hhmoore
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Sneaking around once in a while
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Post by hhmoore on Mar 25, 2014 13:47:55 GMT
I've had this 1x30" belt sander for a while now; but only used it sporadically until recently. As I've used it more, I'm noticing that I periodically get zapped (I remember it happening a few times in the past; but I just assumed that it was something I was doing). If anything, I would say it happens more frequently while I am shaping/sanding wood; other than that, I can't recall specifics about when it happens. I think it's mainly my left hand; and I think it only happens when my hand is at the end of a piece (not when I'm keeping my hand behind it to stabilize the the pressure against the belt). It isn't something that happens regularly; but it's been often enough to raise my awareness, and to make me want to fix the problem. I can say that recently I have not always been replacing the side panel (tired of taking it off all the time for belt changes). I had removed the back plate a while back; but reinstalled it recently. The table is off. I do brush/wipe/vacuum it to remove buildup of sawdust.
Any ideas?
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Alan Schiff
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Manufacturers and Vendors
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Post by Alan Schiff on Mar 25, 2014 19:26:04 GMT
I occasionally have the same issue, but only when working with metal. I assume that it's static buildup from the friction between the belt and the workpiece. Wood is an insulator, not a conductor, and theoretically shouldn't move the static charge from the belt into your person. Some sappy woods can conduct, though, so that might be it.
As far as preventing that shock, you could try wearing rubber gloves.
Hope that helps, Alan
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hhmoore
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Sneaking around once in a while
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Post by hhmoore on Mar 25, 2014 19:43:19 GMT
I think it mostly happens when I'm guiding the piece with both hands (one on either end), and my left hand passes too close to the back plate (or other portion of the unit). A static charge can "jump" a short distance, so I could get the shock without actually contacting a metal piece - that would explain why it doesn't happen when I shift my hand to apply pressure from behind the wood. I'm trying to think if I've ever gotten shocked when I was wearing leather gloves...I usually have gloves on when grinding metal - that might be why I notice it more when working with wood.
Thanks! (I actually never considered a static charge)
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Post by Timberwolf on Mar 26, 2014 4:58:21 GMT
Hi, Harald. Well, I was a contractor for quite a while, and I've used every type of sander and sanded way over 100,000 sq ft of wood. Although the static buildup theory might be plausible, I've NEVER been shocked or even tingled while sanding. For that matter, I've never been shocked doing any sort of metalwork, either. And we did a LOT! Of course, I've been shocked by keeping tools running and dragging 100ft of ratty-assed 12 gauge cord through small lakes on the slab, but that's another issue. :lol: Here's my theory: You bought that thing from Harbor Freight, it's basically cheap junk, and it's intermittently grounding itself on YOU. :shock: I used to go to HF for "throwaway tools", stuff we'd use and/or abuse for a week, and then toss in the dumpster when it fried. Why buy a nice toy if you only use it once a year? Most everything there is what we call a "homeowner special". Fine for limited or sporadic usage, but it's not designed for quality or durability, like Bosch or a Milwaukee. Ya know, bro? So, I think it's just falling apart and you're getting the first signs of its imminent demise. If you plan on doing a decent amount of work with anything, don't go to HF, go elsewhere and buy a real tool. You'll never regret it. Until then, as Alan said, get some thick rubber gloves. If you can get a huge set, you put on the $1.00 brown cloth gloves first, so your hands don't sweat to death in those danged rubber gauntlets! I'd advise that you keep an eye on that thing, it could possibly give you a REAL jolt someday soon. I've also seen tools burst into flames or spew out smoke, but that isn't a big deal, just toss it on the deck. Makes for some good stories, though.
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Greg
Senior Forumite
Posts: 1,800
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Post by Greg on Mar 26, 2014 15:19:25 GMT
It's static.
If you want proof it's static, start the machine and hold the belt still with your fingers (not great for the motor, but it will serve to show it's static.) When the belt is not moving, no static will be built up, and you'll experience no static discharge.
I've noticed that I only get shocked when I hold the black close to the top (where the metal bits are.) The machine is grounded properly, it's the blade that is not grounded.
If you want to eliminate this problem, clamp an alligator clip to your blade and attach the other end to the body of the grinder, or any other source of ground. However, when grinding a blade, we need to spin it on several axises and a grounding clamp would get in the way, or downright dangerous.
Another option would be to ground yourself. Since you are making contact with the blade, in theory, you could discharge the buildup as it's building up rather than waiting for a discharge through the chassis of the grinder. But even having a cord hanging off you would still make sharpening dangerous.
>>>Probably the best option>>> Another option will would be to rig a metal bearing or roller of some sort that would press up against the interior of the belt and would ground out the build up electrons. This would probably be the safest, as far as avoiding trip or tangle hazards.
The reason this doesn't happen in higher end sanders is because there are internal components meant to discharge any electrons that get built up. $3,000 grinder vs $30. Of course the more expensive grinder will have some bells and whistles, and it may be as simple as a conductive wheel. (More on that in the next paragraph)
But this discharge would happen even if we had a belt grinder that was spun by hand. We are moving metal (aluminum oxide) across a dielectric material (the plastic grinder wheels.) There will be static buildup.
To conclude. Nothing is 'wrong' with the grinder. You don't need to be worried that the grinder will someday send a bolt of lighting at you. This may pose a risk of igniting flammable vapors nearby, but avoid cleaning your tools with gas and this shouldn't be a problem.
Source: Degree in Electronics Engineering
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Post by Voltan on Mar 26, 2014 17:11:55 GMT
I use mine VERY often, as I run a small sharpening service with it. I get shocked from time to time as well, and I too believe it's static.
