.

Wrapping up the most interesting people, there’s also an interview with [Sound], developer of the Slic3r firmware. We’ve seen an interview of [Sound] before, and this interview continues the earlier one by talking about multiple extruders and how awesome the RepRap community is.

Lastly, and unfortunately, is a short video of [Prusa] interviewing me at the world Maker Faire last September[Prusa] is a huge fan of Hackaday, so this interview is just two guys being star struck at each other.

Actually, the 2012 World Maker Faire had the largest number of current and former Hackaday alumni in one place ever. A group interview of  [Ian] (now of Dangerous Prototypes), [Phillip Torrone] (Adafruit), [Phil Burgess] (Adafruit), current Hackaday boss man [Caleb] and myself would have been awesome. We’ll try harder next year.

You can check out the good videos after the break.

[Prusa]’s nozzle prints polycarbonate, PEEK, & nylon

Oh, we’ve been sitting on this one for a while.

[Josef Prusa], brainchild behind what is probably the most popular 3D printer, has just unleashed a new hot end that is capable of printing objects in polycarbonate, PEEK, and nylon.

This new hot end is completely made out of stainless steel – there are no plastic parts made out PTFE or PEEK to keep the heat from transferring up to the extruder. Because the Prusa Nozzle can print these plastics, it’s also now possible to print parts for other hot ends such as the J Head and the Budaschnozzle.

We ran into [Prusa] at NYC Maker Faire a few months ago, and he was kind enough to go over the advancements in his new nozzle and new i3 printer. So far, it looks like the lack of a PEEK insulator isn’t doing the new hot end any harm – [Prusa] has left molten plastic in the nozzle for a few hours and nothing bad has come of it.

You can check out the interview below.

Again, thanks to [Prusa] for granting us an interview and providing some free advertising for Hackaday’s hosts for the NYC Maker Faire. Before you complain about the delay in getting this interview out to you, don’t worry; I slapped a few Makerbot stickers on the back of [Prusa]’s jacket. Everything’s cool.

Printing custom whistles for everyone at your RepRap conference

When [Josef Prusa] speaks at a conference extolling the virtues of 3D printing, he likes to give out printed objects to show off the possibilities home-brew fabrication. A favorite of [Prusa] are whistles – they’re functional and show off exactly what a 3D printer can do. Printing out hundreds of whistles is a job for a factory and not a printer, so [Prusa] decided to customize each whistle with the initials of a conference attendee.

When [Prusa] was asked to attend the INFOTRENDY conference in Bratislava, he had a small audience (only 150 people) and a list of all the attendees a week before hand. It was the perfect scenario to whip up a Python script to generate the models for a whistle with the initials of each attendee emblazoned on the side.

The WhistleGen code is up on [Prusa]’s GitHub ready to print out custom whistles for your next conference. While the capabilities of WhistleGen are limited to just two letters of text, we’re sure someone will figure out a way to automate the generation custom conference badges very shortly.

See the example he sent us after the break.

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