Cable lacing - Page 1
Forum section: electronics / general

author: Burczyk
author_rank: Contributor
timestamp: May 05, 2018, 03:22:36 pm
content: Hello everyone.Some time ago i got an old impulse generator. The first thing that i noticed was the "cable lace/ wiring loom" (see picture). I was impressed how easy it is to see the connections and how wired dont make a mess, without using zipties.Recently I have been working on a project. I have some cables running from the front display to the back where i have all the switches. The problem is the wires dont stay together and i end up with a tangled rats nest. At first i thought of using zipties, but i remembered what i saw inside that generator.It tuns out cable lacing is sort of a lost art. On the internet I could only find instructions for "kansas city stitch" and "chicago stich", but these also need support structures for the wires, which I, of course, dont have.So i decided that I will ask about it here. How do I sew cables together like in the picture?Can I use normal sewing thread? I heard that you needed a special kind of thread that was infused with wax or somehing.I also heard there are lots of different techniques.I am sure that there are some folks here who remember how to do it. Could you help me?Regards,Witkor

author: Iwanushka
author_rank: Frequent Contributor
timestamp: May 05, 2018, 03:40:45 pm
content: Quote from: Burczyk on May 05, 2018, 03:22:36 pmHi, just use regular nylon thread or whatever you want no wax or any other is needed, later when I get back home I will update the post with detailed instructions, idea is regular knots on both end of cable to secure thread in between straight thread apox 10-15cm then wrap it around cables twist thread and repeat.

author: edpalmer42
author_rank: Super Contributor
timestamp: May 05, 2018, 04:00:28 pm
content: The magic phrase to search for is "lacing twine" or "lacing cord". The standard telco stuff is waxed so that once it's in place, it won't unravel - ever! To remove it you practically have to cut every knot. One time I tried my hand at lacing with no training. Later I asked one of the older guys how I'd done. He smiled and said that all my knots were backwards.It looks like waxed lacing twine is also used in rugmaking so you might be able to find it at a local craft store.EdP.S. If you look on ebay, I'd suggest you use the search string("lacing twine","lacing cord"). If you try to simplify it, you'll get a lot of hits that have nothing to do with what you're looking for - but might be interesting anyway.

author: jmsc_02
author_rank: Regular Contributor
timestamp: May 05, 2018, 04:45:53 pm
content: You can also read the ipc-a-610, section 4.4

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2018, 05:00:48 pm
content: Lacing is (/was) such a satisfying thing to do. It may not be the best thing for crosstalk on fast or sensitive signals but the three-dimensional creations you can come up with are things of beauty when you do it right.The best stuff is waxed and flat (just like proper laces).

author: MarkF
author_rank: Super Contributor
timestamp: May 05, 2018, 05:05:52 pm
content: I use standard waxed lacing cord but you could try waxed dental floss. Although it's thinner and may cut into the wire insulation. Tie the knot is very easy. Here is a video. I only use his first clove hitch knot at two or three inch spacing. I don't do the running knots.

author: SL4P
author_rank: Super Contributor
timestamp: May 06, 2018, 02:23:24 am
content: In production items, the lacing of the loom was done BEFORE it went into the equipment.A sheet of timber with the loom drawn, and a bunch of 'nails' (including curved sections) to guide the various wires to their respective end-points.Once it's all in place, work along with your lacing twine - and it stays nice & tidy.End result is very clean.The alternative for larger cables in larger frames is lace-in-situ.That's a real skill set.https://www.google.com.au/search?q=video+rack+lacing&source=lnms&tbm=isch&sa=X&ved=0ahUKEwie36jJg_DaAhUFv5QKHQYyB2sQ_AUICigB&biw=1842&bih=1109#imgrc=Rp-gManAYwktZM:

author: tpowell1830
author_rank: Frequent Contributor
timestamp: May 06, 2018, 02:36:42 am
content: Quote from: Burczyk on May 05, 2018, 03:22:36 pmNo, it is still done on professional harnesses, I guess what you are calling a loom. The term in the US is lacing tape, and in my field as a harness design engineer, the lacing tape is wax coated fiberglass, as I work on space vehicles, so we don't want materials that will catch or propagate fires. I utilize lacing tape in all of my harness designs. The other method that helps with individual segments of a harness or 'breakouts' as I call them, is giving the individual bundles of wires and/or cables a slight twist of about 1-2 turns per foot or 30cm before lacing occurs.EDIT:QuoteThis is what we call a formboard.

author: dcarr
author_rank: Regular Contributor
timestamp: May 06, 2018, 04:38:02 am
content: This is the real stuff:http://www.aircraftspruce.com/catalog/elpages/BreydenLacingTapes.php?clickkey=3874Once you get a little practice, it's not much slower than zip ties.

author: TerraHertz
author_rank: Super Contributor
timestamp: May 06, 2018, 07:51:20 am
content: There's also spiral wrap. Widely available, just google it.I used to lace cable looms, but like spiral wrap better now. Easy to undo, modify, add wires, etc.

author: nanofrog
author_rank: Super Contributor
timestamp: May 06, 2018, 11:48:03 am
content: Quote from: TerraHertz on May 06, 2018, 07:51:20 amLooks easier than using split loom + fabric wire loom tape as well.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 06, 2018, 12:33:48 pm
content: If lacing is good enough for the Mars rover, it is good enough for anything on Earth that I may build:Plus, I like how it looks. I have two types of lacing. One is a "conventional" (i.e., older) waxed flat cord. It is tan and feels waxy. The other is a little newer (bit still>20 years old) that is black and has a micro-crystalline wax. It does not feel waxy at all and is similar to what is used in the video already posted.