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Post by drdata on Mar 27, 2014 20:07:12 GMT
I have one, and live in dry so-cal. No shocks.
Cannot recall if its a grounded plug. If so, ohm the center/ground to the chassis. Perhaps the connection has failed. If so, an easy fix.
HTHs
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Greg
Senior Forumite
Posts: 1,800
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Post by Greg on Mar 28, 2014 20:59:51 GMT
Yeah, that would be a much easier method than trying to create a roller system to ride the interior. Just drill and screw a piece of wire that would brush the belt.
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Post by Shane Ireland on Sept 8, 2019 12:05:13 GMT
I am getting shocked a lot. I don’t believe mine is static and I’m in the middle of taking it apart and looking for damage wires. I’ve never had a static shock this stout. It’s to the point I am dropping the pieces I’m working on.
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Post by nickws on Oct 11, 2019 0:42:01 GMT
I am getting shocked a lot. I don’t believe mine is static and I’m in the middle of taking it apart and looking for damage wires. I’ve never had a static shock this stout. It’s to the point I am dropping the pieces I’m working on. Have you resolved this? I am getting shocked a lot too.
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Post by joeybones on Oct 11, 2019 17:26:56 GMT
Rubber gloves ?
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Post by mblove48 on Oct 12, 2019 1:50:04 GMT
First thing if you're getting any kind of shock, is make sure your cord is grounded, as in a three prong cord. Then make sure your receptacle is grounded. Any shock from anything electrical is dangerous. The lower the voltage the higher the amperage
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Post by Keitha430 on Sept 15, 2020 17:52:20 GMT
I am getting shocked a lot. I don’t believe mine is static and I’m in the middle of taking it apart and looking for damage wires. I’ve never had a static shock this stout. It’s to the point I am dropping the pieces I’m working on. Have you resolved this? I am getting shocked a lot too.
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Post by nebulatech on Sept 17, 2020 21:10:35 GMT
You probably have a loose wire somewhere, or a short in the motor. I'm guessing its because 1.) it's from Harbor Freight and 2.) it vibrates a lot. Without knowing the actual machine, I would also venture to guess the chassis is not grounded. If it was, and if this is mains electricity (not static electricity), your breaker should trip. Since the unit is grounding on you instead of the ground wire leading to your electric panel, this shock is the machine telling you in the only way it can that you need to fix it.
At the very least, I would unplug the machine, take off any covering and tighten all wiring. I would probably also re-wire it with a 3 prong plug if it doesn't have one, and ground the ground wire to the machine chassis. If nothing stood out as problematic, I would use a multimeter to check for continuity between the machine chassis and the wiring. This seems like an intermittent problem, and trying to troubleshoot the problem with a meter when the machine is not running might not be fruitful. However, ensuring a proper ground from the chassis to the wall plug will at least give the electricity a different route to ground than straight through your body. Once properly grounded, the event leading to shocks should lead to a tripped breaker instead.
If nothing stands out in the wiring, it might be in the switch, but it could easily be in the motor, as is often the case. The obvious solution at that point is a new sander or a new motor.
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Post by TxA55hole on Jan 1, 2021 17:39:03 GMT
Just found your thread after father in law complained of his doing the same thing. We took it apart to investigate because no one should have to wear rubber gloves to keep from being shocked while using power tools. We found that the flux has melted down from the windings, made contact with the motor case. The motor case cover is mounted with three screws and one of those screws were making contact with the base of the sander assembly. Evidenced by arc marks in that location. Not satisfied with knowing why we got shocked, we dug deeper, I search for the root cause of the failure. We found that the motor shaft bearings are sealed bearings and while one bearing felt normal, the other was very loose with no felt resistance/friction. We believe this to be the root cause. Sealed bearing failure caused excessive heat buildup, melting the flux out of the windings which made contact with the casing, transferring electricity through to the base plate thus energizing the tool’s metal body. Have pics to share if you’re interested. scottwoodard1911@gmail
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Post by nebulatech on Jan 2, 2021 3:54:52 GMT
Just found your thread after father in law complained of his doing the same thing. We took it apart to investigate because no one should have to wear rubber gloves to keep from being shocked while using power tools. We found that the flux has melted down from the windings, made contact with the motor case. The motor case cover is mounted with three screws and one of those screws were making contact with the base of the sander assembly. Evidenced by arc marks in that location. Not satisfied with knowing why we got shocked, we dug deeper, I search for the root cause of the failure. We found that the motor shaft bearings are sealed bearings and while one bearing felt normal, the other was very loose with no felt resistance/friction. We believe this to be the root cause. Sealed bearing failure caused excessive heat buildup, melting the flux out of the windings which made contact with the casing, transferring electricity through to the base plate thus energizing the tool’s metal body. Have pics to share if you’re interested. scottwoodard1911@gmail Thank you for sharing your thorough analysis! Did you by chance repair the motor?
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Post by TzA55hole on Jan 5, 2021 16:14:16 GMT
No sir. We decided to throw it out. It was a lot of flux that melted and leaked down into the motor casing. We didn’t want to risk replacing the faulty bearing and reassembling just to find out there’s an insufficient amount of flux for the windings to last
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Post by treeslicer on Jan 8, 2021 1:32:11 GMT
No sir. We decided to throw it out. It was a lot of flux that melted and leaked down into the motor casing. We didn’t want to risk replacing the faulty bearing and reassembling just to find out there’s an insufficient amount of flux for the windings to last By "flux", did you mean "solder', or did you mean that the insulation was melting off of the motor windings? Either way, pitching it was the proper response.
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