CHAPTER XVI ELECTRIC MOTORSThe first American patentee and builder of an electric motor was Thomas Davenport. The father of Davenport died when his son was only ten years old. This resulted in the young inventor being apprenticed to the blacksmith’s trade at the age of fourteen.Some years later, after having thoroughly learned his trade, he married a beautiful girl of seventeen, named Emily Goss, and settled in the town of Brandon, Vermont, as an independent working blacksmith.About this time Joseph Henry invented the electro-magnet. Davenport heard of this wonderful "galvanic magnet" which it was rumored would lift a blacksmith’s anvil. This was his undoing, for never again was he to know peace of mind but was destined to always be a seeker after some elusive scientific "will-o’-the-wisp." Although many times he needed iron for his shop, the greater part of his money was spent in making electro-magnets and batteries.In those days insulated wire could not be purchased, and any one wishing insulated wire had to buy bare wire and insulate it himself. It was then supposed by scientists that silk was the only suitable material for insulating wire and so Davenport’s brave young wife cut her silk wedding gown into narrow strips and with them wound the coils of the first electric motor.Continuing his experiments in spite of almost insurmountable difficulties and making many sacrifices which were equally shared by his family, he was enabled to make a trip to Washington in 1835 for the purpose of taking out a patent. His errand was fruitless, however, and he was obliged to return home penniless.Nothing daunted, he made the second and third trip and finally secured his memorable patent, the first of the long line of electric-motor patents that have made possible both the electric locomotive that hauls its long train so swiftly and silently, and the whirring little fan which stirs up a breeze during the hot and sultry days.These are a few of the reasons why a modest country blacksmith, in turn an inventor and an editor, through perseverance in struggling against adversity and poverty succeeded in placing his name on the list which will be deservedly immortal among the scientists and engineers of the world.A Simple Electric Motorcan be made in fifteen minutes by following the plan shown in Figure 242.The armature is made by sticking a pin in each end of a long cork. The pins should be as nearly central as it is possible to make them, so that when the cork is revolved upon them it will not wabble. The pins form the shaft or spindle of the motor. Then take about ten feet of fine magnet wire (Nos. 28-32 B. & S. gauge) and wind it on as shown in the illustration, winding an equal number of turns on each side of the two pins.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.When this is finished, fasten the wire securely to the cork by binding it with thread.Bend the two free ends (the starting and the finishing end) down at right angles and parallel to the shaft so as to form two commutator sections as shown in the upper left hand corner of Figure 242. Cut them off so that they only project about three-eighths of an inch. Bare the ends of the wire and clean them with a piece of fine emery paper or sandpaper.The bearings are made by driving two pins into a couple of corks so that the pins cross each other as shown in the upper right-hand corner of Figure 242.They must not be at too sharp an angle, or when the armature is placed in position, the friction of the shaft will be so great that it may not revolve.The motor is assembled by placing the armature in the bearings and then mounting two bar magnets on either side of the armature. The magnets may be laid on small blocks of wood and should be so close to the armature that the latter just clears when it is spun around by hand. The north pole of one magnet should be next to the armature and the south pole of the other, opposite.Connect two wires about one foot long and No. 26 B. & S. gauge in diameter to a dry cell. Bare the ends of the wires for about an inch and one half.Take the ends of the two wires between the forefinger and thumb and bend them out, so that when the armature is revolved they can be made just to touch the ends of the wire on the armature, or the "commutator sections," as they are marked in the drawing.Give the armature a twist so as to start it spinning, and hold the long wires in the hand so that they make contact with the commutator as it revolves.Very light pressure should be used. If you press too hard, you will prevent the armature from revolving, while, on the other hand, if you do not press hard enough, the wires will not make good contact.The armature will run in only one direction, and so try both ways. If you start it in the right direction and hold the wires properly, it will continue to revolve at a high rate of speed.If carefully made, this little motor will reward its maker by running very nicely. Although it is of the utmost simplicity it demonstrates the same fundamental principles which are employed in real electric motors.The Simplex Motoris an interesting little toy which can be made in a couple of hours, and when finished it will make an instructive model.Fig. 243.—Details of the Armature of the Simplex Motor.Fig. 243.—Details of the Armature of the Simplex Motor.As a motor itself, it is not very efficient, for the amount of iron used in its construction is necessarily small. The advantage of this particular type of motor and the method of making it is that it demonstrates the actual principle and the method of application that is used in larger machines.The field of the motor is of the type known as the "simplex" while the armature is the "Siemens H" or two-pole type. The field and the armature are cut from ordinary tin-plated iron such as is used in the manufacture of tin cans and cracker-boxes.The simplest method of securing good flat material is to get some old scrap from a plumbing shop. An old cocoa tin or baking-powder can may, however, be cut up and flattened and will then serve the purpose almost as well.Fig. 244.—The Armature.Fig. 244.—The Armature.The Armature.Two strips of tin, three-eighths of an inch by one and one-half inches, are cut to form the armature. They are slightly longer than will actually be necessary, but are cut to length after the finish of the bending operations. Mark a line carefully across the center of each strip. Then, taking care to keep the shape symmetrical so that both pieces are exactly alike, bend them into the shape shown in Figure 243. The small bend in the center is most easily made by bending the strip over a knitting-needle and then bending it back to the required extent.Fig. 245.—The Field.Fig. 245.