Do-it-yourself drilling machine for printed circuit boards: drawings, photos, videos

A drilling machine for printed circuit boards belongs to the category of mini-equipment for special purposes. If desired, you can make such a machine yourself using available components. Any specialist will confirm that it is difficult to do without the use of such a device in the production of electrical products, the circuit elements of which are mounted on special printed circuit boards.

Simple mini PCB machine

Motor speed controller

To control the rotation speed of the 12-volt DC motor, on which the miniature drilling machine is built, this PWM module was purchased. Its cost on Aliexpress was 108 rubles, excluding delivery costs in the fall of 2022.

Module characteristics:

• Operating voltage: DC6V-DC28V
• Power control: 0.01-80W
• Maximum current: 3A
• Quiescent current: 0.01A (standby)
• PWM duty cycle: 0%-100%
• PWM frequency: 15 kHz
• Board size: 32mm * 50mm * 15mm

During operation, a red SMD LED lights up on the module, which changes the brightness of the light in accordance with the selected power mode.

The module circuit is based on chips and microcircuits:

• LR8726 (IOR) - 30V, HEXFET Power MOSFET.
• S10 45 GKIKG412 (ST) - It is possible that this is a Schottky Barrier Rectifier (current rectifier) ​​45V 5A.
• NE555 is a universal timer - a chip for generating single and repeating pulses.

A small heatsink was installed on top of the elements with the TO252 housing, but there was no thermal interface in the form of thermal paste. In addition, the surface of the radiator was not smooth enough.

These shortcomings were easily eliminated - the radiator was sanded and KPT-8 thermal paste was applied. However, newer revisions of these modules do not have such a heatsink, and the descriptions on the sellers’ pages indicate that the device can safely operate like this.

December 15, 2022. Additions February 7, 2022.

GTXpert

Add-ons

Other people who have already assembled such a machine made many suggestions. If you allow me, I will list the main ones, leaving them in their original form:

1. By the way, it would be good to remind those who have never worked with such parts before that plastic from 3D printers is afraid of heat. Therefore, you should be careful here - you should not go through holes in such parts with a high-speed drill or Dremel. Handles, hands...
2. I would also recommend installing the microswitch at a very early stage of assembly, since you still need to be able to screw it to an already assembled frame - there is very little free space. It would also not hurt to advise craftsmen to at least tin the microswitch contacts in advance (or even better, solder the wires to them in advance and protect the soldering points with pieces of heat-shrink tubing), so that later during soldering they do not damage the plywood parts of the product.
3. Apparently I was lucky and the chuck on the shaft was not centered, which led to serious vibration and hum of the entire machine. I managed to fix it, but it's not a good option. Since the rotor axis bends, and it is no longer possible to remove the cartridge, there are fears that I will pull out this very axis entirely.
4. Tighten the screws with locking washers as follows. Tighten the screw until the lock washer closes (straightens). After this, turn the screwdriver 90 degrees and stop.
5. Many people advise attaching a speed regulator to it according to Savov’s scheme. It turns the engine slowly when there is no load, and increases speed when load appears.

Dual spindle machine

A two-spindle machine is used to bore holes on both sides and turn the ends of parts. But there are several nuances in this equipment that are worth getting acquainted with:

1. The OS-402A vertical double-spindle deep drilling machine has a stepped and automatic drilling cycle.
2. To increase its own productivity, a double-spindle rotary milling unit has been developed.
3. The design of a two-spindle machine for lapping reinforcement was designed and manufactured at the Lenenergo enterprise.
4. To screw two threaded parts simultaneously from both ends of the roller, a two-spindle unit with a mechanical drive with a horizontal spindle was manufactured at another production facility.
5. The three-spindle unit type C - 13 and the unit type C - 12 are similar in technical characteristics and design. But there is also a difference between the machines, where the table of a two-spindle machine has a shorter length.
6. There are rotary table surface grinders with one or two spindles. The difference is that with a dual-spindle machine, one spindle is used for preliminary grinding and the other is used for final grinding.
7. Devices for rolling rods and fillets on shafts are in great demand among the population. Only in some cases can one count on the simultaneous rolling of two shafts on their side for a two-spindle machine; the installation of a special valve is also present on the machine.
8. The specialized machine has manual control and, thanks to the 4723D model, a mechanical drive. The machine is also used for multi-position processing of many parts. Its kit includes the following: a machine tool, a machine generator of unipolar pulses, a high-frequency electronic semiconductor generator. In contrast to this model, the double-spindle machine is reinforced with an L-shaped traverse.

It is worth noting that each dual-spindle unit represents the most powerful equipment for any workshop, which any master should use.