author: BradC
author_rank: Super Contributor
timestamp: May 06, 2018, 12:47:04 pm
content: Timely thread. I had a spool of lacing tape turn up last week. It has been on my list of "to learn" for years now.

author: nanofrog
author_rank: Super Contributor
timestamp: May 06, 2018, 12:59:55 pm
content: Quote from: jpanhalt on May 06, 2018, 12:33:48 pmEasy to inspect, sospace travelgovernment approved.

author: GlennSprigg
author_rank: Super Contributor
timestamp: May 06, 2018, 01:18:55 pm
content: Wow, you brought back memories !!!In Australia, string (& knots) is very old style, and even though I'm still talking about backin the 1970's most 'lacing' was done with small plastic tubing, in simple Half-Hitches.....These days 'PVC' ducting is used for larger projects, but I remember when it was as mucha work of 'Art', as well as functional, and for Strength. My largest was.....Pre-PLC's, involving 10,000 relays/timers etc, split over a huge room of 13 Panels, for alarge process automation plant interstate, all having to be tested before shipping.All laced perfectly, with every termination including inter-panel wiring being numbered.After testing, ALL hundreds of gigantic LOOMS were boxed & rolled out again later, andre-terminated on site. Without 'looms' it would have been a nightmareI now (then?) made all wiring harnesses 'tight' !!! (Not like the Space-Shuttle though)P.S.We later calculated about 300 kms of internal wiring !!!!!!

author: TimFox
author_rank: Super Contributor
timestamp: May 06, 2018, 02:01:42 pm
content: The ARRL "Radio Amateur's Handbook", which should be available in public libraries, used to have explicit instructions on how to lace cables, including a picture of the knot that doesn't work.

author: chris_leyson
author_rank: Super Contributor
timestamp: May 06, 2018, 02:59:19 pm
content: @Gyro The best stuff is waxed and flat (just like proper laces).@dcarr That's the proper lacing cord - thanks for the linkThat's also my preferred lacing cord, flat braided and waxed, I don't like the round nylon cord. Google for cable lacing or aircraft cable lacing and there should be a few images of how it should be done. My preferred method is to use the recomended aircraft wiring loom type of knot, start off with a clove hitch and finish the knot with a square knot or reef knot.There is a actually a better knot to finish with but I can't remember the name, it uses the end of the clove hitch as part of the square or reef knot, it takes two steps less to tie than the standard aircraft knot and probably has the same mechanical strength.Aircraft manufacturers still lace cable looms, it works well and does the job. I was once tasked with looking onto a robotic knot tying machine for aircraft wiring looms, all I managed was to come up with an equivalent knot to the aircraft knot but with two less steps. Boeing made a knot tying machine and had a patent for it but I don't think it worked because they still lace cable looms by hand.If you could make a machine to tie aircraft knots onto wiring looms you would make millions, it still hasn't been done.

author: nctnico
author_rank: Super Contributor
timestamp: May 06, 2018, 09:51:53 pm
content: Dental floss works excellent as lacing wire for small looms. I've learned to do cable lacing in school but I have not used the technique for decades. Nowadays I prefer to use braided sleeving (and zip ties). Still lacing wire is nice for a loom which has many branches.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: May 07, 2018, 07:49:46 am
content: You need to be particular about the running knots. They are basically overhand knots but there is a left-handed version and a right-handed version.Here is a site to tell you all about it.:http://www.dairiki.org/hammond/cable-lacing-howto/I laced the cables in a couple of gizmos that I built a few years ago. I didn't use the real stuff because I couldn't find any so at my wife's suggestion, I used embroidery thread drawn over a lump of wax. That worked pretty well.

author: DeanCording
author_rank: Contributor
timestamp: May 07, 2018, 08:00:47 am
content: Ahh, memories....My Dad used to be a PMG exchange tech in mid-sixties and I spent many a night in the local large town exchange when he was on a callback. Everything in that place was laced up with wax string to form bundles 12 inches wide and 3 inches thick containing hundreds of pairs. I reckon you could have removed all of the support racks and the place would have supported itself just on the laced wiring alone. Making any sort of modification was a nightmare.Eventually they just put mesh panels between the tops of the racks and pairs were just run from point to point as needed.

author: GerryBags
author_rank: Frequent Contributor
timestamp: May 07, 2018, 08:19:40 am
content: There's a section on cable lacing in the NEETS US Navy EE training course. You can see why they'd be a fan.The technique is based on "whipping" marine cables and hawsers, and that is incidentally what you need to look for: Whipping twine/line. It may also be called marl/marling/marlin twine, you can get waxed or tarred versions. The basic knot used is the clove hitch, which is also used on the ratlines connecting the shrouds on old square-rigged sailing ships, but with extra turns taken around the standing part (in this case your cables) behind the working part, and through the hitch. You can also make a very neat looking job if you use, say, four or five half-hitches right next to each other, then a gap of an inch followed by another set of half-hitches and so on. If you get the spacings equal it can look great.In my opinion, it's worthwhile for everyone to learn a few good knots, as they can come in so handy for all sorts of things.http://www.instructables.com/id/How-to-tie-various-knots/

author: DeanCording
author_rank: Contributor
timestamp: May 07, 2018, 08:49:24 am
content: QuoteAs an old Scout leader, I can only agree. One of the best resources is the 'Knots 3D' app which is currently available for free on Androidhttps://play.google.com/store/apps/details?id=com.nynix.knots3d&hl=en_AU

author: TerraHertz
author_rank: Super Contributor
timestamp: May 07, 2018, 02:21:10 pm
content: Quote from: TimFox on May 06, 2018, 02:01:42 pmThanks for reminding me!Here's a scan of the lacing diagram from the 1964 edition of The Radio Amateur's Handbook.The 1975 edition has the same diagram on page 549.