Archive for April, 2011

CupCake Wants a Heated Build Chamber

Sunday, April 24th, 2011

I’m doing fairly well printing on my CupCake now that I have (1) my heated build platform (2) levelable with (3) a bearing-supported axle on my filament drive motor. Still need (4) a stepper filament drive and (5) roller-bearing X-Y guides.

My workshop temperature has been pleasantly cool for humans lately (currently about 67°F). The heated build platform keeps the first layer from shrinking and pulling up off the platform; but at 67°F ambient, upper layers shrink also and deform the build.

Uneven shrinkage of ABS plastic object printed on MakerBot CupCake

I’ve been combating upper-layer shrinkage by leaning things against the openings in the CupCake walls while printing; it traps the heat of the build platform and significantly reduces the shrinkage.

Here you can see shrink in early layers from the front of the CupCake being open while I was removing the test extrusion before the print (long recovery time for the build platform to reheat the chamber) and dramatically less shrink in the upper layers (because eventually it recovered after I blocked the front with my laptop screen). It doesn’t take very high temperatures to reduce shrinkage.

(The bottom of the object is shiny from the heated build platform, doodled with a marker for revisions, and holding a screw as an experiment with acetone and mounting boss thread durability.)

I’m (still) thinking of cutting acrylic pieces to cover the CupCake’s windows. The challenges are

  • How best to attach the acrylic for easy removal for service? Hinges? Magnets?
  • How to route the heated build platform cables out the back window so they don’t snag? Maybe I should rotate it 90° CW and bundle them with the Y drive and X-Y endstop cables?
  • How to remove the test extrusion before printing? An auto-scrubber would be lovely, but in the short term I might get a loooong tweezer and leave an access hole in the front window, biohazard gloves sandblaster style.

Why Does It Do That?

The ABS all cools to room temperature eventually (okay, we could talk asymptotes, but I’d rather not), but it appears that only rapid cooling makes it shrinkalot. Interesting, n’est-ce pas?


Devil bunny needs a ham.

Crisitunity: SSD for the MacBook

Tuesday, April 12th, 2011

A couple of weeks ago, I had my MacBook plugged in and open, but idle for a while, so it parked the hard drive. When I came back and hit a key to wake it, it started saying, “ting wssh wssh wssh.” This is not the kind of language I like my computers to use. The hard drive hasn’t spun up since.

Cort had told me of his impressive performance boosts after upgrading his MacBook to a solid-state drive (SSD) and I’d been interested anyway, so I took advantage of his research and ordered a 115G Other World Computing Mercury Extreme Pro for $230.

MacBook with dead hard drive and new solid state drive

It shipped promptly and I swapped drives that weekend. The rubber shock rails in the MacBook had come loose, so I wasn’t able to slide the old drive out and the new one in through the battery compartment and ended up dismantling the entire MacBook case bottom to make the switch.

I had to reinstall the OS and all of my applications; but fortunately I keep a personal wiki with the download links and installation instructions for all the software I run and instructions to duplicate every configuration change I make to every built-in and third-party application, so reinstallation was a breeze. Also fortunately, I had a synchronized copy of most of my work, so I lost very little data.

The new SSD is just unbelievably fast. Installing apps now happens in the blink of an eye rather than the drag of a progress bar. The boot sequence is still perceptible but the login screen pops up before I’m even quite ready for it. OpenOffice launches so quickly I hardly have time to take a bit of a sandwich, much less go make one.