Features of equipment for drilling holes in printed circuit boards

A machine for drilling printed circuit boards is one of the types of drilling equipment, which, given the very small size of the parts processed on it, belongs to the category of mini-devices.

Any radio amateur knows that a printed circuit board is the base on which the components of an electronic or electrical circuit are mounted. Such boards are made from sheet dielectric materials, and their dimensions directly depend on how many circuit elements need to be placed on them. Any printed circuit board, regardless of its size, simultaneously solves two problems: accurate and reliable positioning of circuit elements relative to each other and ensuring the passage of electrical signals between such elements.

Depending on the purpose and characteristics of the device for which the printed circuit board is created, it can accommodate either a small or a huge number of circuit elements. To fix each of them in the board, you need to drill holes. Very high demands are placed on the accuracy of the location of such holes relative to each other, since it is this factor that determines whether the elements of the circuit will be positioned correctly and whether it will be able to work at all after assembly.

Drilling holes in foil getinaks on a homemade machine

The difficulty of processing printed circuit boards also lies in the fact that the majority of modern electronic components are miniature in size, therefore the holes for their placement must have a small diameter. To form such holes, a miniature tool (in some cases even micro) is used. It is clear that it is not possible to work with such a tool using a conventional drill.

All of the above factors led to the creation of special machines for forming holes in printed circuit boards. These devices have a simple design, but can significantly increase the productivity of this process, as well as achieve high processing accuracy. Using a mini-drilling machine, which is easy to make with your own hands, you can quickly and accurately drill holes in printed circuit boards intended for assembling various electronic and electrical products.

Drilling machine from an old microscope

Do-it-yourself mini electric drill - very simple and fast

And again, good day to all, dear enthusiasts of homemade devices, tools and other mechanisms.

Today I am pleased to share with you a simple method for making a simple, budget-friendly option for making a mini electric drill. Then we will consider with you the identified pros and cons of the resulting product. The mini drill has become widespread and is used to perform an incredibly large number of tasks at home, in the garage, in the country or for repairs. A mini drill is used for a wide variety of small jobs. In particular, it is used for drilling electrical printed circuit boards; a conventional electric drill is completely unsuitable for such work. A mini drill equipped with special attachments can be used as an engraver, a grinder or a router. To use it in this capacity, special nozzles with a rough working surface are used. During operation, the nozzle processes the part or applies the required pattern to the product being processed. Of course, a mini drill will not be able to handle thick iron, but a hole in a metal sheet up to one millimeter thick will be enough to drill. There are an unimaginable variety of options for making a mini-drill with your own hands. Everything fits into your flight of imagination, fantasy and is limited solely by the components available to you for making a drill. So your imagination is limited only by your spare parts bins. The heart of any mini drill is a small but quite powerful electric motor. Also, for the manufacture of our mini drill, you will need a collet chuck (a collet chuck is a type of drill chuck. They hold the drill in the drill during the drilling process. The quality of the work performed by the electric drill depends on the quality of the collet chuck and, accordingly, the fastening of the drill to the electric motor. Therefore, the choice of collet cartridge should be approached with all responsibility), it is quite problematic to make a high-quality collet cartridge on your own at home, so it is better to purchase it in a store. Standard chucks (with collets for drills with a diameter of 0.5 to 3.2 millimeters) can be found in any online store at an affordable price, the price varies from 100 to 150 Russian rubles

An important part of the mini drill, where all the components are placed and attached, is the body. There are many options, in our case we use a pipe from a fan pipe, the inner diameter of which perfectly matches the outer diameter of the electric motor

When fixed in the housing, the engine stood up with virtually no gaps. Connecting electrical wires are selected based on the power of the drill, but due to the fact that we are using an electric motor with low power consumption, we select insulated electrical wires of small cross-section. For high-quality soldering of an electrical circuit, we will need soldering acid and tin rods, a soldering iron or connectors. Almost any novice DIY enthusiast can assemble a mini drill on their own. It's a matter of desire and perseverance. As always, about observing safety precautions when working with high-risk tools. Work carefully. Following all safety regulations. Do not taste electricity with your tongue, do not stick your fingers where the dog does not stick its tail. Before any action, turn on your brain. And then, take my word for it, each member of your friendly family, including the dog, will have their own mini drill.

The procedure for assembling a homemade device

As practice shows, it is most convenient to assemble a homemade machine for drilling holes in printed circuit boards in a certain sequence. You must act in accordance with the following algorithm.

• The frame is installed, and legs are attached to its underside, if they are provided for in the design.
• A movement bar and a holder frame on which the drilling head will be mounted are attached to the assembled frame.
• The holder frame is connected to a shock absorber, which is also fixed to the equipment frame.
• A handle for controlling the movement of the drilling head is installed, connected to a shock absorber or holder frame.
• An electric motor is mounted, the position of which is carefully adjusted.
• A collet or a universal drill chuck is attached to the shaft of the drive motor using adapters.
• A power supply connected to the electric motor via electrical wires is being installed.
• A drill is installed in the chuck and securely fixed in it.
• The assembled homemade machine is tested by trying to drill a hole in a dielectric sheet with its help.

