SHARPENING MACHINE
FROM HARD DISK
For dressing small tools, drills and various parts, it is convenient to use a small emery that can be held in your hand. A variant of this design is shown in Fig. 1:
Rice. 1
It is desirable to take a hard disk "from an earlier time", with a capacity of about 1 GB. It has more solid magnetic pancakes. The disk must be disassembled:
Remove the top cover;
Remove the magnets and the head drive;
Excessive leads are removed, only the motor power remains.
Further, for testing, the standard power supply + 5V, + 12V is supplied to the disk. The author used an ordinary AT format power supply. As a rule, at this time a pleasant surprise is found: in the absence of heads, the disk stops rotating after a few seconds.
You can deal with this phenomenon in different ways:
Assemble a separate generator to power the engine;
Use short-term automatic interruption of the supply voltage;
When disassembling the disk, try not to remove all the heads (leave the lower one);
Correct the existing motor power supply circuit.
Rice. 2
Unfortunately, it is impossible to give a rigorous method of searching for characteristic points. If you can get schematic diagram, then a lot of questions will disappear by themselves. The author was looking for the classic poke method. The general gist is this:
The microcircuit is determined - the motor driver;
With the help of an oscilloscope, the signal levels at its outputs are examined before and after stopping;
Signals similar to control signals are identified and examined.
The task is to block the signal (s) that cause the engine to stop. In the author's case, it turned out to be enough to evaporate a couple of transistors:
Rice.3
After long rotation is ensured, you can cut a ring of the desired size from a sheet of abrasive paper. The ring is glued to the upper disc with a few drops of glue around the circumference. The author used Moment glue.
When sharpening the tool, be sure to take into account the direction of rotation of the disc and place the tool blade in the direction of rotation. Otherwise, scuffing of the skin sheet is inevitable, which can be fraught with injuries.
Files for the article
Surely, for most people, old ones lie idle in their bins. hard drives... It can be used to make a necessary and useful thing for sharpening knives, scalpels and other items - a miniature grinder with a wheel speed regulator.
It will take
- old HDD, even if it doesn’t spin, or even without a fee.
- Sandpaper.
- A pair of terminals for connecting the power supply.
The three main components are:
Hard drive in any condition. The engine is difficult to burn in it, so it will be 100% suitable. And we will have a purchased board with a control driver.
The motor in the HDD is three-phase, brushless and very powerful. It will not work just like that on direct current and to start it you will need a controller or driver for controlling a three-phase motor.
To control the controller, you need a speed regulator, it looks like this:
Assembling a sander from a hard drive
So, let's open the hard drive. Here you will have a problem - you will need specialized screwdrivers, since the bolts and screws there are non-standard. I advise you not to suffer and buy or rent a set with such screwdrivers.
In general, we spin everything: both above and below, since nothing but the installed motor is needed.
We remove the board, leaving only the contacts for connecting to the motor. Now look: motors in hard drives can have three or four pins.
Everything depends on the method of turning on the windings. Somewhere they are switched on according to the "star" scheme, and somewhere according to the "triangle" scheme. Both options will work for us.
Except for the fact that in a three-pin HDD everything is clear with the phases - "ABC", and in a four-pin HDD, you will have to find out the phases with the help of a tester. We do not need the middle or common wire - it will not be used.
We connect the wires to the engine from the controller, isolate and fix it with a metal jumper (you can cut it out of a tin can).
With the same jumper we fix the controller itself from the side of the rotating disk.
To cut a circle out of sandpaper, remove the disk itself from the HDD motor. We will attach it to sandpaper, trace it with a pencil on the back side and cut it out with ordinary scissors.
It's time to glue the cut out circle onto the metal disc. It's all glued to double-sided tape. Your circle will not go anywhere, and it will be easy to change when worn out.
We screw on the disk.
We make a protective cover for the controller from the cover. We cut out a semicircle with a dremel.
And from a piece of tin we make a protective casing so that wear products do not fly to the controller.
The tin strip is soldered to the lid with a soldering iron hard disk.
We collect everything. We connect the speed regulator. Connection is made using a pin connector. These two modules are specially designed for each other and are actively used in modeling.
Connect the 12 V power supply. Use the regulator knob to adjust the rotational speed of the disk. Everything should work without configuration.
With the help of a PWM controller, the speed is regulated very smoothly and within wide limits.
Now you can sharpen metal or plastic. Such a useful design will surely find application in your home.
Thank you for the attention!
