Hackaday Links: June 27, 2010

Precision CRT manufacture

Here’s a great video from Tektronix about building a precision cathode ray tube. The tube manufacture method was developed to use in oscilloscopes and we’d guess it dates back to the early 1960’s. [Thanks Bill]

Snake on an LED matrix

We would have done a full post o this beautifully built LED matrix but we just couldn’t find much information on it. For now, enjoy the video of the device playing the classic game of Snake. [Thanks Xdr]

Wire bundling

We’re not sure if this is brilliant or just snake oil. Here’s a method of bundling wires together by twisting them with an electric drill. We’ve always just used our hands but we’ve never really worked in any kind of volume either. [Thanks Kacper]

38 thoughts on “Hackaday Links: June 27, 2010

  1. Twisting wires using a drill gets them a lot tighter than by hand. Very important if you’re looking to cut down on noise due to time varying magnetic fields (not a problem for most people, but we’ve had to do it in the lab for low noise measurements).

  2. Just a note about twisting a few wires together with a drill… It makes them a lot shorter :p

    Also make sure you don’t do it too tight or with solid strand wire. You can break the strands/strand and have to start again :(

  3. Over 20 Years ago I was helping my dad rebuild valve amps for jukeboxes…

    The heater supply wires were twisted together using a drill – just 2 core, one end in a vice the other in a drill – pull hard and use the drill to twist the wires – the wire gets a lot shorter… about 25%…

    The original wires were twisted to reduce hum picked up by other parts of the amp.

  4. Wire twisting is one of those design elements that can prevent many categories of frustrations.

    The original article+ comments on that site does a good job of explaining an overview etc about how it’s done at a basic level.

    It’s a safe bet that many of us posters on HaD will have some divergences from or enhancements to these methods. Let’s compare notes on what’s worked or not.

    My most used variant of wire twisting uses a VSR drill that has a “speed setting knob” on it’s trigger. Drill gets clamped to table and drill power is controlled with a foot switch. which gives me both control and an inherently “Less Unsafe” condition. As that foot switch keeps the operator’s hands a bit further from the wire path while allowing for some single operator uses.

  5. I’ve only used drill twisting in an attempt to make speaker cables from Cat5, which is typically done by hand and very, very time consuming. To lessen the shortening effect and the resulting # of twists per foot, I used a piece wood about 18 inches long to connect the two Cat5 strands to the drill. Just three equally spaced holes: Cat5 connected to the outer two and the drill to the center one using threaded rod and a couple of nuts. This gave a gentler twist. All in all, it wasn’t satisfying though and wasted some spare cable. It never did make it into my home theater setup.

  6. I can’t believe people find twisting wire with a drill so facinating. 20 years ago we were doing this at car stereo installation shops.

    Nowadays I use it to create automotive CAN (J1939) cable of the proper impedance, which consist of yellow and green twisted together with a twist rate of one twist every 0.8″. I cut two lengths of wire (longer that I need as someone already mentioned,twisting makes them shorter) anchor the “free” end to something that won’t move, make sure the two wires are not already twisted, insert the other end into the drill, pull tight and pull the trigger. If you do it right you will get a very uniform twist the whole length of the wire, which is important when creating impedance critical twisted pair. I’ve made nearly 30ft lengths at once using this method.

  7. Oops, I forgot to say why I used the method that I did. I first twisted two Cat5 cables like in the article but found that due to the slipperiness of the jacket that the twist wouldn’t stay without A LOT of twisting time and thus extreme over-shortening of the cable and stress on the cable cores. The use of the wood beam had two goals. It didn’t really decrease the shortening effect by as much as you’d hope but what it does do is increase the angle of twist which decreased the number of turns required to keep the twist in place, which should mean less stress placed on the wire cores.

  8. The Tek video was amazing! That’s what skilled manufacturing and engineering gets you. When something has never been done before people invent a way to get it done, analog computer simulator of a CRT, custom fixtures and jigs.

  9. At work we always twist wire for noise reduction. It helps a lot with test leads, even on power supplies but particularly on high-impedance signals, like when you’re trying to measure the voltage in the middle of a resistive divider that drives the feedback to an amplifier. I’ve found it’s best to twist the wires until they’ve shortened about 10%, then stop the drill and give a brief light pull to set the twist, so they won’t spin or kink when you undo the drill.

    Note that twisting them together works great, but if you want them to be reusable (as in not stuck twisted) if you rotate each wire individually they will coil around each other naturally, without taking a set. This is the way people make rope.

  10. Well, I can say it isn’t snake oil. I did this many, many years ago to build a makeshift “jumper cable” to connect cigarette lighters in different cars or, in my case with a van with dual battery system, to connect the under-the-hood battery to my aux batterry via the lighter.

    Twisting the wires with a drill at one end and clamped to a table at the other end worked like a charm. It also shortened the wires by about 25% though. I needed 30 ft. of wire for a 18 ft. jumper.

  11. Snake oil? I’ve always twisted my wires with a drill, and it never occurred to me that anyone would want to do it by hand. It’s a lot easier, faster, and it yields a much nicer result.

  12. @vaporland yeah and what’s so wicked about it is that you’ve got all this stuff controlled down to 0.00001 inch and figured out on paper with slide rules and analog computers and chewing gum and spit and then, at the critical point where you’re mating the electron gun assembly to the rest of the tube, you’re WAVING A BIG BROAD FLAME AT IT BY HAND to “reduce stress” and “anneal the glass.” Quantitative methods much?

  13. If you twist two wires together by hand, the result tends to have an uneven number of twists per inch,and what’s more, the individual wires don’t pick up very much twist, so if you let go of the end, the pair tends to come untwisted.

    OTOH, if you use a drill, each wire gets individually twisted, as well as being twisted around the other. When you let go of the end of this kind of pair, it doesn’t untwist itself, due to this inherent twist in the individual wires. And you get a very even number of turns per inch, too.

  14. On the hybrid vehicles I build, I braid the wires to the AC Induction motor (three phases). These are 2/0 gauge superflex wire that are braided together by hand. Unfortunately, I have yet to see a drill that will braid, lol. And braiding wire with a 3/4″ diameter *really* shortens the length, heh.

  15. @Inventorjack: How about a 30 year old with no professional career in any kind of engineering? I figured this out all by myself as a wee lad while fucking around with wires in the basement.

  16. “I can’t believe people find twisting wire with a drill so facinating.”
    [tektronix video]
    Well, you know, “lost arts.”

    I remember “annealing” glass as being rather more complicated as well; I suspect the video was somewhat “simplified.” Or perhaps that’s where “skill and experience” comes in: Debbie can anneal the tube without losing tolerance; Dennis can’t.

    (and were they dumping that used chromic acid cleaner down the sink? Oh … my.)

  17. Yep, was introduced to ‘drill twisting’ myself years ago.

    Great stuff, pass it along.

    (Just don’t twist it too tight because then it burns down one side, er I mean…backs up into the mains!)

    Off to vacation! be well everyone.
    See ya in a week or so!

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