To ensure that your homemade mini-drilling machine can always be disassembled and modified, it is best to use bolts and nuts to connect its structural elements.

If you want to make your own mini-equipment for making holes in printed circuit boards, you can always use the drawings and advice of those who already own such a machine and are actively working on it in their home workshop.

Parts for assembly

1. Engine with chuck and collet. On the one hand, a jaw chuck is very convenient, but on the other hand, it is much more massive than a collet clamp, that is, it is often subject to beats and very often they have to be additionally balanced.
2. Plywood parts. A link to files for laser cutting in dwg format (prepared in NanoCAD) can be downloaded at the end of the article. You just need to find a company that deals with laser cutting of materials and give them the downloaded file. I would like to note separately that the thickness of the plywood may vary from case to case. I come across sheets that are a little thinner than 5mm, so I made the grooves 4.8mm each.
3. 3D printed parts. A link to files for printing parts in stl format can also be found at the end of the article
4. Polished shafts with a diameter of 8mm and a length of 75mm - 2 pcs. Here is a link to the seller with the lowest price for 1m that I saw
5. Linear bearings 8mm LM8UU - 2 pcs.
6. Microswitch KMSW-14
7. Screw M2x16 - 2 pcs.
8. Screw M3x40 h/w – 5 pcs.
9. Screw M3x35 slot - 1 pc.
10. Screw M3x30 h/w – 8 pcs.
11. Screw M3x30 h/w with countersunk head - 1 pc.
12. Screw M3x20 h/w - 2 pcs.
13. Screw M3x14 h/w - 11pcs
14. Screw M4x60 slot - 1 pc.
15. Bolt M8x80 - 1 piece
16. Nut M2 - 2 pcs.
17. M3 square nut – 11pcs
18. Nut M3 – 13pcs
19. M3 nut with nylon ring - 1 pc.
20. Nut M4 - 2 pcs.
21. M4 square nut – 1 piece
22. M8 nut – 1 piece
23. Washer M2 - 4 pcs
24. Washer M3 – 10pcs
25. M3 washer enlarged - 26 pcs.
26. M3 locking washer – 17 pcs.
27. M4 washer - 2 pcs.
28. M8 washer - 2 pcs.
29. M8 locking washer – 1 piece
30. Set of installation wires
31. Heat shrink tube set
32. Clamps 2.5 x 50mm - 6 pcs

Description of design

The design is based on a fairly powerful 12-volt motor from China.
Included with the engine, they also sell a cartridge, a wrench and a dozen drills of different diameters. Most hams simply buy these motors and drill the boards while holding the tool in their hands. I decided to go further and, based on it, make a full-fledged machine for similar engines with open drawings for independent production.

To move the motor linearly, I decided to use 8mm diameter polished shafts and linear bearings. This makes it possible to minimize backlash in the most critical place. These rollers can be found in old printers or purchased. Linear bearings are also widely used and available in 3D printers.

The main frame is made of 5mm thick plywood. I chose plywood because it is very cheap. Both the material and the cutting itself. On the other hand, nothing prevents (if possible) from simply cutting out all the same parts from steel or plexiglass. Some small parts with complex shapes are 3D printed.

To lift the engine to its original position, two ordinary rubber bands were used. In the upper position, the motor switches itself off using a microswitch.

On the reverse side I provided a place to store the key and a small case for drills. The grooves in it have different depths, which makes it convenient to store drills with different diameters.

But it’s easier to see all this once on video:

There is a slight inaccuracy on it. At that moment I came across a defective engine. In fact, from 12V they consume 0.2-0.3A at idle, and not two, as they say in the video.

DIY drilling machine

What to do if you don’t have a drilling machine for printed circuit boards at home? Of course, it’s expensive to buy, and it happens that the machine is not needed for frequent use.

I offer you 2 simple ideas for making your own drilling machine with your own hands. The first option is very simple; to make it we will need an electric motor from cassette recorders.

Remember these? Such motors can be removed from any Chinese or Soviet-made tape recorder.

They look something like this:

So, we have an electric motor, we also need a drill of the required diameter, usually 0.7-1 mm, we need to take thin paste from a ballpoint pen, a thin thread of 10 centimeters, scissors and instant glue.

Is everything ready? Let's start collecting.

We take the scribbled paste from a ballpoint pen (you can use a new one) and cut off 15 mm, then we need to put it on the motor shaft a little less than half (6-7 mm). Then remove it with a screwdriver or tweezers and put it aside (although you don’t have to remove it).

