August 23, 2014

3D Printer Progress

Despite the lack of posts on the subject, progress is slowly being made on my 3D printer. A few months ago I got the structure pretty well flushed out in CAD. As sized in the model, this allows for something more than a 12 inch diameter build area. The height of the build is limited by how long I want to make the drive axes, in this version I targeted 12 inches tall.

As part of the Smart BLDC Commutator development I needed something to hold the hall sensor board in the correct position relative to the motor. With the CAD model far enough along I went ahead and had the motor mounting plate made by a friend with a CNC machine in his garage. You may recognize it from the videos I posted.

As I neared the end of the Smart BLDC Commutator development I started putting together a shortened version of the drive axes (shortened because it's cheaper and I want to work out all the bugs and make any unforseen design changes).

I'm trying hard to keep the number of custom parts too a minimum, but there are a few that require machining. The two trapezoidal plates on either end, the black carriage in the middle (that piece could probably be 3D printed), the threaded rod has some modifications on either side, and the motor has a new drive shaft to extend out the bottom of the motor. I plan on releasing the mechanical drawings and CAD files for all these components, and depending on interest I may even try to find a source for them.

The frame of the printer is made from extruded aluminum t-slot rails. I'm using the 80/20 brand because I already work with one of their vendors at my job. I was just going to buy a piece long enough for the one drive axes, but that didn't meet their minimum order amount, so I ordered a few of the other pieces, too.

My next task is to work on the system identification of the drive axes, which in layman terms is getting an equation that approximates how the position responds to a given input to the motor. Once I have that I can start coding the closed loop controller and tweaking it to get the very best position accuracy I can. I'll start posting code and videos as I get it figured out..

1 comment:

  1. Nice job....really good post....thanks to sharing these information....
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