I have a multi conductor cable with very small wires. I guess 22 or 24 gauge. ( Its an antique printer cable from when the wires were way bigger) I'm trying to spread all the wires out to a small terminal strip and I'm having a couple problems.
First, my wire stripper wants to pull out several strands of wire when trying to pull off a short length of insulation. This is just the standard multi electrical pliers type multi tool that strips up to #10 wire. Do I need a better tool or a better method.
Second, I don't want a failure of the wire under the terminal strip screw. I'm thinking of folding back 1/2 inch of bare wire to double it and then solder tinning the end to make it durable. or, is there a better way?
Karl The best way to strip thin wires is with a Stripmaster (made by Ideal) or similar tool; it has blades notched for each wire size, the blades can be changed for different wire sizes. If you are using terminal strip, try to find the type with wire protection leaves, in these the screw bears on the leaf preventing the wire from fracturing; alternatively crimp boot lace ferrules onto the wires (small plated copper or brass tubes) to protect them. Tinning the wires tends to make them behave like a solid wire and can lead to a complete fracture of all the strands, also the solder can creep under pressure leading to a loose connection. Martin
Karl, I started off wiring my CNC controller box with printer cable like you are doing. It became so frustrating and unreliable that I got a solder-tail connector for the end of the cable then used short lengths of 'real' hookup wire, terminated with crimp-on loops, to run from the connector to the end point. The connector is mounted in a D-cutout in the case, isolated to avoid ground loops.
Note: All standard PC cables have shields and bodies connected at both ends, often requiring a 'shieldectomy' on one end.
My suggestion would be *not* terminate those under screws.
If it's a standard, double screw terminal board barrier strip, take out one of the screws and solder the wires directly to the terminal.
To strip those I use a standard el-cheapo stripper made of what looks like strap iron. Those typically have a limit screw that allows them to only close so far, so the V-shaped notches only cut the insulation. I find that the simple ones work better, overall, than the fancy ones.
I suggest you do like I do, and throw away the limit screw, and do it by feel.
Strip only 0.1 inch or so of insulation, and tin the wires without melting much of the insulation if you can. If you can get the solder to flow up under the insulation a bit, that's OK even if it cooks up the plastic a teeny bit. Gives it extra strength at the stress point.
Then tin the barrier strip, and then tack the wires onto the region where you tinned them.
The key to this approach is you need to mechanically strain relieve the cable jacket near the strip so the wires *never* see any stress. Unless you have a strain relief set up somehow, I would suggest you drill a couple of holes in whatever is supporting the barrier strip. Drill two pairs of holes, with each pair separated by about the diameter of the cable jacket. Then pass a nylon zip tie through the holes from underneath and cinch them down across the cable jacket, immobilizing it.
The trouble with crimp or solder lugs on conductors of this size, is that eventually the wire will flex near the termination and fail at that point. Also it's tough to get crimp lugs that work really reliably on 24 gage conductors.
A microscope is actually pretty handy for stuff like this.
AWG22/24 wire is nice hefty hookup wire by my standards, but if you don't have the right size of terminal block etc. I suppose it could be troublesome.
If it's the kind of terminal block with two screws and a link, and the wires are big enough, you could crimp insulated lugs onto the wires (onto the wire, and another crimp onto the insulation as a strain relief) and then put those under the screws. This is okay for 12V at a few mA or higher, but if the voltage or current are very low, you need a good crimp that might require a more professional tool than the hardware store kind. Don't try to use automotive type crimp terminals designed for huge fat wires, get ahold of some electronic ones (probably not at Radio Shack).
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The really good professional ratchet ('controlled cycle') crimp tools are pretty pricey new, a couple hundred dollars up, plus die sets, but they show up on ebay regularly for a fraction of that.
Ordinary fingernail or toenail clippers make ver good wire strippers for the folks who couldn't spring for the spendy ones. Just file a groove in each side to make a notch for your wire.
This is the Ideal tool Spehro refers to. They nick most of the way thru the insulation but not quite to the wire, then pull on the insulation to separate it at the nick. I have one I've been using since 1966 that has stripped a lot of 24 and 26 gage wire
As Jim said, if you tin it be sure you have very good strain relief. Tinned stranded wire will not tolerate much flexing.
