Tools for terminating high density cable connectors, Lemo, Fischer, etc - Page 1
Forum section: electronics / general

author: rx8pilot
author_rank: Super Contributor
timestamp: September 27, 2016, 04:24:25 am
content: For years I have done repairs on a variety of high-end connectors from Lemo, Fischer and others for the broadcast and entertainment industry. While they are fantastic in a lot of ways, they have very tight pin pitches and repairs are difficult.I am now in a position where I need to manufacture these from scratch in modest quantities which will clearly require a more engineered approach from what I have hacked in the past. Commercial assembly houses are available in my area but they are not practical for short turn around and constant changes which is our normal way of working. Wire prep is one of the first challenges. The jacket, shields and conductors have to be precision prepped to have a hope of a good final termination. I have a variety of typical wire cutting and stripping but they are not good for the very fine wires- especially being stripped to a precise length.Any recommends on production quality hand tools for fine wire prep? I have a thermal stripper but it is only effective to about 22ga and I would be in the 26-28AWG range with about 10-20 conductors. Maybe there is a thermal stripper specifically for small wires? On most connectors, the main jacket of the cable and the shield is only stripped a very short distance from the ends of the conductors. This makes it really difficult to strip the wires that are bundled fairly tight.The next challenge is more procedural. Getting the tiny conductors soldered to the tiny solder cups. Some connectors are crimp pins and some are solder. Start from the middle and work out? Are there any fixtures, grippers, or tweezers that can be the most helpful? I have enough experience to know that this is a practice, practice, practice type of skill but I would like to minimize the number of sacrificial connectors and hair pulling. In the end, I would like to develop a training program for an employee too.How do the professionals do this?

author: H.O
author_rank: Frequent Contributor
timestamp: September 27, 2016, 12:31:46 pm
content: I'm interested to see what comes out of this thread, what specialist tools etc are available (if any) to assemble these sorts of connectors. I feel there has to be "some" special tools because doing it "manually" is such a pain. Then again, these sorts of cables tends to cost quite a bit of money so I don't know, perhaps "they" are doing it the same way as we....Anyway, a while back I had to assemble a couple of Hirose HR25 series 16-pin connectors. To do that I manufactured a small fixture to which both the connector body and cable sort of snaps into and kept in place while still being able to rotate the assembly gain access all around the connector body, it worked fairly well but it obviously does nothing to help prepping the cable.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 27, 2016, 05:05:54 pm
content: I like that fixture. It looks simple and effective to manage alignment.Wondering if it is common to dip the conductors in flux/solder as a pre-tinning to prevent stray strands from ruining the termination. I struggle with stray strands, but I also struggle with pre-tinning when a small solder bulge prevents the wire from fitting into the cup of the pin.

author: nctnico
author_rank: Super Contributor
timestamp: September 29, 2016, 10:22:51 pm
content: When dealing connectors I try to connect the wires in the same order as they are in the cable so I don't have to bend and twist the wires into submission. And yes start with the centre conductors. Pre-tinning (especially lead free) starts with good quality solder and the right temperature.

author: H.O
author_rank: Frequent Contributor
timestamp: September 30, 2016, 01:38:03 pm
content: IME the decision on where to start highly depends on the type of connector.Doing MIL-C-5015 stuff, for example, it's a lot easier (for me at least) to do them row by row starting from the "bottom" and work yourself up because, at least the on the type we usually buy, the pins are pressed into a rubber body of the connector and doesn't want to rotate without a lot of force so it's tricky to get proper "access" to the soldercups from anywhere except above.On the Hirose connectors I mentioned previously the two center rows of pins are longer than the others and the cups faces opposite direction so there it was easier to start with one of the center rows and work outwards on either side.On yet others it might be easier to start with the center pin and work in circles/spiral out.Yes, trying to get a good "layout" is important (if you have the option to do that) so you don't have to cross a lot of wires. It's pretty easy if you have male/female connector at each end but more difficult when you have the same gender in both ends.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 30, 2016, 04:56:20 pm
content: Some of the LEMO connectors have a conical arrangement where the pins in the center are taller than the outside. Those, I think you would have to go with a spiral.It always seems the natural arrangement of the wires in the cable manages to alternate where the connector pins are. I wonder if making a 'wire aligner' would be useful - something like a disk with holes drilled in the same pattern as the pins. Strip the outer jacket much further than needed and put all the wires through alignment disk to get them crossed, un-twisted, and aligned before the final trim to length. That way (in theory) the wires would be the proper length after they are pulled to the termination point.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 01, 2016, 09:50:24 am
content: Quote from: nctnico on September 29, 2016, 10:22:51 pmYes, choosing the correct end of a cut cable is a good start - they ARE directional!

