Soft-soldering with the Copper Bit
=Choice between Blowpipe and Bit.=--The method of heating depends on the
size of the work, or rather the area to be soldered, and the
conveniences at the command of the worker. The soldering bit, although
so commonly used, is not necessarily the best for the beginner to use
for small work. A blowpipe flame--from a bunsen burner or a spirit
lamp--is far more convenient and neat, and its effects can be applied
and localised with the greatest precision, down to the merest pin point
of heat applied at a definite spot. The bit is chiefly useful for long
joints such as in tinplate work, and for pieces bound together to which
the bit is applied to heat up and melt solder between them. But for work
where the soldering area does not measure more than an inch or so (and
there is a vast amount of this kind), the blowpipe flame is far
preferable. It must be admitted, though, that this is a matter in which
some workmen might have two distinct opinions; and, as already remarked,
the bit is far more commonly used.
[Illustration: Fig. 2.--Soldering Bit]
[Illustration: Fig. 3.--Pivoted Soldering Bit]
=Copper Bits.=--The soldering bit or bolt (miscalled an “iron”) carries
a pointed lump of copper at the end (Fig. 2), riveted in, or
alternatively, in small sizes, screwed on to the shank. Some bits are
pivoted (see Fig. 3) to enable them to point at various angles for
dealing with difficult situations.
A home-made bit (Figs. 4 and 5) may be made by drilling and tapping a
short length of 1-1/2-in. or 2-in. square copper to receive the screwed
end of a rod of 5/16-in. iron, the copper being afterwards heated and
drawn to a point or to a blunt edge as preferred. This forms a good bit
for most ordinary purposes. An axe-head or hatchet bit is shown in Fig.
6; the copper bolt is riveted in the eye of the iron rod, the bit,
however, being free to revolve, as this is essential when making joints
in heavy lead pipe, for which purpose it is principally used. Fig. 5
represents a bit which is a combination and modification of the two
others, and it is largely used for the internal soldering of bottoms of
large drums, milk churns, etc., where great local heat is required.
[Illustration: Fig. 4.--Home-made Soldering Bit]
[Illustration: Fig. 5.--Bit for Internal Soldering, etc.]
[Illustration: Fig. 6.--Hatchet Soldering Bit]
As to the size of bit required, for ordinary small work the straight
type should not be less than 8 oz. or 10 oz. (weight of the actual
copper).
Two bits are very useful in doing a large job, as the work can then be
arranged to progress continuously, one bit heating while the other is in
use.
A bit suitable for quite light work can be easily made by drilling and
tapping a piece of copper, say 1/2 in. by 1/2 in. by 1-1/2 in. long,
either in the end or in the side, for a 3/16-in. steel rod 12 in. long,
a handle being then fitted at the other end.
In the “Tinol” telescopic soldering bit for amateurs’ use, the handle is
in three parts: (_a_) the actual wooden handle bushed with metal, and
provided with a set-screw shaped like a screw eye, and therefore easily
turned; (_b_) a steel tube which telescopes into the first part, and
which is also provided with a set-screw; and (_c_) a short rod, having
at one end a hatchet-shaped copper bit. The extreme length of the tool
is 12 in., and the length, when the parts are telescoped together, is
about 5 in.
The “Fluxite” bit is larger and heavier. It has a hollow cast-iron
handle, perforated to dissipate the heat, threaded internally at one end
to receive the screwed end of the iron stem, only 5 in. or so in length,
which at the other end screws into an adapter or holder which, in turn,
receives the screwed end of the copper bolt, itself about 4 in. long.
The bit is taken to pieces in a few moments, and is quite a workmanlike
tool.
[Illustration: Fig. 7.--Spirit-heated Bit]
=Spirit-Heated Soldering Bits.=--Bits heated by benzoline or spirit may
be made with a small barrel-shaped reservoir which also forms the
handle. One end of the reservoir is fitted with a filling cap, and from
the opposite end protrudes the tube carrying the burner. To the tube end
of the reservoir an iron clip is attached, and this secures an iron bar
which stands out over the burner head. At the end of this bar the copper
bit is attached and held either vertically or horizontally in the
flame. Tool merchants’ catalogues show a variety of such implements.