We take a drill, wind a thread on it turn to turn in 2 layers, below is the photo:

Holding the end of the thread (so as not to unwind), apply a drop of second glue and quickly push the drill into the tube. If you hesitate, the glue will harden.

Here's what we got:

If the drill rotates crookedly, you simply bend the paste in the desired direction until the drill is centered, and you can start drilling your board

Second version of the drilling machine

Now I’ll tell you about the second version of the drilling machine, the one I use. Making it will be a little more difficult. I will not give detailed drawings with dimensions, because...

the machine was assembled from what we have, let the article be for informational purposes only, but I will still describe the machine in photographs and schematically.

You can try to assemble a similar machine for yourself using my drawings. This machine looks like this:

• It is built on a lever mechanism, when pressed, the motor and the drill are lowered, and if the lever is released, the motor rises up again.
• Here is a photo of the mechanism itself:

The lifting and lowering part is made of sheet metal, the sheet is cut to the desired shape, bent and holes are drilled. Instead of the bent rod shown in the photo, you can use something similar, for example, replace it with two long M4 screws with a thread at the end.

1. Mechanism drawings:
2. Drawing of the lifting mechanism.
3. To avoid confusion, I drew the lifting and lever mechanisms separately
4. This is what you get if you combine the two top pictures
5. I think the essence is clear and now, using my sketches, if you wish, you can put together something similar, I gave you the idea, so go for it!

I also want to give a little advice about drills, drills become dull very quickly and begin to drill poorly, if you don’t have a sharpening machine, then why not throw them away? I found the following way out of this situation: we take a drill and carefully break off the end of the drill with pliers (a millimeter or a little more), and we don’t need to break it off haphazardly, as correctly shown in the pictures below.

Assembly

The whole process is shown in detail in the video:
If you follow exactly this sequence of actions, then assembling the machine will be very simple.

This is what a complete set of all components for assembly looks like

In addition to them, assembly will require a simple hand tool. Screwdrivers, hex keys, pliers, wire cutters, etc.

Before starting to assemble the machine, it is advisable to process the printed parts. Remove possible sagging, supports, and also go through all holes with a drill of the appropriate diameter. Plywood parts along the cut line may become stained with smoke. They can also be sanded with sandpaper.

Once all the parts are prepared, it's easier to start by installing the linear bearings. They creep inside the printed parts and are screwed to the side walls:

Next, the handle with gear is installed. The shaft is inserted into a large hole, the base of the handle is installed on it and the whole thing is tightened with an 8mm bolt. The handle itself is an M4 screw:

Now you can assemble the plywood base. First, the side walls are installed on the base, and then the vertical wall is inserted. There is also an additional printed piece at the top that defines the width at the top. When driving screws into plywood, do not use too much force.

It is necessary to make a countersink in the table on the front hole so that the head screw does not interfere with drilling the board. A printed fastener is also installed at the end.

Now you can begin assembling the engine block. It is pressed with two parts and four screws to the movable base. When installing it, you must ensure that the ventilation holes remain open. It is secured to the base using clamps. First, the shaft is threaded into the bearing, and then clamps are snapped onto it. Also install an M3x35 screw, which in the future will press the microswitch.

The microswitch is installed on the slot with a button towards the engine. Its position can be calibrated later.

The rubber bands are placed on the bottom of the engine and threaded through to the “horns”. Their tension must be adjusted so that the engine rises to the very end.

Now you can solder all the wires. There are holes on the engine block and next to the microswitch for clamps to secure the wire. This wire can also be routed inside the machine and brought out from the back. Make sure you solder the wires on the microswitch to the normally closed contacts.

All that remains is to install the pencil case for the drills. The top cover must be clamped firmly, and the bottom cover must be tightened very loosely, using a nut with a nylon insert for this.

This completes the assembly!

Design

At first glance, the scheme seems complicated, however, it is not. In fact, the mini machine is not very different from the classic one; it is smaller in size with some nuances in the design layout.

Since this equipment is not large in size, it should be considered as desktop equipment. The homemade version of the equipment is usually slightly larger than the purchased one, due to the fact that when assembling it yourself, it is not always possible to optimize the design by selecting small-sized components. But even in this case, the homemade machine will have small dimensions and weight no more than 5 kg.

Assembly video

Elements of a drilling machine

To assemble a mini device with your own hands, you will need the following:

1. Bed;
2. Transitional stabilizing frame;
3. Bar for moving;
4. Shock absorber;
5. Height adjuster handle;
6. Engine mount;
7. Engine;
8. Collet (or cartridge);
9. Adapters.

