This is the 11th post in a series detailing my efforts to construct a RepRap Mendel, an open source 3D printer. For the rest of the build series, see here.

Introduction:

When I last left off things were almost done. The printer had run into a hotend issue, but that had been corrected. The mechanical systems were assembled and verified, the extruder was thoroughly tested and worked correctly, and I ran through some software debugging to allow the print head proper motion and operation. Things were looking up.

Buuuuut, the plastic, while extruded correctly, was not sticking to the printbed, but rather was simply being dragged along with the printhead on the table surface. Further investigation suggested that the print surface needed to be heated for the plastic to stick to the build surface correctly. The Mendel-Parts kit I originally ordered included parts to build a heated printbed, so I set out to build and test this printbed.

Heated Printbed Assembly:

The Mendel-Parts heated printbed is essentially 4 power resistors that are bolted to the bottom of the aluminum build surface. Power is then run through these resistors, heating up the surface. There is no control over the build surface (so if you wanted to, for example, kill power to the heated printbed when the printer’s not in use, you need to do this manually by disconnecting the power supply), but by setting the power supply voltage with some small fuses, a handful of temperatures can be achieved for printing.
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Some time ago, we ordered a round of boards for the Class-D Audio Amplifier v2 and VoIP32v3 projects. Historically, Sparkfun’s BatchPCB service or Advanced Circuits has been our service of choice for PCBs. This time around, though, we decided to try Seeed Studio’s Fusion PCB service. There’s been a lot of good press for Seeed’s service lately, and with the price of their PCB service reduced to $9.95 for 10 boards, they are considerably cheaper than services we’ve used previously.

The boards arrived at the NBitWonder lab this weekend. Some photos of the boards appear below:

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This is the tenth post in a series detailing my efforts to build a RepRap Mendel, an open source 3D printer. For the rest of the series, see here.

Introduction:

When I last left off, the hotend for the Mendel had broken, necessitating a replacement be ordered. This was installed and the printer was back in working order. I was able to move the print head, and even performed a successful extrusion test, as shown below (note the healthy coil of white, rather than blackened, plastic)

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Over in the forum, we’re designing a software-defined radio modeled after Jeri Ellsworth’s Hackaday post from earlier in the summer.  We ordered PCBs for the first revision perhaps a bit too hastily, as some forum members with valuable experience in the area found a number of shortcomings in our design.  Those have been corrected (we hope!) with this latest round of updates.

Changes that have been made include moving to a better oscillator module (wider frequency range, better stability, less phase noise) and to an external 24-bit ADC (for higher dynamic range).  We have a few boards of the old design already fabbed, but things like work and school keep getting in the way of building up a prototype or two to start coding.

Check out the schematic and layout over on github (or just grab the latest NBitWonder Eagle Library update), and let us know what you think in the forum!  We might not always respond right away, but we value your input.

This is the ninth post in a blog series detailing my efforts to construct a RepRap Mendel, an open-source 3D printer. For the rest of the blog series, see here.

Introduction:

Previously, the Mendel blocks were constructed and everything was put together. Then came the lengthy process of machine calibration. I was closing in on a successful first test print, and victory looked assured.

During machine calibration, I tried to fix an axis issue using the “latest” firmware from Mendel-parts, only to be mortified as the latest firmware proved to be completely non-functional. Desperate to make things work, I switched to the Sprinter alternative firmware and Printrun software toolsuite. The extruder heated up and turned, the stepper motors moved, we were ready to try a test print!

I took some 3mm ABS plastic and fed it into the extruder. In pronterface, there are a number of pre-defined temperature settings, one of which is 230 celsius for ABS plastic. I dialed that on and watched the temperature rise…

Craaaaaaaaaaaap:

And looked on in horror as the temperature sky-rocketed well past 230 celsius all the way to 265 degrees celsius. That’s right, the PID control system was so poor that a 35-degree temperature overshoot was deemed acceptable. The funny thing is, at 265 celsius ABS plastic starts to burn. The plastic in the nozzle carbonized into a hardened, unmeltable substance, completely jamming the hotend.

