The most common heater is the soldering iron (copper) with sizes ranging from small pencil types to large clubs. Although some may be iron clad, almost all are copper tipped, since its heat conductivity is among the best. Originally heated on coals or by a flame, almost all tips are now heated by an electrical current through an external resistance. Some few are heated by self contained gas torches. With current flowing through the tip, a variation is the faster heating, trigger controlled soldering gun for quick jobs. Tip shapes vary from sharp cones through chisels to large flats for circuit board work. Many are easily replaced. Special hollow tip versions with vacuum assist are commonly called "solder suckers".
Fancy, expensive soldering stations with regulated temperature controls, holders, cleaning sponges and even vacuum pumps for solder suckers are available, but are generally not very useful for casual hobby soldering.
Wattage is usually one of the selection criteria. One of the main problems, is dull gray, cold solder joints from insufficient heat or movement during solidification, closely followed by loosening other parts while heating the joint. Although many sources recommend 25 W irons for circuit boards, in 1950, the Navy taught me to use a hot iron and work fast. Many will shriek in horror, but over the last 11 years, I have used a cheap Radio Shack electric solder sucker and a 47 W, 900 º F. Unger pencil with 3/16" chisel tip to unsolder and resolder 10's of thousands, computer integrated circuit pins without ruining one. Of course no daydreaming is allowed. Several sizes may be used for different applications and tastes.
Although thread-on tips may conduct heat slightly better, thread-in types are less expensive and bulky, provide more variety and are definitely easier to remove for exchange or replacement. Application of Anti-seize helps prevent frozen tips.
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Thumbwheel switch eliminates unplugging when switching iron types.
Newer all metal 47 1/2 watt element shows results of frozen thread-on tip removal attempt.
Pencil w/ older 51 watt ceramic element and larger 80 watt irons. Both chisel tipped.
Holders vary drastically from cheap, simple open wire or sheet metal affairs with a vee notch to enclosed cages or coils to keep objects from contact with the hot parts. Some are free standing, others require mounting, while some may be both. To avoid cooling and mishaps, tip and element should not contact enclosure. One bad burn or ruined object will convince you, that the few bucks spent on these is well worth it.
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Typical safer, free standing or bench side mounting iron holders.
Battery powered irons are very convenient, since they can be used almost anywhere without umbilical chord wires. Most are in the pencil size with the charger, holder and sponge in a not so portable bench top unit. As with all ni-cad powered devices, recharging is sometimes a big pain and if not used often the memory problem crops up.
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Ni-cad portable soldering pencil.
Quick heating, soldering guns are very convenient for larger hurry-up jobs, particularly in wiring under the layout. Wattage may range beyond 500.
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Hot Shot soldering gun.
An excellent idea, but unfortunately of inferior design, this tool could stand quite a bit of improvement. The rapid heating element works well in tight places. A two position trigger allows heating with a light squeeze and feeds solder with a deeper one. However the solder feed is not good. As shown feed is to the tip and not beyond it to the work. There is a disposable cartridge with solder spool, but no provision for reloading it with solder variations. Replacements are very limited, sole sourced and relatively expensive. Feed from cartridge is crude and often jams . Retracting solder to spool is difficult, prohibiting cartridge modification for reloading.
Basically on standard soldering guns, the tip is a resister, heated by current flow through it. Many shapes are available including knife, flat and spoon for cutting, smoothing and shaping various materials. Some have two position on/off trigger switches to select wattage from a tapped transformer. I often use the highest rated soldering gun for faster, less delicate jobs.
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Weller dual heat soldering gun.
For melting casting alloys and solder; ladles for pouring and pots for production type dip soldering are coating, are frequently used. Small ladles are often found in "lead" soldier casting kits. These are handy for pouring low temperature, weighting alloys such as Bearmetal. They are usually heated by flame or on an electric range.
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Simple pouring ladle w/ crude handle support similar to cheap iron holders..
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Bottom pouring ladle w/ internal spout, used to eliminate pouring surface dross.
Although some may be gas heated, even on a kitchen range with precautions; electrical , resistance heated pots are more convenient and safe, when used correctly. Since complete removal of metals is almost impossible and even trace contamination can ruin alloy properties, these containers should be used with one alloy only. Dross buildup on surface creates a problem, which requires occasional skimming. Reheating non-eutectic alloys left to cool in pots, may effect alloy properties.
DANGER!!: Extreme caution must be
taken to ensure pots are well anchored to avoid spilling very hot, molten
metals. Dipping and pouring can produce very hot, errant drops. Work area
and people should be well protected with non-flammable shields. A pair of
asbestos, or other heat resistant, gauntlet gloves should be worn to protect
hands and wrists. Severe burns, damage and possibly fire may result from
spillage.
Occasionally very inexpensive pots may be found for less than $ 10 on surplus listings.
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Inexpensive 1 lb surplus solder pot before wiring and mounting on larger heavy base
showing tapped pedestals and terminals.
Usually mounted on very heavy bases, industrial pots are usually far more expensive.
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Industrial pot,
Although many are gas heated, electrically heated furnaces are more convenient for melting very hard solders and brass for lost wax casting. These may resemble ovens, kilns or be cylindrical and usually use carbon, ceramic or stainless steel crucibles to contain metals. These are usually handled by specialized tongs. Able to attain temperatures in excess of 2,000 º F, they are extensively used in small foundry work. Normally a pyronometer in conjunction with a current control is used to set very critical pouring temperatures.
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Electric furnace.
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Large hot rheostat current limiter.
The rheostats formerly used to set temperatures were not only very bulky, and very hot, requiring mounting on a solid, non-flammable structure; but they were extremely wasteful and costly in power consumption. At lower temperature settings, over half the input power could be dissipated in them. A simple heat sinked, 35 A triac control replacement proved far more useful for accurate settings and economy. Reaching higher temperatures may take over 20 minutes at greater than 20 A. Some triac light dimmer or speed controls may be used to set temperatures on any of the smaller electrically heated soldering or other tools.
SOLDERING-HEAT SOURCES
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