It is worth noting that we are describing a homemade mini drilling machine, assembled from improvised materials with your own hands. The factory design is distinguished by the use of specialized components that are almost impossible to make with your own hands. The basis of a mini drilling unit, like any other, is the frame. It serves as the base on which all the nodes will be held. The frame can be a handy device, for example: the skeleton of a microscope; stand for linear measurements with a digital indicator.

Or you can make it yourself, for example, a light wooden frame - by connecting the boards with self-tapping screws, or a heavy and stable one - by welding a steel profile to a metal sheet. It is better when the weight of the frame is higher than the main weight of the other components, this increases the stability of the unit and reduces its vibration during operation.

Motors for PCB Drilling Machines

Another interesting scheme based on spare parts from a CD-ROM and a hair dryer with automatic adjustment of the engine speed depending on the load.

Homemade bed

When making a steel frame with your own hands, you can screw the legs under it to fix its position. The stabilizing frame can be made, for example, from a slats or corners, but it is better to use steel. The type of bar for moving can be chosen in any way, the most convenient, and at the same time better combine it with the shock absorber. In some cases, the shock absorber itself may be such a bar. The functions of these parts are to vertically displace the equipment during operation. You can make the shock absorber yourself or remove sliding slats from office furniture, or buy them in a store. The height adjuster handle is installed on the body, stabilizing rail or shock absorber. The motor mount is installed on the stabilizing frame, it could be, for example, a simple wooden block. It is needed to bring the motor to the required distance and securely fix it. Then the motor is installed directly on the mount. A chuck or collets are directly attached to the motor, to which adapters used for installing drills are attached. Adapters are selected individually, depending on the motor shaft, its power, type of drills, etc. In conclusion, we can say that the assembled mini drilling machine can be constantly modified during operation. For example, you can stick an LED strip on the chuck to illuminate the samples being drilled.

General information about drilling machines

Any drilling machine is necessary in order to ensure the ability to efficiently and accurately process parts made from various materials. Where high precision processing is required (and this also applies to the process of drilling holes), manual labor must be eliminated as much as possible from the technological process. Similar problems are solved by any drilling machine, including homemade ones. It is practically impossible to do without machine equipment when processing hard materials, for drilling holes in which the efforts of the operator himself may not be enough.

Design of a benchtop belt driven drill press (click to enlarge)

Any drilling machine is a structure assembled from many components that are securely and accurately fixed relative to each other on a supporting element. Some of these nodes are rigidly fixed to the supporting structure, and some can move and be fixed in one or more spatial positions.

An example of motors used in the manufacture of a homemade mini drilling machine

The basic functions of any drilling machine, through which the processing process is ensured, is the rotation and movement in the vertical direction of the cutting tool - the drill. On many modern models of such machines, the working head with the cutting tool can also move in a horizontal plane, which allows this equipment to be used for drilling several holes without moving the part. In addition, automation systems are being actively introduced into modern drilling machines, which significantly increases their productivity and improves processing accuracy.

Below, as an example, are presented several design options for homemade drilling machines for circuit boards. Any of these diagrams can serve as a model for your machine.

List of components

Here is a complete list of everything needed for assembly:

1. Printed circuit board (link to manufacturing files at the end of the article)
2. U1 - MC34063AD, switching regulator, SOIC-8
3. U2 - LM358, operational amplifier, SOIC-8
4. U3 - L78L09, stabilizer, SOT-89
5. D1,D3 - SS14, Schottky diode, SMA - 2 pcs
6. D2 - LL4148, rectifier diode, MiniMELF
7. C1 - capacitor, 10uF, 50V, 1210
8. C2 - capacitor, 3.3nF, 1206
9. C3, C4 - capacitor, 4.7 µF, 1206 - 2 pcs
10. C5 - capacitor, 22uF, 1206
11. R1-R3,R7,R9,R11 - 1 Ohm resistor, 1206 - 6 pcs.
12. R4, R10 - resistor 22 kOhm, 1206 - 2 pcs.
13. R5 - 1kOhm resistor, 1206
14. R6 - resistor 10-27 kOhm, 1206. The resistance depends on the rated voltage of the motor used. 12V - 10kOhm, 24V - 18kOhm, 27V - 22kOhm, 36V - 27kOhm
15. R8 - resistor 390 Ohm, 1206
16. RV1, RV2 - subscript resistor, 15 kOhm, type 3224W-1-153 - 2 pcs.
17. XS1 - terminal, 2 pins, pitch 3.81mm

We also made a limiter ring on a 3D printer for easy installation on the engine. The download link for the STL file is at the end of the article.

Homemade mini drill for drilling circuit boards

The task of drilling or even simply making holes in circuit boards is found everywhere in amateur radio practice. At the same time, it is not at all necessary to design your own boards, or even use the printed manufacturing method - holes are needed even with the hinged installation method, or simply during the reworking and modification of industrial boards.

