Save Fingers, Save Lives With A No-Voltage Release For The Shop

Imagine the scenario: you’re spending some quality time in the shop with your daughter, teaching her the basics while trying to get some actual work done. You’re ripping some stock on your cheap table saw when your padiwan accidentally hooks the power cord with her foot and pulls out the plug. You have a brief chat about shop safety and ask her to plug it back in. She stoops to pick up the cord and plugs it back in while her hand is on the table! Before you can stop the unfolding tragedy, the saw roars to life, scaring the hell out of everyone but thankfully doing no damage.

If that seems strangely specific it’s because it really happened, and my daughter was scared out of the shop for months by it. I’ll leave it to your imagination what was scared out of me by the event. Had I only known about no-voltage release switches, or NVRs, I might have been able to avoid that near-tragedy. [Gosforth Handyman] has a video explaining NVRs that’s worth watching by anyone who plugs in anything that can spin, cut, slice, dice, and potentially mutilate. NVRs, sometimes also called magnetic contactors, do exactly what the name implies: they switch a supply current on and off, but automatically switch to an open condition if the supply voltage fails.

Big power tools like table saws and mills should have them built in to prevent a dangerous restart condition if the supply drops, but little tools like routers and drills can still do a lot of damage if they power back up while switched on. [Gosforth] built a fail-safe power strip for his shop from a commercial NVR, and I’d say it’s a great idea that’s worth considering. Amazon has a variety of NVRs that don’t cost much, at least compared to the cost of losing a hand.

True, an NVR power strip wouldn’t have helped me with that cheap table saw of yore, but it’s still a good idea to put some NVR circuits in your shop. Trust me, it only takes a second’s inattention to turn a fun day in the shop into a well-deserved dressing down by an angry mother. Or worse.

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Doubling The Capacity of Power Tool Batteries

YouTube User [Vuaeco] has come up with a novel idea, combining power tool battery packs to double the capacity.

Starting off with two slimline 2.0Ah compact battery packs, [Vuaeco] wanted a larger 4.0Ah rebuilt drill battery pack. These battery packs are different in size so it wasn’t just a case of adding in more cells in empty slots, instead he goes on to show us how to connect the batteries in parallel using some thin nickel strips. Once completed he modifies the battery casing so it fits another stack of batteries. He does this by bolting the top and bottom together with long screws, and insulating the otherwise exposed battery terminals with insulating tape. The final product isn’t as aesthetically pleasing as a real battery pack, but it looks good enough.

There are a few things we might have done differently, for instance providing some hard plastic around the insulation so should the battery get knocked in an awkward position it would still have a hard shell protecting it. Also, instead of combining the batteries together fully charged as the video suggests, we might have done the opposite approach and fully drained them, avoiding unnecessary risks. If you try this, how about giving it a 3D printed case?

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In Defense Of The Electric Chainsaw

Here at Hackaday we are a diverse bunch, we all bring our own experience to the task of bringing you the best of the hardware scene. Our differing backgrounds were recently highlighted by a piece from my colleague [Dan] in which he covered the teardown of a cordless electric chainsaw.

It was his line “Now, we’d normally shy away from any electric chainsaw, especially a cordless saw, and doubly so a Harbor Freight special“. that caught my eye. I’m with him on cordless tools which I see as a cynical ploy from manufacturers to ensure 5-yearly replacements, and I agree that cheap tools are a false economy. But electric chainsaws? Here on this small farm, they’re the saw of choice and here’s why.

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Snow Blower Turned Power Wagon

Winter is now gone and it’s time to put away that snowblower. Well, it seems that [SWNH] either didn’t hear the news or thought not using his snowblower for most of the year was a waste of a great resource. No, he’s not using it to blow dirt around, he converted it into a Power Wagon.

A Power Wagon is just what it sounds like, a wagon that is motorized and it is used for moving stuff around your yard. [SWNH] started by disassembling the 2 stages of the snowblower. They came off as a unit with only 6 bolts. Next up, the wagon bed was made, starting with an angle iron frame with a plywood bottom and sides. Two large casters with rubber wheels supports the front of the wagon.

Using the power wagon is easy, fill up the bin and use the snowblower controls to drive the cargo around. [SWNH] says that it steers like a shopping cart. And since the wagon bed is bolt-on, it can be removed and the blower assembly re-installed next winter to take care of that pesky snow.

Building A 20 Inch Disk Sander

A small disk sander is a useful and cheap addition to the shop. For about $100, you can buy a cheap combination 6″ disk/belt sander that’s extremely useful. The size and cost of power tools does not scale linearly, and if you want a big disk sander you might as well make your own.

The motor for this build is a 1kW single phase motor pulled from a floor polisher found in the trash. That’s enough to push a sanding disk around, but when you get to tools this large, you need a good base, good tilt mechanism, and everything should be extremely heavy.

This build meets all those requirements while still using mostly recycled components. The work table is actually made of three pieces of recycled aluminum epoxied together. Yes, you should cringe at this, but it actually makes a little bit of sense: thinner pieces can be cut on a table saw, and if you’re extremely careful during the glue-up, you can cut the mitre slot without a mill. This frame attaches to a frame made from aluminum extrusion and filled with a homebrew epoxy granite mix. Remember, heavy is better here.

In keeping with making a huge disk sander out of stuff pulled out of the trash, the trunnions and motor hub were cast out of aluminum melted in an old propane tank furnace. Once these were cleaned up, a disk was mounted on the hub and trued up in the most unsafe manner possible.

With a few additions including a machined mitre gauge, dust collector, and legs made out of wood that’s far too pretty for a simple shop tool, this huge assemblage of trash turned out to be a great sander. You can see a few videos of it below.

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Emergency Power Based on Cordless Drill Batteries

[Don Eduardo] took matters into his own hands after experiencing a days-long power outage at his house. And like most of us have done at least one, he managed to burn his fingers on a regulator in the process. That’s because he prototyped a way to use power tool batteries as an emergency source — basing his circuit on a 7812 linear regulator which got piping hot in no time flat.

His next autodidactic undertaking carried him into the realm of switch-mode buck converters (learn a bit about these if unfamiliar). The device steps down the ~18V output to 12V regulated for devices meant for automotive or marine. We really like see the different solutions he came up with for interfacing with the batteries which have a U-shaped prong with contacts on opposite sides.

The final iteration, which is pictured above, builds a house of cards on top of the buck converter. After regulating down to 12V he feeds the output into a “cigarette-lighter” style inverter to boost back to 110V AC. The hardware is housed inside of a scrapped charger for the batteries, with the appropriate 3-prong socket hanging out the back. We think it’s a nice touch to include LED feedback for the battery level.

We would like to hear your thoughts on this technique. Is there a better way that’s as easy and adaptive (you don’t have to alter the devices you’re powering) as this one?

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Rechargeable Work Lamp Brightens Your Night

Portable power station has DC, AC and Light on board.

Most of us tinkerers will at some point find ourselves needing electrical power in a remote area. Cordless tools are an option, but what if you need more than that? [Garage Monkey San] set out to solve this problem by creating a portable power station that has on-board AC outlets, 12v and 5vdc outputs and an integrated spot light.

This project is housed in a plastic ammo case that’s large enough to contain all of the necessary parts and has a convenient carrying handle. The 12vdc sealed lead acid battery power source is kept topped off by a car battery float charger. Light is provided by an LED off road fog lamp mounted to the top of the case that has a small appetite for power, ensuring long battery life. An easy addition at this point was a 12v car accessory outlet which only adds to the versatility of the project.

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