Mendel is designed in such a way that successfully doing work on the hotend requires ripping apart the X-carriage block, a considerable work effort. Not wanting to do that, I attempted to save the hotend by forcefully clearing it. I started hand feeding plastic into the hotend, and watched as a paltry amount of blackened plastic came out the end. Things looked like they were working, until plastic forced its way through the hotend’s kapton insulation. Craaaaaaaaaaaap.

I shut down the machine, and, when cool, pulled the X-carriage block off the X-axis and disassembled, granting me access to the extruder. As I had hypothesized, the hotend was “shot”. Hardened, unmeltable plastic everywhere, and it had forced its way through the screw threadings in the hotend, locking the parts together very thoroughly. Attempting to unscrew the nozzle with a pair of pliers, I broke the nozzle in half. It was official, I was going to need to buy a new nozzle. Craaaaaaaaaaaap.

Replacement Hotend:

I went back to Mendel-parts (not by choice, but only because they had the only hotend I could absolutely guarantee would work in my machine), and ordered a replacement hotend. Mendel-parts, who continues to charm me with their lack of customer service, wooed me further by requiring a 25 euro minimum order and charging flat 25 euro shipping. Still, they will send you your stuff if you give them your money, so I had a replacement hotend roughly a week later. An extruder test, thermal overshoot test, and some reassembly later, and I was back in business!

The Reprap build is ongoing, but in the meantime, be sure to check out our flickr set for the latest build photos!

The RepRap Mendel saga is a series detailing my efforts to build a RepRap Mendel, an open source 3D printer. For the rest of the posts detailing the project build, see here.

In addition to photographing the Mendel as I built it, I set up my cameras and let them roll throughout much of the build (8 hours of footage in total). I compiled the Mendel build footage into a time-lapse video for you to enjoy.

Check it out! Additionally, don’t forget to see high quality build photos of the Mendel in our flickr set!

Over in the forums, we’re working on improving our project documentation templates. We released a set of LaTeX documentation templates some time back in February, which we have been using to document projects over the last 6 months. However, LaTeX is somewhat inconvenient to edit and has a steep learning curve. As such, we’re pleased to announce development of a new set of documentation templates in Open Office 3.

The switch to Open Office means we now have macro functionality, which is largely absent in LaTeX. It is now possible to write intelligent BOM templates, incorporate logged test results directly into reports, and much much more. We’re looking for good script ideas to make documentation easier and better, so if you have any, pop over to the forums and post em up!

This is the eighth post in an ongoing series about my attempts to construct a RepRap Mendel, an open source 3D printer. For more posts on the RepRap Mendel, see here.

Introduction

After a considerable amount of effort, I successfully built all of the blocks, tested the individual components, and put everything together.

Between the victory lap for actually having everything assembled and successfully printing objects comes the process of calibration and test. This ended up being a somewhat lengthy process with many different steps.

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A few weeks ago, Jeri Ellsworth of DIY YouTube fame put out a fantastic software-defined radio (SDR) project. The build caught the interest of our very own Ben Laskowski, who is working on developing an SDR over in the NBitWonder forums. From the forum:

This is quite similar to Jeri’s in that is uses a Tayloe detector and some DSP to recover a signal. This design, though, achieves frequency agility using a DS1085 programmable oscillator module — it can be set from 8kHz to 133MHz in 10kHz steps. A CPLD performs clock division, level conversion, and quadrature clock generation, and feeds a high-speed bus multiplexer that actually does the demodulation. After some simple subtraction performed by a high-bandwidth op-amp, the in-phase and quadrature signals are passed to a PIC32 via a low-pass anti-aliasing filter. Inside the PIC, an FFT is used to filter the signal to any of several possible bandwidths, then an IFFT is taken and demodulation is performed in the time domain. Finally, an audio signal is reconstructed via PWM, low-pass filtered, and sent to the output.

Modes of operation are set by firmware, and are slated to include AM, USB/LSB, FM, and an unprocessed IQ output.

This is going to be a very fun and interesting project. If you like it, consider joining our forum and pitching in your ideas!

This is the 7th post in an ongoing series detailing my efforts to build a RepRap Mendel, an open source desktop 3D printer. For the rest of the RepRap build progress, see here.

The X, Y, and Z stage blocks were put together successfully, the extruder was constructed, the electronics were tested (everything moves or heats up), it’s time for the most exciting part of the build: putting it all together! (continue reading…)