|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Drilling machine. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Ham Radio Technologies Many radio amateurs use microdrills in the manufacture of printed circuit boards. The proposed development allows you to create a machine for drilling printed circuit boards based on a microdrill. For the manufacture of the machine, metalworking skills and a minimum set of tools are required: a hand-held electric drill, a hacksaw for metal, files, a vice and scissors for cutting metal. From materials - sheet steel, aluminum, plastic, fasteners. In general, everything that almost every radio amateur has. The microdrill is fixed on the bracket motionlessly, a movable table is used to supply the material being processed. The electrical circuit of the machine is shown in fig. 1. The electric motor is controlled by the limit switch SF1, which is mechanically connected to the table lifting lever. In the initial state of the machine, under the action of the lift lever, contacts 1 and 2 of the limit switch are closed, which corresponds to a stopped motor M1. When the lever is pressed, contacts 1-2 will open and contacts 1-3 will close. Relay K1 will work and connect the negative output of motor M1 to the collector of transistor VT1, but the transistor will remain closed for now, since capacitor C1 is discharged. Through the resistor R3, the capacitor will slowly charge, and the transistor will gradually open, which will ensure a smooth start of the engine. After drilling is completed and the lever is released, the limit switch SF1 will return to the state with contacts 1-2 closed and contacts 1-3 open. Capacitor C1 will be discharged through resistor R2, and in parallel with the motor disconnected from the collector of transistor VT1, resistor R5 will be connected, which ensures effective braking of the motor shaft.
The diagram shows the approximate values of the capacitance of the capacitor C1 and the resistance of the resistor R5, they depend on the desired acceleration and deceleration rates of a particular electric motor. Increasing the capacitance will increase the duration of the acceleration, and reducing the resistance of the resistor R5 will speed up the stop of the rotating drill. White LED EL1 illuminates the drilling site. Relay K1 should be selected with a nominal winding voltage of 12 or 24 V and a permissible switching current of 1...2 A. It can be, for example, SRD-12VDC-SL-C (winding resistance - 320 Ohm) or SRD-24VDC-SL-C (winding resistance - 1280 Ohm). When using a 12V relay, put a resistor in series with its winding equal to its DC resistance. To power the machine, any source of direct voltage 24 ... 30 V at a load current of 1 A is suitable. If there is a ready-made microdrill with a control and power unit, it can be successfully used in the proposed design. I started manufacturing the mechanical part of the machine by fixing the electric motor on an aluminum plate measuring 110x55x2,5 mm (Fig. 2). The mounting bracket is cut from a metal sheet 0,5 mm thick. A plastic lining is installed between the motor housing and the plate (the cover of the canister for graphite rods). The pad fixing screws prevent axial movement of the motor.
A sketch of the design of the table for the processed board and the mechanism for its rotation and lifting is shown in fig. 3. Parts of the tape drive mechanism of a cassette tape recorder were used - a flywheel 2 with a capstan 4 and its bearing 8. In the absence of a cassette tape recorder, which is not a pity to disassemble for spare parts, for the manufacture of a movable table, you can use, for example, suitable parts from a video player.
The bearing 8 is attached to the upper wall of the base 11 of the machine, the flywheel serves as the base of the table 1, and the capstan - the axis of rotation of the table and a guide for its movement in height. A spring 3 from a ballpoint pen is put on the capstan, which rests against the thrust bearing 6, fixed with a locking screw 5. This design has practically no radial play and ensures that the drill is perpendicular to the drilling plane in any position of the table. The table itself 1 is made of a 4 mm thick plastic sheet and attached to the flywheel 2 with three countersunk screws. The table lifting lever 7 is made of a metal rod with a section of 8x4 mm. As already mentioned, in the initial position (with the table lowered), he presses the limit switch 10 (SF1 - according to the diagram in Fig. 1), which keeps the motor off. When you press the handle extended beyond the base 11, the lever 7 rotates around the axis 9, releases the limit switch 10 and raises the table. The course of a little table - 5... 10 mm. As the base of the machine, I used a rectangular aluminum case G0247 (URL: http://gainta.com/pdf/g0247.pdf) with dimensions of 187x118x56,5 mm from among the radio components sold in stores. Of course, in the presence of sheet aluminum, the base can be made independently. First, assemble the mobile table assembly described above on the base and measure the required height of the motor assembly. After that, the table can be removed so that it does not interfere with the manufacture of the bracket on which the motor assembly is to be fixed. The bracket indicated in fig. 4 number 5, make a metal U-shaped profile (channel). It should ensure the perpendicularity of the drill chuck clamped into the motor shaft mounted on the motor shaft to the surface of the table and a convenient distance between this surface in the lowered state and the end of the drill. Mount the bracket blank 5 on the side wall of the base 1 strictly opposite the table and fasten it with screws. Then, having made cuts in the sidewalls of the profile, bend the workpiece at an angle of approximately 60о to the plane of the base and fix the bent part in this position with support 6.
Using a bench square, mark the place of the second bend on bracket 5 so that the drill clamped in the chuck is on a line passing through the center of the table. Bend the bracket in this place, fix the bend with pads 3 and cut off the excess workpiece. Attach motor assembly 2 to the bracket, as well as lampshade 4 with LED EL1. The control unit board can be installed on the bracket or in any free place in the “basement” of the machine base. The machine I made allows you to drill boards with a maximum size of up to 200 mm. By the time this article was written, a control node board and several more printed circuit boards, including those with printed conductors located on both sides, had been drilled on it. What are the advantages of the machine tool over the manual microdrill? Drilled holes are obtained strictly perpendicular to the surface of the board. It is much more convenient to position the drill in the center of the future hole. Drills of small (less than 1 mm) diameter are much less likely to break, since bending forces are not applied to them during the drilling process. Author: N. Salimov
Artificial leather for touch emulation
15.04.2024 Petgugu Global cat litter
15.04.2024 The attractiveness of caring men
14.04.2024
▪ Optical fiber with data rate up to 255 Tbps ▪ Fasting improves the quality of life ▪ Hybrid crossover Chery Tiggo 7 Plus ▪ Hubble's Cosmological Stress Paradox Explained
▪ section of the site Electrician in the house. Article selection ▪ article by Golda Meir. Famous aphorisms ▪ article Stilozantes probe. Legends, cultivation, methods of application ▪ article Sweep generator from SK-M-24-2. Encyclopedia of radio electronics and electrical engineering ▪ article Session with cylinders (several tricks). Focus Secret
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page