Progress Update

Things have slowed down a bit recently as school, work, and studying for the FE exam have taken priority. The leadscrew and guide rods should be cut to size this week, and more brackets are being printed.

I have been reading up on the SPI interface with arduino and it seems to be fairly straight forward. It seems as though the hardest part will be the control of the motor via computer.

The drive system is being redesigned to reduce weight on the top of the printer and to consolidate the electronics. In addition, I have Ben toying with the idea of keeping the threaded rod unconstrained on one end, and using just the two smooth rods and captured but for alignment. This would prevent the system from becoming over constrained and binding.

The container for the photo polymer and the build plate have yet to be designed. I do not think they will be too difficult, and am focusing on moving the leadscrew at the moment.

After April 13 (when I have my fundamentals of engineering exam) I hope to really pick up the pace.

Frame Built

The frame has been built! It seems fairly sturdy and should hold up well for this purpose. I'm not sure I would trust the 3d brackets for a long term solution only because I printed them at a lower temperature than I should. There are some layer adhesion issues that I can fix with higher extruder temperatures and lower layer heights if I want to make them again.

The brackets also took a lot of post processing work to get them to fit right. Each hole had to be drilled out, and the alignment tabs needed to be filed down. Still, they're pretty amazing considering the cost savings compared to aluminum brackets. If I had a better printer, like a DLP projector based printer, I think these brackets would work perfectly.

Printing Corner Brackets

Using Lupe, my RepRap Prusa Mendel, to print the Corner Blocks for my frame. Printing two at a time really helps to distribute the heat from the nozzle and improve print quality.

Electronics are In!

I ordered some parts last weekend from SparkFun and they've already arrived! Pictured from left to right is the Arduino UNO R3, the L6570 Stepper Driver Breakout Board, and a 68oz.-in Stepper Motor with 400 steps/revolution.

The Stepper I chose had a higher current draw than what was supported on the Easy Driver or Big Easy stepper controllers, so I had to step up (haha, step) to a bigger board. Plus, the L6570 supports up to 128 microsteps per full step. This could help theoretically increase my resolution even further.

Extrusions Cut and Tapped

The Aluminum came in last week and my coworker, Josh, helped to cut them to size. After numerous hours of watching Bob's Burgers and tapping the ends of each extrusion with an M5 tap, the frame is ready to be assembled.

Materials

I found a great site with various photopolymers available to use. I am not sure yet whether or not they are compatible with a DLP printer, but I have sent an email to find out more.

One material in particular, the ABStuff, has very similar properties to ABS. This will make it ideal for printing and prototyping. Other materials can break down in the body, some are more elastic, and others look beige and fleshy. What a world we live in.

(fleshy plastic. source:digfablab.wikispaces.com )

Projector Offset, Materials, and More

I found a great resource online that provides the dimensions of a projected image from a specified projector given various parameters of how you will set up your home theater system. I can use this information to determine where my image will be in relation to the center axis of my lens.

(projected dimensions based off of distance from screen)

The site also provided me with the official product manual and mounting hole locations on the back. The less guess work I have to do, the better!

(projector mounting hole locations)

I am now working on designing my Z axis. My current plan is to have it run on three LM8UU linear ball bearings. I will use two bearings on one side, and one on the other. This helps to lock the z axis into a plane, by fixing three points. These bearings will run on 8mm smooth polished drill rod. The 5/16"-24 nuts will be captured above and below the z axis, with a spring between the axis and the top nut. This system is also used in the RepRap Prusa x ends, and helps to prevent binding.

(Z axis concept)

I have a week off of school, and will divide my time between work and the printer. All of the components have arrived, so I just need to start building the frame.

Printing Corner brackets!