Saturday, December 12, 2009

Makerbot Hiccups

It's interesting reading the Makerbot list at Google Groups, because you find out that some people seem to be having no problems at all with their Makerbot, and others seem to be having no end of problems. My particular problem has been builds hanging while the extruder keeps extruding. I've seen different guesses at the cause:

  • #1: The USB/serial cable can't send data quickly enough (supposedly solved by printing to the SD card on the Makerbot motherboard).
  • #2: The ReplicatorG control panel is up, so it's constantly polling the extruder for the current temperature (or the "monitor temperature" setting in ReplicatorG's preferences is set); closing the panel or un-checking the setting supposedly solves that. I've also guessed at a few.
  • #3: The computer sleeps or slows down, and loses contact, solved by turning off sleep.
  • #4: Electrical noise on the USB or extruder cable causes the Makerbot motherboard and extruder to lose contact.
  • #5 Noise on the USB cable causes problems. (In both cases, move the cables away from the higher current stepper motor wires.)
  • #6 Too close to fluorescent lights. (This might actually be an issue. My first few prints worked fine, and most of my problems have been with the Makerbot on my workbench underneath a fluorescent lamp.)

None of these has made much of a difference for me. My first print usually goes well, and then I'm fiddling around trying to get another good print. Tonight's adventure was printing these legs for the Makerbot. Each is about a 12 minute print; to get four good ones, I did around twelve total prints tonight, some failing late in the print, others hanging within a minute or two. I still don't have a handle on what's going on, but I'm going to keep looking.

I did have one bit of good news. I'd had problems in the past because a well-adhering part could actually bend the 1/8" plexiglas build surface and cause the part to warp. I hold the plexiglass to the wooden build platform with double-stick tape, but several pieces of tape weren't enough to keep the plexiglass from bending.

Luckily, I found a scrap of 1/2" clear plexiglass at our local plastic shop, cut it down to 110 mm square (or 10 mm bigger than the default build surface!), and started printing. The leg models I was using didn't have rafts, but I found they still stuck wonderfully to the new plexiglass and gave me some nice, unwarped parts. Woohoo!

Making the new build surface was easy. I cut the new piece to rough size with a hack saw, then filed and sandpapered the edges smooth. The official Makerbot build surface has a grid of lines scratched in it, so I scratched some similar lines in my piece - a few for adhesion (which didn't seem to matter), and a pair of lines in the center of the piece so I could position the build platform at the start of the build.

Regardless of the headaches, I've got four legs for my Makerbot. I'll still need to file them down to equal height (one's a bit shorter), but they're almost done.

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