Friday, September 3, 2010

Mk5: Plastruder Messiah*

* After a few, relatively minor improvements.

Although I was warned by the web site that it might be a few weeks before the Mk5 was delivered, I was happy to see it arrive within a few days. After an uneventful assembly and installation, I fired up replicatorG and pulled up the control panel to test the temperature and then extrusion capabilities.

Minor Improvement 1: For some odd reason, the Mk5 is glued (as was the Mk4) onto a piece that is bolted to the Z axis plate. This means that the glue is holding the Mk5 in place, which struck me as an invitation to pop loose at some inconvenient time. I simply drilled the holes wider and used a larger bolt and nut to bolt both pieces (on each side) at the bottom of the Mk5 directly to the Z axis plate. Since I had them handy, I used 1/4" machine screws and nuts, but a metric size would be more in keeping with the theme.

Minor Improvement 2: As soon as the temperature of the plastruder passed 185C, the solder joints bringing power to the resistors melted and the heater wires popped off. After some mucking about I settled on stripping the plastic off of some handy crimp rings, making some short shunts from a piece of #14 solid copper wire with a crimp ring on each end, crimping another ring to the ends of the feed wires, then using #2 bolts and nuts (again, metric would be politically correct) to bolt the rings directly onto the ends of the resistors, which come with handy #2 sized holes already in them. This avoided worrying about high temperature solders and how long the joints would hold.

Minor Improvement 3: Bolt the thermal cape to the top of the arch using the assembly bolts, and between the two layers at the bottom of the arch assembly. The fact that the Mk5 comes with its own cape strikes me as implying that perhaps it's a superhero rather than the messiah, but I'll leave my post title as is.

After this point, I'm happy to report that the Cupcake CNC began extruding its little heart out. I still had the heater PID set for the MK4, so to compensate, I simply set the temperature target at 240C. The temperature swung down to 215-ish at times, but ABS seems to melt down to about 208 or so, so I left the temperature adjustment to another day.

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