For these purposes, you can use a specially sharpened awl with a pyramidal tip, which makes it easier to grab the board material and make a hole. But in this case, you have to apply a lot of force, which can lead to deformation and bending of the board, and the final hole is far from what you would like. Some radio amateurs install a thin drill in the chuck of a regular drill or screwdriver, which is very inconvenient to work with, especially if you need to make a hole on the board next to an already installed radio component, which in this case will get in the way and be very easily damaged.

More experienced and motivated radio amateurs struggle with such difficulties and independently make small hand-held devices for drilling, and even entire drilling and milling machines - it all depends on the means and capabilities. There are options with automatic and semi-automatic control, with rotation speed stabilization and torque adjustment.

In this article, readers will be presented with one of, probably, the simplest and easiest to manufacture options for drilling tools made from scrap materials. The only thing that was purchased was a collet chuck to hold the drill, and actually a set of drills themselves of different diameters, including thin drills for making holes for the most common standard radio components.

The tool is made in a lightweight but durable plastic case of small dimensions. There is LED backlighting and protection against overload, and as a result, against jamming and overheating of the engine, and control is carried out by a single button without locking. To power the instrument, a switching power supply with an output voltage of 12 Volts and a maximum load current of 1 Ampere was used, although the consumption of the device in this case does not exceed 0.6 Amperes, and it can be powered with a voltage ranging from 9 to 15 Volts:

Appearance of a homemade tool for drilling boards

A little background

There were quite a large number of small-sized DC electric motors in stock, and for use in a miniature drill, we took the one that was available the most, so that in case of failure, it could be easily replaced. It turned out to be a motor from an old tape drive mechanism of a Soviet-era cassette recorder. The motor itself is small in size, but it is located in a metal casing, and it was decided not to remove it from there, since in terms of dimensions, this casing with the motor inside is ideally inserted and held in the working part of the plastic antiperspirant case, which in turn fits well for such a design, as it is compact in size and fits comfortably in the hand:

Electric motor from the tape drive mechanism of a tape recorder

We will not focus on the specific characteristics of the electric motor, such as power and shaft diameter, since in this design you can use any suitable small-power motor, and for each it may differ from the one used here. The design of the body can also be any, and for such purposes it is convenient to use plastic pipes of suitable diameter. Next we will show how you can make a simple miniature drill for drilling circuit boards with your own hands.

Tool design

Together with the motor, two wires were laid to power the backlight, for which a surface-mounted LED was installed openly on the antiperspirant cover, which plays the role of the cover of the working side of the case. A hole was previously cut in the cover for the electric motor shaft, along the outer diameter of the future collet chuck, which will be discussed a little later. The LED is well glued to the cover with universal quick-hardening glue, and the cover itself is freely installed in its original place:

The working part of the tool with an electric motor and LED backlight

But simply installing the engine into the body is not even half the battle. Be that as it may, but somehow it is necessary to maintain the stability of its operation and ensure the reliability and durability of the tool. Last but not least is the ease of use. You can assemble a popular circuit with positive feedback, where the engine constantly rotates at low speeds, and as the load on it increases, the rotation speed increases.

But in this case, with battery power, you still have to install an additional switch and flip it often in between drilling, and besides, the motor used has little power, and even simple stabilization of the rotation speed will be dangerous for it, since with increasing load , the current through it will also increase, and with possible jamming and complete stop of the motor, this is almost equivalent to a short circuit.

It was decided to stabilize the current through the motor, thereby preventing it from overloading, and consequently overheating its windings. This method provides acceptable rotation speed stability, and jamming, if not completely eliminated, is not severe and can be easily eliminated. In this case, the current does not exceed the specified value, and the engine produces scanty power.

At appreciable powers, you can use a pulse current stabilizer, but in this case, the optimal operating current of 500 mA was determined experimentally, and such a current through the idling engine used is provided by a voltage of the order of 7 - 8 Volts, and since the one allocated at the regulating element, the power is not very high, even with a short circuit in the load, it was decided to assemble a simple but reliable linear-type current stabilizer using a medium-power transistor.

For easier and more accurate positioning of the drill on the board being drilled, it was decided to install additional local lighting on the tool itself. Since the entire device will be powered by a voltage of more than 9 volts, instead of a single-chip LED, a 5050 type surface-mount LED was used with three crystals in one package, the crystals of which were connected in series.

