This peculiar setup allows [Ben Krasnow] to control an alternating current device using one pin on a microcontroller. He’s experimenting with a power drill and has relocated the trigger circuitry that makes it spin. On that board he found a variable resistor combined with a capacitor which control a triac, actuating the speed of a drill. [Ben's] solution works great and isolates the drill from the control circuitry. He replace the variable resistor with a cadmium sulfide photoresistor (basically a variable resistor whose resistance depends on the intensity of light). Pulse-width modulation is used to adjust the brightness of an LED shining on that photoresistor and thereby affect the speed of the drill. This is such as simple alteration to the drill we’d call it MacGyver-esque.

See a demonstration after the break.

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Being able to see what you’re doing can be the hardest part of drilling the through holes in those freshly etched printed circuit boards. We don’t know why we didn’t come up with this, but [Markus Gebhard] solved his shadowy woes with his 20-LED Dremel light ring. Honestly, how many times have we seen lights rings in photography without putting it together that a light ring is perfect for this purpose. So kudos to [Markus], now we’ve got to go and dig up some surface mount LEDs and uncork the copper chloride.

An accurate drill press is an essential tool for making your own through-hole printed circuit boards at home. Reader [Josh Ashby] offers up a solid design using scrap bin materials.

A major issue with PCB drilling is that even the slightest horizontal play will snap the delicate carbide drill bit. Hobbyist-grade tools such as Dremel’s drill press attachment are usually too sloppy for this task, while a more precise instrument might set you back a couple hundred bucks.

[Josh’s] design uses a nylon “sled” moving vertically in an aluminum u-channel track. Most of these materials were salvaged or were acquired inexpensively from a local hardware store, and assembled in less than a day. Surprisingly, this low-tech approach has proven sufficiently smooth that he’s yet to break a bit while drilling. And the entire setup, including the knockoff Harbor Freight rotary tool, cost less than the wobbly name-brand accessory alone.

If you’ve ever been caught in the situation of needing to drill a clean straight hole down the center of a bolt or rod, you’ve probably tried and ended up with a broken bit or tilted hole, and a ton of cursing to boot.

[Vik] let us know about this nifty trick for drilling ‘down the middle’ using a simple hobby drill press and vice. He claims it’s ‘physics guiding the bit’ but in reality its just crafty use of a chuck. Either way the quick trick works, and will hopefully save a lot of hackers some headaches in the future.

Let us know in the comments if you have any simple quick tips that you use when you’re out in the shop.

Here we have a toy car modified to use a drill as the powertrain. [Hans] has thrown a 12v 4.5 amp battery in to power the motor and it tops out around 9 miles per hour. This is similar in concept to the trash-based go cart from last week but this time there’s video. He’s built a couple of these and there’s footage of both after the break. Our favorite part is from the first video when dad chuckles with glee from behind the camera as son whips around the neighborhood on the mean-sounding machine.

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[lucassiglo21] let us know about his finished 3 axis CNC (Translation via Google). While home CNCs are nothing new, we really liked this masterpiece. The CNC is entirely custom, from the electronic control boards (connected to a PC via parallel port) to the physical mill (with an end result of 30x30x15cm workable area). Our favorite part is the use of screw/band clamp zip ties to hold the Dremel – a true showing of hacker geekyness. For those who haven’t seen a CNC drill a circle before (and honestly, who hasn’t?), check a video after the break.

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We’ve seen a glut of time-keeping projects lately. We guess time was the original motivator for technology so we’re okay with it (but we’re not calling ourselves Clockaday quite yet). This clock, or more appropriately this timer, is a homemade hourglass that [Andrei] put together. The finished look is simple but he put some real time into its production.

The glass portion is a combination of two wine glasses. He removed the stems, ground the bottoms flat, then drilled holes to allow the sand to pass. He used plumbers putty around the top of the upturned reservoir to create a temporary bowl of water which cooled the glass during drilling. This prevented cracking by keeping the friction generated heat at bay. Working with the glass took a total of around five hours.

To assemble, he epoxied the two wine glasses together, routed out a ring in the wood bases for the lips, and used dowels to connect the two ends. [Andrei] concluded that the gentle slope at the bottom of the wine glasses is not the ideal shape as some sand can get stuck in them. Perhaps champagne flutes for his next build? At any rate, we think it’s a unique, non-automated hourglass build.

Drilling precise grids without a CNC machine can be tough to pull off. [Ookseer] has come up with a nifty method for dilling aligned holes with a drill press. He uses a right-angle jig on a Dremel drill press with stacks of business cards as spacers. The same number of cards is added between the substrate and the jig to space each new hole evenly. This method comes in handy when drilling grids in an enclosure for speakers, temperature sensors, or for an aesthetically pleasing design.