SHOP APPLIANCES
Homemade Substitutes for Expensive Tools.—The tool of first importance in any metal working shop is a good vise. There is no substitute for this tool and a good one that measures three or three and a half inches across the jaws should be purchased from a reliable tool dealer. The next tool of importance is some form of anvil or anvils for flattening or rounding the tin. A small bench anvil may be purchased from the tool dealer. These are much like a blacksmith’s anvil with a flat face and a conical horn and are made of iron and steel. The large mail order houses offer various small anvils of cast iron for farm use and these are excellent for the tin shop.
Excellent substitutes for these anvils are easily made from old flat irons and pieces of gas or water pipe. Short lengths of iron and steel bars may be picked up about any junk pile, and these are very useful to form the tin over.
The Flat Iron Anvil.—An old flat iron, the kind with the handle attached, may be found about almost any household. The handle should be broken off as close to the top of the iron as possible. Use a hammer and cold chisel for this and cut the handle ends deeply all around where they join the iron. When they are deeply nicked, several sharp blows from a large hammer should break the handle away.
File away all roughness until the iron will set level with the smooth or ironing face uppermost. Then you have an excellent flat hard surface for straightening out tin or wire.
Pipe and Bar Anvils.—Short lengths of iron pipe, round and square iron and steel bars of various diameters may be held in the vise jaws and used to form the work over. Large wire nails may also be used for this purpose.
The smaller sizes, such as ¼, ⅜, or ½ inch in diameter, should be solid iron or steel bars 8 or 10 inches in length, as small pipe crushes and bends rather easily in the vise. Larger sizes, such as ¾, ½, 1 or 2 inches in diameter, are better made of pipe as they are lighter and easier to handle and also easier to obtain.
Get all the sizes suggested if possible and as many short pieces of square or flat bars as you find convenient to store away about the shop. They will come in very usefully for bending or forming operations. The method of holding them in the vise is plainly shown on [page 89, Fig. 26].
If you have plenty of bench room and are handy with tools, several of the most used sizes of pipe and bars may be clamped or bolted directly to the bench with wooden or metal holding strips. The larger sizes, such as ¾, 1, 1½, 2 and 3 inches in diameter, will be found very convenient if fastened to the bench in this manner.
The Bench.—The shop bench should be about 31 inches in height. The top of the bench should be about 2½ by 6 feet or larger if possible, and may easily be built by any one familiar with tools. The top should be made of maple about 1½ inches thick. If one cannot afford this bench a common kitchen table makes an excellent substitute. A good strong table of this sort may be purchased at any house-furnishing store. These tables are furnished with a large drawer in which small tools may be kept.
If much of the tin work is done, it will prove advantageous to have some light wooden shelves or racks built about the walls of the shop to store the various sized cans where they may be easily seen and reached.
Fig. 5.
The Forming Mallet.—The special forming mallet designed by the author will have to be made. It was designed especially for work with the tin cans. It is very simple and easily made of maple by any carpenter. One end is a slightly rounded dome shape and the other is in the form of a blunt wedge. The dimensions and general shape of the mallet are shown in [Fig. 5]. The handle may be made of a piece of ½-inch dowel rod. A substitute for this mallet may be made of a piece of broom handle the end of which is already rounded to about the proper curve. Measure off 4½ inches from the rounded end of the broom handle and saw it off. Bore a ½-inch hole through the center of the piece to fit the piece of dowel rod used for the handle. Whittle down the end to a blunt wedge shape leaving it about ⅜ inch thick at the end. The rounded end may be left as it is.
A piece of ½-inch maple dowel may be picked up in any carpenter shop. This should be 8½ inches long. It should be driven into the hole drilled for it in the mallet, taking care not to split the mallet in so doing. If the broom handle is rather small in diameter it would probably be better to use a piece of ⁷⁄₁₆-or ⅜-inch dowel for the handle. A small nail or brad may be driven through the mallet and handle to secure it in place.
CHAPTER III
Making a Biscuit Cutter from a Small Can
CUTTING THE CAN TO SIZE FOR BISCUIT CUTTER—PUNCHING A HOLE IN TIN—FORMING THE HANDLE—FOLDING—MAKING A SUGAR SCOOP BY THE SAME METHOD
A biscuit cutter is about the simplest thing that may be made from a tin can. It is an excellent thing to begin with as it is so simple and involves three very essential operations in the tin can work: cutting the can to size, forming the handle, and lastly, soldering (see [Plate VII, a]).
