FIXED -- THANKS -- Was: Drill leaks electricity to case

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Thakns to all. I fixed it. I took the cover off and blew out accumulated carbon crud. It made a little cloud, I tried not to breathe and walked out of the garage for a little while to let it settle.
After that, the drill runs (as it did before), but it no longer trips the same GFCI breaker. I tried starting and stopping it many times, shook it while running etc, but the breaker would not break. I made some pictures, but I doubt anyone would be interested -- just brushes touching the rotor.
I want to say big thanks to all people who gave me good suggestions! It was the easiest fix of my life.
I also tested hot to ground with a multimeter, no obvious leaks (I did not use a megger, but I used the 1M setting of the multimeter).
For the record, I used rubber boots and gloves while I was trying the drill.
Indeed, there is a big threaded hole on top of the drill, for inserting a big handle. Maybe it is even meant to be held by 2 people with a big handle.
i
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A good jolt once in a while improves libido. Poor man's Viagra?? Honey, I'm ohm.... -- Mr. P.V.'d formerly Droll Troll

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The problem was the carbon dust, since its conductive.
I have to remember this!!!!
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Yep sure is. Commonly known in Australia as a "belly buster". Get the bit jammed some time when you're using it and you'll find out why!
Tom
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My 1/2" DeWalt drill (not the one I fixed) can work as a wrist buster, as I discovered!
i
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Ignoramus15109 wrote:

Glad you had such an easy fix, Iggy. Doesn't happen often enough. Bill.
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Did you redo the gearbox grease while you had it apart?
Ignoramus15109 wrote:

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I did not open the gearbox. Maybe I should.
What kind of grease should I use. I have two kinds at home, green marine grease for inboard/outboard motor shafts, and white lithium grease for trailer hubs. Would it work?
thanks
i

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use the marine grease, it is stickier.
Ignoramus22178 wrote:

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Ignoramus15109 wrote:

This brings to mind something I encountered a couple years ago. Someone in a Campground tripped the Camp Group power GFCI when he plugged in his Travel Trailer. He said it did not happen when he used it at home and other places (that did not have GFCI).
The problem was that the Ground and Neutral wires were tied together inside the trailer. Of course the Ground and Neutral were also tied together in the Campground. Therefore some of his return current was flowing in the Ground tripping the GFCI.
Same thing was happening in the drill but only a tiny bit was probably flowing through the carbon dust but it was enough to cause the GFCI to trip.
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A dirt/crud induced conduction path in a device that causes a GFCI to trip is not _likely_ to be between the ground and neutral leads.
Think about it: A GFCI requires 3-5ma to trip. If the dirt/crud resistance is 1000 ohms (it certainly won't be zero), you'd have to have at least 3 volts between neutral and ground for it to trip. Given allowable voltage droops due to load, that device has to be drawing a _lot_ of current before you'll see that much ground-neutral voltage. Meanwhile, a hot leak of 1000 ohms (100+ ma) can be quite lethal (eg: you use Igor's drill before repair in a circuit without ground).
Secondly, assuming enough voltage between ground and neutral to trip, provided that the device is nominally wired correctly (switching the hot), the device will trip the GFCI without switching it on.
For the most part GFCI tripping under these sorts of circumstances will mean that the defect is on the hot itself, or somewhere in the motor winding (which acts as a voltage divider between hot and ground). These can potentially be quite lethal if you use it in the wrong circumstances.
Igor: You mentioned previously that you thought that this thing had too much torque for you, and you were going to sell it. Remember: this class of drill is intended to be used two-handed for where you really do need the torque. Used two-handed this drill will be fine.
[I mentioned I had a similar drill. When I got it it was missing the extra detachable handle. So I made one. Yours has two viable handles. It's just that mine now has three ;-)]
I don't know what sorts of work you do, and whether you need occasionally something of this class or not, but think carefully... A drill of this type with gears/bearings/wiring/chuck in good shape is worth quite a bit (many hundreds to buy new), and occasionally can't be beat for work around the home without renting something that costs a lot more per hour than what you have invested in this thing so far.
Heck, on our property[+], you can just about auger post holes with such a unit ;-) Great drill for making mortise and tenon log rail fencing or slapping together timber structures (lag screws etc) or boring big holes in concrete.
If you decide to sell it, do ask a decent price for it.
[+] fine sand.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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wrote:

Yes, I realized yesterday that my drill has a threaded hole for another handle.

Check this out
http://www.toolbarn.com/product/dewalt/DW131 /
You can see a similar drill costs only $202 new.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&itemu87046213
You can see that the used dewalt sold for $102.

Thanks Chris. I am a little undecided. I mean, I definitely cannot auger holes in our heavy clay soil with this drill, and I can drill 1/2" holes in steel angle with my own Dewalt drill (the regular two speed electric hammer drill). This dewalt drill also drills big holes in wood. So, what is the benefit of having the 450 rpm one?
I'll keep it for a month or so before I decide what to do with it.
I appreciate your good words of advice. A good tool was saved, either for myself or for someone else.
i
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<snip>
A GFCI works because in a single phase circuit that is working properly, the current in the neutral must match the current in the hot conductor. When both conductors are passed through a coil, the coil won't energize because there is no current imbalance. If some of the current has a different path to complete the circuit, then there will be a net difference in current at the sensing coil, and it'll trigger. That's why GFCI's work on two wire cords just as well as grounded cords.
Pete Keillor
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wrote:

Actually, a similar (but broader) statement applies to polyphase circuits, such as three phase circuits. The sum of currents going through hot conductors must be zero at all times.
i
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Slight correction: through all _current_carrying_ conductors. Eg: the hot conductor current in a 240/120V circuit (eg: stove or dryer or "kitchen split receptacles") doesn't balance very often - the GFCI has to sum the neutral current too.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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wrote:

good correction , I should have said "current carrying".
i
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Glad to hear it!
If the big threaded hole is like 3/4 or 1" - it is likely a pipe thread for an extended reach hold. Very likely it coasts when the trigger is stopped so it might take you with it (in turns) if the bit locks into the work.
Using a protection bar prevents these fast turns that might mangle a wrist.
Martin
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
Ignoramus15109 wrote:

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Not likely to be a pipe fitting. More likely it's for a 3/8' bolt stuck into a short broom handle. Works the same though.
Martin H. Eastburn wrote:

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Hole Hawgs and some of the old drills use pipe thread.

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I think the one on mine (that I made a new handle for in machine shop) is the right diameter for 1/2" pipe thread, but the threads are too fine to be pipe thread.
But I didn't think to check before I made the handle (aluminum round bar stock, lathe-cut threads).
--
Chris Lewis, Una confibula non set est
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