"jim rozen" wrote in message news: snipped-for-privacy@drn.newsguy.com... | In article , Karl | Townsend says... | >
| >I have a multi conductor cable with very small wires. I guess 22 or 24 | >gauge. | | Those are huge wires. :^) | | My suggestion would be *not* terminate those under screws. | | If it's a standard, double screw terminal board barrier strip, | take out one of the screws and solder the wires directly to | the terminal. | | To strip those I use a standard el-cheapo stripper made of | what looks like strap iron. Those typically have a limit | screw that allows them to only close so far, so the V-shaped | notches only cut the insulation. I find that the simple | ones work better, overall, than the fancy ones. | | I suggest you do like I do, and throw away the limit screw, | and do it by feel. | | Strip only 0.1 inch or so of insulation, and tin the wires | without melting much of the insulation if you can. If | you can get the solder to flow up under the insulation | a bit, that's OK even if it cooks up the plastic a teeny | bit. Gives it extra strength at the stress point. | | Then tin the barrier strip, and then tack the wires onto | the region where you tinned them. | | The key to this approach is you need to mechanically strain | relieve the cable jacket near the strip so the wires *never* | see any stress. Unless you have a strain relief set up | somehow, I would suggest you drill a couple of holes in | whatever is supporting the barrier strip. Drill two pairs | of holes, with each pair separated by about the diameter | of the cable jacket. Then pass a nylon zip tie through the | holes from underneath and cinch them down across the cable | jacket, immobilizing it. | | The trouble with crimp or solder lugs on conductors of this | size, is that eventually the wire will flex near the termination | and fail at that point. Also it's tough to get crimp lugs | that work really reliably on 24 gage conductors. | | A microscope is actually pretty handy for stuff like this. | | Jim |
I handle wires in the 24 gauge range all the time, and while Jim is right on about the issues, I'll add a few more.
Soldering wires this size (or any size of stranded wire, for that matter) creates a stress point at the spot where the solder stops. One side flexes, the other doesn't, so fatigue breaks the wire. It isn't enough to just support the wire near the joint, you really need to stick the whole thing down. I like silicone RTV for jobs like this. Just slather the joint and wires to about half an inch back (gotta go about 1/4" beyond the solder wick point) so that no part of the joint sees any sort of vibration. There are terminals and lugs made for this size wire. Amp is the common one I use, in aerospace grade, but there are others. This size usually takes special luggers, though. The terminals work best because they crimp the strands of wire (without solder) but most importantly have an insulation grip. Wires that size we also have to add shrink sleeving over the whole thing for more support.
At home, if I have to so something like this, I cut the end of the ribbon cable straight, and do not separate the wires yet. Mark the strip lengths on the end wires on both sides. Go get a brand new razor blade, and with the lightest touch, just nick the insulation on both sides with a single pressing motion, rather than a cutting motion, and not deep enough to get near the conductor. Fold the "tab" until you see strands on both sides, indicating that the insulation has "ripped" clean through. Now, gently separate the conductors without removing the insulated part of the wire. Only at the very last moment when you are ready to make the connection will you gently pull the piece of insulation off. You will find it is perfect, stranded neatly still, and nick free. If you have to tin it, put a _wiped off_ iron tip on the wire in the middle of the exposed strands. Touch your
65/35 (not 60/40!) solder to the end of the wire and you will see the solder wick to just beyond the iron tip. As son as the wire starts to wick up the solder, pull the iron and solder away. You'll get more wicking when you do the next solder operation, so you need a small dollop of solder at the joint already in place. Melt the dollop, insert the wire, and pull the iron away quickly. If you use 65/35, you will not get a cold joint and the wicking will be at a very minimum. If you prefer, Rat Shack used to/still sells flat tipped alligator clips that you could use for anti wicking tweezers, but they always took up too much open space on the strands for my taste.
Slathering RTV on there may not be the best idea. There are two types of RTV. A two part mix and one that cures by adsorbing moisture out of the air. The latter produces an organic acid similar to acetic acid. This will attack the lead in the solder and cause the solder joint to fail. It will take a while and may not cause you any problem. However I know it has happened and it cost you the taxpayers a bunch of money. Dan
You could adapt a pin header to your terminal strip, and use a mating connector on the cable end, or mount the pin header on the circuit board (if that's what you're working with). Many of the cable connectors are insulation displacement types (IDC) and provide some support for the cable by firmly gripping the cable's insulation. You didn't specifically say flat ribbon cable, so an IDC connector might not be ideal.
