Crimping tools (UK) again.. (non-insulated/open barrel crimps) - Page 1
Forum section: electronics / projects

author: Buriedcode
author_rank: Super Contributor
timestamp: August 18, 2025, 07:17:41 pm
content: So far in my career I have managed to only use a handful of crimp connectors for work, and lucked out on a cheap rachet crimper - no-bame brand - that does a surprisingly good job of "dupont" and Molex KK terminals, done thousands. But I'm currently rewiring mains equiment and its full of6.3/4.8mm fastons, or whatever the generic name is.It looks like the wiring has failed at the crimps (melting/burnt insulation right at the crimp), they've used the insulated crimps, and 6 strand thick copper wire, which just isn't suitable for crimping. And it looks like the crimps weren't done tight enough - not that you can see the result given the insulation.So I'm replacing all the wiring with decent stranded type, but need a half decent crimping tool. I can't see me doing this work all day every day, so I just can't justify the >£100 types, but given the current rating (16A on the power in) I don't want to mash these up with the cheaper pliers. And I dont' like the pre-insulated types since you can't really see the crimp.So just pinging anyone who owns some crimping tools for the open barrel faston/spade connectors - the type with a seperate shroud. The web isfullof generic types, brands (Iwiss, Precivica, Knipex) and model numbers (SN-58B, 48B, 28B etc..). I'll be using 14AWG on the power and 16/18 on the much lower current wires.I'm tempted to just buy a few really cheap (£15-20) just to test, but a post on a forum in case anyone has specific models that work is free. Attached an image of the type just in case there is any ambiguity.And I have these exact terminals:https://www.rapidonline.com/truconnect-female-crimp-receptacle-6-3mm-22-16-awg-pack-of-100-33-0270

author: shabaz
author_rank: Frequent Contributor
timestamp: August 18, 2025, 08:06:13 pm
content: Hi,Knipex has a tool for this that works really well, but price is circa 200 GBP. However the die photo is attached, so you can see what the shape should look like for those non-insulated crimps (those three die positions support 6.3 and 4.8 mm).This one is a much better price (36 GBP) and looks like it has a suitable die, but I've not tried it:https://www.rapidonline.com/toolcraft-1486699-crimper-non-insulated-connectors-0-5-6-mm-reliable-07-7062This Knipex page indicates the crimp terminal size and supported wire AWG range, for the dies:https://www.knipex.com/en-uk/products/crimping-pliers/crimping-dies-for-manual-and-electromechanical-knipex-crimp-system-pliers-art-no-97-43-xx/crimping-dies-manual-and-electromechanical-knipex-crimp-system-pliers-art-no-xx/974905For quite thick metal crimps, there is TE Faston 250 e.g. an example part code: 5-160432-4) (for 6.3 mm but I think there is 4.8 mm in that range or a similar range)EDIT: It's not a very high quality image, but I've added a photo showing a crimped result using that die shape (with the Knipex tool and Faston 250).

author: Benta
author_rank: Super Contributor
timestamp: August 18, 2025, 09:07:05 pm
content: I have this 25 Euro one and it works perfectly.The supplied connectors are crap, though.https://www.amazon.de/dp/B07H4LCNKT

author: artag
author_rank: Super Contributor
timestamp: August 18, 2025, 10:03:03 pm
content: Miniature connectors like Dupont need the right tools - or your lucky acquisition - but I've never had a problem with the insulated ones - there seem to be plenty of tools (as long as you get the locking ratchet type, not the crude pliers) which work well.I don't use the uninsulated ones but if the Rapid example is the same as those common tools (just with the right die for uninsulated terminals) I'd be pretty confident of a good result.Ideally, do a pull test. It feels wrong to try to destroy your careful and beautiful crimp but if the earlier worker had done that it might not have needed doing twice !

author: Benta
author_rank: Super Contributor
timestamp: August 19, 2025, 12:05:58 am
content: The insulated crimps are total garbage and the reason why the OP has problems.Forget those.

author: Buriedcode
author_rank: Super Contributor
timestamp: August 22, 2025, 03:25:32 am
content: I've ordered a couple of "cheap" ones - fully expecting to have to buy some decent ones, but I'm just too curious to not take the opportunity to at least see what these are like. I have some decent terminals on order too to test, because its the only way to fairly test...Because, yes, often they are bundled with a load of crimp terminals that are almost always awful. Weirdly, the "cheap" insulated terminals, actually look quite decent, thick walled, tin plated brass, but I avoid them on principle.The non-insulated (note: other search terms for these are, "uninsuated", "open barrel", and "cable lugs") terminals that get sent with tools tend to be almost like foil. I ordered a batch of 30 for.. a £1.50, (not going to name and shame the seller, but its from a place that begins with "A" and ends in "mazon".) .. again just to see, and I can bend them in half with one hand. Any crimp tool will happily mangle those, and I would be surprised if they gripped a spade terminal at all. I wonder how many terrible reviews of the tools are because people inevitably test them with the terminal provided?

