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.

Mechanical Fixes

The first simple fixes for the printer took place with the mechanics of the RepRap. While mostly solid, the Z-axis leadscrew washers clicked, and the Z belt would slip off the Z-motor pulley. These fixes were fairly straightforward, requiring some simple tightening and, in the case of the Z motor pulley, moving the pulley down the motor axis so that it stuck out further from the Z motor bracket and tightening the set screw.

Extruder Testing

While I previously tested that the heating element on the extruder worked and heated up and that the stepper motor on the extruder moved, I didn’t do a full extrusion test with the extruder up to this point. I stressed for awhile, as I believed that Greg’s extruder was designed for 1.75mm filament and the hotend was designed for 3mm filament. A brief conversation on the #reprap irc channel, however, and I discovered that Greg’s extruder is in fact designed for 3mm filament. The problem: I only had 1.75mm filament, which buckles in a 3mm hole.

The good news: earlier in the summer, I constructed one of the last Makerbot Cupcake CNC machines that they were selling for the father’s day sale for my family, and as such had a spare roll of 3mm filament I could use for testing.

“Wait a minute”, you might say, “testing with that roll of filament is going to require you to haul your Mendel with you almost a thousand miles for vacation. Are you crazy?”

Yes. Extremely.

Hauling the Mendel home, I did a test extrusion with the RepRap Mendel, and it worked great! I went to try a test run…

Homing

…And cringed as the machine’s X-axis crashed into the side of the Mendel. It seems that the Mendel-Parts Gen6 electronics firmware has the X-axis backwards as compared to the standard Mendel construction. To fix this, I could either switch the endstop/endstop flag to the opposite side of the machine, flip some motor wires, or correct the issue in the Gen6 firmware. Firmware was deemed to be the easiest choice, so I went with that.

Generation 6 Electronics Firmware:

The Mendel Generation 6 electronics are based on the Sanguino project, so the first thing I had to do was to install Arduino and the Sanguino addon onto my computer. Once that was done, I went and downloaded the latest version of the Generation 6 Electronics from Mendel-parts. After correcting an issue that prevents the firmware from compiling (c’mon Mendel-parts, patch this already! It’s been around for at least 10 months), I uploaded the firmware to the board, and was mortified to find the board “bricked” (not really the right word, but you’ll see in a minute). The motors didn’t respond, the extruder didn’t heat up, nothing. I thought perhaps I had downloaded the wrong firmware, so I tried some of the other firmwares, to the same result.

Frustrated, I turned to the #reprap IRC channel again. One of the IRC channel members recommended the use of the Sprinter alternative firmware, and helpfully pointed me to this Sprinter firmware, configured especially for Gen6 electronics. I inverted the X-axis, uploaded the firmware, and everything worked correctly on the Printrun toolchain. Well, individually, anyway.

There’s still more to tell about this build, so stay tuned as I work towards the first successful test print! In the meantime, be sure to check out our flickr set for the latest build photos!