Almost every project I’ve done over the last quarter century (if it has any wiring involved) has had at least one crimp connector. for 20mm vials crimper, There are many different types of crimpers, but in this case I’m talking about the ubiquitous variety of crimpers with red, blue, or yellow plastic sleeves indicating the size of wire they are designed for. They provide a physically strong and electrically reliable connection, are resistant to wire fatigue due to vibration, and can easily handle high currents at high voltages.
You might want to start discussing the details of crimp connections now, but my colleague Dan has already gone into detail about the good and bad aspects of crimping. Instead, my constant search for weird and wonderful things for your amusement has lately led me to a new crimping tool and, therefore, curiosity about the effectiveness of different tool styles. So, I’m going to evaluate three different crimping methods I can use: my new shiny ratchet crimping pliers, my old plain crimping pliers and, for comparison, regular pliers. I’ll look at the physical strength of each crimping method and then its electrical effects, but first it’s worth taking a look at the tool itself.
There’s not much to say about this set of pliers, except that it’s a perfectly ordinary set of pliers, sometimes called lineman’s pliers, that ended up on my desk, so I call them “desktop pliers.” You almost certainly have a very similar set.
My simple crimping pliers were purchased from a car supermarket in the 1990s. This is a versatile automotive power tool that many people probably own. They have many functions, but what interests us is their container shape with colorful dots on the chin. Clamp the crimp connector inside and insert the wire, squeezing the handle to ensure proper connection.
Finally, ratchet crimpers are a more expensive version of the same tool, but they come with a set of removable dies with dots of the same color to indicate the crimp size. I could buy molds for other types of connectors, but in this case I probably won’t. Interestingly, their cheap origins (via one of the Chinese hardware channels) have been revealed by applying colored dots to irregular shapes, but this does not detract from their effectiveness as tools.
If I were to evaluate some crimping tools, I needed to make some crimp connections first, so I pulled some wires out of the clutter of an old ATX power supply and used three red crimp cable connectors of the appropriate size. metal line. There is nothing special about them, they come from cheap retail crimp connectors.
The ratchet pliers had the greatest effect on the red plastic, deforming it most noticeably into the shape of the mold. Adjusting the ratchet will most likely change this, I’m just using it temporarily. Meanwhile, simple crimping pliers do their usual neat job, and benchtop pliers simply flatten the connector into an oval shape.
What do you need to know to measure the effectiveness of a crimp connection? In the lab, you can cut it with a precision saw and polish the open ends for inspection, or study it like a metallurgist, using X-rays to see the effect on the metal crystals. But I don’t have any on my desk and anyway I need a crimp connection which is more practical. What I need to know is: Will it fail? And will it draw the current I want to provide? So I need to test its tensile strength and resistance.
I don’t have a laboratory with a tensile strength testing facility, but I live on a farm and have easy access to a ladder and fruit picking buckets. The ladder is a tripod of about 6in/2m or so depending on how you position the legs, so I hung some rope on it and tied the bucket to it with wire and a crimp connector. I could roughly measure the strength by filling a bucket with water from a measuring cup until the joint came apart. The plastic bucket weighs very little, but since my resolution is a liter of water, or about 10 newtons, if you take slight liberties with the strength of British gravity, I’d say it’s within experimental error.
It was probably one of the weirdest things I’ve ever done on Hackaday, sitting in the sun and slowly pouring water into a bucket. If any of you feel the need to do this, a good tip is to hang the bucket about 25mm above the ground as there is a lot of potential energy in the water when the connection is loose and the bucket could break. . bucket. In fact, every failure resulted in an impressive splash and slightly wet feet, but in the world of farmhouse projects, you have to accept that there’s a bumpy road ahead.
We can immediately see that my vice does not produce good results, since the breaking force is only 50 Newtons. This isn’t surprising, but it’s worth documenting. It’s also not surprising that ratcheting pliers produce stronger results than regular pliers, which may be a result of the better shape and its leverage. Surprisingly, they work much better, but since the purpose of a crimp connection is electrical and not physical, that doesn’t mean that 140N of a simple crimp connection isn’t strong enough.
So, we have established that you get what you pay for in terms of the strength of the joints formed with this crimping tool. So, in our other area of evaluation, what about connected resistors? This is where we immediately run into a problem, and it lies in the tiny resistors involved. Crimp connectors are designed to provide the best possible connection so they have very little resistance. To measure resistance in the milliohm range, it is almost impossible to pick up a reliable multimeter and disconnect the probe. We live in a world where resistance is measured in kiloohms, and conventional devices are not designed for such low resistance values.
