CRIMPS and soldering heavy connectors fer yer bus wiring ...By Gary Stadler 1962 Crown FIRST, let me preface this by telling you that I'm one of those who, regardless of what the code says, ALWAYS solders large wires that have previously been crimped. Nasa would probably never hire me- but that's OK with me because my soldered crimps will never see Outer Space unless my bus somehow gets launched out there, and that's unlikely because I don't drive that fast! I've owned an electronics manufacturing company for 35 years that designed and manufactured high power equipment for the laser industry, and I've seen (and learned from) connection failures of every imaginable type, from as many manufacturers. While what I have to share here may not be "correct" in some people's minds, it works for me, and my techniques presented here have seen zero failures in the history of my company. SO take the following as my OPINION, not as gospel, and decide what you will use or not. NEVER CRIMP SOLID WIRE unless the terminal you're using is specifically designed for solid wire (which is rare). Soldering solid wire in a crimp is OK, but why are you using solid wire in your conversion in the first place? It's a NO NO. Side Note: My first hint that the "Minions of The Code" might not have all the clues was 15 years ago, when I did an addition to my house. In doing the electrical, I soldered the ground wires together in all of my plug boxes, and then put wire nuts on them. The best method to insure total safety and reliability as far as I could see. The inspector came in, took one look, and said "take all those apart and redo them with CRIMPS and NO solder"... WHAT?!!!! Crimps on solid wire are HORRIBLE!!! I said. His reply: "Son, it doesn't matter WHAT is best or safest...what matters is what the CODE SAYS"... I couldn't believe what I'd just heard I changed them all to crimps until he passed the inspection and left for good, then redid it "my way" End of my believing in many aspects of the code.... SOLDERING LARGE CRIMPS without torches or giant soldering irons... I usually solder any crimp that is made with wire 8 gauge or larger... Here's a neat trick that I doubt many folks know... take the tip OFF of your 210 watt Weller soldering gun and toss it. Soldering guns are useless in my opinion, as originally intended. You have little control of how hot they get and you can easily ruin the thing you're trying to solder with excess heat. BUT now that the tip is gone, you have these two heavy posts sticking out of the gun that won't do anything, right? Wrong!!... simply cram your big heavy lug (With it's wire already crimped in it) up between the gun's posts and hit the trigger!! Electricity will now flow *through the terminal* and it will self-heat. And amazingly quickly, and with surprisingly large terminals! We've used this trick to solder anything from #8 up to #2 wire for years in our power supply manufacturing line. It works GREAT!! Here's some photos of my trusty old weller that has been used in this service for the last 15 years. It's kinda crusty now but it still works great! (Click on the image for bigger photo) Often times you'll have to pull the trigger and then wiggle the connector a bit to get a good contact- you'll immediately hear the gun load down and grunt. It's working!!! Note that I have twisted up a number of finer sized pieces of solder to get a big piece. This makes it easier to get a lot of solder into the joint in a hurry. I usually watch the tinning on the crimp as a giveaway to the temperature. As the connector heats up to soldering temperature, the plating will melt and mottle, and a visible "line of heat" will rapidly make it's way down to the end of the connector. This signals that it's about time to apply the solder and be done with it. Be sure to keep it completely still while it's cooling, because if there's any vibration, a cold solder joint can easily occur. If the solder cools off and is still shiny, you've done it right. If it's dull or flat in appearance, try it again, and maybe with some fresh solder to get some additional flux in there. Like Fast Fred says, it's a good idea to be sparing with the solder so as to not get it "behind" the crimp (this would reduce the flexibility of the wire coming in to the terminal and possibly cause an early failure), but with large wires flexibility usually isn't a problem anyway, so it's not a super critical thing in my OPINION. Proper soldering of crimps absoutely insures that the crimp won't someday get too hot, oxidize, increase in resistance and cause a failure (which in my time I've seen a LOT due to faulty crimps that could have been fine had they been soldered). Much as we don't like to admit it, we are ALL capable of making faulty crimps if we're doing it by