Soldering fine stranded wire isn't usually a good idea, as the other replies mentioned, if the cable flexes the wires will break at the point where the solder stops. Using hot glue instead of RTV is a better solution if there isn't adequate space for a mechanical clamp. I would rarely suggest this method, but the stripped section of bare wire could be wrapped around the insulated end of each conductor, and the terminal screw snugged firmly against the end. This isn't an approved method by any standard, but I might consider it for signal conductors, not power connections.
The trouble with using electrical pliers on fine wire is that the strippers are in the center of the tool usually, and even with a good tool such as Thomas & Betts, it's a little cumbersome. The T&B and better quality tools (such as the Ideal mentioned) have ground cutters for the insulation. Before pulling the wire out, relax/loosen your grip on the tool, so the cutting edges aren't against the wire. Vaco and other electronic tool manufacturers make an inexpensive stripper with an adjustable disk for setting the size of the cutter gap. These have the stripper at the end and are easier to use.
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For crimp pin terminals to use with small wire gages, the pins that are used in D-type connectors (the usual computer connectors) can be bought bare, even from that Shack store I think. These migh be too small for the wire you have. You'd probably want shrink tubing over the crimp area extending to the insulated area for strain relief.
Molex male terminals provide tabs for holding the insulated area, but if they're not crimped with the correct tool, they won't grip very well. Again, you'd probably want to use shrink tubing.
We used to use Hotweezers (made by Meisei Corp.) on 28 AWG wire all the time. New ones are spendy, but sometimes they show up on E-Bay. I believe they're made in California, but the only website I can find for them is in the UK -- .
There was also the "Nickless" stripper, which used medium soft plastic to strip wires down to (at least) 28 ga. They deform over time, so get a wheel of replacement blades at the same time.
And there are strippers which use hot wire to melt through the insulation from both sides. I think that down around 22 ga you start getting too small for it to work well.
Ideally -- you strip the insulation only a short distance with a tool, and then pull it off while twisting (clockwise for most wire, but some has a CCW lay. This twist keeps the wires from fraying out, making the crimping easier.
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I agree that it is a common cable wire size. Ribbon cables for IDC connectors tend to be 28 or 30 ga.
The red insulated crimp terminals are for 22-16 ga, and the (relatively rare) small yellow insulated ones are for 26-24 ga, IIRC. Large yellow is for 12-10 ga, and regular blue for 16-14 ga. Each uses its own size of dies -- or separate crimper if you get the *good* cycle controlled ones made by AMP. When new, these have a color on the ends of the handles showing which size terminal should be used, but this chips off over the years, other than inside the handles. Most of them just have a handle color matching the terminal insulator, except for the crimper for the blue, which has one handle blue, and one green.
Note that the colors repeat through several cycles -- all the way up to 4-0 wire (blue). Past the 12-10 ga yellow comes red (8 ga), blue (6 ga), yellow (4 ga) red (2 ga), blue (1-0), yellow (2-0), red (3-0) and blue again at (4-0).
Those up through the yellow (12-10 ga) are purely mechanical. red (8 ga) through red (2 ga) are interchangeable dies which fit in a relatively small hydraulic crimp head, and blue (1-0) though blue (4-0) are interchangeable dies which fit a larger hydraulic crimp head. The smaller head is available in a hand-pumped self-contained unit. The larger head is either electrically pumped with automatic shutoff, or driven by a foot-operated pump. The smaller head is available detached for the electrical operation too. I'm still looking for a set of dies for the 4-0 size -- I have all of the rest.
Agreed. The ones which crimp the insulation support at the same time as the wire termination are called (by AMP) P.I.D.G (Pre Insulated Diamond Grip), and the terminals are sold with the same designation. Others are available, but with not as good an insulation grip.
For the standard Jones barrier strip, I would suggest that you get forked terminals to fit around the screw shanks. The ring type are more of a pain -- and you risk losing the screws. (As well, some of the terminal strips have the ends of the screws peened over so they don't come out easily.
Mouser does stock the small yellow terminals, if you really need them, but you will have to watch eBay for a bit longer to find those.
All of the AMP P.I.D.G. crimpers have adjustments for how tight the insulation crimp is, to adjust to differing thicknesses of insulation.
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