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Power Tool Repair Made Easy

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Step 6: New Power Cord

Picture of New Power Cord
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Old tools and drills in particular tend to die from power cords. Here's how I put one on a Bosch jigsaw.

Power cords can be tricky to diagnose. Which is a good thing, because you'll get tools for free and they're easy to fix with random power cords.

I used to do a continuity test by shoving needles into the cable and hooking my meter's clips to those. That way I could find out just where the break was without messing up the insulation.
If it's just the plug at the end you'll want to replace that.
It's also easy to cut the cord and splice a new one on halfway.

Vincent gave me this one with no cord at all so the decision was already made.
I had a scavenged power cord, probably from a computer with the computer end cut off.
I wired it in. This tool had a clamp for keeping the cord from pulling out. If there isn't one of those you can improvise with wire ties or tying a knot in the cord.

Once I looked inside I saw it was an insulated case with no place for a ground attachment. So I cut the green ground wire off my cord. Then I broke off the ground pin from the connector so no one would get confused.

Older tools sometimes have a metal case that is grounded through the third pin. The theory there is that if any wires get loose and short inside, they'll short to the case and blow a fuse instead of electrocuting you.
 
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flamesami3 years ago
What make is the knife in the 1st picture? or is it a custom one? I would appreciate it very much if you could tell me.
P.S. Is it good? It looks really nice, but I'm an ignoramus compared to many people on here.
I have a possibly very stupid power cord question...what are the small holes on the end of the two prongs on a regular power cord (the part that plugs into the wall)?? My husband and I can't seem to find the answer. They don't exist on older power cords only newer ones.
I was wondering that exact same thing a few months back, the holes are for the old-style sockets. The new sockets hold the plugs in by means of friction, the old style ones used two ball bearings that held the prongs in place.
I am putting a new power cord on an old bench grinder I bought at auction, since the old one looks unsafe. I know the green wire on the new cord is the ground and I see how to attach it, but the old cord isn't color coded, so I don't know which wire is equivalent to the black and which to the white. How do I figure it out, or doesn't it actually matter? BTW, the new cord is a 14 gauge/15 amp cord, which the fellow at the store told me would be good. Is he right?
pharmer16 years ago
Great instructable. Thanks for sharing your knowledge :)
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