hand. Solder is great insurance. The only thing to watch out for when soldering is to get ALL the flux off of the terminal when you're done (which could be a worse thing than a bad crimp!) A cotton ball or Q-tip and acetone do a marvelous job. TYPES OF LUGS AND CRIMPS TO USE (remember, this is only my opinion...) In the photos below, I show a few types of terminals that I use. I like to stick with "closed" crimps that have been made into a complete "tube", and as the photo shows, I like to stay away from "opened" style crimps. (Click on the images for bigger photos) Lugs, terminals and crimps are made by many companies, from super cheap to super expensive. I stick with connectors made by AMP if at all possible. Other good makers are MOLEX, BURNDY, ETC, and a host of others. Often times the ones you see in Radio Shack or your local Home Depot or auto parts store are total junk. The reason they are junk is due to the gauge and alloy of metal that they are made from. Especially push-on connectors should be made out of a metal that will keep it's springiness at higher temperatures. Any crimp connector made of cheepo or thin metal will eventually loose it's springiness and cause failures. It's hard to tell what's good or bad if you're not working with these on a daily basis- about the only thing I can tell you is to look at the construction. In general these photos show basic styles to use and one to stay away from. Try to stick with insulated crimps unless it's for a ground connection. In general, the better connectors will be made of heavier metal. Insulated crimps that have the internal part of the strain relief made of metal as shown below will generally be of better quality. (Click on the image for bigger photo) CRIMPERS TO USE and TO STAY AWAY FROM (Click on the image for bigger photo) Crimpers are also made by many companies, from super cheap to super expensive. The WORST kind of crimper is the little stamped out steel cheapies that you get from auto stores, Home Depot, or Radio Shack (sorry guys). With these cheepies, You just can't get enough pressure. In my hands the cheap crimpers actually bend or break before they will do a proper job! The BEST crimpers are, of course, flywheel machines that resemble die-presses- they cost thousands. The next best thing is a crimper that has a catch that won't release until the crimp pressure has reached a set value. These are mucho bucks, (like $200 and up) and usually only set up for one size terminal. So for the average bus-guy it's financially impractical to have a set of these around. My absolute fave is the red-handled Lineman's tool shown in the photo- it's availiable at a good electrical contractor's supply house or places like WW Grainger (Klein part number 1N041, $47) or McMaster-Carr (part number 7289K1 $22) and if you use both hands and squeeze the heck out of it, it will make a good crimp on anything from #22 up to #10 or even #8 wire. But if you're a weak handed guy it can make lousy crimps as well. It takes a lot of force to do it right. This tool will crimp insulated and uninsulated crimps, and the strain relief part as well. Even though this crimper has a separate set of positions marked "INS" and "NON", I ALWAYS use the "NON-insulated" position for all of my crimps. I only use the "insulated" jaws for the strain releif section of a crimp. REMEMBER that I prefaced this whole article with "take the following as my OPINION, not as gospel, and decide what you will use or not"... using the "NON-insulated" position in this particular crimper for all crimps insulated or not has given me the best results with no failures for as long as I've been doing this. Using the "insulated" position has, in my early days, resulted in more than one crimp failure. So no matter what the manufacturer of this particular tool recommends, I've found that in my experience it's not necessarily correct. Also please note, this tool is ok for cutting wire but NOT so good for stripping insulation due to the symmetrical angles of it's cutting edges. While we're talking about crimps, there's a right way and a wrong way to position your terminal in the crimper, as shown in these two photos. It has to do with where the joining line is within the crimp, vs where the divot is "pushed" in by the crimper. (Click on the images for bigger photos) While I'm on the subject of stripping... I thought I'd share this little trick with you. It surprises me how few people know it... (Click on the image for bigger photo) Turn your cutters UPSIDE_DOWN when stripping!! This causes the "flat surface" of the cutters to easily push the insulation off of the wire, as opposed to a "wedge" that is trying to compress the insulation as you attempt to remove it, usually resulting in a nicked wire and a LOT more effort!!