I toyed with several ideas to solve this problem and finally settled on a current limiting power supply. My multimeter is good at measuring tiny voltages, so if I apply the same constant current to all the different crimp connections, I can measure the voltage across them for a given current and use Ohm’s law to determine the resistance. We set Ryden’s ubiquitous switching regulator module to its maximum current setting of 5A and measured the voltage across all three crimp connectors and the same length of wire. The obtained values along with the calculated resistance are shown in the table below.
At first glance, this seems like a clear but unexpected story that crimp connections made with simple crimping pliers have the least resistance, but the reality is a serious contradiction. Even by switching to voltage readings, we’re measuring at the lower end of what a cheap multimeter can measure, and relying on the current limiters on cheap regulator modules to be the benchmark for measurement performance is a strategy that will never work. all the best. Thus, these readings have a significant margin of error and are therefore not as clear-cut as the numbers themselves would lead us to believe. These numbers do tell us that there is a noticeable difference between the two dedicated crimping tools and pliers, but as long as the crimp is compressed properly, it will have very little effect on the final resistance.
So, having delved deeper into the properties of crimp connections than ever before, I’ve come to the conclusion that while it’s nice to have a pair of fancy ratchet crimp pliers on your desk, they’re really no better than the basic ones. much better than I originally thought. At the same time, no one should expect standard pliers to do a good job of crimping, and I have proven that to be the case. All this information about crimp connections, showing that if you use the right tools, you can get a very strong, ultra-low resistance connection at a very low cost per crimp connector, has me intrigued by these ubiquitous connectors. New respect.
First. Avoid those terrible pre-insulated crimpers. It’s impossible to get a good curl on that pesky plastic.
Purchase several double crimp types that can also be crimped onto wire insulation. As well as appropriately sized crimping tools and W-shaped crimping tools. Then put on the insulating sleeve or heat shrink tubing. .
Now if only they could make heat shrinkable versions of the threaded connector sleeves for the RF connectors…
This is called shrink tape, and if you use it, be sure to follow the instructions. https://buyheatshrink.com/heatshrinktubing/heat-shrinkable-insulation-tape.php
This is called self-adhesive silicone tape. Look for the good stuff “Mil Spec AA-59163/Mil-I-46852″.
Like many articles on Hackaday, this one performs a valuable service: rather than trying to tell everyone about the “best” solution and making fun of the less successful ones, it provides information about what the reader might have or find. Information about tools and materials. Local hardware store.
Fair. The point is, if you have nothing and need to invest in tongs and pliers, don’t buy them, buy the right ones 
Buying is probably the wrong word. I think the phrase “found in a trash heap” is appropriate. Spend money on parts haha.
But overall I find them to be just as useless as those non-ratchet crimping pliers. If you buy them, you might as well burn your money, it will give the same results.
If you don’t have one and feel the need to invest in crimping, consider purchasing a soldering iron or soldering solution that is suitable for the size of wire you want to join.
^ this. I always use insulating pliers but I try to buy decent Amp/Tyco pliers and if used with a decent ratchet pliers (mine are only £30 but they are good quality and work great) they are absolutely fine.
I’ve used both £1000 and £1 tongs and without a doubt one is better, but if you know what a good tong looks like you can make it work with £1 tongs and if you didn’t know , then even for a pound. 1000 tongs can save you.
I prefer the TE PIDG insulating crimp. http://www.te.com/usa-en/products/terminals-splices/intersection/pidg-terminals-splices.html?tab=pgp-story The insulating layer is nylon or PVC, partially transparent, and the crimp itself is metallic a ferrule that grips the insulation for two-point crimping. They are used in avionics and are quite expensive, but they are some of the best crimp connectors I have ever encountered. Unfortunately, these products of similar quality are not available from overseas sources.
I searched their website for “bullet” connectors commonly found in older cars/trucks and they showed “something else”! (Probably for shooting! B^)
The role of the ratchet mechanism is to provide control of the crimp cycle. Now my left wrist is injured in a skating accident. I won’t be able to squeeze as hard as I did yesterday. Crimping with anything other than a ratchet crimper only guarantees one thing: zero consistency. It works on the same principle as a torque wrench. If the crimper is working correctly, it will not release until the set point is reached. I have used and continue to use Sargent’s controlled cycle crimper. In addition, the quality of the terminals used has a great influence on the quality of the crimp.
The “sticky” crimper should be squeezed until it reaches the mechanical stop, and if you do this you will get fairly consistent results. If you are not getting consistent results, you are using the wrong tool.
