Pin header crimps that match SN-28B ? - Page 1
Forum section: electronics / general

author: 741
author_rank: Frequent Contributor
timestamp: July 21, 2021, 08:32:10 am
content: As this related thread mentionshttps://www.eevblog.com/forum/chat/crimp-tool-for-small-pinsthis tool needs much care to make a usable result. //Link correctedI've bought varous crimps on ebay, the longer ones are a bit easier to position in the tool. Usually though(a) There is some unwanted distortion is the resulting contact, it's a bit twisted(b) After some usage, the crimp's grip loosens and it becomes useless. This could be simply the pin header is a little larger then the crimp is designed to connect with. Given pin headers seem to be fairly standard though, I am not sure what the reason is.I'd be interested to know if there are crimps (pins and also sockets) which work especially well with this tool.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 21, 2021, 09:24:35 am
content: That link didn't work for me. This one did:https://www.eevblog.com/forum/chat/crimp-tool-for-small-pins/QuoteWhich tool? The SN-28B? That tool is covered in the other thread.

author: 741
author_rank: Frequent Contributor
timestamp: July 21, 2021, 11:39:21 am
content: Thanks for correcting the link.Yes the tool is mentioned as you say - I'm really after a current good-value source, maybe eBay, of pins known to work well with this, by someone who has used this tool a fair amount.I have just been using the tool today. The problem is that some of the crimps are a bit short. This means the part which should 'clink' into place inside the header mouding gets squashed.It is usually rather hard to tell from photos of crimps how these would sit inside the jaws of the SN-28B (mine is branded "WEIERLI").

author: Ranayna
author_rank: Super Contributor
timestamp: July 21, 2021, 01:47:18 pm
content: Maybe this thread is worth a read as well on this topic:https://www.eevblog.com/forum/reviews/affordable-crimp-tools-for-small-connectors-(dupont-etc-)/

author: jpanhalt
author_rank: Super Contributor
timestamp: July 21, 2021, 04:28:03 pm
content: Quote from: 741 on July 21, 2021, 11:39:21 amThat's what we might call getting the cart before the horse. Your design(s) should determine the best pins for the purpose. Then you get a crimper to work with those pins.That is apparently a poorly made generic crimper. Maybe the best fit would be the cheapest made in China pins you can find.

author: tooki
author_rank: Super Contributor
timestamp: July 21, 2021, 07:28:56 pm
content: There’s nothing inherently wrong with a decent quality SN-28B, other than the fact that it’s advertised for use with terminals it’s plainly not designed for. The “28” in the model number refers to 2.8mm spade terminals, which are much, much larger than DuPont, KK 254, and other 0.1” pitch contacts.Somehow the Chinese got the idea that all smallish open barrel crimp terminals are “DuPont”, and almost no vendors make any attempt to actually match tools to terminals, even if they carry the right tool! 🤦‍♂️