Fig. 7 illustrates one of the most elaborate of them all, the weight
complete being 2-1/4 lb. It has a polished brass container A, of 1/5
pint capacity--sufficient for 45 to 60 minutes, whence the benzoline
flows to the burner B, the flame from which heats the copper bit C. This
bit may be of any of the regular shapes, and weighs about 1/2 lb. The
position shown is that for heating the bit preparatory to soldering. The
tray D catches any drips that might occur at starting, E is the stand, F
the filler cap, G is the regulating handle, and H is the clamp that
holds the bit in place.
[Illustration: Fig. 8.--Bit attached to Blow-lamp]
[Illustration: Fig. 9.--Gas-heated Bit]
A writer in _Popular Mechanics_ has stated that the ordinary blow-lamp,
with the burner end equipped with a copper bolt (see Fig. 8), makes an
excellent soldering device. The point can be easily kept at the proper
heat, and there will be no want for hot coppers. The end of the burner
is threaded on the outside, and a hole is drilled in the copper point
and threaded to match. Small holes are drilled in the copper in the same
manner as in the burner, to make vents for the flame.
=Gas-heated Bits.=--These are largely used in factories, and are
cleanly, expeditious, safe, and convenient. The type shown by Fig. 9 is
very handy, and the illustration and description are due to F. X.
Sommers, Jun., in the _American Machinist_. A mixture of air and gas
enters the pipe at about 10 lb. pressure, or enough to give a hot, blue
flame. The part A is of cast-iron, which, on experiment, has been found
to last longer without corroding than steel, although copper would be
better. The soldering bolt B was made of steel because it kept the
correct shape point much longer than cast-iron or copper, although the
latter metal is better for transmitting the heat. The point should be
tinned before using. This form of soldering head is being used on
automatic can-soldering machines, and does the work effectively. It also
saves gas. It will heat to the correct temperature in about 1-1/2
minutes.
[Illustration: Fig. 10.--Gas-heated Bit complete]
[Illustration: Fig. 11.--Air Inlets in End of Air Chamber]
[Illustration: Fig. 12.--Section through Air Chamber and Gas-reducing
Valve]
[Illustration: Fig. 13.--Details of Cones or Needles]
A gas-heated bit invented by W. G. Ryan is shown in Figs. 10 to 13. The
actual bit A is held in a steel sheath B having a space underneath the
bit to allow the gas to pass. The sheath has a row of holes on each side
to allow the gas to come through, the flame enveloping the bit when in
use. The gas, supplied through a flexible tube, passes through the tube
that forms the handle, at the end of which is a small chamber C to admit
air, which mixes with the gas to cause it to burn atmospherically, the
supply of gas passing through a small cone valve D and thence through
the air chamber. In the air-inlet holes E at the end of the air chamber
are fitted small cones F to regulate the quantity of air. All the cones,
including the gas-valve cone, are connected rigidly together, so that
when cutting down the gas supply temporarily, the air supply is
automatically reduced, and the gas flame remains in being, although its
size is much reduced. It has been found that, in some gas-heated bits,
the cutting down of the gas seriously interferes with the proportion of
the gas and air mixture, resulting in a back-fire. The device here
described has been invented especially to obviate that trouble. To
reduce the gas supply and, with it, the air supply also, all that is
necessary is a slight forward movement of the fitting to which the cones
or needles are attached. The copper bit is kept in position by the
sheath or clip, the small bolt in which can be taken out in a moment
when special attention to the bit becomes necessary. The connection to
the flexible gas tubing is at G, while H indicates a guide and stuffing
box for the gas-valve cone or needle.
[Illustration: Fig. 14.--Gas-stove for Heating Bits]
=Stoves for Heating Soldering Bits.=--Although a copper bit may be
heated in any fire, it is better to avoid the dirt, smoke and tarry
stickiness which are often present in a coal fire. In the absence of
gas, a bright, clear coke fire or a charcoal fire should be used
whenever available. Portable oil stoves of the wickless type can also be
employed, but the ideal fuel is gas, which may be regulated at will to
give a uniform temperature. Two gas-stoves specially constructed for
copper bits are shown by Figs. 14 and 15.
