If you have a few hobby servos lying around, here’s a hack that let’s you recycle them and put them to good use. [Kedar Nimbalkar] took a micro servo and converted it into an electric screwdriver. It is simple enough to deserve a short video showing how he did it.
He starts by opening up a 9G micro servo and removing the electronics. All that’s needed is the DC motor and the gears. The two motor wires go directly to the battery via a polarity reversal switch to allow the motor to turn in both directions. The servo horn is cut to size so that it is a tight fit inside the screwdriver socket. A liberal amount of glue is used to make sure it stays in place. The horn is then attached to the modified servo, ready to take interchangeable bits. One last mod before closing up the servo is to convert it to continuous rotation by cutting off the stopper in the drive gear.
He built the power supply from scratch, using a 18650 Li-Po battery, a 5V USB charger, a DPDT switch to allow direction control and a push button to actuate the screw driver. A pair of LED’s connected back to back serve as direction indicators as well as some local illumination.
There’s lot’s of scope to improvise and do everything differently, but the basic premise of using unused servos for a handy electric screwdriver is pretty neat.
28 thoughts on “El Cheapo Electric Screwdriver”
this thing barely has any torque and will strip its gears quite quickly if you ask me. not to mention it’s not any faster than hand screwing.
Yeah, I was hoping that with the use of a servo, it would actually have decent torque, but that doesn’t appear to be the case. If I built it I would definitely use a beefier servo.
A more useful product would be to turn a cheap electric screwdriver into a powerful servo.
+1 for this, battery-powered tools are very often discarded due to dead batteries, there’s still a powerful motor & gearbox in them. Hell, I have two zero-cost 12v drills with jump-leads for use in the field from the car’s battery.
The 4V and 6V B&D are pretty good for this. The older 2.4V, which show up for 0.50 at yard sales don’t have the efficiency, but I have used them as they a re cheap and I have a bucket full. They pull upwards of 10A at stall. They all have two stage of planetary reduction and 1/4″ hex. The main issue is high current draw-the 4V pull about 6A at stall. This requires either a relay or a beefy bridge for servo use. Unidirectional isn;t an issue, though. Best part is the front end comes out of the housing as a unit, making a fairly compact drive.
I have tried a few of the larger, drill shaped drivers, and have not found them as easy to work with. One of these days a brushless will show up for me to play with. I think that these are likely much easier to work with than the brushed, as they have the controller built in.
Steve Ciracia SP? did that a few decades ago in Byte.
Yes as I can buy cheap electric screwdrivers for less than $6.00 around here. I found a china brand that takes 4 AA batteries for $3.00 in the clearance aisle at walmart and bought 4 of them.
I use a small pen-sized electric screwdriver for installing hundreds of tiny screws. It’s not the torque you really need, it’s the speed. Plus, using a tiny manual screwdriver cramps your fingers pretty soon. Professional assembly houses have high quality electric screwdrivers. Yeah, turning one screw is easy and you don’t need a complicated solution. Turning a thousand screws? Helps a lot. Glad to see some DIY in this direction.
I was interested in these pen-sized drivers but never managed to find one with a torque limiting clutch that won’t strip small screws or break plastic they are often screwed into. Where did you find yours?
There are the assembly line screwdrivers, but those are bulky, often require non-standard bits and are pretty much out of my price range …
I attached one of those drivers to a current limited supply so that I don’t need batteries, and the current limit effectively acts as a torque limit.
Every place I have seen pro level assembly uses a more refined version of these. put screw on end, get it started and push. zero chance of marring the head that comes with a power driver.
Not usable for my application, I’m using 1.4mm screws that are 10mm long, and have to hold the work in one hand.
Just as useful as indian programmers.
Wow, that was definitely not funny.
I know you were trying to reference the Therac-25 article, but bigotry is just plain stupid, and I suspect that millions of Indians would agree with me on that.
Not Indian but need to chime in lest Hackaday fall to the trolls. Hopefully all educated, civilized, enlightened humans can agree that bigotry is not funny.
wow! Thanks for pointing me to Therac-25, interesting read.
So, why is the HaDge .io page so quiet?
I was all fired up to watch it develop, and all I hear are crickets…
Is Bigotry an euphemism for xenophobe?
Wow…haha. I have done the same thing a long time a go, but with a bigger metal gear servo. Using exactly the same of push button that failed a few times. I now know that those switches are designed for some mA of current only.
I gave up on it like i gave up on a real electric screwdriver because i find the trouble of charging it and finding it discharged too much for the amount of screwing I do (phun intended).
This is cute, but perhaps it would make more sense to put something decorative in the “chuck” rather than a screwdriver bit. You can buy a vastly superior electric screwdriver on AliExpress for $9.99, shipping included.
Actually, I really like the idea of a quick-change chuck (rather than a hex bit adapter as our friend here used) on a servo to use in my lighting experiments. I think I’ll try this with something out of my big pile of Dremel chucks.
Many years ago, while programming automatic board test equipment, we took a stepper motor and put a shrouded screwdriver tip and a pistol-grip handle on it. It was connected to drivers in the board test hardware (run by a minicomputer). While testing analog board circuitry, this “servo-screwdriver” was used to automatically adjust trimpots on the board, under software control. You’d hold the screwdriver up to the trimpot, press it’s trigger button, and the software would automatically adjust the pot setting. Quite cool, at the time…
That is a very cool idea. Have the machines adjust themselves.
A minicomputer? That is sure dating yourself!
“using a 18650 Li-Po battery”
It’s a small thing but a 18650 is a Li-Ion battery, not a Li-Po battery. The energy density is significantly higher these Li-Ion cells than just about any Li-Po.
Neat! Cheap and effective.
Great job, upcylced what could be a servo with a blown driver board and some servo’s have metal gears and decent bearings so it could be reasonably robust. Best part is i never once thought about doing such a mod and finding an original idea is such a rarity.
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