[Rich] couldn’t find any instances where RepRap owners had used polycarbonate as a 3D printing source material. He’s filled that knowledge gap by running multiple polycarbonate printing tests. Polycarbonate is a plastic that is highly resistant to shattering yet it’s still rather soft. With enough effort it can be bent and stretched, but it’s fairly difficult to break the material.

The test spool of polycarbonate was special ordered for this project. [Rich] sourced 1.6mm filament since 3mm material would have been difficult to spool. It melts at a temperature range of 280-300 degrees Celsius, which he reaches with a hot-end extruder design. The printed material comes out a bit cloudy, which may be due to the heating process itself, or due to extruder reversals (he’s not quite sure what’s causing it). But as you can see above and in the video after the break, it’s certainly a viable printing medium.

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[Gavilan Steinman] just printed and assembled his own RepRap machine and filmed the process. This isn’t news but we found it very interesting to watch. He started with a RepStrap, a rapid-prototyping 3D printer that as built by hand instead of printed by a similar machine. This is the seminal step in the self-replicating process.

From there he prints an extruder head which improves the quality of the parts the RepStrap can produce. We then see time-lapse footage of the printing process for a Mendel unit, the second generation of RepRap machines. We’ve embedded the video after the break. It’s a great way to spend ten minutes on a Sunday afternoon.

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Imagine if you will for a moment, you’re printing along on your Makerbot clone and all of a sudden your PTFE hot end melts, what are you going to do now? One solution is to mill your own all metal end from a bolt with some careful drilling. Or you could follow [Peter Jansen] who has made his own all metal hot end using the existing extruder. All that’s required is some aluminum sheet and cutting down the nozzle and hat (and fans to help, but technicalities), and you’re in business with no more melted PTFE hot end.

This table-top extruder was modeled after the Makerbot. Instead of laser-cut wood this is built from acrylic, uses salvaged rods from laser printers, some inexpensive stepper motors, and a homemade extruder. All said and done, [Peter Jansen] figures this build came in somewhere around $200-300. It may not look as nice, but at half the price of the Makerbot base kit you also get the fun of building from scratch. Hopefully your fabrication skills are up to the challenge. If so, you’ll be printing useful items soon enough.

[Nophead] started the year off by successfully extruding acrylic using a RepRap machine. The problem when working with this material is that when the hot ooze hits the cold air the printed material tends to warp, badly. [Nophead] raised the ambient air temperature around the part being extruded by replacing the bed of the RepRap machine with a heated aluminum plate.

We took at look at his build details for the hotbed. The plate itself is aluminum that he had milled by a machinist friend of his. It looks like the heat is produced by a network of power resistors bolted and soldered to the bottom of the plate. The original idea was to produce a controllable SMT soldering platform. Unfortunately this heating method doesn’t have the power needed to raise the temp quickly but that failure turned out to be a RepRap success.

The RepRap project has been working on bringing 3D printing to the masses by creating a extrusion printer that can also make the majority of its own parts. For the most part, these print ABS or HDPE plastics which are strong and recyclable. In order to create these replicating printers, similar machines called RepStraps are built out of either laser-cut parts or machined elements. They are functionally equivalent to RepRap printers, but are not made of printed parts. [nophead] documented his RepStrap, HydraRaptor, that is based off a milling machine. He had already printed a set of RepRap parts, and he documented printing a second set. The machine worked for about 100 hours over the course of 2 weeks, printing about 1.5 kg of parts. He made a few adjustments, such as replacing ABS bearings with HDPE to reduce friction. The parts are for Factor e Farm so they can get started with 3D printing.

Related: RepRap pinch wheel extruder

What you see above is the culmination of [Zach Smith]‘s work building a pinch wheel style extruder for the RepRap. The current RepRap 3D printer uses a screw mechanism to push 3mm polymer filament into a heating barrel where it is melted and then extruded through a fine nozzle. [Zach]‘s new version uses a drive gear from SDP/SI mounted directly to the DC motor we saw him teardown earlier. He’s redesigned the carrier for the extruder as well. It’s now much lighter and has provisions for mounting current and future controller electronics along with a magnetic rotary encoder. In the last two days, he’s been doing real world testing. It’s been doing well, but he’s learning to do things like always using a full spool and not trying to run short lengths back to back.