—The Field.A piece of knitting-needle one and one-half inches long is required for the shaft. Bind the two halves of the armature together in the position shown in Figure 249. Bind them with a piece of iron wire and solder them together. The wire should be removed after they are soldered.Fig. 246.—The Field and Commutator.Fig. 246.—The Field and Commutator.The Field Magnetis made by first cutting out a strip of tin one-half by four and then bending it into the shape shown in Figure 245.The easiest way of doing this with accuracy is to cut out a piece of wood as a form, and bend the tin over the form. The dimensions shown in Figure 245 should be used as a guide for the form.Fig. 247.—The Bearings.Fig. 247.—The Bearings.Two small holes should be bored in the feet of the field magnet to receive No. 3 wood screws, which fasten the field to the base.The Bearingsare shown in detail in Figure 247. They are easily made by cutting from sheet-tin. Two small washers, serving as collars, should be soldered to the shaft as shown in Figure 243.The Commutator Coreis formed by cutting a strip of paper five-sixteenths of an inch wide and about five inches long. It should be given a coat of shellac on one side and allowed to get sticky. The strip is then wrapped around the shaft until its diameter is three-sixteenths of an inch.The Baseis cut from any ordinary piece of wood and is in the form of a block about two by one and one-half by one-half inch.Fig. 248.—The Complete Motor.Fig. 248.—The Complete Motor.Assembling the Motor.The parts must be carefully prepared for winding by covering with paper. Cut a strip of paper one-half inch wide and one and one-eighth of an inch long and give it a coat of shellac on one side. As soon as it becomes sticky, wrap it around the top bar of the field magnet. The armature is insulated in exactly the same way, taking care that the paper covers the entire flat portion.The field and armature are now ready for winding. It is necessary to take proper precautions to prevent the first turn from slipping out of place.This is accomplished by looping a small piece of tape or cord over it. The next two turns are then taken over the ends of the loop so as to embed them. Wind on three layers of wire and when in the middle of the fourth layer embed the ends of another loop, which may be used at the end of the fourth layer to fasten the end so that it will not unwind. After the winding is finished, give it a coat of shellac.The winding of the armature is somewhat more difficult.The wire used for winding both the armature and the field should be No. 25 or No. 26 B. & S. gauge double-cotton-covered.In order to wind the armature, cut off about five feet of wire and double it back to find the center. Then place the wire diagonally across the center of the armature so that there is an equal length on both sides. Place a piece of paper under the wire at the crossing point to insulate it. Then, using one end of the wire, wind four layers on half of the armature. Tie the end down with a piece of thread and wind on the other half.The ends of the wire are cut and scraped to form the commutator segments. Figure 246 shows how this is done.Bend the wires as shown so that they will fit closely to the paper core. Bind them tightly into position with some silk thread. Use care so that the two wires do not touch each other. Cut the free ends of the wires off close to the core.When finished, the relative positions of the armature and the commutator should be as shown in Figure 248.The brushes are made by flattening a piece of wire by a few light hammer blows.The brushes are fastened under a small clamp formed by a strip of tin held down at each end with a wood screw. They can be adjusted to the best advantage only under actual working conditions when the current is passing through the motor. One or two dry cells should be sufficient to operate the motor.Fig. 249.—Details of the Motor.Fig. 249.—Details of the Motor.One end of the field winding is connected to one of the brushes. The other brush and the other end of the field form the terminals to which the battery is connected.The motor, being of the two-pole armature type, must be started when the current is turned on by giving it a twist with the fingers.A Larger Motormay be built in somewhat the same manner as the one just described by cutting armature and field out of sheet tin. It will be more substantial if it is built up out of laminations and not bent into shape, as in the case of the other.Lay out an armature disk and a field lamination on a sheet of tin in accordance with the dimensions and pattern shown in Figure 249. These pieces are used as patterns for laying out the rest of the laminations.Fig. 250.—Complete Motor.Fig. 250.—Complete Motor.Place them on some thin sheet-iron and trace the outline with a sharp-pointed needle. Then cut a sufficient number of pieces of each pattern to form a pile three-quarters of an inch thick.Four laminations for the field should be cut with extensions shown by the dotted lines. They are bent out at right angles for mounting the motor and holding it upright.Assemble the armature and field by piling the pieces on top of each other and truing them up. Enough laminations should be used to form a pile three-quarters of an inch thick when piled up and clamped tightly.File off any burrs and rough edges and then bind the laminations together with some string to hold them until wound.Wrap a couple of layers of paper around those portions of the armature and field which are liable to come into contact with the iron. Five or six layers of No. 18 B. & S. gauge double-cotton-covered magnet wire are sufficient to form the field coil.The armature is wound with three or four layers of wire of the same size.The commutator is made out of a circular piece of hard wood or fiber, fitted with segments cut out of thin sheet-copper. The segments may be fastened to the core with thick shellac or some melted sealing-wax. The ends may be bound down tightly by wrapping with silk thread.The brushes are cut out of thin sheet-copper similar to that used for the commutator segments.The bearings are strips of heavy sheet-brass bent into the shape shown. They are mounted by passing a nail through the holes in the ends and through the holes, A and B, in the field and then riveting the ends over.Assemble the motor as shown in Figure 255. If desirable, a small pulley may be fitted to the shaft and the motor used to run small mechanical toys. If it is properly constructed, two or three dry cells will furnish sufficient current to run the motor at high speed.DYNAMOS