[Illustration: Fig. 15.--Gas-stove for Heating Bits]
=Tinning a Bit.=--Before a bit can be used, it must be “tinned,” that
is, coated with solder in a smooth complete covering, for which
purpose--by one method, not the best, but the most general--the end is
heated to a dull red, rubbed quickly with the file on the facets, dipped
in killed spirit or “fluxite,” or rubbed against a piece of
sal-ammoniac, and then applied to a stick or lump of solder, the facets
being quickly wiped or rubbed on a piece of tinplate so as to spread the
solder evenly. When properly done, the nose of the bit is coated with a
smooth film of solder. This must always remain so, or the bit will not
act, and when it is honeycombed, or the “tinning” is present in patches,
it must be re-tinned. A bit must never be raised to a red heat
sufficient to melt the tinning. The bit does not operate well at such a
heat, because its contact makes solder too fluid and apt to run too
quickly.
When dipping a hot bit, prepared for tinning, into killed spirit, a
sharp pop, without smoke or spluttering, denotes the right temperature.
If, on withdrawing the bit, it is damp and still unclean, it had not
been heated sufficiently.
Another method of tinning may be mentioned. Into a small and clean tin
box (a 2-oz. tobacco tin about 3/4 in. deep) put some scraps of solder
and powdered resin. Heat the bit to a very dull red, quickly file up
clean on one side of the point, and then plunge into the solder and
resin and rub about; it will at once take on a coat of the alloy. A
second side of the bit may be tinned by then repeating the operation,
re-heating if necessary. The bottom of the box should be covered with
solder, which adheres easily enough, with a film of resin on top. It is
probably most convenient to tin the under side and the left-hand working
face of the bit. “Tinol” could be used in this way without admixture
with anything.
Still another method is to use a firebrick having a hollow in which the
solder and resin are placed; but the tin box plan is thought to be
better.
Undoubtedly the best method of tinning a bit is that in use by the
plumber who well knows the invaluable qualities of sal-ammoniac
(ammonium chloride) for the purpose. He has no wish to squander energy
on those vigorous rubbings of the bit--on paving-stone, bath brick,
tinplate, etc. etc., and he believes that the habit of dipping the bit
into zinc chloride is both slovenly and wasteful, for not only is this
corrosive stuff sprayed about broadcast, but the remainder is soon
rendered unfit for its purpose by contamination with copper chloride and
dirt from the fire. The outlay of a few halfpence on a sizable slab of
sal-ammoniac will keep the bit in the best condition for years, and save
hours of superfluous labour. Commercial sal-ammoniac is obtainable in
large, rugged crystals of a tough, fibrous texture. A piece weighing
upwards of 1/4 lb. can be trimmed to a roughly rectangular slab, a few
inches long and wide and about 1 in. thick; and a cavity should be
scooped in one of the flat sides to accommodate the bit.
[Illustration: Fig. 16.--Tinning Bit in Sal-ammoniac Block]
Let the bit-faces be made shapely and filed bright and the tool
thoroughly heated in a clean fire, removed, flicked free of ash, and
then held down firmly in the cavity of the sal-ammoniac block (see Fig.
16). Profuse white fumes will arise, and the surface of the salt will
fuse. Bear heavily on each facet in turn, and then melt a few beads of
solder into the cavity along with the bit, and the latter will become
brightly tinned in a moment or so. The bit should be applied to the
“ammonia block” every few heats, or as required, as the work progresses,
and flicked with a tuft of dampened cotton-waste.
The sal-ammoniac has one great disadvantage--it is deliquescent
(collecting moisture from a damp atmosphere), and its near proximity to
most metals oxidises and corrodes them. Iron and steel, particularly, it
rusts rapidly and deeply. Therefore the tools (saw and chisel) used to
shape the block must be washed, dried, warmed, and greased before they
are laid by, and the waste fragments must be carefully swept up and
disposed of. The block itself must always be kept apart from tools.
Plumbers enclose it in a sheet-lead box wrapped in a greasy rag;
amateurs may store it on a dry shelf, parcelled in waxed paper secured
by a rubber band, or in a length of motor-tyre inner tube, rolled up.
