Making a Cat5 o’ Nine Tails

A cat of nine tails made from cat 5 cableThe traditional naval ‘cat’ was made of a thick piece of rope which had been unwound into its nine constituent strands, and knotted. It’s pretty hard to knot Cat 5, which usually bends in a radius 4 times its width. However, we can add modular connectors. To make this a really painful piece of kit, we’ll leave the protective boots off the connectors, but if you’re going to want to soften the blows, then remember to put a pair of boots onto each length of wire before you crimp the ends.

You will need a scalpel or Stanley knife, side clippers, a Cat 5 crimp tool, cable, and modular connectors. Most crimp tools have a cutter on them, but we’ll need the side cutters to tidy up the last end of cable anyhow, and they are less unwieldy than the whole big tool. Optionally, you may want a flat screwdriver or awl to help tighten the big end knot. First, grab several lengths of cable. Four will be about the length of your full two-arm span, and the fifth should be at least three times that, depending on how long you want your handle to be. The crimp tool cutters are ideal for cutting these. I have chosen black, but there is no reason you shouldn’t use another colour, or a mix of colours. You will definitely want see-through modular connectors, as you need to see inside the block while you are building it. Start with the shorter pieces of wire, and add ends to each.

Cat 5 cable with stripped end.The outer coloured layer is softer than the inside. Strip off about half an inch of outer cable by scoring lightly around with a sharp knife. It should then pull off easily. If there is fibre inside the cable, trim that off. Untwist the wire pairs inside, and flatten them into the order in the photo. (This is not the only order, but it’s one standard to prevent cross-talk.) This order, T568A Wiring, is Green-and-White, Green, Orange-and-White, Blue, Blue-and-White, Orange, Brown-and-White, Brown. The wires are stiff, but you can flex them forward and back in the fan, and that will help to straighten them. There is no need to strip them, because the crimp tool will punch metal through to the inner wires.

Cutting Cat5 EndsAt this point, the wire lengths will be different. Once all of the wires are aligned and held easily in one hand, trim the ends. You’ll want to push the whole wire as far as it goes into the connector, so the ends need to be the same length. If the wires are still trying to escape you, bend them back and forth gently until they ease into their new positions, before clipping. Take off as little as you can in squaring up, because you’re going to need much of that half inch inside the connector.

Uncrimped Cat5Now take the connector and push it gently over the coloured wires. There are channels inside the connector and each wire will, with only a little wiggling, go into a single channel. I’ve found it’s best to angle them very slightly, so they go in one at a time, but as long as they are all straight you shouldn’t have a problem. Push in gently at first, but make sure the whole wire beds down to the end, for the best electrical connection. Then push the coloured wire sheath up into the plastic housing. This will also be crimped down, but needs to be shifted up a little around the inner wires.

Crimp ToolThe cable will bed down into the crimp tool. Here you can see the ridges on the tool are pushing down on the metal that is part of the connector. That forces the metal into the inner wires, right through their coloured sheathing. If you have a crimp tool with a ratchet on, this is much easier. Otherwise, you’ll need a little dexterity in with your strength. Keep pushing the outer soft sheath into the connector while you close the crimp tool as far as it will go. The connector below has not yet been crimped, but shows how far the sheath needs to be for a decent bite.

Once you have the crimps finished for the shorter pieces, take the longer piece of Cat 5 and put a decorative knot most of the way towards one end. Leave one length that we will crimp later. A monkey’s fist knot is ideal. Start this by winding the wire three times around your fingers. You want it to be loose. Take the winding off your fingers and, again loosely, run the wire around the winding three times, to make a cross shape. Now feed the end inside your first loop, but outside your second loop, three times. Image below is courtesy of Wikipedia.

Monkey's FistTighten it slowly and carefully, by feeding the wire through the whole knot, repeatedly. Don’t try to close it all at once, or the knot will become shapeless, and don’t close it all the way yet. Get it most of the way closed, and arrange it as a rounded ball. As a purely decorative knot it can take a centre to ensure a spherical shape, but we’re going to rely on the strength of the cable to hold the shape for us.

Before you tighten the knot completely, feed the four shorter lengths of cable through it so they sit centrally. Arrange the shorter end of the uncrimped piece so that it is as long as the other tails, feeding the spare wire through the knot, and the reshaping it. The long bit, the working end, should still be considerably longer than the rest.

Take a hitch around the base of the whip with the working end, and then wind it loosely around the nine other strands, to make a handle. Take another hitch at the end then feed the working end back down as a tenth strand, inside the windings, and then tighten them until everything is held snug. As with the monkey fist knot, you may have to tighten and move the wires repeatedly, but the end result will be a tight, comfortable handle. Use the side clippers to take off any extra length from the working end once you’ve tightened it. Put on the last connector, and you’re done.