CHAPTER XVI ELECTRIC MOTORSThe first American patentee and builder of an electric motor was Thomas Davenport. The father of Davenport died when his son was only ten years old. This resulted in the young inventor being apprenticed to the blacksmith’s trade at the age of fourteen.Some years later, after having thoroughly learned his trade, he married a beautiful girl of seventeen, named Emily Goss, and settled in the town of Brandon, Vermont, as an independent working blacksmith.About this time Joseph Henry invented the electro-magnet. Davenport heard of this wonderful "galvanic magnet" which it was rumored would lift a blacksmith’s anvil. This was his undoing, for never again was he to know peace of mind but was destined to always be a seeker after some elusive scientific "will-o’-the-wisp." Although many times he needed iron for his shop, the greater part of his money was spent in making electro-magnets and batteries.In those days insulated wire could not be purchased, and any one wishing insulated wire had to buy bare wire and insulate it himself. It was then supposed by scientists that silk was the only suitable material for insulating wire and so Davenport’s brave young wife cut her silk wedding gown into narrow strips and with them wound the coils of the first electric motor.Continuing his experiments in spite of almost insurmountable difficulties and making many sacrifices which were equally shared by his family, he was enabled to make a trip to Washington in 1835 for the purpose of taking out a patent. His errand was fruitless, however, and he was obliged to return home penniless.Nothing daunted, he made the second and third trip and finally secured his memorable patent, the first of the long line of electric-motor patents that have made possible both the electric locomotive that hauls its long train so swiftly and silently, and the whirring little fan which stirs up a breeze during the hot and sultry days.These are a few of the reasons why a modest country blacksmith, in turn an inventor and an editor, through perseverance in struggling against adversity and poverty succeeded in placing his name on the list which will be deservedly immortal among the scientists and engineers of the world.A Simple Electric Motorcan be made in fifteen minutes by following the plan shown in Figure 242.The armature is made by sticking a pin in each end of a long cork. The pins should be as nearly central as it is possible to make them, so that when the cork is revolved upon them it will not wabble. The pins form the shaft or spindle of the motor. Then take about ten feet of fine magnet wire (Nos. 28-32 B. & S. gauge) and wind it on as shown in the illustration, winding an equal number of turns on each side of the two pins.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.When this is finished, fasten the wire securely to the cork by binding it with thread.Bend the two free ends (the starting and the finishing end) down at right angles and parallel to the shaft so as to form two commutator sections as shown in the upper left hand corner of Figure 242. Cut them off so that they only project about three-eighths of an inch. Bare the ends of the wire and clean them with a piece of fine emery paper or sandpaper.The bearings are made by driving two pins into a couple of corks so that the pins cross each other as shown in the upper right-hand corner of Figure 242.They must not be at too sharp an angle, or when the armature is placed in position, the friction of the shaft will be so great that it may not revolve.The motor is assembled by placing the armature in the bearings and then mounting two bar magnets on either side of the armature. The magnets may be laid on small blocks of wood and should be so close to the armature that the latter just clears when it is spun around by hand. The north pole of one magnet should be next to the armature and the south pole of the other, opposite.Connect two wires about one foot long and No. 26 B. & S. gauge in diameter to a dry cell. Bare the ends of the wires for about an inch and one half.Take the ends of the two wires between the forefinger and thumb and bend them out, so that when the armature is revolved they can be made just to touch the ends of the wire on the armature, or the "commutator sections," as they are marked in the drawing.Give the armature a twist so as to start it spinning, and hold the long wires in the hand so that they make contact with the commutator as it revolves.Very light pressure should be used. If you press too hard, you will prevent the armature from revolving, while, on the other hand, if you do not press hard enough, the wires will not make good contact.The armature will run in only one direction, and so try both ways. If you start it in the right direction and hold the wires properly, it will continue to revolve at a high rate of speed.If carefully made, this little motor will reward its maker by running very nicely. Although it is of the utmost simplicity it demonstrates the same fundamental principles which are employed in real electric motors.The Simplex Motoris an interesting little toy which can be made in a couple of hours, and when finished it will make an instructive model.Fig. 243.—Details of the Armature of the Simplex Motor.Fig. 243.—Details of the Armature of the Simplex Motor.As a motor itself, it is not very efficient, for the amount of iron used in its construction is necessarily small. The advantage of this particular type of motor and the method of making it is that it demonstrates the actual principle and the method of application that is used in larger machines.The field of the motor is of the type known as the "simplex" while the armature is the "Siemens H" or two-pole type. The field and the armature are cut from ordinary tin-plated iron such as is used in the manufacture of tin cans and cracker-boxes.The simplest method of securing good flat material is to get some old scrap from a plumbing shop. An old cocoa tin or baking-powder can may, however, be cut up and flattened and will then serve the purpose almost as well.Fig. 244.—The Armature.Fig. 244.—The Armature.The Armature.Two strips of tin, three-eighths of an inch by one and one-half inches, are cut to form the armature. They are slightly longer than will actually be necessary, but are cut to length after the finish of the bending operations. Mark a line carefully across the center of each strip. Then, taking care to keep the shape symmetrical so that both pieces are exactly alike, bend them into the shape shown in Figure 243. The small bend in the center is most easily made by bending the strip over a knitting-needle and then bending it back to the required extent.Fig. 245.—The Field.Fig. 245.—The Field.A piece of knitting-needle one and one-half inches long is required for the shaft. Bind the two halves of the armature together in the position shown in Figure 249. Bind them with a piece of iron wire and solder them together. The wire should be removed after they are soldered.Fig. 246.