author: tooki
author_rank: Super Contributor
timestamp: August 22, 2025, 12:29:34 pm
content: Quote from: Benta on August 19, 2025, 12:05:58 amThey are fine if done properly. That means, as with any crimped connection:1. The terminal is of high quality.2. The wire used is correctly matched to the terminal.3. It is crimped with the correct tool, used properly.I use insulated terminals all the time at work. But I use name-brand terminals, and good Knipex tools. They pass pull tests, which bad crimps generally do not.A huge problem is cheap terminals from aliexpress, etc. The sheet metal they’re made of is too thin to begin with, but even worse, they skip a critical manufacturing step: annealing. After the contacts are shaped, they are left work-hardened, which causes them to fracture or just spring back after crimping. So they must be annealed to restore their plasticity so that crimping works.Matching wire size to terminal is critical. I have seen bad crimps in devices where a too-large terminal was used for the wire. Similarly, I’ve seen some where the terminal was correctly matched, but crimped in the wrong cavity (e.g. a red terminal crimped in the blue cavity).Finally, it is important to know that there are, broadly speaking, three different types of insulated crimps:- standard (PVC or nylon non-shrinking insulator, over a single or double-layered conductor crimp barrel), e.g. TE/AMP Plasti-Grip and Molex InsulKrimp- “luxury” (PVC or nylon non-shrinking insulator, over a double-layer conductor crimp barrel with a metal crimp barrel for the insulation), e.g. TE/AMP PIDG and Molex AviKrimp- heat-shrink insulatedEach of these requires a different crimp shape. But within each type, they’re basically interchangeable between brands, so you can use one brand of crimper and another brand of terminals. (That is much less so with open-barrel uninsulated crimps, like OP is after.)

author: tooki
author_rank: Super Contributor
timestamp: August 22, 2025, 12:35:07 pm
content: Quote from: Buriedcode on August 22, 2025, 03:25:32 amI completely agree. Years ago I bought cheap crimpers and insulated terminals from China, and found them to be very fickle to crimp reliably, only gripping tight if used with the very maximum wire size for a terminal, if at all, or by overcrimping in one cavity smaller than normal. I also initially blamed the tools. But then I tried those terminals with good crimp tools at work, and found they failed then, too. The same tools that consistently produce good crimps with name brand terminals.I’ve since started testing my cheap crimpers with good terminals, and some of the tools are actually fine.

author: Buriedcode
author_rank: Super Contributor
timestamp: September 08, 2025, 09:14:05 am
content: Well I haven't forgotten about this thread, and have a couple of new crimp tools (and terminals) to test and photo to post here. I don't have a decent camera but will try at least to show a comparison between tools with two types of temrinals (JST decent ones, vs, the thin ones all over ebay).But I have another question/request thats too related to create a new topic, so I'm tacking it on here.On one of the units I'm working on, a mains terminal connection (6.35x0.8 spade/faston) is really too close to a low-voltage PCB for my liking - the 14AWG wire that connects to this is squished up against a PCB with a ground plane that the user could make contact with. Sure its power supply is double insulated, but the fact there is only wire insulation isolating it bothers me, especially since the last failure with this very insuation. So.. to save space I thought about usingflag terminals. - This will create a clearance of about 6mm off the board, since the wire comes off at 90 degrees rather than straight out and hving to bend.The trouble is, these will of course require another tool, but there are both insulated, and uninsulated terminals. There seems to be a standard for the Nylon insulated ones, where-as the non-insulated requires a much better match between terminal and tool - thousands of types of terminal, and many types of crimping tool. So once again, I'm out of my depth. My question is:has anyone tried the insulated Nylon flag terminals?Example image added to the end of the post.Again, I instinctively dislike insulated/covered crimps, because one cannot directly see the connection, so its almost blind faith that its a decent crimp. With that said, these nylon ones are semi transparent, and TE connectivity makes quite a few - so they can't be that unreliable. They are also much more widely avaiable, and the crimping tool for them seems to be cheaperandmore standarised. It pains me to have to buy yetanothercromping tool for something that is rather specialised, but as this unit can run up to 16A and the original wiring was so poor, I'm not leaving things to chance - I might even make a loss on this job, but I want it done properly.

author: tooki
author_rank: Super Contributor
timestamp: September 08, 2025, 07:35:58 pm
content: Do you already have a decent crimper for regular insulated terminals? If so, there’s a very specific style of insulated flag terminals, which they call the “long barrel” style, that are specifically designed to work in an ordinary tool for straight terminals. I have tried the ones from Panduit (DNFR18-250B specifically) and they seem to work well. Other companies make them too, but they are somewhat hard to find.Note that Panduit makes both types, so be careful when choosing part numbers. You want the ones that end in -B, NOT in -FIB. See the attached drawing for the ones you want. (Note that the -L or -M suffix after -B is just the package size.P.S. I used to be more leery of insulated terminals, but since I started using only name-brand terminals with a name-brand tool, I’ve become much more comfortable with them.