author: 741
author_rank: Frequent Contributor
timestamp: July 22, 2021, 08:01:19 am
content: Your design(s) should determine the best pins for the purpose. Then you get a crimper to work with those pins.Well OK - however - in my case at least - add the caveatSuch that the price of said crimper is within budgetSee also the 2nd paragraph of a link suggested above (https://www.eevblog.com/forum/reviews/affordable-crimp-tools-for-small-connectors-(dupont-etc-)),starting "In an ideal world..."The pins in question are what Farnell term "Pin Header, Board-to-Board, 2.54 mm", whether it is Molex KK 254 or something generic from eBay.Over the years my own experience has been that the cross-sections of various known and unknown brands are sufficiently alike that a standard commercially made cable (such as sometimes seen inside desktop PCs linking to HDD LED etc) fits any of the pins I've used very well.So here, the 'horse' (if I understand the analogy made correctly) is "nothing-special generic 2.54mm Pin headers". I have lots lying around here from various sources.As for the design, typically I use these pins for prototyping. The current requirement I have is to break out an emitter-detector pair (LED & PIN diode) - but normally the LEDs are soldered through-hole, direct to the PCB.If I did a design PCB using these pin-headers however, the BOM could say 'free issue', because pins from any source seem compatible with commercially made receptacle assemblies.The background research I did at the time of tool purchase led me to believe the SN-28B would be worth trying. With great care, lots of time, I can get fairly acceptable results, but only with the longer crimps.I'd perhaps be prepared to risk buying another tool, but I have not got hundreds of pounds available for that.The image shows the results I have.The crimp-pin (left side, purple sleeving) actually works well - but this is because the crimp itself is considerably simpler then the crimp-receptacle.On crimp-receptacle, you can see the distortions made though.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 22, 2021, 10:55:53 am
content: As a little perspective, here are the only crimpers I use:I have used ones like on the left (A) for well over 40 years. The bottom pair work well for butt splices in automotive/aircraft work. The top pair is more recent and works well with the larger Molex-type (0.156" spacing) pins.I got the center (B) crimpers about 30 years ago from Radio Shack. It works well with pins used for model servos (0.100" pitch). That seems to be similar to what you are using.Finally, I got the crimpers on the right (C) about 10 years ago. That is probably a "SN-28B" type. Its advantage over B is the compound action of the crimp. For the contacts you describe, I use either B or C. For really small stuff, I have better control with B, but will also use C. For 2-mm and 0.100" pitches, I usually use C. Two things about C you may not realize: 1) The amount of crimp is adjustable;and 2) You can release early before the automatic release engages.For crimp adjustment, there is a small ratcheting dial. For early release, there is a lever hidden by the jaws on the handgrip side that if moved releases the crimer.Some pins will be distorted a little, particularly if it is misplaced in the jaws or the crimp is too tight. I have no problem straightening those that bend a little. If the distortion is severe (rare), then I replace and redo. For small stuff, that's where the feel of the really cheap crimper (B) comes into play. I will often use a pair of needle nose pliers or "hemostat" to start the crimp, particularly at the part that grips the insulation.About the same time that I bought C, I was browsing through used equipment at HGR (a very large surplus/used equipment dealer in East Cleveland) and came across an industrial hand crimper by AMP (Model 90123-5-E, 24-18, Type F)*. It was very cheap (about $5). It has compound action, adjustable depth for pins or sockets, a ratchet, and what looks like a stripping gauge. The ratchet was hard to release early, so I removed that. It is still more awkward to used than the ones shown, and I almost never use it. I can appreciate that in a setting with always the same wire, stripping, and pin or socket, it give nice crimps, but for my hobby use, the bother is not worth it.*Here's a similar one on ebay:https://www.ebay.com/itm/AMP-90123-5-Hand-Crimping-Tool-Crimper-24-18-TYPE-F-/263792380755

author: 741
author_rank: Frequent Contributor
timestamp: July 23, 2021, 10:48:23 am
content: Many thanks indeed for the informationI have used the early release on occasion, but only when I felt the crimp was positioned badly when the ratchet first engaged. I might now try deliberately releasing early - and then maybe I can then adjust the ratchet so the auto release matches that. As it is though, the ratchet is set all the way to '-' (most clockwise), so I'm not sure of that yet.I now realise of course the SN-28B was not actually designed for the header type I use. But from what you say the SN-28B (image 'C') can be used with good results for my '0.1" pin header crimps' (?)It would be nice to have a close-up of the dies of your 'C' example - the dies on my crimper are shown below

author: jpanhalt
author_rank: Super Contributor
timestamp: July 23, 2021, 12:24:13 pm
content: Here you go. I do not have a really good Macro lens or lights. The first two are the cheaper crimpers that I use most. The last two are the expensive AMP crimper. It looks like the sharpness of machining (?) on my cheap ones is a little better than on yours and similar to the AMP.EDIT:Afterthought: I don't think the entry edges make much difference. The curl edges might. As mentioned, I usually pre-bend slightly past parallel the two wings that hold the insulation. That makes it easier to get the wire inserted to the right depth and hold it there.

author: ElektroQuark
author_rank: Unknown
timestamp: July 25, 2021, 06:09:05 am
content: FWIW here it is how I use my cheap SN-28B with cheap Chinese terminals:CLICK!It's a very short blog entry with clear images. Short text in Spanish but easily translatable.Hope this helps.