—The Field and Commutator.Fig. 246.—The Field and Commutator.The Field Magnetis made by first cutting out a strip of tin one-half by four and then bending it into the shape shown in Figure 245.The easiest way of doing this with accuracy is to cut out a piece of wood as a form, and bend the tin over the form. The dimensions shown in Figure 245 should be used as a guide for the form.Fig. 247.—The Bearings.Fig. 247.—The Bearings.Two small holes should be bored in the feet of the field magnet to receive No. 3 wood screws, which fasten the field to the base.The Bearingsare shown in detail in Figure 247. They are easily made by cutting from sheet-tin. Two small washers, serving as collars, should be soldered to the shaft as shown in Figure 243.The Commutator Coreis formed by cutting a strip of paper five-sixteenths of an inch wide and about five inches long. It should be given a coat of shellac on one side and allowed to get sticky. The strip is then wrapped around the shaft until its diameter is three-sixteenths of an inch.The Baseis cut from any ordinary piece of wood and is in the form of a block about two by one and one-half by one-half inch.Fig. 248.—The Complete Motor.Fig. 248.—The Complete Motor.Assembling the Motor.The parts must be carefully prepared for winding by covering with paper. Cut a strip of paper one-half inch wide and one and one-eighth of an inch long and give it a coat of shellac on one side. As soon as it becomes sticky, wrap it around the top bar of the field magnet. The armature is insulated in exactly the same way, taking care that the paper covers the entire flat portion.The field and armature are now ready for winding. It is necessary to take proper precautions to prevent the first turn from slipping out of place.This is accomplished by looping a small piece of tape or cord over it. The next two turns are then taken over the ends of the loop so as to embed them. Wind on three layers of wire and when in the middle of the fourth layer embed the ends of another loop, which may be used at the end of the fourth layer to fasten the end so that it will not unwind. After the winding is finished, give it a coat of shellac.The winding of the armature is somewhat more difficult.The wire used for winding both the armature and the field should be No. 25 or No. 26 B. & S. gauge double-cotton-covered.In order to wind the armature, cut off about five feet of wire and double it back to find the center. Then place the wire diagonally across the center of the armature so that there is an equal length on both sides. Place a piece of paper under the wire at the crossing point to insulate it. Then, using one end of the wire, wind four layers on half of the armature. Tie the end down with a piece of thread and wind on the other half.The ends of the wire are cut and scraped to form the commutator segments. Figure 246 shows how this is done.Bend the wires as shown so that they will fit closely to the paper core. Bind them tightly into position with some silk thread. Use care so that the two wires do not touch each other. Cut the free ends of the wires off close to the core.When finished, the relative positions of the armature and the commutator should be as shown in Figure 248.The brushes are made by flattening a piece of wire by a few light hammer blows.The brushes are fastened under a small clamp formed by a strip of tin held down at each end with a wood screw. They can be adjusted to the best advantage only under actual working conditions when the current is passing through the motor. One or two dry cells should be sufficient to operate the motor.Fig. 249.—Details of the Motor.Fig. 249.—Details of the Motor.One end of the field winding is connected to one of the brushes. The other brush and the other end of the field form the terminals to which the battery is connected.The motor, being of the two-pole armature type, must be started when the current is turned on by giving it a twist with the fingers.A Larger Motormay be built in somewhat the same manner as the one just described by cutting armature and field out of sheet tin. It will be more substantial if it is built up out of laminations and not bent into shape, as in the case of the other.Lay out an armature disk and a field lamination on a sheet of tin in accordance with the dimensions and pattern shown in Figure 249. These pieces are used as patterns for laying out the rest of the laminations.Fig. 250.—Complete Motor.Fig. 250.—Complete Motor.Place them on some thin sheet-iron and trace the outline with a sharp-pointed needle. Then cut a sufficient number of pieces of each pattern to form a pile three-quarters of an inch thick.Four laminations for the field should be cut with extensions shown by the dotted lines. They are bent out at right angles for mounting the motor and holding it upright.Assemble the armature and field by piling the pieces on top of each other and truing them up. Enough laminations should be used to form a pile three-quarters of an inch thick when piled up and clamped tightly.File off any burrs and rough edges and then bind the laminations together with some string to hold them until wound.Wrap a couple of layers of paper around those portions of the armature and field which are liable to come into contact with the iron. Five or six layers of No. 18 B. & S. gauge double-cotton-covered magnet wire are sufficient to form the field coil.The armature is wound with three or four layers of wire of the same size.The commutator is made out of a circular piece of hard wood or fiber, fitted with segments cut out of thin sheet-copper. The segments may be fastened to the core with thick shellac or some melted sealing-wax. The ends may be bound down tightly by wrapping with silk thread.The brushes are cut out of thin sheet-copper similar to that used for the commutator segments.The bearings are strips of heavy sheet-brass bent into the shape shown. They are mounted by passing a nail through the holes in the ends and through the holes, A and B, in the field and then riveting the ends over.Assemble the motor as shown in Figure 255. If desirable, a small pulley may be fitted to the shaft and the motor used to run small mechanical toys. If it is properly constructed, two or three dry cells will furnish sufficient current to run the motor at high speed.DYNAMOS
