Second Print: A Raft of Chain Links

Second print - this time the drag chain (for supporting and protecting the cable to the extruder.) Thingiverse has a Gcode version of this that prints six on the same raft. The raft didn't stick well, but things appear to have worked. The big flat sections did start cupping a little from the heat, but not enough to affect the final pieces. The cupped-in link points weren't thick enough, and so they're sort of half-bonded together.

The other interesting thing is I learned how much filament it takes to print objects like these. These links took 45 minutes, and used a bit less than 6 feet of ABS filament. I know because I'd only cut 6 feet, and I was starting to fear I'd have to stop the print job before the end got lost inside the plastruder...

First prints!

My makerbot's printing! First print jobs were the engagement ring and the whistle. Thingverse has G-code for both, so I could print them directly without having to run Skeinforge to turn the 3D shapes into extruder lines.

My biggest problem was figuring out the starting setup before printing each. The startup code is in the G-code, not in the ReplicatorG program, so each has a different expectation of where the extruder tip should be. The whistle expected the extruder to be at 0,0,0, barely touching the build platform, while the ring expected the extruder to be 10 mm above the platform (I think). I crashed the extruder into the build platform a couple times trying to get this right.

I also found that the raft won't stick to the build platform unless it's really close, so as soon as the raft started printing, I adjusted its height by turning the Z axis pulleys.

The whistle came out beautifully (and it works!) The ring missed a few layers, and my model wasn't solid so it wasn't quite ring-like enough for me. Still, that's two successful prints!

First real extrusion!

I picked up a spare insulator spacer from the MakerBot store, and replaced the plastic insulator in the extruder nozzle with the new piece. This time, I again had problems getting the extruder started. After a couple jams, I tried using a tiny drill to unclog the nozzle with no luck. What did work was removing the old plastic filament, cutting it flush, putting in a new one, and trying again. After a couple rounds of this, the extruder started working perfectly! You can see the two piles of extruded plastic. The left one got formed by raising the Z platform as the plastic pile got larger. The second was made by moving the X and Y table as the plastic extruded.

My suspicion is that I had some debris clogging the nozzle. Backing out the plastic rod and cutting off the stretched end eventually got rid of the debris.

I was having good luck extruding at 215 degrees C. Heating it higher didn't appear to change how things worked.

It's too late to try running a noisy print job - guess it'll be tomorrow or the next night.

Plastruder done!

The plastruder's done, so I set it up and gave it a try.


Good news: I actually got my first plastic out of the nozzle!


Bad news: at some point, the plastic clogged up and pushed the heater barrel right out of the PTFE plastic.

I'm waiting for things to cool down enough so I can figure out what happened. My guess is that I had the feed speed too high, or maybe the plastic was melting too high up, or maybe the plastic rod kinked.

This oughta be a fun repair...

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: gnu.io.RXTXCommDriver cannot be cast to 
gnu.io.CommDriver thrown while loading gnu.io.RXTXCommDriver 

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.

Arrival of the Makerbot

Readers of my other blog about progress on my 1930's-era model railroad have heard about my experiences using CNC machines to try to build models. (Well, maybe not real CNC machines, but a scrapbook paper cutter from the fabric store.) I'm trying 3d printing, too, and ordered a Makerbot 3D printer.

Makerbot 216 just arrived at my house. Within an hour, the plywood pieces were being varnished. I'm a little impatient.

I'm using Watco Danish Oil, a combination varnish/stain. I've used this before for staining our 1960's house's paneling. It's easy to apply, and produces a smooth, shiny finish that seeps into the wood. You can also fix scratches by rubbing on more stain. I used Watco's "Natural" color with some extra tinting intended to match our house's paneling. Danish Oil is pretty easy to apply - you brush on the stain, put on a second coat 30 minutes later, and wipe any extra that hasn't soaked in. I'm coating all the pieces - not just the exterior panels, but all the small pieces as well. We'll see how it goes.