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 07:11:01 am
content: Quote from: ElektroQuark on July 25, 2021, 06:09:05 amThose aren’t DuPont terminals, they’re KF2510 (Molex KK 254 clone), which are MUCH more flexible about the crimp tool used. (Though a -28B is still nowhere near ideal for them, the jaws are too thick.)Quote from: ElektroQuark on July 25, 2021, 06:09:05 amYou don’t show any image of the top of the crimped terminal.

author: 741
author_rank: Frequent Contributor
timestamp: July 26, 2021, 10:49:16 am
content: Nice crisp images!The crimps I have are "not great", shown here for comparison.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 26, 2021, 11:35:09 am
content: The one in the foreground is too fuzzy to tell. The triangle style leaves for insulation support are most difficult to get right, in my experience. For them, I start the proper alignment and bend over manually before putting in the crimper; otherwise, they tend to go askew.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 26, 2021, 12:21:14 pm
content: I just pulled apart a couple of connector on my bench. Probably made about 5 years ago. All crimps were done with the green handled crimper I showed earlier.1) I categorize the "Berg" type, which is what you show and is sometimes called DuPont type, as being "indent" or "barb" retention. The Berg type is in my mind a female "pin" with a cantilevered contact. The company is now owned by Amphenol, I think. The indent retention is a cantilever on the housing that pops into the crimped side. The barb type has a barb on the non-crimped side of contact that pops into a hole on the housing. I prefer the indent type. They are easier to remove without any damage to the contact.2) The first photo shows a barb type retention, non-Berg contact at top. The barb was pressed into the contact to get it released. The bottom contact is a Berg type with indent retention. It also has the pointed leaves as discussed earlier. Notice, I clipped the very tips of the leaves off to facilitate crimping and insertion into the housing.3) The second photo is a close up of the Berg-type connector.

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 01:38:00 pm
content: Quote from: jpanhalt on July 26, 2021, 12:21:14 pmI feel this comment needs a lot of explanation.What's depicted here are a Molex KK 254 (or clone) contact and an Amphenol (formerly Berg) Mini-PV contact.What jpanhalt is talking about (for unknown reasons, since it wasn't the subject of the topic at all) is how the contacts are retained in the connector housings.On most connectors with stamped contacts (including KK 254, JST XH, AMPMODU Mod series), the retention is via a barb somewhere on the contact. On most barbed contacts, it's on the bottom, but some have it on the top (like Molex SL and C-Grid III) or on the side (like AMPMODU HE13/HE14). On larger connectors, it's common to have multiple barbs.On other connectors, like Mini-PV, JST PH, and the common Chinese "DuPont" (and the JST RE and RF series, which I suspect is the original that the Chinese DuPont clones are copies of), the barb is part of the housing, and clips onto part of the contact.Quote from: jpanhalt on July 26, 2021, 12:21:14 pmNeeding to trim the insulation crimp by cutting off the tips of the insulation crimp wings (they're called wings, not leaves) is a huge flashing red "WARNING, THIS AIN'T RIGHT" sign.The pointy, asymmetrical crimp wings are intended to hugaroundthe insulation, not biteintoit. This is one of the key things 99.9% of the Chinese crimpers marketed for DuPont pins get wrong. This insulation wing typerequiresa circular insulation crimp die. (Whereas the symmetrical, flat-ended insulation crimp wings can be used with either a circular die to hug around the insulation, or with an m-shape die to bite into the insulation.) Ergo, any crimper with an m-shape insulation die is categorically incapable of correctly crimping a DuPont terminal, and indeed aren't even capable of crimping them in a minimally passable way.This issue is all explained in detail in my thread that was already linked above:https://www.eevblog.com/forum/reviews/affordable-crimp-tools-for-small-connectors-(dupont-etc-)/