CHAPTER XVI ELECTRIC MOTORSThe first American patentee and builder of an electric motor was Thomas Davenport. The father of Davenport died when his son was only ten years old. This resulted in the young inventor being apprenticed to the blacksmith’s trade at the age of fourteen.Some years later, after having thoroughly learned his trade, he married a beautiful girl of seventeen, named Emily Goss, and settled in the town of Brandon, Vermont, as an independent working blacksmith.About this time Joseph Henry invented the electro-magnet. Davenport heard of this wonderful "galvanic magnet" which it was rumored would lift a blacksmith’s anvil. This was his undoing, for never again was he to know peace of mind but was destined to always be a seeker after some elusive scientific "will-o’-the-wisp." Although many times he needed iron for his shop, the greater part of his money was spent in making electro-magnets and batteries.In those days insulated wire could not be purchased, and any one wishing insulated wire had to buy bare wire and insulate it himself. It was then supposed by scientists that silk was the only suitable material for insulating wire and so Davenport’s brave young wife cut her silk wedding gown into narrow strips and with them wound the coils of the first electric motor.Continuing his experiments in spite of almost insurmountable difficulties and making many sacrifices which were equally shared by his family, he was enabled to make a trip to Washington in 1835 for the purpose of taking out a patent. His errand was fruitless, however, and he was obliged to return home penniless.Nothing daunted, he made the second and third trip and finally secured his memorable patent, the first of the long line of electric-motor patents that have made possible both the electric locomotive that hauls its long train so swiftly and silently, and the whirring little fan which stirs up a breeze during the hot and sultry days.These are a few of the reasons why a modest country blacksmith, in turn an inventor and an editor, through perseverance in struggling against adversity and poverty succeeded in placing his name on the list which will be deservedly immortal among the scientists and engineers of the world.A Simple Electric Motorcan be made in fifteen minutes by following the plan shown in Figure 242.The armature is made by sticking a pin in each end of a long cork. The pins should be as nearly central as it is possible to make them, so that when the cork is revolved upon them it will not wabble. The pins form the shaft or spindle of the motor. Then take about ten feet of fine magnet wire (Nos. 28-32 B. & S. gauge) and wind it on as shown in the illustration, winding an equal number of turns on each side of the two pins.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.When this is finished, fasten the wire securely to the cork by binding it with thread.Bend the two free ends (the starting and the finishing end) down at right angles and parallel to the shaft so as to form two commutator sections as shown in the upper left hand corner of Figure 242. Cut them off so that they only project about three-eighths of an inch. Bare the ends of the wire and clean them with a piece of fine emery paper or sandpaper.The bearings are made by driving two pins into a couple of corks so that the pins cross each other as shown in the upper right-hand corner of Figure 242.They must not be at too sharp an angle, or when the armature is placed in position, the friction of the shaft will be so great that it may not revolve.The motor is assembled by placing the armature in the bearings and then mounting two bar magnets on either side of the armature. The magnets may be laid on small blocks of wood and should be so close to the armature that the latter just clears when it is spun around by hand. The north pole of one magnet should be next to the armature and the south pole of the other, opposite.Connect two wires about one foot long and No. 26 B. & S. gauge in diameter to a dry cell. Bare the ends of the wires for about an inch and one half.Take the ends of the two wires between the forefinger and thumb and bend them out, so that when the armature is revolved they can be made just to touch the ends of the wire on the armature, or the "commutator sections," as they are marked in the drawing.Give the armature a twist so as to start it spinning, and hold the long wires in the hand so that they make contact with the commutator as it revolves.Very light pressure should be used. If you press too hard, you will prevent the armature from revolving, while, on the other hand, if you do not press hard enough, the wires will not make good contact.The armature will run in only one direction, and so try both ways. If you start it in the right direction and hold the wires properly, it will continue to revolve at a high rate of speed.If carefully made, this little motor will reward its maker by running very nicely. Although it is of the utmost simplicity it demonstrates the same fundamental principles which are employed in real electric motors.The Simplex Motoris an interesting little toy which can be made in a couple of hours, and when finished it will make an instructive model.Fig. 243.—Details of the Armature of the Simplex Motor.Fig. 243.—Details of the Armature of the Simplex Motor.As a motor itself, it is not very efficient, for the amount of iron used in its construction is necessarily small. The advantage of this particular type of motor and the method of making it is that it demonstrates the actual principle and the method of application that is used in larger machines.The field of the motor is of the type known as the "simplex" while the armature is the "Siemens H" or two-pole type. The field and the armature are cut from ordinary tin-plated iron such as is used in the manufacture of tin cans and cracker-boxes.The simplest method of securing good flat material is to get some old scrap from a plumbing shop. An old cocoa tin or baking-powder can may, however, be cut up and flattened and will then serve the purpose almost as well.Fig. 244.—The Armature.Fig. 244.—The Armature.The Armature.Two strips of tin, three-eighths of an inch by one and one-half inches, are cut to form the armature. They are slightly longer than will actually be necessary, but are cut to length after the finish of the bending operations. Mark a line carefully across the center of each strip. Then, taking care to keep the shape symmetrical so that both pieces are exactly alike, bend them into the shape shown in Figure 243. The small bend in the center is most easily made by bending the strip over a knitting-needle and then bending it back to the required extent.Fig. 245.—The Field.Fig. 245.—The Field.A piece of knitting-needle one and one-half inches long is required for the shaft. Bind the two halves of the armature together in the position shown in Figure 249. Bind them with a piece of iron wire and solder them together. The wire should be removed after they are soldered.Fig. 246.—The Field and Commutator.Fig. 246.