Thursday, November 29, 2012

Power Cord Replacement

In an earlier post, I pointed out that I needed to replace the power cord on my drill, which is a Milwaukee 3/8” “Hole Shooter” about 10 years old. I don't know if there's something special about the air here in Atlanta, but the outer insulation on power cables seems to degrade faster here than anywhere else I've lived. When you see that the outer layer of a power cord is cracking, it's time to replace it. No ifs, ands, or buts. Don't wait until the drill (router, sander, whatever) stops working - - - by that time it may start shorting out and tripping breakers, or in a really bad case, give you a nasty shock.

This is good advice for all woodworkers, but especially for those of us trying to equip a shop on a shoestring. If you hunt for tools at estate sales or pawn shops, you may come up with some real gems at bargain prices - - if you can settle for an “as is” deal. The power cord is definitely something to inspect before you fire up a used power tool for the first time. In fact, if you're the type who likes to negotiate the purchase price, pointing out frayed insulation and saying you'll have to replace the power cord might help you find out how low the seller's willing to go.

Whether it's a vintage jewel/old beater you've just purchased, or a tool you've had for years, when you look down and see this,

then it's time to install a new power cord.
If you wanted to, you could order an “official” replacement cord from the manufacturer's service center. I know that some power tool service centers automatically replace the cord on every tool they service, so they must have bales of the things lying around. But if, like me, you're cheap and in a hurry, you'll just head for your local hardware store. Take a peek inside the tool and see whether you need to buy some crimp-on lugs for the ends of the wires. If so, you might bring the old ones along, so you get the right size. If you'll have to solder the connections, make sure to get some heat-shrink tubing. And bring along a short section of the old power cord with you. Most hand-held power tools will have 16 or 14 gauge wires and either 2 or 3 conductors. The cable will be identified by the gauge and the number of conductors; for instance the cord for this drill is 16/2. Sometimes this information is printed on the old cable, but usually it's worn off or faded. So take a short section to the hardware store with you. Look through the spools of cable until you find what you need. Then find an employee to help you cut the cable at the length you want.

Which raises a question: how long should the cord be? Some people like a long cord, like 8 or 10 feet long. I think a long cord makes sense on a sander that gets plugged into a shop vac as it's run - - the cord should be at least as long as the vac hose, maybe longer. But on other tools, it might make sense to install a drastically shorter cord, say 2 feet long. If you are usually in a situation where you're plugging your tools into an extension cord anyway, like a carpenter on a job site, the tool's cord doesn't need to be long, and a short cord makes for less clutter when you put your tools away. On the other hand, if you're a cabinetmaker like me, who almost always is standing within 6 feet of an outlet while I work, it might make more sense to install a long cord. Think of this, though: if you own 6 power tools and replace all their cords with 10-footers, you have to buy 60 feet of cable every few years, while if you go with 2-foot cords, you'll only buy a dozen feet.

While you're at the hardware store, buy a good plug. What do I mean by “good”? It should be beefy, with some form of strain relief so your idiot neighbor doesn't pull the cord right out of the plug when he yanks on the cord to unplug the tool she borrowed. It should also have lugs with screws that are easy to reach and will be easy to hook up to the ends of the cord. Buy the same format as the old plug, meaning, 3-prong or 2-prong. If the old plug is 2-prong, notice whether it's polarized or not, that is, is one of the prongs wider than the other? (They almost all are, these days.) This is to make sure you don't get the prong intended for the “hot” wire plugged into the “neutral” part of the circuit. The convention is that the “hot” wire is black, and the narrow blade of the plug is the “hot” blade.

Now you're back home, and you have your power tool, a new cord, and a new plug. Here's a basic procedure. I'm including pictures of a Makita router in addition to the pictures of the Milwaukee drill to show you some differences.
  1. Unplug the tool. This should be obvious. In fact, if you hadn't thought of this on your own, you shouldn't be replacing your own power cord. Send the tool to a service center. Stop reading this.
  2. Unscrew the casing of the tool where the cord enters. Some tools have to be taken completely in half to do this, others have a little hatch which makes it convenient. This drill is somewhere in between; half of the handle comes off to reveal the switch.

     The router has a nice little box on the side of the motor housing that opens easily. 

    Use the correct screwdriver! Many manufacturers use Torx screws now. Torx driver bits are readily available at the hardware store.
  3. Undo the strain relief. In the Milwaukee, there are no screws accomplishing the strain relief, just a pinch point in the handle. 

     The Makita has two black screws that tighten a red plastic strap that holds the cable securely.
  4. Disconnect the old cord from the power switch. In the Milwaukee, this means cutting the wires, because they're attached inside the switch housing, which I can't open. I suppose that means I'm supposed to replace the switch too, maybe? Or maybe it's an indication that this is a cheap drill, meant to be disposable? On the Makita, on the other hand, you loosen two screws to release lugs crimped on to the end of the wires. In the picture below, you can follow the black and white wires from the new cord to the lugs where they attach.

  5. Pull the old wire through the plastic sleeve. Save the plastic sleeve. If it is torn or broken, replace it. This plastic sleeve or collar does two things: it helps with strain relief and it protects the cord from being worn by sharp corners on the housing of the tool.
  6. Install the plug on the new cord. Black wire goes to narrow prong, white wire goes to wide prong, and green wire goes to round (ground) prong. Screw each wire in nice and tight, and check for tightness before you close up the plug and tighten the strain relief.
  7. Thread the other end of the new cord through the plastic sleeve.
  8. Strip enough wire to connect the new cord to the tool. If you're crimping on some lugs, or screwing the wire under a post, half an inch is usually about right. If you have to solder wires together, strip an inch on each wire and twist them together, but before you do, cut a length of heat-shrink tubing and slip it over the new wire.
  9. Make the connection. Black to black, white to white, green to green. Use the screwdriver or soldering iron. 

    And here is where I tell you to do as I say, not as I do. I won't show you a picture of the finished joint. Let it be sufficient to say that it is adequately insulated. I want you to do it with heat-shrink tubing, which works quite well.
  10. Screw everything back together. Tuck the wires back into place. Put the plastic sleeve back where it belongs. Gently put the tool back together and see if the screws will start. If not, open it back up and see which wire is in the way of reassembly.
  11. Admire! Plug in the tool and briefly switch it on. Does it work? I bet it does. My drill worked in reverse, but not forward, when I reassembled it. I took it back apart, found I had put a wire in the way of the forward/reverse selector, and put it back together correctly. Then, it worked.

Hopefully you'll only have to do this occasionally, and your tools will look more like the Makita than the Milwaukee inside. I wish for all of you that you never cut, sand, or rout a brand-new power cord with its own tool. But if that happens, now you know what to do. And it doesn't involve duct tape.

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