That’s all. You can still make a better crimp using hand tools, but you can just as easily make a bad crimp. Ratchet tools always provide good crimps.
I have always believed that soldering is better than crimping, but there is no experimental evidence. Experiments comparing solder and crimp should likely include long-term stability in salty or corrosive environments.
My understanding of low resistance measurements for decades is that the double Kelvin bridge is the best method.
The problem with welding is not that it fails or is too susceptible to corrosion – evidence shows that the knob and tube wiring that powers millions of homes is welded and wrapped in rubber/asphalt tape.
The main problem with welding is that it is not idiot proof. Neither crimps, but using ratchet pliers is almost impossible to mess up;
When we were taught welding in college, the rule was that the connection must be both electrically and mechanically safe before welding. You can apply solder to the crimp. I used to do this until I started noticing that the stranded wire was breaking where the solder stopped moving up. This will always be a YMMV thing.
I saw that too, but I don’t think it’s YMMV. The problem with soldering stranded wire is that when you bend it close to the end of the solder, the solder becomes a (very poor) stress reliever. The strands on the outside of the bend take on the entire load and break.
This largely depends on your environment. In robotic applications, solder is inferior to crimp because it acts as a voltage riser and can penetrate wiring. The length of wire that can compromise its flexibility varies and is much longer than when crimped. In contrast, good crimp connectors have strain relief (see the wings that hold the insulation on the crimp pins) and permanent strain relief can be added. Additionally, crimpers have fewer issues with extreme temperatures (see 3D printer hot ends, ovens, etc.) and fewer issues with temperature cycling. However, if you do not require kinematic stress relief, solder is more compact, has very low resistance, is quite strong in tension (Lineman joints, etc.) and is easier to mass produce. Corrosion resistance depends largely on the environment and methods. A good crimp is sealed to the wire itself, as is a solder joint, meaning they are probably equivalent if it is a dry environment without a corrosive atmosphere. Both are heat shrinkable and include tubes coated with hot melt adhesive, meaning both can easily be made waterproof (one could argue that applying heat shrink to the crimp piece first is better than remembering to use heat to shrink the solder joints).
So unless you are using wiring that can be moved or requires reconnection (i.e. unscrewing a terminal and then replacing it with another terminal), soldering may be cheaper and, with practice, faster. If you need to be able to move the wiring during connections or between connection points, it is better to use a crimp. Anyone who tins screw terminals is in for a tough time.
Soldering crimp connectors is a bad practice because it creates a huge stress point where the wire exits the solder. If you need to solder to get a good connection, you should use a better quality crimping tool. What is the cost of disconnection? The cheapest thing to do is to do it right the first time.
It is true that soldering crimp (and some other types) connectors increases the likelihood that extreme vibration will cause the wire to harden and break. In my solar system, there is no problem connecting No. 2 to No. 000, just crimping can cause a fire with a load of 1000 A and charging current. You wouldn’t shake a 2-ton battery (or, for that matter, a “wire” made from 10 strands of wire larger than yours…) hard enough to cause joint fatigue – and if you did, then something really went wrong.
However, relying on crimping for good stress relief is a cop-out. If something like this is a problem, you should solve it in other ways*. With the exception of repairs, most things should not allow much variation.
I worked as a stereo repairman in the 1970s. The fact that the wires can support the weight (including the weight of the wires as well as any large components such as electrolytes) is one of the top 5 causes of failure, followed by… Using only solder to secure the headphone jack (In this case, in the case , if half the solder joints have failed, or the rails have come off the board, or the board has broken). I also fixed a lot of bad wires that failed at the end of a good strain relief – they were too stiff compared to the wire, although much more flexible than I’ve seen in press-fit connectors.
Well, that must be why the electricians soldered all the connections to our new 480V, 200A transformer and load center…oh, no, wait, they used screw terminals. There is nothing wrong with using mechanical connections for high power loads.
I repair musical equipment – amplifiers, etc. These days, lead-free soldering means PC mount sockets burn solder joints first, but I’ve seen some PCB lifters before.
Crimping works very well at high currents, you only need very expensive dies and tools: https://uk.rs-online.com/web/p/crimp-tools/0445885/
A good crimp creates a tight connection, so there are no problems with corrosion, at least internally. As others have said, soldering creates a stress point where the solder moves up the wire. That’s where they break.
FYI… The FAA prohibits soldering connections! Sometimes they do things just to be an asshole, but others… it’s for a reason! Vibration will eventually lead to failure. But there is no AAA at 30K feet. 
It’s a classic internet argument that the TL;DR is that soldering or crimping is equally effective and works great if done correctly.
Post time: May-24-2024