Automated programming and testing jig built with Raspberry Pi

automated-programming-testing-rig-built-from-RPi

[Doug Jackson] makes word clocks, and he must be doing quite a bit of business. We say that because he put together a programming and test bed for the clock circuit boards.

This is a great example to follow if you’re doing any kind of volume assembly. The jig lets the populated PCB snap into place, making all the necessary electrical connections. This was made possible by a package of goods he picked up on eBay which included rubber spacers to separate the board from the acrylic mounting plate, pogo pins to make the electrical connections, and a spring-loaded board clamp seen to the left in this image.

The switch in the lower right connects power to the board and pulls a Raspberry Pi GPIO pin high. The Python script running on the RPi polls that pin, executing a bash script which programs the ATmega169 microcontroller using the GPIO version of AVRdude. We looked through his Python script and didn’t see code for testing the boards. But the image above shows a “Passed” message on the screen that isn’t in his script. We would wager he has another version that takes the hardware through a self test routine.

We first saw one of [Doug's] word clocks back in 2009 and then again a few months later. The look of the clock is fantastic and it’s nice to see the project is still going strong.

Router jig for a perfect circle

router-jig-for-cutting-circles

We once enlisted a contractor to cut a plywood circle for a cat condo we were building. Now we’re embarrassed that we couldn’t come up with a solution as eloquent and easy to use as this circle cutting router jig which [Grays42] built.

He’s using a small trim router for the job. The jig is made up of two thick-walled pieces of PVC pipe. We don’t think the router is attached to jig. Instead you hold it against the wooden spacer which is on the outside edge of the cut. He doesn’t mention how he made the spacers, but we’d recommend cutting a hole the size of the pipes and then ripping down the middle to remove some of the material (tape the two spacers together during fabrication to ensure proper alignment). It just takes some nuts and bolts from the hardware store to assemble everything.

[Grays42] is using this to cut rings for his telescope build. We have our eye on it for making our own wooden Bulbdial clock.

[via Reddit]

Simple solution makes rocket fin alignment a breeze

If you’re building model rockets you want to make sure they fly straight, and most of that is dependent on the stabilizer fins. It has long been a problem come assembly time. How can you make sure that they’re being aligned without any variation? [Rrix] mentioned that one technique is to use a square to position them perfectly perpendicular to the bench on which the rocket is being assembled. But this is still prone to error. His method uses a couple of precision jigs made out of cardboard.

He designed this pair of jigs in Inkscape, then used the files to fabricate them out on a laser cutter. It worked like a charm, but led him to another issue that can be solved in a similar way. Model rockets have rail guides that travel along a rod attached to the launch pad as the craft accelerates to a point where the fins have enough effect to keep it going in a straight line. If those guides aren’t straight, your fin alignment will be all for naught. His second version of the jigs includes a cut out for these guides.

CNC Table Saw Jig

table saw jig

[Woodgears.ca] seems to be a wealth of clever hacks, and this CNC box joint jig is no exception.  Although one has to manually move the jig to make the actual cut, it still gives the user a lot of extra functionality. One only has to click the mouse button to advance the workpiece.  One drawback to using a table saw, even with this jig is that some internal parts still may have to be cut. Check out the video after the break to see this device in action, or skip to around 3:08 to see what hand operations still have to be done.

Besides just being a cool build, we loved the box-jointed project enclosure for the electronics. As this was made in 2003, it’s nice to see that the idea of “self-replication” (at least in part) didn’t start with the [Rep-Rap]. The 10 year old (as of 2003) Thinkpad notebook computer running QBasic in DOS is a nice “hacker” touch as is using 100 Watt light bulbs as power resistors. Pretty clever electronics, especially for someone that’s known more for his excellent woodworking skills than his obvious electrical engineering knowledge! [Read more...]

CNC milled bicycle frame jig

This bicycle frame jig is cut from MDF. It’s the latest in a growing trend that we love to see: the increasing availability of manufacturing techniques for the common hacker. This is a Kickstarter project, and alas it appears the designs are not available for you to cut your own. But we love the potential this shows, and maybe you can use the concept the next time you’re welding together a frame for something.

We really never look at building traditional frames at home. Mostly it’s the oddities that catch our eye. But if you’re into cycling and want to get your own custom-fit frame this has got to be the lowest-cost option available. In fact, you can get the jig and a tube set for under $600. The frame can be fit with just a few hand tools (a hack saw and a file). It uses lugs so the joints will be strong as long as you get the pipes fitting well enough for a quality welded joint.

Milling interlocking wooden rings

[Johan von Konow] wanted to make something special as a wedding gift to his wife. He decided a pair of interlocking miniature rings would be the perfect keepsake. He started his search for a way to mill the wooden rings from a solid piece of wood, and documented his journey for our enjoyment.

This project poses an interesting challenge. Most CNC mills offer three axes of freedom, but he only had a 2D mill meant for routing PCBs. This means the cuts can only be made from the top down at one depth. In order to fabricate the rings he needed to cut from more than one side. With more study, [Johan] discovered that it would be necessary to cut the wood stock from eight different angles before the rings would be complete.

The solution to the problem was to first mill a jig to hold the wood stock. It has positions to hold the stock at each different angle. The final step before starting the cut was to mill the stock itself to perfectly fit his custom jig. We think it turned out great, thanks in part to hand filing, sanding, and polishing to smooth the marks left from milling.

Photographing stuff that’s not there by using stencils

This image was not made in post production, but captured during a long camera exposure. The method uses stencils to add components to a picture. [Alex] built a jig for his camera from a cardboard box. This jig positions a large frame in front of the camera lens where a printed stencil can be inserted. He printed two identical sheets of paper with black covering the area all around the 8-bit joggers. When properly aligned and inserted in the jig, the black parts of the stencil will act to mask the areas where he wants to capture the natural surroundings of the image. Once the camera shutter is triggered, he uses a flash to illuminated the stencil, then removes the the paper image from the jig and ambient light from the dark surrounding is captured during the remainder of the 20-30 second exposure time. The real trick is getting the light levels between the flash and the ambient light to balance and produce a result like the one seen above.

Is anyone else hearing the Punch Out cut-scene music in their heads right about now?

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