—The Field and Commutator.The Field Magnetis made by first cutting out a strip of tin one-half by four and then bending it into the shape shown in Figure 245.The easiest way of doing this with accuracy is to cut out a piece of wood as a form, and bend the tin over the form. The dimensions shown in Figure 245 should be used as a guide for the form.Fig. 247.—The Bearings.Fig. 247.—The Bearings.Two small holes should be bored in the feet of the field magnet to receive No. 3 wood screws, which fasten the field to the base.The Bearingsare shown in detail in Figure 247. They are easily made by cutting from sheet-tin. Two small washers, serving as collars, should be soldered to the shaft as shown in Figure 243.The Commutator Coreis formed by cutting a strip of paper five-sixteenths of an inch wide and about five inches long. It should be given a coat of shellac on one side and allowed to get sticky. The strip is then wrapped around the shaft until its diameter is three-sixteenths of an inch.The Baseis cut from any ordinary piece of wood and is in the form of a block about two by one and one-half by one-half inch.Fig. 248.—The Complete Motor.Fig. 248.—The Complete Motor.Assembling the Motor.The parts must be carefully prepared for winding by covering with paper. Cut a strip of paper one-half inch wide and one and one-eighth of an inch long and give it a coat of shellac on one side. As soon as it becomes sticky, wrap it around the top bar of the field magnet. The armature is insulated in exactly the same way, taking care that the paper covers the entire flat portion.The field and armature are now ready for winding. It is necessary to take proper precautions to prevent the first turn from slipping out of place.This is accomplished by looping a small piece of tape or cord over it. The next two turns are then taken over the ends of the loop so as to embed them. Wind on three layers of wire and when in the middle of the fourth layer embed the ends of another loop, which may be used at the end of the fourth layer to fasten the end so that it will not unwind. After the winding is finished, give it a coat of shellac.The winding of the armature is somewhat more difficult.The wire used for winding both the armature and the field should be No. 25 or No. 26 B. & S. gauge double-cotton-covered.In order to wind the armature, cut off about five feet of wire and double it back to find the center. Then place the wire diagonally across the center of the armature so that there is an equal length on both sides. Place a piece of paper under the wire at the crossing point to insulate it. Then, using one end of the wire, wind four layers on half of the armature. Tie the end down with a piece of thread and wind on the other half.The ends of the wire are cut and scraped to form the commutator segments. Figure 246 shows how this is done.Bend the wires as shown so that they will fit closely to the paper core. Bind them tightly into position with some silk thread. Use care so that the two wires do not touch each other. Cut the free ends of the wires off close to the core.When finished, the relative positions of the armature and the commutator should be as shown in Figure 248.The brushes are made by flattening a piece of wire by a few light hammer blows.The brushes are fastened under a small clamp formed by a strip of tin held down at each end with a wood screw. They can be adjusted to the best advantage only under actual working conditions when the current is passing through the motor. One or two dry cells should be sufficient to operate the motor.Fig. 249.—Details of the Motor.Fig. 249.—Details of the Motor.One end of the field winding is connected to one of the brushes. The other brush and the other end of the field form the terminals to which the battery is connected.The motor, being of the two-pole armature type, must be started when the current is turned on by giving it a twist with the fingers.A Larger Motormay be built in somewhat the same manner as the one just described by cutting armature and field out of sheet tin. It will be more substantial if it is built up out of laminations and not bent into shape, as in the case of the other.Lay out an armature disk and a field lamination on a sheet of tin in accordance with the dimensions and pattern shown in Figure 249. These pieces are used as patterns for laying out the rest of the laminations.Fig. 250.—Complete Motor.Fig. 250.—Complete Motor.Place them on some thin sheet-iron and trace the outline with a sharp-pointed needle. Then cut a sufficient number of pieces of each pattern to form a pile three-quarters of an inch thick.Four laminations for the field should be cut with extensions shown by the dotted lines. They are bent out at right angles for mounting the motor and holding it upright.Assemble the armature and field by piling the pieces on top of each other and truing them up. Enough laminations should be used to form a pile three-quarters of an inch thick when piled up and clamped tightly.File off any burrs and rough edges and then bind the laminations together with some string to hold them until wound.Wrap a couple of layers of paper around those portions of the armature and field which are liable to come into contact with the iron. Five or six layers of No. 18 B. & S. gauge double-cotton-covered magnet wire are sufficient to form the field coil.The armature is wound with three or four layers of wire of the same size.The commutator is made out of a circular piece of hard wood or fiber, fitted with segments cut out of thin sheet-copper. The segments may be fastened to the core with thick shellac or some melted sealing-wax. The ends may be bound down tightly by wrapping with silk thread.The brushes are cut out of thin sheet-copper similar to that used for the commutator segments.The bearings are strips of heavy sheet-brass bent into the shape shown. They are mounted by passing a nail through the holes in the ends and through the holes, A and B, in the field and then riveting the ends over.Assemble the motor as shown in Figure 255. If desirable, a small pulley may be fitted to the shaft and the motor used to run small mechanical toys. If it is properly constructed, two or three dry cells will furnish sufficient current to run the motor at high speed.DYNAMOS
The first American patentee and builder of an electric motor was Thomas Davenport. The father of Davenport died when his son was only ten years old. This resulted in the young inventor being apprenticed to the blacksmith’s trade at the age of fourteen.
Some years later, after having thoroughly learned his trade, he married a beautiful girl of seventeen, named Emily Goss, and settled in the town of Brandon, Vermont, as an independent working blacksmith.
