The makerbot has proved to be less ready to go than I first believed. Though the initial Darth Vader print was successful on the first try, since then I have been battling with the machine to get it to print out anything accurately. In fact, I’ve been trying to print a draft of the module shell which quite a bit a larger than the Darth Vader, maybe 6 times the size. It also has a lot more detail. But the problems (so far) have not been rooted in any complex geometry, rather it’s just getting the damned thing to print right.
First, you have to get the raft just right. The raft is a base layer of plastic that the rest of the model is then printed on. If it doesn’t stick properly then later on the model will surely start to peel and lift causing skewing distortions in the print. As the print head strokes back and forth it tends to want to pull the raft when it switches directions, and often leaves a little curl. This curl will either likely get snagged by the head on future passes, causing rippage, or it will just slowly lift. The head then has to be very, very close to avoid this. Unfortunately, the print base is likely not perfectly level with the print head so the raft will likely curl at one edge of the board. This is my most frequent problem. So far shims have been the answer.
Second problem, and probably the most frustrating one is that the extruder has on occasion decided to just quit. The motor which feeds through the plastic stops turning, and I believe the heater stops heating, which seems like the whole extruder just stops. After days of battling with this it seems the fix has been to shield the cat5 cable which feeds data to the extruder. Once I did that the whole thing started working consistently. Thinking that clogging of the nozzle was the problem I also updated the thermistor settings for a 1mm thermistor which my machine uses, which doesn’t hurt.
The inversion of this issue which has just resurfaced since the extrusion problems went away is that an hour into my most recent and most successful print attempt the stepper motors conk out. The extruder keeps on pumping out plastic but the head just stays in the same place. It’s as though the machine is stuck on a current instruction. I came across this a few times in my solution seeking, again they recommend a shielded cat5 so I need to buy a proper one (right now just using a makeshift shield). At least I have some hope now.
There are more problems I’m aware of, like some issues with overhanging parts. Because the makerbot doesn’t print any support material you can’t have any overhangs, or you have to build in your own supports. I’m trying the latter.