Automated Table Saw Cuts Photovoltaic Solar Cells

[sudarshan] is a solar hobbyist and needed a way to cut solar cells for his projects. He had previously created a rotary tool saw but manually feeding them through was sketchy at best. With just a slight wrong movement of his hand or flex in the work surface would cause the cell to break. These cells are extremely brittle and break easily. He needed a method of cutting these cells that was free from jitters and would cut in a straight line. He looked around his junk bin and found an odd solution… a scanner. Yes, the type you would scan photos in your computer with. The scanner had two critically important features, a flat surface and a carriage mechanism that moves perfectly parallel with that flat surface.

[sudarshan] made a solar cell cutting mini table saw with that scanner and made the cutting happen automatically. He mounted a motor with a diamond saw disk to the carriage, that is responsible for the cutting. The blade was positioned just high enough to poke through the plexiglass that replaced the original glass bed. A power switch turns on the cutting disk motor and an Arduino was used to move the carriage, including the cutting blade, back and forth. Two of the stock scanner buttons were reused and wired to the Arduino to keep the saw looking good.

The first few passes of the saw were done to cut a slot in the plexiglass. In order to cut a solar cell, the cell is taped to the bed with the desired cut location aligned with the slot in the plexiglass bed. Once everything is set, hit the ‘go’ button and the saw blade is slowly pushed through the cell, leaving a straight, clean cut.

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Wood-Only Kart Race Inspires Fancy Wooden Bearings

The mountainous Italian town of Artena holds an annual soap box derby for wood vehicles – and they mean 100% wood, not a speck of anything else. Fierce competition led [Alessio] to engineering and CNC fabricating these gorgeous wooden roller bearings for the wheels to give him an edge.

Thousands in costume attend the renaissance faire known as “Palio delle contrade di Artena”, and the popular wood-only race is called “La Carettella.” The karts are operated by a two-man team: one in front who brakes, the other in the rear who hops on and off to push as needed throughout the course. There appears to be no steering from the wheels** so turning is also a two-man effort. The wooden levers dragging on the pavement provide some steering from the “driver”, and the push-man often manhandles the entire rear end, drifting where necessary.
HAD - Carettella2The course also includes full-width obstacles like hay bales. Teams are divided by community or “contrada”, and it was [Alessio]’s team captain who came to him with the special request of roller bearings. Unable to find evidence of other wooden bearings, [Alessio] knew he would have to invent them himself – so he did.

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Arduino vs. Phidgets vs. Gadgeteer

A few days ago, we saw a dev time trial between the Arduino and Phidgets, a somewhat proprietary dev board that is many times more expensive than an Arduino. The time trial was a simple experiment to see which platform was faster to prototype simple circuits. As always in Hackaday comments, there was a ton of comments questioning the validity and bias of the test. Not wanting to let a good controversy go to waste, [Ian Lee] tossed his hat into the ring with the same dev trial with the Gadgeteer.

The Gadgeteer has the same design philosophy as Phidgets: modular components and a unique software system -the Gadgeteer is based on .NET Micro Framework – that allows you to get up and running quickly. Unlike Phidgets, the Gadgeteer is priced competitively with the Arduino, and the mainboard is priced within an order of magnitude of a single ATMega chip.

[Ian] pulled off three projects with the three development platforms: blinking a LED, moving a servo, and building a pedometer with an accelerometer. For each trial, the time taken and the price of all components were added up. Here’s the relevant graph:

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Fail of the Week: Cat6 != Coax

With a new Kenwood 5.1 receiver acquired from questionable sources, [PodeCoet] had no way to buy the necessary coax. He did have leftover Cat6 though. He knew that digital requires shielded cable, but figured hacking a solution was worth a try.

HAD - Coaxfail4To give hacking credit where credit is due, [PodeCoet] spent over a decade enjoying home theatre courtesy of a car amp rigged to his bench supply. Not all that ghetto of a choice for an EE student, it at least worked. To hook up its replacement he pondered if Cat6 would suffice, “Something-something twisted pair, single-sideband standing wave black magic.” Clearly hovering at that most dangerous level of knowledge where one knows just enough to get further into trouble, he selected the “twistiest” (orange) pair of wires in the cables. Reasonable logic, one must select the strongest of available shoelaces for towing a car.

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Electroplating Copper and Silver onto 3D Prints

While researching copper plating graphite for a project, [Dave] stumbled upon a blog post illustrating a brilliant approach to metal plating 3D printed parts.

Our pioneers in this new technique are [Aaron], who runs a jewelry business, and [Bryan], a professor of Digital Media. By mixing graphite powder into an acetone solution, it is possible to make a kind of graphite paint that sticks extremely well to ABS plastic.

Using the graphite painted part as the cathode, and a chunk of copper as the anode, it becomes possible to electroplate the part with a variety of electro-forming solutions. In the first test (seen above), [Bryan] uses a Midas Bright Electro-forming Copper Solution (copper sulfate solution).

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CastAR Hands-On and Off-Record Look at Next Version

At long last I had the opportunity to try out the CastAR, a glasses-based Augmented Reality system developed by Technical Illusions. The hardware has been in the works now for a couple of years, but every time we have come across a demo we were thwarted by the long lines that accompany them. This time I was really lucky. [Jeri] gave us a private demo in a suite at the Palazzo during CES 2015. Reflecting on the experience, CastAR is exactly the type of Virtual Reality hardware I’ve been longing for.

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Odd-Looking Mini EV Yard Tractor Is Made From Plywood And Bike Parts

Mini EV Tractor[Ian] likes to build small Electric Vehicles and his most unique project is certainly this yard tractor. During the design phase of the project [Ian] came up with a few requirements to ensure that this vehicle would be useful around the house. First, it had to be maneuverable in tight spaces. This was accomplished by the short wheel base and small diameter front-steering wheels. Next, it had to get great traction as leaving torn-up grass around the yard was not going to cut the mustard. Four mountain bike drive wheels used in the rear double the traction while at the same time distributing the friction over twice the surface area of the grass. To increase the traction even more, the rider’s seating position was intentionally put directly over the rear wheels.

The frame was kept simple by using plywood as structural members. Two 40Ah 12v batteries are set low between the front and rear axles and power the 4 DC drive motors. The motors are connected to the axle by means of sprockets and chains which results in a 36:1 reduction. That’s a large gear reduction and limits the tractor to a top speed of 12 km/h (7.5 mph). Bike tires front and rear were used because they are easily available and are super low-cost. And of course, a tractor wouldn’t be complete without a trailer hitch to tow around plants, rocks, wood or any other general yard debris.

[Ian] makes plans for his mini EV tractor available on his website. If your kid is envious of this electric tractor, maybe you can make him one of these