author: jpanhalt
author_rank: Super Contributor
timestamp: July 26, 2021, 02:24:20 pm
content: @tookiAs usual, no substantive input. The reason the pointed leaves are cut is to fit a very tight housing when using a cheap crimper that cannot smoothly wrap them. Any overlap is too big.How about showing those of us who don't know how, your successes using the same type of crimper and connectors with various mechanisms for insulation and retention, including but not limited to pointed leaves/wings?

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 04:21:26 pm
content: Quote from: jpanhalt on July 26, 2021, 02:24:20 pmHmm, there seems to be no emoji for the gesture I have in mind.Quote from: jpanhalt on July 26, 2021, 02:24:20 pmI got that. But that doesn't indicate to you that something is seriously wrong?!?Quote from: jpanhalt on July 26, 2021, 02:24:20 pmI dunno how many more times I need to say: the SN-28B is not suitable for crimping those terminals. I've explainedwhy. I've created an entire multi-page thread discussing numerous affordable options. But no, I guess none of that is "substantive"…I can't provide you any instructions for "successes" with DuPont contacts and an SN-28Bbecause it's categorically impossible to achieve. Nor have I yet encountered any other contacts for a 0.1" header that are not mangled in some way or another when crimped in an SN-28B, since its jaws are too thick for small contacts. The closest to working are the KK 254 type, but it still damages the contact and wire.Nor do I want to encourage people to try and wing it anyway: it's a bad idea, and given that there exist crimp toolsfor the same pricethat do a much better job, why screw around with the wrong tool? It's a fool's errand. So I'm not going to coddle you or anyone else by saying "oh, well you can press the SN-28B into service anyway and make do with it, here's how to make it 2% less sucky".What I can do (and was actually in the process of doing when you responded) is to dig out my DSLR, macro lens, and flashes, then find and take pictures of various contacts as crimped with various crimpers, to show what good and bad crimps look like.As for retention methods: huh? No part of that is up to the user as such; it's an inherent part of each connector design. Hence why I'm puzzled that you feel it needed discussion at all. You get the right contacts for a particular housing and that's that, the retention will work. (Provided you don't mangle the contact in the wrong crimper.) I'm not aware of any connector type where there were any choices of main retention mechanism. (Some connector families do offer optional secondary retention mechanisms that can be added on.)

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 04:37:53 pm
content: Quote from: 741 on July 21, 2021, 08:32:10 amUpshot is, no. The SN-28B is designed for much, much larger terminals, so it ends up mangling the contacts at the same time as not applying enough force to the conductor area, since it's just too big.Read the big thread herehttps://www.eevblog.com/forum/reviews/affordable-crimp-tools-for-small-connectors-(dupont-etc-)/for the best overview so far of both cheap crimpers and other websites with good info (there's a link there to a Matt somethingorother that has great info). But ultimately, it's almost like a sick joke, in that DuPont connectors are both the most common for hobbyists, yet also are one of the most fickle, needy contact types out there, with nobody producing a cheap tool that actually does atrulygood job on them.The TZ-4228B tool discussed in that thread is probably the closest so far. It's still not perfect (IMHO the DuPont crimps are a smidgen too loose with 24AWG wire; if I had to use it, I'd probably buy some thin-walled 22AWG wire instead), but it's the best so far of the ~$20 tools.All else held equal, if you can instead use the KK 254 (or clone) type, I find its contacts to be far more tolerant of the tool choice (the TZ-4228B, the IWS-3220M, as well as various "D-sub" tools like SN-01BM/-02BM/-03BM, HT-255D, etc work well), but the contacts themselves don't loosen up after a few insertions the way most DuPont female contacts do. The downside is that it only comes as a single-row connector.