Based on the required parameters, a circuit diagram of the device was calculated and developed using outdated but common radio components, in particular direct conduction germanium transistors:

Schematic diagram of a miniature drill

The input supply voltage is supplied to connector X1, from which, through fuse F1, it is supplied to the instrument circuit, the nodes of which are separate current sources for the backlight and the electric motor. Diode D1, together with the fuse, protects the entire circuit from reverse polarity of the supply voltage, during which it opens and closes the circuit, thereby burning the fuse and de-energizing the device.

A current stabilizer is assembled on transistors Q1 and Q2 to power the LED backlight, the level of which is set by resistor R1. You can use a single transistor with a high transfer coefficient of the base current; here, a composite connection of transistors is used to minimize the control current. Its level is determined by the voltage drop across the silicon diode D3, which is applied to the base of the composite transistor. In the case of using one silicon transistor with a high current gain, another diode will need to be added in series with this diode, and in the case of a composite silicon transistor, one more diode will need to be added, so that the number of diodes is one more than the number transistors installed in this node.

The source of stable current for powering the electric motor is assembled on transistors Q3 - Q5, and the level of this current is set by low resistance resistor R4. Here, instead of two transistors Q4 and Q5, you can install one transistor with a high base current transfer coefficient, use composite or silicon. Transistor Q3 can also be replaced with a silicon one, but in this case it will be necessary to increase the resistance of the current-setting resistor R4 by 2 - 2.5 times, which entails an increase in the voltage drop across it, and as a result, an increase in the heat generation of the resistor itself. Choke L1, together with capacitor C2, reduces the amount of electromagnetic interference emitted during operation of the tool, and diode D4 protects the power transistor from parasitic reverse surges of high voltage on it, characteristic of an inductive load, which is actually the electric motor connected to the output.

The tool is controlled by button S1, through which the bias voltage, through resistor R3, is supplied to the base of transistor Q4, opening transistor Q5 along with it. Transistor Q3 is included in the negative feedback circuit, and when opened, it shunts the bias circuit, setting the operating point of the entire assembly. The control signal is simultaneously supplied to the backlight unit, lighting it. After closing the contacts of the control button, capacitor C1 quickly charges, and the bias voltage, through resistor R2, is supplied to the base of transistor Q2, opening it and transistor Q1. When the button is released, the power supply unit of the electric motor is de-energized immediately, and the backlight unit continues to be powered for some time from capacitor C1. This is done for convenience, so that the backlight burns for some time in short pauses during drilling. Diode D2 prevents the capacitor from discharging through the motor assembly.

Setting up the tool comes down to setting the operating currents for the backlight and electric motor. The backlight current is set by selecting the resistance of resistor R1, and for three series-connected crystals of one 5050 LED it should not exceed 20 mA. The operating current of the electric motor was determined as follows. Using a conventional ammeter, its current consumption was measured under normal load, during drilling without jamming or jamming. Next, the level of this current, which in this case was 500 mA, was set by selecting resistor R4, and in the event of a jammed motor shaft, the value of this current will remain the same and the windings will not overheat.

As transistors Q1 - Q4, you can use transistors MP39 - MP42 with any letter indices, or other germanium pnp transistors of low and medium power. Transistor Q5 can be replaced with another direct conduction transistor of medium or high power with a permissible collector current of 1 A. When using a more powerful electric motor with a higher current consumption, it will be necessary to use an appropriate transistor, and it may be necessary to install it on the heat sink. It is possible to replace all transistors with reverse conduction transistors. In this case, you will need to reverse the polarity of the power supply, the electrolytic capacitor and all diodes, including the LED.

In this case, the Soviet inductor DM-0.6-50 can be used as inductor L1; it must be able to withstand the supply current of the electric motor for a long time. Diode D2 can be anything, D3 can be any small-sized silicon diode for a small current, and the remaining diodes D1 and D4 can be used for a current of 1 A or more and a reverse voltage of 30 Volts. The LED can be any suitable one, preferably with a white glow color, for reasons of convenience of further work with the tool. Button S1 is any small-sized, without locking.

Although the radio components used were widespread at one time, they are quite ancient and today are very outdated. Therefore, a printed circuit board was not developed for them, and everything was assembled by surface mounting, on a board the size of the case used. Connector X1 was not installed, and the power cord was soldered directly to the board, but further practice showed that this is not entirely convenient, and it is still better to install a suitable power connector and connect the AC adapter or battery through it. Inductor L1 was wound on a small ferrite rod with a 0.81 PEL wire, and resistor R4 with a nichrome wire, on the body of an MLT-0.5 resistor with much greater resistance than required.

