Cable soldering for beginner - where to begin?

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• BillDL Frets: 9013

  October 2021 edited October 2021

  I know that this seems as though I am "answering" your questions with another question, but I feel that I need to ask something to establish exactly what your plans are.

  
  

  If this project is just a one-off to make your own patch cables to exact lengths for different patches, then I would have to wonder whether the outlay on soldering tools, the cable, and the jacks is cost effective at all when you would be able to buy good quality ready-made patch cables in a variety of fixed lengths for much less than it will cost to buy all the tools.  It would certainly be an investment if you plan a lot of ongoing electronic tinkering.  It would be very much like having to buy a selection of herbs, spices, baking ingredients, and so on that you didn't already have so that you could cook or bake one-off meal or cake as opposed to already having all of them in the pantry ready for future use.

  
  

  YouTube is bulging with hands-on training videos showing you how to "sodder" (as Americans say) a variety of electronic items.  A search on YouTube for "how to solder patch cables" will return dozens of quite well presented videos showing you how to connect and solder cables to square right-angle jacks, "pancake" jacks, and ordinary straight jacks.  It is just a case of watching and listening, then comparing different presenters' techniques against each other to see what seems to be the best way for you.  Different people do things in different ways and have different opinions, but the principles are mostly the same:

  1. Wires solder better and more easily to other metal parts if both parts are lightly "tinned" in advance by coating them with a thin layer of solder.  For example, the lug you are soldering the wire to should have a light coating of solder around the hole as well as the wire you feed through the hole.  This helps the new solder to flow together onto both parts in a continuous connection when melted.  The braids in some cable are already tinned, but there's no harm in tinning them again anyway.
     
  2. You hold the tip of the soldering iron against the component and then place the solder to the heated connection rather than melting solder onto the tip of the soldering iron and trying to smear it onto the joint.  The hard part is knowing how long to do this for so that you don't overheat the component and damage it or melt the insulation of the cable.  Heat sinks are useful for this.  Even an alligator clip can help to divert some of the heat away from a component or wire.
     
  3. You need to be able to immobilise the soldered parts for long enough to allow the solder to harden completely and go nice and shiny.  Devices like "helping hands" with alligator clips on adjustable arms help you to hold things together without needing more hands than you already have.
     
  4. You need to clean off the old solder from the tip of the soldering iron regularly and cover it again with a very thin coating of solder to prolong its life and to ensure the best functionality.  Wipe off the solder regularly with a rag (taking care not to burn yourself or set fire to the rag and burn the house down), then just flow a small amount of new solder onto it again.  I use an old tub of flux and just dip the tip into it between each solder jointing to clean it.
  5. Soldering flux is useful for preventing metal parts from oxidising during the process and for helping solder to flow and stick, but some soldering wire already contains flux.
  6. Avoid inhaling the fumes or smoke created by soldering.  Even though solder is now lead free, the fumes are nasty and you need to be in a well ventilated room and preferably be wearing a respirator mask if you are sitting soldering things for a while.
     

  I can offer some helpful tips.

  
  

  If you are soldering to the back of a potentiometer, the inside of a pancake jack's body, or some other piece of cold metal larger than a lug on a jack socket, it sometimes helps to scratch the surface of the metal part to provide a key for the solder and cut through an oxidised layer to the metal below.  A rough piece of carborundum paper or even the end of a file or nail file can roughen up the surface into the metal to provide a good soldering surface.

  
  

  Practice stripping back the different insulation layers of the cable using an offcut. You most likely won't be able to strip off the insulation of the inner core on instrument cable with your teeth as you might well manage with plain wires with a single layer of insulation, for example wires connecting pots in a guitar control cavity.  Even using a cable stripper designed for fine wires can be tricky unless you have practiced using it for a while. If you haven't done this before you can end up messing up repeatedly and having to go further back into the cable for another shot, and before you know it you have used up the extra inch you needed to keep the cable the correct length.
  

  
  

  Practice on old components for a while before committing to the real job.  The cores of shielded instrument cables are very thin and you can burn through them quite easily.  Practice on old potentiometers.  The idea of soldering is to have a hot enough iron that you can get on and off components quite quickly leaving as small and as shiny a blob of solder as possible
  

  
  

  As far as tools are concerned, I will leave this aspect for others to make suggestions about soldering irons.  I use the same fixed power little soldering iron I bought about 20 years ago from Maplin when they still had physical shops and sold just about everything you could need.  I cannot even tell you its wattage.  Before that I had a gas-powered iron that did most jobs I need and gave pretty instantaneous heat.  People who have to solder lots of different kinds of joints tend to use a soldering "station" that allows you to vary the power when needed.
  

  
  

  If I was buying lengths of instrument cable I would probably buy from RS Components, CPC Farnell, or one of those types of companies, but you can buy cable and jacks from guitar stores or on eBay just as readily.  I tend to stick to the good quality Neutrik jacks these days and I don't mind spending a little bit more for the quality.  Many generic no-name jacks are probably as good, but you might have to buy a bunch of different ones while discovering that some are better than others.

  
  

  Regarding the actual cable, your best bet is to look at the technical specifications of ready made patch cables and assess how many strands the core wire contains and the diameter of each strand that is used in the more expensive and well regarded branded cables.  For example, if you saw a multipurpose shielded instrument cable with an outside diameter of 4.2mm (that's including the outer insulation sheath) where the core contains 7 x strands each 0.2mm diameter, compare these specs with those quoted for the most expensive and top rated patch cables you can find that show the specs and then use them as a comparison.  Bear in mind that patch cables often have more flexible and rubbery outer sheathing than straight guitar cables because they often have to bend quite sharply close to the jacks.  Be aware also that some jacks have integral strain relief sheaths, often just thick heatshrink tubing that extends down beyond the jack body onto the cable itself.  This might prevent the patch cable from being able to bend sharply enough between, for example, effects pedals side by side on a pedal board.
  

  
  

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