author: Dago
author_rank: Frequent Contributor
timestamp: October 11, 2016, 05:00:45 am
content: Having worked with broadcast electronics I can say that these types of connectors are a bane on the existence of human kind and whatever you do you will probably start hoping euthanasia would be legal (due to cable assembly induced severe depression).

author: Dubbie
author_rank: Unknown
timestamp: October 11, 2016, 11:49:18 am
content: Glad to see it's not just me who has a love hate relationship with Lemos. Hate soldering them, but love them when they are done.Sent from my iPhone using Tapatalk

author: rx8pilot
author_rank: Super Contributor
timestamp: October 11, 2016, 06:49:37 pm
content: Quote from: Dago on October 11, 2016, 05:00:45 amQuote from: Dubbie on October 11, 2016, 11:49:18 amYes. Yes. Yes.There are not a lot (if any) resources that have tips, hints on the termination process.Step 1: I need some really nice wire strippers that can deal with the small wires. 24ga - 30 ga without nicking, pulling, stretching, and needs to be consistent strip length. They also need to work within a tight wire bundle. Most are too big, clumsy to do the job easily.Maybe this type?http://www.all-spec.com/Catalog/Hand-Power-Tools/Stripping-Tools/Wire-Strippers/330011-65551?gclid=CjwKEAjwm_K_BRDx5o-sxq6ouXASJAC7TsFL1ekDvoPatieoSePeKbltakKvTrkhIq5ZT0PkL1yJLhoCLT3w_wcB

author: eliocor
author_rank: Unknown
timestamp: October 11, 2016, 08:40:56 pm
content: I own a pair of them: I use them very few times but they works very well.Not intended for heavy usage, but good enough for laboratory use

author: rx8pilot
author_rank: Super Contributor
timestamp: October 11, 2016, 08:50:42 pm
content: Quote from: eliocor on October 11, 2016, 08:40:56 pmDo you suppose they will not stand up in general - too flimsy or weak? I am looking for a tool that would maybe do 250+ strips per day - 5 days/week. Not crazy, but a lot more use than a lab tool would ever see.Not sure where to look for the best option. By 'best option' I mean highest performance even if I have to pay for it. The cost of labor and bad connections will be much higher than the cost of fancy tools to do the job right.

author: eliocor
author_rank: Unknown
timestamp: October 11, 2016, 09:05:49 pm
content: never used in a such way: thermal strippers* maybe?*) sorry, not my domain: I can't help you

author: rx8pilot
author_rank: Super Contributor
timestamp: October 11, 2016, 09:36:51 pm
content: Quote from: eliocor on October 11, 2016, 09:05:49 pmThank you for the input! I am looking for some operational review of the HAKKO thermals. I have an entry level thermal stripper that is amazing for larger wires 22ga and bigger. It is hard to use with small stuff.

author: eliocor
author_rank: Unknown
timestamp: October 11, 2016, 09:59:14 pm
content: In my previous work (not now) when visiting firms which made custom cable assemblies, I have seen that they were always using thermal strippers for very small batches of assemblies.I think that for larger productions they used different strippers (mechanical?)

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 12, 2016, 02:46:03 pm
content: These CK strippers are good for fine wireshttp://cktools-superstore.co.uk/CK-Precision-Wire-Stripping-Pliers-140mm-T3796-5

author: plazma
author_rank: Frequent Contributor
timestamp: October 12, 2016, 03:44:15 pm
content: Quote from: rx8pilot on October 11, 2016, 08:50:42 pmThey are good Made in Germany quality. I have owned one for 15 years and stripped tens of thousands of wires.

author: Kean
author_rank: Unknown
timestamp: October 13, 2016, 11:08:19 am
content: I use those small plastic CK strippers for making cables with 26-30AWG wires, and they're pretty good for consistent length stripping. Especially when you need like a 1mm strip for a small crimp, but also with fine multi-core cable going into a circular connector. The main problem with them is that with finer wires and short strip lengths, the small bits of removed plastic sheath often get stuck in between the jaws as they can't escape with the end-stop so close. I end up having to do a lot of tapping on the bench or use some fine point tweezers to get them out. Sometimes I just strip them much longer, then trim to length. So i'd hate to be doing something like 250+ strips a day with them, probably never done more than 100 in a day myself. I also have some that spin the blade around the wire, which do a really nice job on PTFE wire or coax, but they were damn expensive and also a bit slower to use.

author: Echo88
author_rank: Frequent Contributor
timestamp: November 04, 2016, 05:44:51 pm
content: I also use the white/yellow-wire stripper since about 5 years at work, build about 100 LEMO-cables with it and am very pleased. Very good tool for its price.