Select a good bright, clean can about 2½ inches in diameter; a baking powder can or a small soup can will do.
Tin cans are usually made up in two ways. One method is to solder on flanged ends, such as condensed or evaporated milk cans, and the other method is to roll the edges of the can together at each end, using no solder. When looked at closely, the two different types of can are easily told apart. A rolled rim can should be used for the biscuit cutter as it is stronger than the can with the soldered ends.
PLATE VII
Biscuit cutters made by the author
Soldering
Cutting the Can to Size for Biscuit Cutter.—The biscuit cutter should be about ¾ inch deep at the cutting edge. Set the dividers to this dimension and proceed to scribe a line around the can parallel to the base and ¾ inch above the rolled rim of the bottom. This simple scribing operation is described in [Chapter I, page 22].
The method of cutting into the can and around the scribed line is very simple and is also described in [Chapter I].
Fig. 6.
When you have cut the can down to the required dimension, it should appear as shown in [Fig. 6]. The biscuit cutter may be slightly out of shape after the cutting operation, but this may be easily remedied by placing the biscuit cutter on a small round anvil held in the vise and by tapping it gently with a flat wooden mallet, turning the cutter slowly around on the anvil during the hammering as shown in [Fig. 7]. Be sure to turn the biscuit cutter slowly around and around the anvil as it is hammered with the mallet. It will soon become round if hammered gently.
Next take a small flat file, one with very fine teeth, usually called a smooth milled file, and with this smooth down any roughness left by the metal shears at the edge of the biscuit cutter. The method of using the file is shown in [Fig. 8]. It should be held lightly against the work when filing. (Never try to file a piece of tin with a large or roughly toothed file as the coarse teeth will catch on the tin and tear or bend it out of shape.)
Fig. 7.
Fig. 8.
Do not try to file the edge of the cutter to a knife fine edge; simply file away the metal raised by the shears when cutting. If it is cleanly cut and filed to the original thickness of the tin, it will cut biscuit dough very well, as the tin is thin.
Punching a Hole in Tin.—A hole should be punched in the top of the biscuit cutter to admit air, as the biscuit dough is apt to stick in the cutter by the vacuum formed unless an air vent is provided. A small hole about ⅛ inch in diameter will do, but a series of such holes may be punched in if desired.
A punch may be filed up from a wire nail or a regular punch or nail set may be used.
The biscuit cutter is placed over the end of a block of wood held in a vise as shown in [Fig. 9], in such a manner that the top of the cutter rests directly on the wood. The punch is placed in the center of the cutter, care being taken to see that the wooden block supports the tin directly under the punch, and then the punch is struck lightly with the hammer until it cuts through the tin.
It may be well to try the punch on a scrap of tin to test it. A clean round hole should result. The punch cuts out a tiny disk of tin and drives it into the wood. The end grain of a wooden block should always be used for punching on.
If a nail is used for a punch, the original point should be filed away. Nail points are usually made in the form of a square pyramid and if these points are driven into a piece of tin a jagged hole will result; such a hole may be used for making a grater for the kitchen, but all other holes should be round and smooth.
To file up a nail for a punch proceed as follows: Place the nail vertically in the vise jaws so that the point projects slightly above the jaws. File the point entirely away until you are filing the entire diameter of the nail and squarely across it.
Then reduce the diameter of the nail at the end you have been filing by filing smoothly around it as shown at A, [Fig. 10]. See that the edge B is clean and sharp and the nail punch is ready for use. The nail used for a punch should always be somewhat larger in diameter than the punching point, as this will provide for a stronger punch and one not so likely to bend. Regular punches are usually made much thicker in the body than at the point, as may be easily seen by looking at one. If desired, punches may easily be made from nails to cut round, square, or triangular holes.
Fig. 9.
Fig. 10.
It is much better to purchase a regular punch or punches for punching round holes, as these may be purchased for 10 or 15 cents at almost any hardware or 5-and-10 cent store. Several different sizes will prove useful, ⅟₁₆, ⅛, ³⁄₁₆ inches in diameter being the most used sizes. As these punches are made of hardened steel they hold their edges for a long time, but nails are made of a fairly soft steel and when used as punches have to be frequently filed sharp.
Forming the Handle.—After the hole is punched in the top of the biscuit cutter, a suitable handle is the next thing to be made. This handle may be made from the piece of tin cut away when cutting down the can for the biscuit cutter. Cut away any rough or jagged edges and then place this piece of tin on the bench or a flat anvil surface and flatten it out with light mallet strokes. Heavy strokes with a mallet will dent the tin.
