Cycling to the Finish Line

Come on down to the Saratoga Cycling Studio to help support your favorite engineers! On Thursday, May 8, there will be a donation spin to help benefit our class! If you click on the link below, scroll over to May 8, and click the donation spin button for 3:30 pm, you can sign up for our class. When you do this, please note that we are collecting donations on the day of the event, and would appreciate $15, but more would be such a great help to finishing touches on our project.
 
Thank you so much!

https://clients.mindbodyonline.com/ASP/home.asp?studioid=25286

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Prototyping the Circuit

The Electronics Team has been hard at work finishing up the design for the basic circuit.  While we are waiting for the Build team to finish the frame, we are making a setup of all electrical components that will be inside the printer. The piece we have found most recently is the PNP MOSFET, which will allow the circuits to be run at varying voltages. This device (shown above) allows us to power the gate pin, which will in turn allow current to travel from source to drain.  This allows us to run some things (like the stepper motor) at 12V, and others (like the smoke sensor) to be run at 5V.  This can all be run from the singular power button that will enable the entire device.

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Brand Spanking New

Our first print was a great accomplishment, we learned a lot and showed that we were capable of printing a three dimensional part, but we know we can make our printer even better. We completely re-designed the printer to be stronger, more accurate, and more compact. The most drastic change in the design will be size. By orienting the projector vertically instead of horizontally, we can eliminate much of the wasted space our old "box" design. The vertical projector will require the use of two mirrors, which need to be perfectly calibrated to avoid distortion. While adding mirrors adds complexity, it saves plenty of space, our new printer dimensions will be about 14"x12"x16", which is a considerable decrease from the old design, which was almost four times the volume.

The most prominent feature of our previous printer was the large tower holding the build platform that rises out of the resin pool during printing (we call it the "z-table"). Our X and Y resolution for each layer were nominal, but the resolution in the Z direction suffered due to the design of the z-table mechanics. The long arm which connected the table to the mechanics for motion inside the tower separated the center of mass of the table from the threaded rod and stepper motor; the high torque bound the gear and made motion inconsistent. Our new design will stabilize the z-table by adding guide rails on each side of the table, as well as moving the motion mechanics nearer to the center of mass.

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A Z-Table-centric Design

Our first print, as many readers know, was relatively successful. However it did reveal problems with the z-table. To print, we improvised on the spot to hold up the heavy z-table structure, but since the z-table was not stable, the design needed to be changed yet again. Over the past week or so we have developed a new design for our printer that works around the issue of our z-table. Our new design has three support points and a more secure locking mechanism involving electromagnets. As soon as the design is finalized this week, the build process will start all over again. The clocking is ticking till our end of the year presentation, but we are confident we can get it done!

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Fourth Time's the Charm

The build team is beginning work on the fourth prototype. Handles have already been heat formed from acrylic, and AutoCad designs are being created for the rest of the fourth prototype. The fourth prototype will use a second mirror in order to conserve space. Other improvements to be seen in the fourth prototype include a sturdier door and lift supports. The Z table and Z tower will also be redesigned in the new prototype to resolve balance issues and improve resolution.

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First Print: Success!

Our print deadline today, and as everyone scrambled to tie up loose ends, the group thought the outlook on printing today was rather grim. During class, everyone went into overdrive and made more progress than anyone could have imagined. A new Z table got milled out that would have more structural integrity than the one before which was warped. The new acylic base and top were almost finished and hopefully will done for tomorrow for all the electronics and other components to move into. The electronics and code were also finalized, so it looked like we could print on schedule.
At the end of the school day, we decided to give it a shot. What did we have to lose? We turned on the wooden machine that had rubber bands, super glue, and bolts keeping it together. Filling the resin pool with our new indigo resin, we started printing our default gear template. As it printed, many of us were skeptical about whether we would actually get a gear. When the last layer finished and the Z table rose, we saw it. In resin was the shape of a gear. Initially we thought it was only the first layer that had printed, but as the Z table rose, we realized it did print almost exactly what we wanted. Needless to say everyone is incredibly excited and happy! We are so excited to move on from here, knowing that what we have works so far. We discovered a few kinks that need to be ironed out, but, it can only get better from here!

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Stepping Up to the Plate

Right now the programming team is working on a settings page interface where the user can change certain aspects of the printer, such as the color, and the layer depth. We are also working with the build team to finalize the stepper motor code, for example when it is given an amount of steps it will move that far. Finally, we are also working on code to implement limit switches so the motor does not go out of range, and code for a rotary encoder to add a check for the position of the motor when it is running. We are hoping to print by 4/3, and we hope to have all of the software optimized by then.

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