=Simple Soldering.=--Scrupulous cleanliness in everything connected with
the process of soldering is essential to success. The ordinary procedure
in making a joint is to clean the surfaces first by filing or scraping
with a scraper or a knife or a plumber’s shave-hook (Fig. 17). In some
cases, dirty metal is cleansed with dilute hydrochloric acid. With or
without preliminary heating of the work, flux is then applied to the
joint, and the heated bit is held in one hand and a stick of solder in
the other, and the stick drawn along the joint while the bit touches it
(or “drops” of solder may be transferred to the work by means of the
bit). This will cause a line of molten solder to run, and some skill and
care are necessary to get just the right amount of solder without
wasting it and allowing it to spread in a lumpy fashion beyond the
necessary area. The bit is next worked up and down the joint to spread
the solder, and by the transmitted heat to make it thoroughly penetrate
the joint. This is an outline of the process, and there is a number of
points requiring special instruction or a few words of caution.
[Illustration: Fig. 17.--Shave-hook]
Note that the work must be filed, scraped, or otherwise mechanically
cleaned, and then chemically cleaned by coating with the flux just where
the soldering is required. In heating the copper bit do not let it reach
even a dull red heat. Lightly dip it into the flux to clean the point;
then, with a small button or blob of solder resting on the work, place
the bit momentarily upon it to cause the solder to flow, and draw the
bit where the solder is required.
Many beginners try to draw along the solder with an insufficiently
heated bit. The result is a series of lumps--“putting it on with a
trowel,” as it is sometimes termed. A good joint cannot be made this
way, however much solder may be used.
Some beginners fly to the other extreme, and try to make a neat job with
a red-hot bit, which results in the solder assuming a sandy appearance
and in the work being discoloured.
Others try to solder uphill--that is, they hold or place the work in
such a way as to cause the solder to flow away from where it is
required. The correct method is to solder downhill by tilting or
inclining the work, so that the solder will always collect around and
travel with the point of the bit. This, besides facilitating the work,
makes a strong joint, and imparts a clean and neat appearance to the
job.
[Illustration: Figs. 18 and 19.--Incorrect and Correct Methods of
Holding Bit]
A common mistake is to hold the bit in a cramped and awkward way, as in
Fig. 18, the hand being twisted under the handle, the thumb being
brought to the top, and the elbow forced to the side. The correct
positions of arm and fingers are shown in Fig. 19; the elbow is held
well out from the body, and the thumb is placed directly under the
handle of the bit, forming a fulcrum over which the bit may be slightly
raised or depressed at will. This is all-important when soldering very
fusible metals such as pewter, tin, etc., on which the weight of the
copper bit should never be allowed to rest, as otherwise a hole will
suddenly be made in the work. The whole weight of the bit should be
supported and balanced on the thumb by the downward pressure of that
part of the hand close to the little finger. The worker should not for a
moment lose control of the copper bit, and control is always assured
when the thumb is underneath the handle.
There is but little strength in a butt joint with the edges of the metal
only just touching--that is, without a lap; to take the example of a
small cylinder, the body seam should have at least a 1/4-in. lap. Fig.
20 represents an example of internal grooved seam soldering, which may
be executed in the following way:--After applying the flux, place a
small button of solder inside the cylinder on the seam, rest the bit
momentarily on the solder to melt it, and then draw it gently along the
seam. The cylinder should be slightly tilted to allow of the solder
travelling with the point of the bit. The hand should avoid touching any
part of the work that comes directly into contact with the copper bit,
as otherwise the hand would be badly burned.
[Illustration: Fig. 20.--Soldering Internal Grooved Seam]
[Illustration: Fig. 21.--Soldering on Can Bottom Internally]
The method of internally soldering the bottom on a canister, etc., is
shown in Fig. 21. The bottom is held in position by gently pressing it
against (but not placing it on) the bench during the soldering process,
while the tilt of the canister and the position of the bit cause the
solder to travel with the bit.
In soldering all such articles, the soldering should be done with one
sweep of the bit, the left hand meanwhile making the necessary
revolution. This saves time and solder, and avoids the unsightly
appearance of a series of starts and stops.
In work of a larger and more substantial nature, as, for example,
galvanised or tinned iron work, the bottom of the article is first
“knocked up,” and then soldered internally. Fig. 21 represents an
example of internal soldering where the whole weight of the bit is shown
resting on the molten solder inside; this provides the local heat
required to “sweat” the solder into the four thicknesses of metal which
constitute the bottom seam; and for this work the bottoming bit shown in
Fig. 3 is often used. Pewter, lead, zinc and tin--the latter should not
be confused with tinplate--do not require sweating, on account of their
low fusibility, and any attempt even to solder them with a very hot bit
will probably end disastrously.
