Jumpwire Jig




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I am embarking on building an LED Matrix that is going to require a few hundred strands of 4" jump wire, and I really didn't want to measure and cut all of those wires. I decided to make this jig that would give a roughly accurate wire length, and allow me to cut down the time I spent measuring and snipping wires.

Stay tuned for a wire stripping jig....

Step 1: Cut Down Stock

I grabbed some 1" mild steel square channel stock from the scrap bin, and cut a 6" piece with the cold saw.

When using a cold saw it is important to properly vice your work. Steel requires a lower cutting speed than  aluminum would require, so be sure to check the cut settings on the saw before you begin your cut. Once there was coolant running through the blade, I slowly pulled the saw through the square stock.

Step 2: Mill the Part

Here at the Instructables/Autodesk workshop at Pier 9, we have an awesome metalshop with a Bridgeport Mill. Using a 3/8" end mill and collet, I was able to make several passes and mill a channel out of the square stock.  

I set the square stock on 7/8" parallel bars in the vice, then raised the bed of the mill up to the end mill. I only had to lower the quill a little bit.

I set a spindle speed of a little less than 1200 based on the the spindle speed equation: (SFPM x 4)/diameter of end mill. That ends up being (110x4)/.375=1175ish RPM - In High Gear/High Frequency I began to mill my part.

I made 5 passes with the mill, sinking the end mill into the material about 30/1000s of an inch with each pass.

Step 3: Finished Part

I deburred the edges of the jig with a metal file, and then threw it in a sandblaster to get all of the tool oils off of the part. Sandblasting also took off all of the printed material info from the square stock, and left me with a perfectly frosted Jumpwire Jig.

Step 4: Wind the Jig

I used a little bit of electrical tape to secure some solid core wire to the edge of the jig, and then began to wind wire around the jig. I got about 50 turns on the jig before I had filled it. 

When I reached the other end, I taped down all the other end to the jig.

Step 5: Tape and Snip!

I was nervous about the wires coming loose as I snipped them away, so I secured them all with masking tape that would be easy to remove. After taping the sides of the jig that I wouldn't be cutting, I began to snip my wires.

Moving across the channel I had just milled, I slowly snipped all the turns on the jig. I was left with perfectly uniform length wires. I repeated this process three times, and it worked great. 



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    38 Discussions


    5 years ago on Introduction

    I have a piece of curtain track that looks quite like your instructable. Unfortunately it only comes to three inches of jumpwire.

    Maybe someone could think how we could make it work for a four inch jumpwire?

    1 reply

    Reply 2 years ago

    @phreddy - glue a yard stick to the curtain rod to the side or opposite of the channel to give you that extra inch or so.


    5 years ago on Introduction

    I'm sorry, but when an Instructable goes to a twenty thousand dollar workshop on page two it drives me nuts. If we all had access to laser thrust vacuum reciprocating lathes out here in Instructables land - we probably wouldn't be reading Instructables ....
    Just saying. Wind the jump wire round a piece of styrene, wood, C channel, Unistrut ... and snip away.
    Milling a jig out of solid steel? Are you making like a hundred thousand jump wires?
    Every week?

    4 replies

    John, I completely agree. I feel like instructables has gone the way of the world and cut out the middle class. Where's the inventiveness? You know? I guess we will just be weeded out, as these high class instructables take the lead.

    Audreyobscura, not to say that your input is not a benefit to this community, I just feel like featuring an instructable such as this makes its users feel incapable of making their own because of the caliber of tools used. That's the moderators bad not yours. Please don't take that as an insult.


    Reply 2 years ago

    Actually, I found this helpful in the fact it helped me see how the industrial world would accomplish something that I'd have to hack out a channel in a PVC tube or wood block. It would have been extremely cool to have cut the channel in a threaded pipe, so your wires would be kept even closer in length. I still don't envy your wire stripping task ahead of you....

    Did you make a jig and machine for that too?


    Reply 5 years ago on Introduction

    Hello John,

    This was an opportunity to build my skill with a machine I had just learned how to use, the Bridgeport, as well as make something useful to me. I agree that maybe steel was a bit over the top for my needs, but I made a device that was successful for my needs and exercised my knowledge about the mill.

    Tin Man

    5 years ago on Step 5

    I had to do a similar thing a few years ago, but had no access to a milling machine. I jammed a short piece of plastic sink-waste pipe over the chuck of my battery drill. With the wire end taped to the tube, squeeze the trigger and wind-away. away. When the pipe had a full layer, I drew a felt-tip line along the length of the winding, wrapped all of it with a single layer of sellotape and slid it off the tube. A quick snippety-snip along the line with the scissors gave the desired result.

    1 reply
    r_harris2Tin Man

    Reply 5 years ago on Step 5

    Yeah, or a combination of the two methods might be to use a sabersaw/jigsaw to cut a slot out of a length of PVC, then proceed.

    err.. Wouldnt a Wooden 2X2 or even a Bamboo dowel be more practical..
    Make a Groove in one Side of the Bamboo Stick..
    Insert in a Lathe / Drill
    Tape the Wire securely to One end
    Rotate the Lathe / Drill Slowly, so the wire is wound on it, neatly and evenly..
    Use Wire Snippers (As you already have) and cut the wires neatly and evenly..
    Best run the whole setup on a Bench Cutter, so the wire lengths are also perfectly even.
    Jus' Sayin''
    Nice setup though..


    5 years ago on Introduction

    What I have done is wind the wires around a plastic bottle. Then lay down a couple beads of hotmelt on either side of the cut to hold the wires. Then cut through the bottle to cut the wires.

    I have an accessory wand for one of my soldering irons with tips meant for heating rows of IC pins. While the wires are still held together in the hotmelt, I strip a bunch of wires at a time.

    Then I can cut the bunches of stripped wires into "ribbon cables," if needed. Or to separated them all, dribble a little alcohol over the hotmelt, and it pulls off in one piece.


    Good idea! Althought milling sounds a little over the top, an angle grinder perhaps?

    I might use this someday, such a nice invention!

    2 replies

    I actually started with an angle grinder and even though i had viced the square stock, it didn't feel safe. the grinding wheel skipped around and chattered a lot.


    Reply 5 years ago on Introduction

    Angle grinders/ die grinders tend to do that if you don't have a firm grip on them with a more or less tense arm. Once you get the groove started for the cut you don't have to be as steady with it.