The button was moved outside the case and installed externally on its own contacts, and a hole was made in the narrow part of the case to enter the power cord. All conductors are soldered to the board for their intended purpose, after which it must be cleaned of flux residues. The board is placed in the case, and its halves snap into place and are securely held together. In general, this is a rather dense and strong plastic case, moreover, it is very convenient and compact, and you can assemble various wearable amateur devices in it:

Assembling a miniature drill and its board in a plastic case

Additional components

But installing the motor into the housing and assembling a circuit for it is still half the battle. In order for the tool to be used, additional components must be purchased for it, and this is the only thing that was purchased specifically for this project. First of all, you need to measure the diameter of the motor shaft, and find a collet chuck with holders for drills of different diameters for this diameter. The cartridge is pressed to the motor shaft with two screws, for which a suitable key was included in the kit. A set of various drills was also purchased separately, but only the thinnest of them will be used with the described tool.

A holder suitable for the drill required at a particular time is installed in the chuck, a clamping head is put on the chuck, the drill is inserted and clamped in the chuck, and the chuck itself with the drill is fixed with screws directly on the electric motor shaft. When you press the button, the backlight LED lights up and the installed collet chuck with drill begins to rotate. During operation of the tool, vibration and vibration are very slight and can be minimized by slightly loosening one and correspondingly tightening the opposite collet screw. The brightness of the backlight is small, but since it shines directly at the drilling site, it is sufficient for work even in complete darkness, and with additional lighting it is completely comfortable:

Installing and checking the drill and collet chuck with the tool

Conclusion

The tool turned out to be not very powerful and it does not make holes instantly, but due to its compactness and small size, it is much more convenient to use than a screwdriver or a regular drill, and after drilling with it, you don’t want to go back to heavy and bulky devices. To power your homemade product, you can use a switching power supply, a homemade collapsible, or a compact rechargeable battery. The tool is well suited for making a small number of holes in getinaks or textolite boards, and when using a more powerful motor, it can be used to drill on a larger scale. The main thing is to choose a collet chuck with a suitable diameter and set the optimal operating mode. This device is of course not exemplary, but it has a finished appearance and practical performance:

Ready-made homemade mini-drill with a drill installed

A variety of collets and drill sets of various diameters can be found on AliExpress. They also sell complete kits along with the engine, but such a kit will still require a housing and a power/control unit.

Whatever the design of the tool, it really makes the life and work of a radio amateur easier. In the future, I would like to improve the development and assemble the device on a more powerful and modern base. If anyone has experience assembling and using such improvised means, please share the information, maybe someone will find it useful or just interesting. Constructive and adequate criticism is also welcome, it always helps to become a little better.

List of radioelements

Attached files:

• MiniDrillCircuit.pdf (56 Kb)

Comments

Ten points for the design! Great development!

A good machine. Will you post the files publicly?

I'll post it a little later. I have a lot of modifications now. It needs to be sorted into folders. And I'll post it there

Hi all. I downloaded the files and printed almost everything. And I had a problem; either the manufacturer changed the design of the 775 motor, or the author did not report something in the folders? In a word, the motor dangles in the cocoon (motor mount lever) like a match in an empty box. I don’t understand how and by what means it (the motor) is attached. There is not a word about this anywhere in the video or article. If you don't mind, explain this. And the backlight is great, but tell us how you implemented it. The files do not contain channels for the backlight wires. Oh, they drilled the parts. It's a shame to spoil such a detail. The bearings I have are different. one is 8x16x5 and the other is 8x15x4 (MR148ZZ). The main problem I have is of course the engine mount. If you choose the time, please give an answer either here or in a personal message. I would like to thank you for the work you have done. The machine is beautiful and differs little from the industrial one. Professional design.

Quite competent from an engineering point of view! But I don’t recommend SD for serving, the feeling on the hand is very important. Well, a heavier bottom plate is better, steel is the best. Good luck!

Beautiful and very aesthetically pleasing. Liked.

In the next modification I want to give up the lever.

Never do this. Make it better - the lever (and spring) is 'removable', and the drive on the stepper is 'disconnectable'.

A drill and a CNC are slightly different things, and one very rarely “bleeds” into the other, but a drill “with a lever” is more often needed precisely in critical situations.

I didn’t even read the text, I just looked at the photos. I liked it very much, upvote!

The machine is super. It’s nice when both the appearance and functionality match. Regarding the stepper, I’ll also add my 5 cents: The stepper will be perfect if it’s made completely by CNC. I put the scarf on, loaded the task, took off the finished result, but this is unnecessary.

Well, to make a CNC drill on the chassis it must be different. This is practically a 3D printer, only instead of an extruder there is a motor with a cartridge. And regarding the stepper, my thoughts are as follows: Pedal under your foot. Wireless control. And the drill movement is two-speed. First, we quickly bring the drill to the board and wait for a deeper press on the pedal. During this time, the board can be installed accurately. press the pedal and drill.

The chassis is something like this:

Simple and if you modify your machine, you’ll get an excellent micro-milling machine for circuit boards