Hello everyone! The idea itself is not new. They say the internet is full of such records, I have not seen it yet, the idea appeared on its own. I was impatient here, you know, to urgently sharpen a knife and a screwdriver ... But "OH GOD!" Emery is in the garage, but at work there is not even a file ... Well, we are “sysadmins” people are simple and I got into the “bins of the Motherland” and took out ... An old hard drive from a PC ...
We take scissors, screwdrivers, sandpaper, our hdd and double-sided tape
Everything we need.
We unscrew the bolts. 7 bolts are always hidden under the sticker.
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We open it. and everything is so beautifully packed there. glitters.
We turn off the actuator and the lever for moving the heads, Magnets for experiments, the rest can be scrapped.
Unscrew the disc mounting cover and remove the washer above the disc, as well as the disc itself
We put the disk on sandpaper, outline the contours and cut out
These are the bagels)
We glue double-sided tape to our disk (you can add it to glue, but it will be easier to replace the sandpaper with scotch tape)
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ISKRIM))))
Well, about the work of this device.
It is better to take sandpaper with a small fraction, it is rather weak for a large engine. But I had enough to sharpen everything I needed, even very much. Bye everyone!
If you have an old hard drive from your computer, do not rush to throw it away, you can make a small handy emery out of it! The motors in such devices almost never break, and we don't need other parts. These motors are brushless, they develop high revs, withstand heavy loads and are durable.
An interesting homemade product in that with the help of a special controller you can control the engine speed. This is very handy when you need to process something very small. The author pasted over both discs on both sides with sandpaper, so they should be enough for a long time. If you are interested in the project, I suggest that you familiarize yourself with it in more detail.
Materials and tools used
List of materials:
- old hard drive;
- sandpaper;
- controller for the engine;
- connector for power supply;
- power supply unit for 12V / 6A;
- wires;
- materials for the body.
Tool list:
- a screwdriver for untwisting the hard drive;
- soldering iron;
- 3D printer (optional);
- glue.
Emery making process:
Step one. Disassembling the hard drive
You will need to disassemble the hard drive first. In most cases, the cover is secured with hex head screws. And on older versions, there may be conventional cross screws. The screws can be quite tight, so without a good screwdriver it can be difficult to remove them.
After removing the lid, we remove the filter, this is such a white bag, it is designed to collect the smallest particles of dust. You also need to remove the read / write head of the hard drive. It is fastened with one screw, and you will also need to remove two powerful neodymium magnets. We also remove the electronic board, we do not need it, even if it is working, there is little sense from it. As a result, only the engine with disks should remain.
Step two. Test engine start
The motor is installed here brushless, which means that it will not work if a constant or AC voltage... Here you need a special controller that generates a voltage of a special frequency, from which the engine runs. To start the engine, you need to buy a controller, you can order it from China. The controller is convenient in that it has a speed control function. The device can be powered from a voltage of 9V to 12V.
We supply power to the controller, the green LED should light up, which will indicate the operability of the controller. The disk is spinning, everything is fine, let's move on.
Step three. We glue the disks
We remove the disks, in most cases they are aluminum, and there are also glass ones. The author glues sandpaper to them. You can glue the discs on both sides, then you don't have to glue the paper often. You can simply rearrange or flip the disks. As a result, we get 4 work planes. If necessary, you can glue paper of different grain sizes. And if you have more discs, you can make yourself a good supply of sanding discs.
We install the disks back, it is not necessary to tighten all the screws, even 3 should be kept fine, but for reliability it is better to tighten everything.
Step four. Installing the legs
Our machine at high speeds will vibrate quite a lot and if nothing is done, the emery will ride on the table. To solve this problem, the author is screwed to hard disk rubber feet. They are quite common, you can order from China, or you can make it yourself from rubber, and so on.
Step five. Device case and assembly
The author has a plastic case, he printed it on a 3D printer. A controller is installed in the case, as well as a socket for connecting a power supply and a speed control knob. You can also make such a case from plywood. Auto screws the case to the hard drive with its own screws.
Step six. Testing
That's all, the homemade product is ready, you can test it! The author's emery easily sharpens a knife, and even sparks fly. The revolutions are conveniently regulated, so it is not necessary to turn on the machine so that it works at the limit of its capabilities.
I hope you liked the homemade product, and now you will not throw away your old hard drives. Good luck and creative inspiration, if you decide to repeat this, do not forget to share your ideas and homemade products with us!
Dec 7, 2018 Gennady