Cat CaseI made a presentation case for my Cat out of an ABS wall box and a laser cut front with hex bolts, but equally you could add a clip to the decorative knot, or have the whip unadorned. Just remember that if you do put pressure on the knot, you’ll be deforming it, as there was no room for an inner core once we passed the wire through it. If you do decide to add a core, let me know in the comments how that went, so I can update this post.

Happy Making!

Colour Clock.

A set of small, lit LEDs used as a clockBlinki the Clock works. Red for 0, Yellow for a bit more than 0, back around to red for nearly 0 again. It’s sort of hard to look at it. Mostly the colours can be seen changing on the seconds, but it’s really cool when the hour ticks round and for a moment everything is different.

I have some of the maths wrong in a way I can’t put my finger on. (I have put my finger on this, to get the …. oh, divide by 6, not 10, there. Back in a sec.)

Yeah, it helps if you feed the correct values in. But anyhow, the maths is right now.

Robot Army, a setback

The method I’ve chosen to find out where body heat is can’t be done at the price I want it. I’ve got the wrong phototransistors, or at least I’ve been told I have. I should put the two transistor test version together, and see if I can get any sensible reading, but it’s been hot and I’ve been busy and I’m a bad robot parent. I also need to tidy my room enough that I can solder in it. Even by my standards it’s been bad lately, as I’ve been working elsewhere. I’ve got borrowed kit here and there as well, which I need to move to my Place For Borrowed Kit. Maybe I’ll just fake a house fire and start again.

Itchy – next steps

I’ve got a few choices to make with Itchy right now. Do I want my own machine for making art, or do I want to make a set of machines that others can use? If I get this ready for kickstarting, it’s one path, if I make it into a better machine for me, it’s another. I really want to make the better machine, but at some point that will probably run out of money as a project. Things that I have to do for both are relatively limited in crossover, but the big one is a redesign of the head so I can put different tools on there. The pen holder and the lino cutter are two different set-ups, and I’ll want a servo for the brush pens, and so on. For me, I want to make the Y axis and the gantry far more rigid. If I make it for lots of people, I’d want to make the frame in MDF with steel rods. I guess I could convince myself I’m doing that to find out how rigid it is…

So, I’m starting with asking tech companies and art councils about funding. If that comes down to nothing, and I’m not getting enough commissions to let me do my own thing on it, I’ll streamline it for kickstarting in my spare time.

Makibox – Oozi

I bought a cheap 3D printer. Once I had bought it, I found out it was from clearance but had probably already been in some way paid for, which is annoying. Someone else didn’t get their machine, and while I know there is no direct connection between me having this and another, particular person not having it, I am still profitting in the cheapness of a clearance machine from the money that someone else put in.

That aside, and it’s not a moral problem for me given the circumstances, I’ve now got a cheap 3D printer. The hot end, where the plastic gets melted, is famously terrible on this machine. It was a new design and tiny tolerances were needed, and it didn’t quite work. And also, I broke mine. So I’ve 3D printed a different big of plastic to hold a different head, and someone who was not using an old heater end and some other bits donated them, meaning I’m still getting a cheap 3D printer rather than an expensive time sink. It’s a cheap time sink instead. Currently bits of the hot end are cable tied together and the whole thing is about as shonky as a unicycle on a rocking chair.

Microswitches and Morality – earning it

I want to buy a couple of packs of microswitches from RS Components on Friday. I don’t have enough in my bank account to cover them right now. So, really, I should not buy them on Friday. I should buy them when I’ve earned cash from painting. So, next in line on the workflow is calling up and checking where my pedlar’s license is. Grrr. This ‘work’ stuff…

Wait, other than the admin I like it. I get to paint stuff. Yep.

ETA: New licence is in the post. Somehow it got lost along the way.

Cooking Lentils and Rice

Lentils and Rice is an easy dish to make, and to keep going for a few days. There is a bit of pre-prep of lentils, according to whatever cooking method they need. In this case, I soaked some for about four hours, after rinsing them.

Take a load of Indian spices from your cupboard. I used caradmom, ginger, ground cumin, dried chillies, turmeric, and garam masala. Cut up some garlic and some fresh chillies.
Anything that’s dry, put into a hot pan and cook for about 30 seconds. Add enough butter to cook wet everything, and then put in the wet spices, which is probably just the garlic chilli mix.

Add two onions which you have minced as finely as you could before you got bored. Smile a rictus smile as they turn yellow in the turmeric. Gaze into the yellowish abyss.

Add your pre-prepped lentils and enough water that everything is a slurry. Boil that for as many hours as you can be bothered. If they are red lentils, 40 minute maximum. Add a can of chickpeas for extra texture if all the crunch has gone.

Steam some rice. There are other ways of doing it, and you’re entitled to them, but steam the damned rice. 1:1 water and rice, in the steamer. Ignore for 20 minutes. Serve. Add hot sauce of any variety you like. Eat.