[Illustration: Fig. 22.--Soldering Can Externally]
Fig. 22 shows an example of external seam soldering. The method there
shown is invariably adopted for simple lap seams, although grooved seams
are similarly soldered. A grooved seam, however, should preferably be
soldered internally. The position of the worker’s elbow and thumb should
be noted, as should also the tilt of the cylinder (more pronounced in
this case than the other) in order to secure the downflow of the solder.
Sweating has already been mentioned. It should be said that one of the
easiest ways in which a beginner may make a reliable joint is to prepare
both faces of the joint by fluxing and covering with a thin film of
solder, and then pressing the two parts together with the hot bit until
the top part “floats” and then settles down. The advantage of this way
is that one can be sure of perfect application of the solder to the
joint faces, since each is dealt with first and thoroughly coated, with
no faulty patches. Sweating is also done in the flame of a bunsen burner
or blowpipe, as explained later.
=Reinforced and Filled-in Soldered Joints.=--The bottoms of square or
cylindrical vessels should, preferably, be soldered from the inside, and
“buttons” of solder may be melted to assume a stout triangular-shape
stud in the corners of the square vessels. A tinned rivet is sometimes
riveted or just placed in a corner, and sufficient solder floated over
it to strengthen the corner. Solder is always liable to run through an
improperly closed seam at the corner when external soldering is resorted
to; but in cases where this is the only practical method, a tinned rivet
may be inserted from the outside, and then soldered over. It sometimes
happens that two “raw” edges require soldering together without a lap.
Where a strong joint is required a good plan is to place a length of
tinned wire over both edges and solder the lot together. In addition to
strengthening the joint, the wire considerably improves the general
appearance. A simpler joint may be made by “skimming” the solder over
with a copper bit heated only just sufficiently to melt the solder. The
quick and skilful touch is required to perform this operation
satisfactorily; but a little practice will soon bring the necessary
proficiency. The idea is to “draw” the solder across the joint quickly,
before it has time to run through. This method is useful when soldering
thin metal goods of a lower degree of fusibility than that of the solder
employed. No preparation for filling cracks previous to soldering can be
recommended, beyond such small pieces of metal that may be afterwards
soldered over and effectively hidden. It is much better to endeavour to
produce work of such quality that this expedient is altogether
unnecessary.
=Soldering Heavy Milk Churns.=--When soldering the bottom rims on large
milk churns, sufficient heat cannot be maintained with only one
soldering bit. At least two heavy bits are required, so that one may be
getting hot while the other is in use. The rims are usually tinned
before being fixed by first pickling them in dilute hydrochloric acid,
washing, and then dipping in a bath of molten tin. When repairing and
resoldering the rims, remove all dirt and rust with a file, use a few
brushfuls of raw spirits further to assist the cleaning process, then
wash with clean water and solder in the usual way, using killed spirits
as a flux.
=Soldering Hole in Enamelled Ware.=--First scrape or file away the
enamel quite clear all round the hole, apply a little raw spirit to the
surface of the iron, and coat it with solder in the usual manner. Then
cut out a tin disc large enough to cover the hole, and solder this in,
using killed spirit as the flux.
=Soldering Leaded Lights.=--For soldering the calmes of a lead-light
window, the calmes having been fitted properly together, shave a small
round dot at the point of junction, sprinkle a little powdered resin on
the shaving, and with a copper bit or with a glazier’s iron having a
tinned face, melt a small piece of tinman’s ordinary solder on the
shaved part so that it tins to the lead and forms a round button.
=Soldering Catch on Gun-barrel.=--In soldering a catch on a gun barrel
it will first be necessary to tin both barrel and catch, and then to
wire them together, in addition binding the barrels for some distance
from each side of the catch, making the ribs secure with wedges. To melt
the solder, use heaters; these are generally made of copper with iron
handles; or iron rods can be used, the ends being made red hot and
inserted in the barrels. Cut some small slips of thin solder and place
them on each side of the catch, using powdered resin. As soon as the
solder melts, remove the heaters and cool the barrels.
[Illustration: Fig. 23.--Mouth Blowpipe]
[Illustration: Fig. 24.--Black’s Mouth Blowpipe]
[Illustration: Fig. 25.--Fletcher’s Mouth Blowpipe]
[Illustration: Fig. 26.--Section through Blowpipe Flame]