Sunday, January 8, 2012

Soldering -- 'How To' for Cigar Box Guitars

I'm not an expert on the subject of successful soldering on a cigar box guitar, but I've found that if I follow a few basic principles, things go well.

Equipment --

Use the right soldering iron, a 15w to 30w wand-style iron will produce desired results, without overheating and damaging parts.  A spade tip is best for starting out as a novice, while the more experienced person may prefer a pointed tip.  And, if you're an expert, you may find an adjustable iron preferable.  They're a little pricey, but a good one can be used as a wood burning tool as well.

A 'third hand' (a little deck mounted device with two adjustable arm extensions with alligator clips) is essential for for holding small parts and wires, while allowing you hands-free maneuvering.

Needle nose pliers, wire cutters, and wire stripper should complete the basic tool needs, but there are other items you'll find useful as you move along.

Materials --

Thin, electronics-grade lead resin core solder is perfect, but blended resin core solder works just fine, too,  and it can be obtained at your local electronics store.

Stranded 22ga. to 24 ga. wire in a variety of insulation colors should satisfy your needs when working with potentiometers (pots), pickups (pups), jacks and switches.

Heat shrink tubing (1/8" for most applications) is useful for covering soldered wire joints and lugs.  It's easier to apply, and less unsightly than scabbed on electrical tape.

Shielding foil or tape works for coating the inside of boxes and cavities, which is essential for reducing/eliminating amp feedback.  There are a variety of recommendations and preferences, but I found that inexpensive aluminum foil my wife uses to wrap the Christmas turkey works just fine, and it doesn't cost an arm and a leg.  She gets a little annoyed, when I don't tell her I 'borrowed' it.

Thin copper sheeting, available from a local hobby store, is good for those times when grounding under bridges, etc., is necessary.

Electrical tape, nylon wire ties and stick-on plastic wire anchors can be useful in special situations.  And they make your creations look professional.

Good Things to Know --

*  Tinning the Iron -- Melt a small amount of solder onto the iron tip.  This will help to transfer heat from the tip of the iron to the joint being soldered.  Do this initially, and occasionally throughout your project.  Quick heat transfer means less time an object is being heated, which is good when soldering pots.

*  Tinning Wire -- Melt a small amount of solder onto stripped and twisted wire ends (1/4" to 3/8" of exposed wire).  This helps heat transfer during the soldering process, and makes the wire easier to insert into the holes on pots, jacks, etc.

*  Tip Cleaning -- Clean the tip of your iron after the initial tinning, and before soldering each joint.  A cheap and effective tip cleaner can be made from a copper pan scrubber (available from your local hardware or grocery store).  Hot glue the scrubber onto the inside of a jar lid.  Jam the iron tip into the scrubber, wiggle it around, and you got a clean tip to work with.

*  Fumes -- Although, the solder fumes you may breathe are from the flux, and not the lead solder, it is a good idea to do your work in a well ventilated area, and to avoid breathing the fumes, by wearing a respirator mask.  Always thoroughly wash your hands with soap and water after handling lead solder.

* Joint Strength -- Solder joints need to be physically strong and electrically conductive.  Good surface preparation is essential for a desired final result.

Soldering to Pot and Jack Lugs

*  Always make sure exposed wire leads are short and tidy (1/4" to 3/8").

*  Twist wire strands together with no stray wires sticking out.

*  Apply heat to the exposed wire for just a couple seconds, and then touch solder to the wire (tinning).  Solder should melt and flow into the wire, just enough to coat the wire -- no large globs needed.

*  Bend the 'tinned' wire into a 90-degree angle at the mid-point of the exposed lead.

*  Insert the bent wire end into the pot or jack lug, and crimp the wire closed over the lug.

*  Apply the iron to the lug for a couple seconds, and touch the solder to the junction.  The solder will quickly melt and smoothly flow into the joint of the wire and the lug.  You should end up with a clean, smooth, and shiny joint.  Let the joint cool slowly -- DO NOT blow on the soldered surface, as this could cause the joint to fail.

*  Heat shrink tubing can be slid over the wire to cover the lug joint.  It is not necessary, but it will look professional.

Soldering to Pot Casing Surface

There are times when 'ground' wires must be soldered to the back casing of a pot.  This can sometimes be a little problematic, but necessary and effective if done properly.

*  Lightly sand the back casing of the pot to ensure a clean surface on which to solder.

*  Heat the casing with the iron, and apply a small amount of solder to the spot being heated. DO NOT OVERHEAT.

*  Strip insulation from the wire in the same manner as when preparing a wire for soldering to a lug (1/4" will work).

*  Twist and tin the wire.

*  Lay the tinned wire against the area on the pot where you applied the spot of solder.

*  Touch the iron tip to the wire and the casing (heat the parts equally).

*  Solder at the junction of the wire and casing will melt together to form a strong bond.  This should not take longer than a few seconds.  DO NOT OVERHEAT the casing, and this may damage the pot.

*  A successful joint should be flat, smooth and shiny.  A 'blob' of solder is an indication of a 'cold' joint, which is not acceptable for optimal conductivity.

Soldering Wires Together

*  Strip the wire ends of the wires to be joined together (3/8" should do it).

*  Slightly 'flare' the wire ends, and mesh the wires together, end to end.

*  Once the wires are meshed, apply pressure with your fingers and twist the wires together, until they are firmly joined.

*  Heat the wires with the iron, while melting a thin but adequate amount of solder to flow nicely into the bare wires, which will complete a solid joint.

*  Let the wires cool, and add a strip of heat shrink tubing to cover the exposed wire.