soldering leads to a male KK connector?

I'm having a dickens of a time soldering leads onto a male 2-pin KK connector. It has these little pins (about 3 mm long, and 2 mm apart),
and I can't seem to get my lead wire and the pin to hold still well enough to heat both up with the soldering iron and get a good join.
Have other people managed to accomplish this feat? Is there some trick to it?
Or, should I try to avoid using male KK connectors in this way? Maybe they're only intended for soldering onto circuit boards, and if you want to join two female connectors together, you simply shove solid-core wire of some appropriate gauge in directly?
How do others who make use of KK connectors deal with this problem?
Thanks, - Joe
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ive done that before...normally i would just place the connector down on the table holding it down with some heavy object like a big plyer or sumthing...then just bend the tip of the wire a lil bit so dat it hooks in the KK connector...if you have a friend in would be easier as he could hold the wire in place while you solder the thing.,..then cover the whole thing with some heatshirnk to make sure theres no short circuit...
Joe Strout wrote:

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Joe Strout wrote:

Don't try to use Molex KK connectors for wire-to-wire connections. They're for wire-to-board connections, and there are no male parts designed to connect to wires. Even if you manage to get wires connected to pins, you won't have any locking or strain relief, so they're likely to fall out at some inconvenient moment.
There are other connector families for wire-to-wire connections. Find some crimp type connector, clip off the connectors you have, and use the right tool for the job. Get a Digi-Key catalog and look in there. Both Molex and 3M have good wire-to-wire connector systems.
If you really have to do this, get some KK type wire wrap header, with longer pins. Wire wrap to the long end of the pins, solder, and put shrink tubing over the soldered pins. This is tacky but will work.
                John Nagle
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Thanks. I'm still surprised (and a little frustrated) that the robotics community hasn't settled on any standard for wire-to-wire connectors. I first started looking for such a standard months ago, did a lot of research, and on the recommendation of many (who perhaps misunderstood the question), finally settled on Molex KK -- only to discover now that they're really not a good choice for this.
I actually contacted Molex and asked for a recommendation (for interlocking, polarized wire-to-wire connectors for carrying small to medium currents). The Molex tech rep recommended their "SL" product line. But nobody in the robotics community that I've spoken to seems to have heard of this, and one of my goals was to pick something already familiar to a lot of builders.
I want something like this because I'd like to take each of my individual components -- battery clips, motors, encoders, and so on -- and solder on shortish (10 cm?) leads with a standardized connector. Then, when assembling a robot, it would be largely a matter of plugging things together, using extension cables as needed to make stuff reach. I don't always know exactly how I'm going to use these things in the future, and I want to keep my options open.
But I feel like I'm swimming upstream here. What do other builders do? Do you sit down, decide to build a particular bot, and then solder leads and connections to fit that bot? And then if you ever take that apart and reuse the parts for something else, you just desolder them?
Or, maybe the need to plug components into each other is quite rare, and what you almost always do is plug them into a board. So maybe you just solder on reasonably generous leads, with a female 0.1" header on the end, and then plug these directly onto a board?
That latter approach makes some sense, except that I'm working toward modular bots, where the board may be in a completely different module -- or in some cases, there may not even be one (e.g., if you lack a controller module, you could plug the motors directly into the batteries and at least test the motor and wheels). So I don't see how to completely avoid the need for wire-to-wire connections. But maybe that need is unusual.
Thanks for any thoughts, - Joe
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Joe Strout wrote:
[snip John Nagle's wire-to-wire advice]

Do not be suprised. There are zillions of connectors out there and they all have their pro's and con's. The only connector that just about everybody could agree on was the BNC connector in the Ham market.
No such luck for us Robotics types!

[snip]
I can't speak for the robotics community as a whole, but I can explain my philosophy when in comes to interconnect.
In general, I want as few connectors as possible because connectors have a tendency to fail, or even worse become flaky. I never use extension cables. If I don't have a cable that is long enough, I will make one that *is* long enough. If a pair of motor leads is not long enough, I will solder on some extension wires and insulate with heat shrinkable tubing.
I tend to use .1" polorized male connectors on my PCB's. Most recently, I've been using the AMP MTA series which looks interchangable with the Molex KK series, although I can not state with certainty that they are interchangable. I have been using polarized female IDC connectors (e.g. Jameco 345965) where the wire can be "punched down" using an appropriate overpriced tool (e.g. Jameco 365974 ~$20.) I have found them to be pretty reliable. Occasionally, I get some wire with really thick insulation, in this situation it takes some extra effort to punch down the wire and get a reliable connection. I always verify my cables with an ohm meter.
Crimped wire connectors tend to be more reliable, but it can be a real struggle to learn how to crimp. A good crimping tool makes crimping easy, but can can cost $100+ where as the cheaper crimping tools require some art and skill to get a good connection.
In short, I would suggest you give up on the idea of extension cables. Just make them long enough in the first place. The choice of .1" Molex KK connectors is actually quite reasonable.
My $.02,
-Wayne
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