About this time Joseph Henry invented the electro-magnet. Davenport heard of this wonderful "galvanic magnet" which it was rumored would lift a blacksmith’s anvil. This was his undoing, for never again was he to know peace of mind but was destined to always be a seeker after some elusive scientific "will-o’-the-wisp." Although many times he needed iron for his shop, the greater part of his money was spent in making electro-magnets and batteries.
In those days insulated wire could not be purchased, and any one wishing insulated wire had to buy bare wire and insulate it himself. It was then supposed by scientists that silk was the only suitable material for insulating wire and so Davenport’s brave young wife cut her silk wedding gown into narrow strips and with them wound the coils of the first electric motor.
Continuing his experiments in spite of almost insurmountable difficulties and making many sacrifices which were equally shared by his family, he was enabled to make a trip to Washington in 1835 for the purpose of taking out a patent. His errand was fruitless, however, and he was obliged to return home penniless.
Nothing daunted, he made the second and third trip and finally secured his memorable patent, the first of the long line of electric-motor patents that have made possible both the electric locomotive that hauls its long train so swiftly and silently, and the whirring little fan which stirs up a breeze during the hot and sultry days.
These are a few of the reasons why a modest country blacksmith, in turn an inventor and an editor, through perseverance in struggling against adversity and poverty succeeded in placing his name on the list which will be deservedly immortal among the scientists and engineers of the world.
A Simple Electric Motorcan be made in fifteen minutes by following the plan shown in Figure 242.
The armature is made by sticking a pin in each end of a long cork. The pins should be as nearly central as it is possible to make them, so that when the cork is revolved upon them it will not wabble. The pins form the shaft or spindle of the motor. Then take about ten feet of fine magnet wire (Nos. 28-32 B. & S. gauge) and wind it on as shown in the illustration, winding an equal number of turns on each side of the two pins.
Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.
Fig. 242.—A Simple Electric Motor which may be made in Fifteen Minutes.
When this is finished, fasten the wire securely to the cork by binding it with thread.
Bend the two free ends (the starting and the finishing end) down at right angles and parallel to the shaft so as to form two commutator sections as shown in the upper left hand corner of Figure 242. Cut them off so that they only project about three-eighths of an inch. Bare the ends of the wire and clean them with a piece of fine emery paper or sandpaper.
The bearings are made by driving two pins into a couple of corks so that the pins cross each other as shown in the upper right-hand corner of Figure 242.
They must not be at too sharp an angle, or when the armature is placed in position, the friction of the shaft will be so great that it may not revolve.
The motor is assembled by placing the armature in the bearings and then mounting two bar magnets on either side of the armature. The magnets may be laid on small blocks of wood and should be so close to the armature that the latter just clears when it is spun around by hand. The north pole of one magnet should be next to the armature and the south pole of the other, opposite.
Connect two wires about one foot long and No. 26 B. & S. gauge in diameter to a dry cell. Bare the ends of the wires for about an inch and one half.
Take the ends of the two wires between the forefinger and thumb and bend them out, so that when the armature is revolved they can be made just to touch the ends of the wire on the armature, or the "commutator sections," as they are marked in the drawing.
Give the armature a twist so as to start it spinning, and hold the long wires in the hand so that they make contact with the commutator as it revolves.
Very light pressure should be used. If you press too hard, you will prevent the armature from revolving, while, on the other hand, if you do not press hard enough, the wires will not make good contact.
The armature will run in only one direction, and so try both ways. If you start it in the right direction and hold the wires properly, it will continue to revolve at a high rate of speed.
If carefully made, this little motor will reward its maker by running very nicely. Although it is of the utmost simplicity it demonstrates the same fundamental principles which are employed in real electric motors.
The Simplex Motoris an interesting little toy which can be made in a couple of hours, and when finished it will make an instructive model.
Fig. 243.—Details of the Armature of the Simplex Motor.Fig. 243.—Details of the Armature of the Simplex Motor.
Fig. 243.—Details of the Armature of the Simplex Motor.
As a motor itself, it is not very efficient, for the amount of iron used in its construction is necessarily small. The advantage of this particular type of motor and the method of making it is that it demonstrates the actual principle and the method of application that is used in larger machines.
The field of the motor is of the type known as the "simplex" while the armature is the "Siemens H" or two-pole type. The field and the armature are cut from ordinary tin-plated iron such as is used in the manufacture of tin cans and cracker-boxes.
The simplest method of securing good flat material is to get some old scrap from a plumbing shop. An old cocoa tin or baking-powder can may, however, be cut up and flattened and will then serve the purpose almost as well.
Fig. 244.—The Armature.Fig. 244.—The Armature.
Fig. 244.—The Armature.
The Armature.Two strips of tin, three-eighths of an inch by one and one-half inches, are cut to form the armature. They are slightly longer than will actually be necessary, but are cut to length after the finish of the bending operations. Mark a line carefully across the center of each strip. Then, taking care to keep the shape symmetrical so that both pieces are exactly alike, bend them into the shape shown in Figure 243. The small bend in the center is most easily made by bending the strip over a knitting-needle and then bending it back to the required extent.
Fig. 245.—The Field.Fig. 245.—The Field.
Fig. 245.—The Field.
A piece of knitting-needle one and one-half inches long is required for the shaft. Bind the two halves of the armature together in the position shown in Figure 249. Bind them with a piece of iron wire and solder them together. The wire should be removed after they are soldered.
Fig. 246.—The Field and Commutator.Fig. 246.—The Field and Commutator.
