Crimp tool for small pins - Page 1
Forum section: electronics / general

author: AdrianLevi
author_rank: Newbie
timestamp: March 16, 2021, 05:35:43 am
content: For many years I have struggled with the POS crimper from Jaycar for small Molex KK series connectors. What is out there? I just recently ordered a Pololu 1928https://www.pololu.com/product/1928from Core Electronics. I hope it's not crap!

author: nctnico
author_rank: Super Contributor
timestamp: March 16, 2021, 10:55:02 am
content: Quote from: AdrianLevi on March 16, 2021, 05:35:43 amFor this price you are better off ordering the original tool from Molex and be done with it (Molex number 640160201). The crimper you ordered doesn't list Molex KK so it likely won't be suitable anyway.

author: tooki
author_rank: Super Contributor
timestamp: March 16, 2021, 11:11:03 am
content: Quote from: AdrianLevi on March 16, 2021, 05:35:43 amThat looks like a standard SN-28B.I address it (with Molex KK) in mysmall crimper overview thread.It should work, but is not ideal, especially with thinner wire. (I use 24AWG/0.22mm2 or 0.25mm2 with them.)One of the crimpers sold for D-sub pins is a better match.At least, generally speaking, the Molex KK 254 (and its clones, like KF2540) is relatively tolerant as far as crimp tools, unlike the DuPont pins, which are much pickier.With that said, the original tool ntcnico lists above is a really good choice if your budget allows. And it’s good for a number of other contacts too.

author: ajb
author_rank: Super Contributor
timestamp: March 16, 2021, 04:05:00 pm
content: $140 isn't all that bad for a proper crimp tool from the connector manufacturer, especially since it does four different connector families. Other tools are commonly $3-500 and may only do part of one connector family (like only some of the supported wire gauges or contact variants), and some of the really annoying ones can be a couple thousand--really specialized tools such as for avionics can be ten times that, and need to be calibrated for reliability. If you do any kind of volume, first-party tools really are worth considering for efficiency and reliability. For a handful of terminals, sure, you can mess around with a generic tool and probably get okay results, but it's going to be harder and slower and less reliable.There are three big things that really make most first-party tools worthwhile: die geometry, contact positioning features, and wire locating features.Die geometry is the most important to getting a good crimp, if the geometry doesn't match the terminal it won't form the tabs optimally, and you may get a good crimp but at the expense of causing stress concentrations in the terminal, even up to cracks in the formed areas in really bad cases, possibly over- or under-crimping the insulation tabs relative to the conductor tabs, and in really bad cases the crimped terminal may not fit into the housing correctly. Tools that require two separate crimps for the conductor and insulation can also tend to bend the terminal, requiring manual straightening to get them into the housing. A related matter is the surface finish on the dies. The terminals will, to an extent, take on the surface finish of the forming geometry, and when that finish is rough, the terminals are formed into the bumps and valleys and scratches in the die surfaces, which can make them a real pain to remove after crimping. First-party tools generally have very good finish (some third-party ones do too, to be fair), and the crimped terminals simply fall out of the dies when the tool is opened, versus some of the bad generic tools where after applying enough pressure to get a good crimp you have to pry the terminals out of the dies.Contact positioning makes a crimp tool VASTLY easier to use and more reliable. This is extremely important on small terminals -- KK are not too bad, but JST ZH (1.5mm pitch) would be a nightmare without it. Many generic tools require the user to very carefully position the terminal in the dies, and when the dies are a poor match to the terminal geometry this can be quite tricky. I've dealt with crimp tools that sometimes require the terminal to be pre-formed a bit to prevent it from rotating in the dies and destroying the terminal when crimped. The mechanisms on good tools vary, on that Molex tool there's a little spring-loaded hold-down, the Molex Mini-Fit tools we have use a block that slides forward into the crimp area with little receptacles to hold the terminals, and JST tools tend to use a flap with little receptacles, but they all work quite well. The JST ones need the locating flap replaced after a few thousand crimps, which is like a $28 part at digikey, which is a minor annoyance but worthwhile for the benefit they provide.Wire positioning is also something that generic tools tend to rely on user skill for, but a lot of first-party tools include either an end stop for the stripped bit of the wire (like that Molex tool) or have a slotted blade that the end of the insulation can be pressed against. This makes it way easier to ensure that the end of the insulation ends up in the correct location between the (usually) two sets of crimp ears, and again makes for a much more reliable and easier crimp process.Unfortunately not every connector family has (accessible) manual crimp tools. At one point we were buying in a component that had some tiny 1.5mm connectors for which there was no basic hand tool that I could find--just the very expensive and single-purpose semi-automatic bench mount tools at many thousands of dollars. I spent many hours trying to crimp enough of those tiny little 1.5mm terminals using generic tools so we could wire up test systems and prototypes until the harness assemblies we jobbed out came in, it sucked HARD. It's well worth considering the tooling availability/cost of the connector families you design into your projects/products, especially if you're doing anything commercial, where I'd go so far as to say you NEED to be using proper tooling, and should therefore budget for it as part of production. It's easy to get caught up in the price of the connectors, which makes sense as your volumes go up, but you have to consider the tooling and harness production cost as well, and sometimes it makes sense to consider tooling an investment across all of your products/production. There's no single connector family that works for everything, but you can probably cover 95% of what you need with two or three tools if you choose the connectors carefully.Edit to add: I understand that even $140 for a tool can sting as a hobbyist (or hobby business). If you don't have the money for it, then it is what it is and you do the best you can with what you can afford. But if you do, you might consider whether you want your hobby to be building electronic devices, or futzing around trying to get good crimps from the wrong tools. Or as an intermediate solution, a lot of connector manufacturers sell pre-crimped individual wire leads or even wire assemblies for a fairly reasonable price if you only need a small number. IMHO even hobby time, where possible, should be treated as the limited asset it is, and it can be well worth spending a bit of money to make that time go farther.

author: tooki
author_rank: Super Contributor
timestamp: March 18, 2021, 04:30:05 pm
content: Quote from: nctnico on March 16, 2021, 10:55:02 amI meant to add: those crimpers also aren’t suited to many of the connectors theydolist! I continue to be baffled as to why the Chinese crimper industry decided to market the SN-28B (intended for 2.8mm spade/Faston connectors) as general-purpose crimpers for small connectors it’s not designed for.

author: nctnico
author_rank: Super Contributor
timestamp: March 18, 2021, 09:47:03 pm
content: I have the SN-28B as well but I only use it for very crude crimps in case I need to wire up a prototype using odd connectors. It isn't suitable for Molex KK or JST XH. For the latter a TNI-U TU-190-08 is a better choice.