Trim away all rough edges including the rolled edge at the top and square up the piece of tin as described on [page 34, Chapter II]. Mark off a strip of tin 1¼ inches in width and 4 inches long. Cut this strip out and be sure that it is square at the ends. Open the dividers and set the divider points ¼ inch apart and scribe a line ¼ inch inside each of the long sides of the strip. The edges of the strip of tin thus marked off must be turned or folded in so that the edges of the handle will be strengthened and will not cut the hand. These edges may be folded over with a mallet or by the use of a folding machine. The mallet should be used for this first folding operation; the folding machine and its use will be described further along in the book, [page 120, Chapter XI].
To fold the edges over with the mallet, proceed as follows: Secure a block of hard wood, maple preferred, the block to be about 3 inches square and 6 inches in length. See to it that the block is cut cleanly and squarely across so that the edges at the end are sharp and at right angles. A maple block of this sort may usually be picked up at any lumber yard or carpenter shop, or a maple log may be secured from the wood pile and trimmed up square. One end of the block may be used to punch on.
Fig. 11a.
Fig. 11b.
The block is held in the vise as illustrated in [Fig. 11] and the tin to be folded is held on the block in such a manner that the line marking the fold is over the edge of the block. Use either a light wooden mallet or the special forming mallet, and with light blows proceed to bend down at the edge and up to the line as illustrated in [Fig. 11], a. Begin at one end and work along the line to the other end of the strip of tin. Do not try to turn the tin down at a right angle at once or in one place and then proceed to turn it down at another, but rather hammer lightly along the whole length at the marking line, turning the tin down at a slight angle from the line to the edge and then going back and starting to hammer where you began, turning the tin down at a greater angle and so on until you have turned the edge at right angles as shown in [Fig. 11], b. Always bend tin over very gently and evenly, never forcing it violently into place.
Fig. 12.
Fig. 13.
Fig. 14.
Reverse the strip of tin on the block so that the part just folded stands vertically at the edge of the block as shown in [Fig. 12]. Hammer the edge of the tin gently over so that it folds back on itself as shown by the dotted line in [Fig. 12].
Do not hammer the tin down hard at the folded edge so that it becomes thin and sharp though doubled. It should be rounded over so as to give a rounded edge. A rounded fold is much stronger than a sharp thin one. When one edge is completely folded over, fold down the other in the same manner, so that both edges of the handle for the biscuit cutter appear as in [Fig. 13].
Fig. 15.
When you have successfully turned or folded over the edges to your satisfaction, then proceed to give the whole handle a semi-circular form.
Place a large round wooden mallet or a piece of 1½ or 2-inch pipe in the vise to use as a form over which to round the handle. The folded part should be inside or next the mallet or pipe form shown in [Fig. 14]. Press the tin down to the form with the palm of the hand so as to round it into shape; it may be completely formed into shape by this method or the rounded end of the special forming mallet may be used to hammer it into shape if the tin should kink during the bending. The mallet blows should be directed toward the center of the strip so as not to thin the edges too much.
Round the handle over until the ends rest inside the rolled rim of the can or biscuit cutter and you are ready to solder the handle in place.
As the soldering is the most important part of the tin work the next two chapters are devoted to it.
The Sugar Scoop.—A useful sugar or flour scoop may be easily made from a small or large can in exactly the same manner as the biscuit cutter, except that the can is cut off slanting instead of square, [Fig. 15]. The edges of the scoop should not be turned or folded but should be left as cut so as to form a sharp cutting edge that will easily enter sugar or flour. The handle is shaped in exactly the same manner as that of the biscuit cutter.
CHAPTER IV
Soldering
SOFT SOLDER—SHEET TIN—THE PROCESS OF SOLDERING—HEATING APPARATUS—ELECTRICAL SOLDERING COPPERS—THE COMMON SOLDERING COPPER—FLUXES—TINNING THE COPPER—HEATING
Soft Solder.—When two or more pieces of metal are joined together with a metallic cement, they are said to be soldered.
Sheet tin, of which cans are constructed, is always soldered with soft solder, a mixture of lead and tin, usually 50 per cent. lead and 50 per cent. tin.
This solder is usually supplied in wire or bar form at any hardware or electrical supply house.
Copper, brass, bronze, iron, silver, gold, and practically any metal except aluminum may be soldered with soft solder.
