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Precision Wire Placement with a CDW

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  • Precision Wire Placement with a CDW

    We have enough people here with Sputwelders now to discuss some special techniques, and useful tricks. We can make some of these threads sticky if we think that they should be. You guys tell me. We will cover other techniques in threads to follow.

    Placing and welding the wire exactly where you want it.

    This method can be used to weld the wire onto the edge of a thin plate, or to weld the wire on the bottom of a blind hole. The test piece was Al barstock, 1/8" thick x 3/4" wide. The wire was 14 AWG (0.064" dia.) 1100 alloy Aluminum. I wanted to weld the wire on the 1/8" side, in the middle of the bar.

    I got some garden variety glass tubing from McMaster-Carr, about $2.50 per foot. The size was 6mm OD x 2.7mm ID. Glass tubing is traditionally spec-ed in metric sizes. This is 0.236" dia. OD x 0.106 dia. ID. I cut a piece about 3" long. Cut this by scratching it where you want the break (glass cutter or carbide tool) it will break easily with finger pressure at the scratch. I fire polished both ends with a propane torch just enough to smooth the sharp edges. You want to select a tube large enough for the wire to slide freely in it, and small enough to to fit in the blind hole if that's what you are doing. Glass has the advantages of; cheap and available, you can see the wire in it, it wont burn or char, and very smooth surfaces.

    Prep the wire by wiping it with a paper towel wet with mineral spirits, and cut a shallow angle (wire cutters) on the weld end. I held the plate on its edge by using two plastic spring clamps to act as "feet", then connected the black cable to it. Insert the wire in the tube so that the weld end is about 1/2" above the end of the tube, and connect the red cable about 1" above the other end of the tube.

    Charge the CDW, I used 28 Joules. I positioned the tube where I wanted the weld on the edge, and quickly slid the wire the rest of the way down the tube into the metal to make the weld. Disconnect the red cable and slide off the tube. All done, and the wire is exactly where I wanted it. The tubing also prevents any weld spatter outside of it.

    This is easiest to do with 14 AWG or larger wire but smaller sizes will work with smaller tubing and some practice on scrap.

    McMaster also has ceramic tubing, more expensive than glass, but very thin wall, I got some 0.125" OD x 0.062" ID.

    Actually, any tubing that is of suitable size and is an insulator will work. Rigid Teflon tubing works good too.

    I was using a Type 5 CDW; since it auto compensates for capacitor leakage, you can take all the time you want to get things lined up the way you want. This is what this feature is for.

  • #2

    what size is the wire that comes with the cdw?

    also a note for cdw users.
    the amount of pressure you use when you make contact with the part is key. when i started using it i was having nothing but issues with, how well it connection was. but with some messing arround and playing with setting have solved most of my problems. and also have noticed if you still have a slight charge left in the cdw after your conection was made. ment one of 2 things. you either have your Joules
    set to high or your not useing enough force when you make contact.

    2 settings i have found that work best with the 2 difrent wires i use

    the wire the comes with the cdw works best arround 26 to 30 Joules

    if you use the radio shack grounding wire ( as it says in the caswell manual) this thick wire seems to work best at arround 55 to 60 Joules

    if you go to high on the Joules it will leave a nasty pit in your work. i'll try and get pictures of this up later.


    • #3
      I deleted your double post for housekeeping reasons.

      All CDWs come with 16 AWG (0.051" dia.) 1100 alloy aluminum wire.

      You have it right; there are three variables in CDW welding, like the manual that comes with it it says. These are Weld Energy (Joules) Weld Force (the pressure) and Weld Time (which is fixed at 2/1000 of a second). You have to learn the correct balance between Weld Energy and Weld Force, no two people do this the same way. The correct way is what is comfortable and works best for you, everyone is different.

      RadioShack grounding wire measures 8 AWG (.129" dia.) and is huge. This size will easily carry 50 Amps in an anodizing setup, are your pieces that big? If not, this makes for a weld blemish way larger than it needs to be. 16 AWG will handle 5 Amps with no voltage drop that you can even measure, it will carry twice that current with no ill effects at all.

      If there is any charge left after the weld you have a bad connection to the wire, or you didn't cut about 1/8" off the weld end of the wire before welding it. Yes it does matter, you are passing 2000 Amps through this connection in 2/1000 of a second.


      • #4
        the blemish isn't an issue with 8AWG

        the problem is the 16AWg is a little to flimsy. and with the agitaor the parts tend to hit each in the tank. only one of the parts i do draws over 5 amps. but to use the smaller gauge i would have to still hook up my old way to to keep them still in the tank. so to avoid using 2 wire to hang a part i just use the heavier wire. with the bigger wire the blemish isn't to bad and in most cases very easy to hide. it leave a mark maybe twice the size the 16AWG leaves.

        but it's all about what easier to use for the user.


        • #5
          I agree.
          If in your case the weld blemish isn't an issue, then use the size you like. I would recommend that you get some 14 or maybe 12 AWG wire, both are plenty stiff, and much cheaper than 8 AWG RadioShack wire. If you have an available thru hole on your work, you can add another wire to stabilize it, this is what I do on AR-15 lower receivers (0.56 Sq. Ft. surface area). This second wire has no electrical purpose and doesn't need to be welded. A nice loose loop or hook will do the job. If it's loose fitting it won't interfere with the anodizing or dyeing.