Tuesday, October 11, 2011

Power Interruption

Last weekend a brief blackout interrupted the SD300 while I was recording a video.  I kept recording and captured the SD300's recovery when the power came on again a minute later.  This video is embarrassingly awkward and rambling, but it's potentially interesting because most 3D printers can't recover as elegantly as the SD300 did in this video.  (More on that below.)

The SD300 is connected to a netbook running on batteries, so it recorded exactly what the SD300 was doing when the power went off.  The log says it was "Taking logical tool 4" which means it was picking up the 1mm Anti-Glue pen for masking fine details, whereupon it suddenly encountered a "WriteFile Error" because the SD300 had lost power and stopped responding.

When the power came on again, the log recorded how the computer re-established its connection with the SD300.  Because the SD300 remembered it had been building a model it calibrated the Z-axis to the top of the model instead of the top of the build table.

Recovering from a power failure isn't always so effortless as it was here, but it's usually quite manageable.
  • The computer didn't lose power.  If the computer had also lost power then it would have been necessary to reboot and start the SDView software again.  The computer saves a copy of the current model on the hard drive so it can recover and continue if the computer is turned off during a build.
  • The SD300 just happened to get interrupted between changing Anti-Glue pens.  As a safety measure the SD300 won't initialize until it detects all pens are parked in their storage holders.  If it had lost power while it was actually using a pen then it would have requested the user manually return the pen to the storage holder before it would re-initialize.
  • Additionally, if the SD300 is interrupted while the top layer of the model is still attached to the material roll then it would need to cut it free before it could initialize the Z-axis.  If that had occurred, the SD300 would have adjusted the table to a safe position, reset the XY axis, and requested permission from the user to "Trim layer?"

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