Sunday, October 11, 2009

Progress: Makerbot done, plastruder in progress

The Makerbot's done. It went together quickly and without any problems. I've been able to connect it up to my Mac and move the various axes to test things, but I'll have to finish the plastruder before I can actually print anything.

Using Watco stain didn't work as well as I hoped. I got a decent stain color on the wood, but the birch plywood doesn't have a strong enough grain to stain well. (It also didn't hurt that the weather's cooling down, so I had to put an extra coat on, and still didn't get a semi-gloss finish. I suspect I might have gotten a better finish with warmer weather or if I hadn't been so eager to finish. The panels are also cut with the grain going sideways; I suspect vertical grain might look better. All said, maybe just spray-painting with a bright enamel would have been better.

My other big problem was with the software. My Mac laptop (MacBook Pro running Mac OS X 10.6) just kept having problems running ReplicatorG. At first, I was getting error like:
java.lang.ClassCastException: cannot be cast to thrown while loading

I'm not surprised that I'm having problems with serial devices; I've run other serial devices (such as programming model railroad locomotive decoder's with the JMRI project's DecoderPro software, and a Cricut scrapbooking cutter via Sure Cuts a Lot. I suspect I have warring Java serial drivers on that machine. Building my own copy of librxtx from sources by following these instructions and copying the resulting .jar and .jnilib file into /Library/Java/
Extensions manually as mentioned in librxtx's README. Unfortunately, then I just got errors that every serial device was in use. Switching to my desktop machine with Mac OS X 10.5 and fewer serial devices made everything run fine.

(Interesting trivia: my laptop had the RXTX code loaded in three places: /usr/lib/java, /Library/Java/Extensions, and somewhere deep in /System/Library/Frameworks. The Mac Mini running 10.5 that ran ReplicatorG with no problems didn't have RXTX installed anywhere. The RXTX code usually comes as two files: RXTXcomm.jar (the Java code for running serial ports) and librxtxSerial.jnilib (the Mac OS X native code that actually talks with the serial device.)

My one hitch during construction was that the small pulley for the X stage mechanism was a little too small to hold a bearing. Rather than try to widen it, I pulled out my hobby lathe and turned a new one from some delrin rod I had handy. I'd been eager to do this because the printed pulleys always look a bit rough, and I knew I could do a better job. Forty five minutes of careful work later, I had a decent pulley... but I'd spent an awful long time just to make one. I'd have to measure dimensions, cut the outside of the rod to appropriate dimensions, bore out the center deep and wide enough to hold the pulley, then carefully cut the space for the belt. I was doing a lot of double-checking with my caliper to make sure I got the right size. Maybe the printed pulleys aren't so bad!

Final helpful hint for other Makernauts: I'd bought the basic kit, and assumed I could buy a power supply at Fry's for cheaper than Makerbot was charging. It turns out that was a silly choice; Fry's has tons of power supplies, but all were in sealed boxes so I couldn't see the wires they provided and where the fan was. I ended up buying a 400W power supply for $28.99 that had all the power connectors I needed, but it has a fan on top that keeps it from being inserted in the Makerbot case. None of the cheaper power supplies had the 20 pin connector (as far as I could tell.) Moral: buy the Makerbot power supply.

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