Sheet Tin.—Sheet tin, so-called, really consists of a thin sheet of iron coated on both sides with tin. This coating of tin serves several purposes. It enables the solder to adhere easily; it prevents the iron from rusting; and when the sheet tin is made up into can form, the tin coating protects the contents of the can from chemical action on the iron.
The Process of Soldering.—Soft solder is applied to the metal to be soldered in a molten state and this operation requires considerable heat. When heat is applied to metal it usually oxidizes that metal; that is, dirties it.
Solder will not adhere to oxidized metal. The metal must be protected with a coating called a flux while being soldered. Soldering paste, soldering fluid or “killed acid,” resin, paraffin, heavy oils, and vaseline all serve as fluxes, some better than others. The soldering paste is by far the best, as will be shown later.
Soft solder is applied to the tin, on the point of a hot soldering copper, often wrongly called a “soldering iron.” A soldering copper consists of a pointed bar of copper suitably fixed to an iron shank which is firmly set in a wooden handle. The point of the copper must be well coated with solder or “tinned,” so that when it is heated it will pick up the solder and convey it to the joint to be soldered.
The hot copper, charged with solder, is passed slowly along the joint and as the tin to be soldered receives enough heat from the copper, the solder leaves the copper and adheres to the tin, firmly uniting it.
Heating Apparatus.—Some form of heating apparatus is necessary to heat and maintain the soldering copper at the melting or flowing point of the solder. The copper may be heated in a gas furnace especially made for soldering coppers, or over an ordinary gas stove burner or a common blue flame oil stove, or a charcoal fire, a wood fire burned down to embers, or a plumbers’ gasoline torch, but never in a coal fire. Coal contains too much sulphur which oxidizes the copper and renders it useless for soldering purposes.
The Blue Flame Oil Stove.—For heating the coppers in my country shop, I use a blue flame oil stove, one of the less expensive sort, with the asbestos ring wick and the short removable chimneys. The stove has two burners and will heat from four to six coppers at once. The flames may be regulated nicely so as to give just the required amount of heat and this stove consumes very little kerosene, and, therefore, costs little to operate. In [Fig. 16], it will be noticed that there is a curved hood over each stove hole. These hoods may be easily made from part of a large can or of a piece of tin or sheet iron bent into shape. These hoods conserve the heat and throw it about the coppers. I also place a piece of heavy wire netting over the grating of the stove holes to support the coppers and to permit their being laid to one side, out of the intense heat, when not immediately needed.
The blue flame oil stove forms the most satisfactory arrangement for heating coppers that I have ever used in the country. These stoves are easily taken care of and are understood by almost everyone. The directions should be nailed up alongside the stove and carefully followed, particularly as to cleaning the burners once or twice each season.
Fig. 16.
The Gasoline Torch.—The plumbers’ gasoline torch is often used by experienced metal workers for heating coppers. In inexperienced hands, this torch is rather a dangerous affair. Only one copper may be heated at a time and it is difficult not to overheat the copper in the fierce roaring flame. The cost of the torch and the cost of operating it are both greater than the blue flame kerosene stove. However, in experienced hands, it is safe enough and very useful about the shop. In using such a torch the directions should be most carefully followed; all joints, filler openings, etc., must be airtight when operating or a disastrous fire or explosion may result. The tiny jet opening in the burner must be kept clean.
The Gas Furnace.—In my winter shop in the city where gas is available, I use the gas furnace shown in [Fig. 16]. This is a most satisfactory and widely used heater for soldering coppers, as it gives an intense blue flame that may be easily regulated.
When using a heater of this sort, one must be sure that it is lighted correctly or a smoky yellow flame will result. To produce a blue flame, air must be mixed with the gas; just as it is in a bunsen burner or an ordinary gas stove, for that matter. Gas is admitted to the furnace through a small nozzle at the end of the mixing flue near the rubber hose connection. Air is admitted in the slot under the gas nozzle; a movable slide encircles the mixing flue over the slot to control the amount of air admitted. This slide must be tightly closed over the air vent when the gas is first turned on.
To light the heater, close the air inlet tightly, turn the gas on full and apply a lighted match to the burner. A yellow flame will result. Now open the air vent slowly, by pushing the slide forward a little way. The flame will change from yellow to blue and purple as air is admitted. When the flame is blue, it is giving out the most heat and is in the best condition to heat the copper.