Fig. 246.—The Field and Commutator.
The Field Magnetis made by first cutting out a strip of tin one-half by four and then bending it into the shape shown in Figure 245.
The easiest way of doing this with accuracy is to cut out a piece of wood as a form, and bend the tin over the form. The dimensions shown in Figure 245 should be used as a guide for the form.
Fig. 247.—The Bearings.Fig. 247.—The Bearings.
Fig. 247.—The Bearings.
Two small holes should be bored in the feet of the field magnet to receive No. 3 wood screws, which fasten the field to the base.
The Bearingsare shown in detail in Figure 247. They are easily made by cutting from sheet-tin. Two small washers, serving as collars, should be soldered to the shaft as shown in Figure 243.
The Commutator Coreis formed by cutting a strip of paper five-sixteenths of an inch wide and about five inches long. It should be given a coat of shellac on one side and allowed to get sticky. The strip is then wrapped around the shaft until its diameter is three-sixteenths of an inch.
The Baseis cut from any ordinary piece of wood and is in the form of a block about two by one and one-half by one-half inch.
Fig. 248.—The Complete Motor.Fig. 248.—The Complete Motor.
Fig. 248.—The Complete Motor.
Assembling the Motor.The parts must be carefully prepared for winding by covering with paper. Cut a strip of paper one-half inch wide and one and one-eighth of an inch long and give it a coat of shellac on one side. As soon as it becomes sticky, wrap it around the top bar of the field magnet. The armature is insulated in exactly the same way, taking care that the paper covers the entire flat portion.
The field and armature are now ready for winding. It is necessary to take proper precautions to prevent the first turn from slipping out of place.
This is accomplished by looping a small piece of tape or cord over it. The next two turns are then taken over the ends of the loop so as to embed them. Wind on three layers of wire and when in the middle of the fourth layer embed the ends of another loop, which may be used at the end of the fourth layer to fasten the end so that it will not unwind. After the winding is finished, give it a coat of shellac.
The winding of the armature is somewhat more difficult.
The wire used for winding both the armature and the field should be No. 25 or No. 26 B. & S. gauge double-cotton-covered.
In order to wind the armature, cut off about five feet of wire and double it back to find the center. Then place the wire diagonally across the center of the armature so that there is an equal length on both sides. Place a piece of paper under the wire at the crossing point to insulate it. Then, using one end of the wire, wind four layers on half of the armature. Tie the end down with a piece of thread and wind on the other half.
The ends of the wire are cut and scraped to form the commutator segments. Figure 246 shows how this is done.
Bend the wires as shown so that they will fit closely to the paper core. Bind them tightly into position with some silk thread. Use care so that the two wires do not touch each other. Cut the free ends of the wires off close to the core.
When finished, the relative positions of the armature and the commutator should be as shown in Figure 248.
The brushes are made by flattening a piece of wire by a few light hammer blows.
The brushes are fastened under a small clamp formed by a strip of tin held down at each end with a wood screw. They can be adjusted to the best advantage only under actual working conditions when the current is passing through the motor. One or two dry cells should be sufficient to operate the motor.
Fig. 249.—Details of the Motor.Fig. 249.—Details of the Motor.
Fig. 249.—Details of the Motor.
One end of the field winding is connected to one of the brushes. The other brush and the other end of the field form the terminals to which the battery is connected.
The motor, being of the two-pole armature type, must be started when the current is turned on by giving it a twist with the fingers.
A Larger Motormay be built in somewhat the same manner as the one just described by cutting armature and field out of sheet tin. It will be more substantial if it is built up out of laminations and not bent into shape, as in the case of the other.
Lay out an armature disk and a field lamination on a sheet of tin in accordance with the dimensions and pattern shown in Figure 249. These pieces are used as patterns for laying out the rest of the laminations.
Fig. 250.—Complete Motor.Fig. 250.—Complete Motor.
Fig. 250.—Complete Motor.
Place them on some thin sheet-iron and trace the outline with a sharp-pointed needle. Then cut a sufficient number of pieces of each pattern to form a pile three-quarters of an inch thick.
Four laminations for the field should be cut with extensions shown by the dotted lines. They are bent out at right angles for mounting the motor and holding it upright.
Assemble the armature and field by piling the pieces on top of each other and truing them up. Enough laminations should be used to form a pile three-quarters of an inch thick when piled up and clamped tightly.
File off any burrs and rough edges and then bind the laminations together with some string to hold them until wound.
Wrap a couple of layers of paper around those portions of the armature and field which are liable to come into contact with the iron. Five or six layers of No. 18 B. & S. gauge double-cotton-covered magnet wire are sufficient to form the field coil.
The armature is wound with three or four layers of wire of the same size.
The commutator is made out of a circular piece of hard wood or fiber, fitted with segments cut out of thin sheet-copper. The segments may be fastened to the core with thick shellac or some melted sealing-wax. The ends may be bound down tightly by wrapping with silk thread.
The brushes are cut out of thin sheet-copper similar to that used for the commutator segments.
The bearings are strips of heavy sheet-brass bent into the shape shown. They are mounted by passing a nail through the holes in the ends and through the holes, A and B, in the field and then riveting the ends over.
Assemble the motor as shown in Figure 255. If desirable, a small pulley may be fitted to the shaft and the motor used to run small mechanical toys. If it is properly constructed, two or three dry cells will furnish sufficient current to run the motor at high speed.
DYNAMOS