Makerbot Cupcake CNC Machine
The Cupcake CNC Machine is produced by Makerbot Industries (makerbot.com). It is mostly constructed out of lasercut wood and acrylic. The machine is open source. I was able to build it in about a weekend, but getting it to work took me a bit longer.
The build is well documented on the wiki. The plastruder documentation is a bit annoying to read through and I was never able to get mine to actually work as it came in the kit. My threaded rod for the Z stage is noticeably bent (shipping?). It caused lots of problems with z stage binding and I opted to replace the rods after a few weeks of using it like that. The first print is coming off the bot now and the z direction is much better on the print. I suggest replacing your rods as soon as possible.
Kit based plastruder
The plastruder that comes with the kit requires the user to wrap nicrome wire and use an annoying amount of kapton tape to hold it all together. It is a nightmare to take apart if well wrapped. The documentation is pretty rocky and further research on their forums leads me to believe that actually getting one to work consistantly takes a large dedication of time playing with it. I am told that this is half the fun, but to me it's just frustrating.
To date I have reconstructed my plastruder 4 times. Trying different ways of wrapping the nichrome and different ways to insulate the barrel. None of these attempts have produced anything that worked. The closest I got was actually the first build where it extruded for about 5 seconds and then jammed as the idler wheel caused the ABS to strip.
Tensioning the idler wheel can be done in short time once you know what to look for. Ideally the motor should make teeth marks in the ABS and the idler wheel seems to flaten out the back a bit. Using the measuring rod worked well for me to set this.
The plastruder by far is the only real downfall of the kit. The rest all seems quality and well engineered.
Luckily the community surrounding the makerbot is great. Many members have created add ons. Of note is Makergear.com. Makergear sells a modularized heater core, modularized thermistor and a PEEK based feed tube (the one that comes with the makerbot is teflon?). After using these parts I must say they are a must for any makerbot purchaser.
The modularized heatercore from Makergear is easy to spin on, provides consistant heat that works every time. I purchased a pre-built one as I was already frustrated with the plastruder in the kit and wanted to be sure I was eliminating a variable as to why it didn't work for me. They sell kits to build your own and it seems fairly easy to do. It was completely worth the money.
The PEEK insulator is a stronger plastic than the one that comes with the makerbot. If your heater barrel gets too hot it will melt the version that comes with the kit. The inside of my original seemed rought and though the plastic went through it was hard to remove from the nozzle. In an attempt to use the stock insulator with the makergear heat core I melted the threads and the tip literally came out of the plastruder head. I've since switched to the PEEK insulator and have absolutely no problems with it.
The modularized thermistor is an interesting piece and while I don't find it incredibly necessary it does make switching print heads much easier if both the thermistor and the heatercore are modularized. Just go for it, plus it comes with the enhanced operators pack.
Insulation on the original plastruder was problematic. I've upgraded twice because of it. The original requires you to wrap everything in kapton tape and then cover with easily rippable ceramic tape. I upgraded the first time to makergears ceramic fabric. While that was a bit easier than the tape, it still didn't want to stay on the print head. Pieces of this would actually dip down into the print and smear plastic from time to time. Maker gear now offers a rubberized insulator which works excellent is easy to install and really cleans up the print head. I highly recommend this upgrade.
I've also replaced my idler wheel with a new 4.5mm idler from Makergear. It really makes a difference and I have no problems with the plastruder now. I've also had to replace the extruder board after the first one died and was no longer reading temperatures properly.
Finally if you have lost all patience with the plastruder makergear also offers completely built plastruders that are garanteed to work right out of the box. I considered this, but decided I wanted to tinker a bit more and just bought the parts I needed.
Replicator G is extremely easy to use on Windows assuming you have 32bit Java installed. It took me about 15 minutes to figure out that 64 bit java was causing issues. Once I had the right Java runtime installed the software worked well. Make sure to flash both motherboard and plastruder controller to the newest firmware.
Heated build platform:
I also purchased the heated build platform for use with my kit. The heated platform keeps the build from warping as the plastic is laid down. Assembly is fairly striaght forward but the surface mount soldering could prove a challenge for some. I did it with a standard soldering iron. It took me a bit longer, but it was a ton of fun. Make sure to keep kids and animals away as you work, the pieces are very very very small. I ran several prints without this and this kit is absolutely needed if you want to print anything big. The ABS warps too much without it. Adhesion to this surface is also excellent.
Relay and relay mount kit:
I heard much commotion about the heated build platform pushing the limits of the extruder. Makerbot offers a kit that includes a relay option and another kit with mounts for both. I've only ever run the heated build platform with the relay so I can't judge if it does need this. The kit though is working fine. Because of my power supply connector height I had to raise the platform using an additional 2 nuts on each bolt so that it would clear. The included wire with the relay kit was a bit too short and I ended up braiding my own input wire for the relay.
Makergear and Makerbot offer an excellent selection of ABS plastic. I currently have 10 colors. I need to develop a plastic management system though as 10 spool boxen from Makerbot is not really cost effective.
Make sure to print out a heated build platform wire protector and also a z axis crank. They are extremely helpful and really make the process a much more plesant experience.