If the flame fires back and lights the gas at the brass nozzle over the air inlet, the gas should be turned off until the flame disappears. The air inlet is then closed, and the gas turned on and lighted, and then the air inlet is slowly opened until the flame turns blue. When the furnace is in use, it should be looked at occasionally to see that the flame has not fired back to the nozzle. Once satisfactorily lighted, the heater may be turned up or down as needed. If the flame is turned down very low the air inlet may have to be closed a bit to prevent the flame from firing back. The copper is placed on the rest provided for it over the flame. After the copper is heated to the flowing point of solder, the flame may be turned down or the copper placed to one side of the flame, so that it does not get too hot.
Charcoal and Wood Fires.—When using a charcoal or a wood fire, the copper should be placed at the bottom among the embers. Small charcoal furnaces used for heating soldering coppers may be bought from the dealer in plumbers’ supplies. Charcoal should not be burned in a closed room as the fumes are deadly unless allowed plenty of constantly changing air. These furnaces may be connected with a chimney or burned in a room with windows opened, without danger.
A soldering copper may be heated in the glowing embers of a camp fire or in the embers in a fireplace.
Electrical Soldering Coppers.—The electrically heated copper is ideal for soldering as the heating coil is enclosed within the copper itself, the wire running out through the handle and connecting with an ordinary electric light socket. The heat is maintained at a proper degree for melting the solder; hence it is an ideal equipment for those who can afford it and where electric current is available. The doctors of certain hospitals have recommended electrical coppers for the use of patients in making tin can toys.
An electric soldering copper costs about $7.50 at the present time.
The Common Soldering Copper.—A suitable soldering copper or “iron” may be purchased at any good tool dealer’s or hardware store; it should weigh about one pound for work with the tin cans.
Almost everyone has purchased a small soldering outfit at one time or another and tried to solder the family wash-boiler or some leaky tinware; usually without success. Such outfits are invariably too small for large work or for the tin can toys.
It must be well remembered that the heat flows from the copper into the work, and that the copper has to heat up the work to the melting point of the solder; hence a large copper weighing several pounds is used to solder wash-boilers, tin roofs, etc., and a small copper weighing a few ounces is used for soldering jewelry, etc.
A large copper in expert hands may be used to solder very small work but a small copper may never be used to solder large work together, because the copper not only has to keep the solder melted to the flowing point, but also has to heat the work itself at the joint to the flowing point of the solder before the solder will leave the copper and adhere to the work.
In actual practice, it has been found that a copper weighing one pound is best. After one gets more adept with the copper, it will be found advantageous to have several coppers of different weights. A half pound and also a four ounce copper will be found very convenient for extremely small work. But, do not begin to solder with a copper weighing less than one pound.
Soldering coppers are usually sold in pairs at the large tool dealers, and coppers listed at two pounds really weigh one pound each; when sending in a written order be sure that you specify that the copper is to weigh one pound singly.
A wooden handle especially made for soldering coppers should be purchased at the same time as the copper; these wooden handles are made large to protect the hand from the heat of the iron shank. The handle is usually furnished with a hole of the proper size drilled in it to permit the pointed end of the shank to be driven in the handle easily with a wooden mallet. If the hole is too small, it should be drilled out so that it is nearly as large as the diameter of the shank. The wooden handle must not be split when driven on with the mallet.
Fluxes.—Before tinning the point of the copper, some flux must be obtained, either a soldering paste or soldering fluid “killed acid.”
An excellent soldering paste called “Nokorode” is by far the best flux obtainable. It is inexpensive, a little goes a long way, and it will not rust or corrode the work as is the case with killed acid and some soldering pastes. It may be easily cleaned from the work after soldering and it makes soldering much easier and simpler for the beginner. Nokorode soldering paste may be obtained at any good electrical supply house or hardware store. If they do not stock it, they will get it for you. There is nothing else just as good on the market, but if for any reason you cannot obtain this particular brand, be sure that any soldering paste you buy is plainly labelled that it will not corrode the work.
Soldering fluid or killed acid is made of muriatic acid in which is dissolved all the pure zinc that it will hold in solution. This fluid is much used by tinners and is certainly an excellent soldering flux, but not nearly as good as the soldering paste for our purposes. However, it is very useful in the shop to dip the tinned point of the hot copper into it to remove the oxide or dirt formed after the copper has been in use for some time. The solder will stick to the point much better after the copper has been cleaned in this manner.
Directions for making the killed acid and the use of other soldering fluxes will be found on [page 68].
Tinning the Copper.—Having procured the soldering copper and handle, some flux and soft solder, and having fixed up some sort of heating apparatus, the next step toward soldering is to coat the point of the copper with solder: this is called tinning the copper.
Fix the copper firmly in a vise if one is at hand, as illustrated in [Fig. 17]. Then file each of the four faces of the point of the copper bright and clean with a flat file. It is better to use an old file for this purpose—one with rather coarse teeth. It will be observed that the copper is placed slantwise in the vise so as to bring one face of the square pyramid parallel with the vise jaws; this position permits filing in a natural horizontal position.
Each face of the point should be rounded slightly toward the point.
Fig. 17.
If a vise is not available, the copper may be held against the edge of the bench with one hand and the point filed clean and bright with the file held in the other, or a coarse sheet of emery cloth may be placed flat on the table and each face of the point rubbed bright on it. A file is by far the best for this purpose, however, and if it is chalked before using, the copper filed away will not clog it.
When the copper is clean and bright at the point each face should be thoroughly covered with a thin film of soldering paste or dipped into the soldering acid.
The copper should then be placed in the fire and heated to the melting point of the solder.
Heating.—While the copper is heating get ready a piece of tin about 2 by 4 inches—any clean flat scrap or part of a can will do. Spread a little soldering paste into the center of the tin and lay it on the bench near the heating apparatus. A few drops of killed acid may be placed on the tin instead of the paste, if the acid is to be used.
After a few minutes heating the copper should be removed from the fire and the end of a strip of solder touched to the point. If the solder melts quickly and easily against the point the copper is ready to tin; if it melts very slowly, “slushy”, the copper should be returned to the fire and heated a bit more. The copper should never be heated red hot under any circumstances; this must be borne in mind. If the copper is heated to a red heat, the soldering paste will be burned off and its action destroyed, for a red hot copper will not pick up solder, nor may it be tinned again until the copper is cool and refiled bright and clean, recoated with flux and reheated. If the copper is heated red hot after the point is tinned, the tinning is burned from the point and solder will not stick to it until it has been cooled, refiled and retinned.
This is the most important point to remember about soldering and is the cause of many failures. Remember that soldering is impossible without a flux to keep the metal clean when it is hot; too much heat will burn soldering paste or killed acid away; the tinning and the solder adhering to the point will be burned or oxidized and rendered brittle and useless.
A heat that will melt the solder almost instantly and cause it to flow with a brilliant glistening color should be maintained at all times when the copper is employed for soldering. This is never a red heat.
When the copper is first heated to be tinned, it should be removed from the fire when it melts the solder easily, and several large drops of solder should then be melted from the bar or strip of solder onto the piece of tin placed by the fire and on which some soldering paste or acid has been spread. Rub each face of the point of the copper into the solder on the tin until each face is thoroughly covered with a bright coating of solder. Hold each face flatly down against the solder on the tin during the rubbing process. The copper may have to be heated once or twice by the beginner, as it may get too cool to melt the solder easily. As soon as the solder begins to work stiffly, “slushy,” and looks gray instead of glistening, it is time to reheat the copper.
An old piece of soft cotton cloth, such as a stocking, on which is sprinkled a little powdered sal-ammoniac is an excellent thing to keep handy when soldering or tinning. The tin coating of the point of the copper should be rubbed on this cloth where the sal-ammoniac is sprinkled, when the copper is hot. This will be found to keep the copper in excellent condition. The sal-ammoniac removes the oxide from the tinning and brightens it up generally about the point.
The tinning will last much longer on the copper if it is dipped occasionally into the soldering paste or acid while hot. This is particularly true if the copper has been a bit overheated.
When the tinning shows signs of wearing off and the copper does not pick up solder readily, it must be retinned, filed, fluxed, heated, and rubbed on the solder which has been put on the tin first used for this purpose. This piece of tin should be kept about the bench, as the copper will have to be retinned frequently. Always remember that the copper will not carry solder to the work unless it is well tinned.
If an electrical soldering copper is used it is usually furnished already tinned at the point, so that it is ready for use as soon as it is connected to a suitable electric socket and the current turned on. The heating coil inside the copper will soon heat it up to the melting point of the solder. After heating, it may be treated as a common copper, wiped occasionally on the cotton cloth and retinned when the tinning is worn away. An electrical copper should never be placed in a vise for filing, but should be held against the bench and filed carefully. A vise is apt to crush the hollow copper and injure the heating coil inside. These coppers should never be placed in a fire or heated in any way except by the electric current.
Electrical coppers do not need as much attention as an ordinary copper for the even heat supplied by the current keeps the copper heated to the flowing point of the solder and is incapable of heating beyond this temperature.