#$^"# Grinder!! -- I'm getting shocked.

Fred.Rowe

Fred.Rowe

Knifemaker / Craftsman / Service Provider
Joined
May 2, 2004
Messages
6,848
I grind my blades while standing on a rubber mat. So, I can't figure out how

I am getting shocked while grinding. It happens while I am holding the blade

with two hands, flat on the belt, a stray finger makes contact with the

grinder frame and ZAP@!~^*&|?: I get bit. It has to be some static charge

The electrical system is running in metal conduit and is grounded.

I can touch the frame while the grinder is running without getting shocked.

I never got this until I installed ceramic platens on both grinding machines.

And I get shocked on both machines.

Why is this happening? Is there an easy fix?



Fred
 
Stop standing on a rubber mat, and ground the frame of your machine. My 1x42 did the same. Very much reduced by getting rid of matt and grounding the frame. Not all the way gone. You could tether (wire with alligator clip) the frame to the blade too, but I thought that could be dangerous. The rubber matt prevents discharge from you to the machine. The static electricity you're getting is likely coming from the frame of the machine to you.
 
yeah you need to clean all ground connections and try it without the rubber mat. There is a method called "Diode method" you can try. I don't know what this method is but I Think Dan Gray can elaborate since he mentioned it in a previous post.
 
Fred, YOU are what's holding the static charge. Grind a bit...then touch another piece of machinery that is grounded....your drill press for example. Still get snapped..? If so, then you know that your body is hosting the charge and it's looking for any ground source to discharge on. Your drill press, a water pipe, or your Grinder for example.

So, the cure is to ground yourself while grinding so the charge is harmlessly leaked without building up. For me, my shop shoes are industrial safety shoes that have a static dissapative sole. Static charge is problematic in many industries and there are a variety of solutions. Semi-conductors for example.

If I grind with my shop shoes on...I have no problem. But if I wear my Nikes...then I may get snapped.

So, to reiterate....if you are holding the charge..then you need to get grounded to dissipate it. If the machine is holding the charge...then it needs to be grounded to dissapate it. Do the test to see if it is the grinder or you.

I'm not suggesting to clip wires or static straps to yourself...just try different shoes that might allow the charge to leak to the shop floor. Try without your rubber mat.. Once you learn where the charge is...then you'll find an easy fix.

I'm not sure if this helps any...this is what works for me. I'm sure you'll get a ton of other ideas.

Good luck!!

-Rob
 
I had the same problem and it was only after installing the ceramic platen. I only got zapped when doing the left side because my body was not contacting the table. If I made sure to contact the table it went away. One more thing,...since it's getting warmer now, I have been doing all my grinding outside in the nude. This really helps. Now the only thing getting shocked are the neighbors.:eek: Just don't forget your respirator safety glasses and kevlar loin cloth. SAFETY FIRST! I can't say for sure that this is the only way, but works for me.:D
Matt Doyle
 
Thanks for the feed back guys. I'll find out where the charge is building up and

go from there. The rubber mats stay. The entire shop floor is rubber. Bad Knees:eek: hate concrete.

This is something that has to be fixed. A grinder running at full speed is no place to get ouchy.:o

Fred
 
Fred, don't feel like you're the only one. I experience the same thing, ceramic platen here too. I usually get it through my forearm when it just brushes the rest or tooling arm while grinding. Its made me jump on more than one occasion, I agree, its not a good time to have a knee jerk reaction.
 
mdoyle said:
I had the same problem and it was only after installing the ceramic platen. I only got zapped when doing the left side because my body was not contacting the table. If I made sure to contact the table it went away. One more thing,...since it's getting warmer now, I have been doing all my grinding outside in the nude. This really helps. Now the only thing getting shocked are the neighbors.:eek: Just don't forget your respirator safety glasses and kevlar loin cloth. SAFETY FIRST! I can't say for sure that this is the only way, but works for me.:D
Matt Doyle
Click to expand...


hmmm...I seem to remember a post awhile back about someone getting shocked on their marbles, just be careful :eek: :eek:
 
An antistatic mat on top of your anti-fatigue mat, with a static dissipating lead to ground will solve the problem.
The lead to ground shoould not be a straight wire to ground, but have an in-line resistor to bleed the charge, not short the charge to ground, as it will keep you from getting a high current path to ground in case you do have a shorted motor...
Something like these mats...
 
howiesatwork said:
An antistatic mat on top of your anti-fatigue mat, with a static dissipating lead to ground will solve the problem.
The lead to ground shoould not be a straight wire to ground, but have an in-line resistor to bleed the charge, not short the charge to ground, as it will keep you from getting a high current path to ground in case you do have a shorted motor...
Something like these mats...
Click to expand...



The shop shoes that Rob mentioned is something I will look into.

The mats sounds like a possibility also.

thanks for the feedback, Fred
 
we get into this every so often here
Rob is right if it were 110 or 220 the spark would'nt jump as far as your getting it
it's out there isn't it :D

Fred you are acting as a capacitor and then discharging, the longer you grind with out discharging the worse it is right??
wear leather sole shoes or boots stand on a ground wire that is connected to earth ground.. run it out side if that makes you feel safer
just make sure your equipment is wired properly so if something should mess up in your motor you can't get hit with household currant..
 
Fred' I am so glad you posted this. I get WACKED constantly. I'm arcing to the intake on my vacuum system. I figured it was something like this.:grumpy:
 
Some have suggested that a periodic spritz of the belt with a fabric static reducer like ClingFree will help. I seem to remember someone mentioning Fabreze, too, but I'm not certain. I've never tried this.
 
mdoyle said:
since it's getting warmer now, I have been doing all my grinding outside in the nude. This really helps. Now the only thing getting shocked are the neighbors.:eek:
Click to expand...

Lmao :D

I cant figure out this problem,I have a ceramic platen and stand on a rubber mat and I never get shocked :confused: I dont wear one specific shoe either.The grinder is bolted to a wooden work bench.
 
Ceramic platen and any grinder will keep you on your toes.Try the static dissipating mat. It looks like an anti-fatigue mat and has a green stripe on it They're avalible at computer stores and janitorial supply houses.
Take Care
TJ
 
Dang, I get the crud shocked out of me all the time. It's gotten better as I usually try to avoid getting too near the platen support now, and I've gotten use to it a littie, but man, i've taken arcs that were kid-you-not over 3/4 of an inch. Every once in a while I'll take one that makes my forearm muscles contract, and that can ruin your day when you suddenly involuntarily flex your wrist while trying to keep a perfect grind line :grumpy: I took a shock once that I felt all the way up to my eyebrow from my left finger. Kid you not.

--nathan
 
Fred,

Got a Grizz and it occasionally will give me fits with this too. I have the rubber matting, grounded chassis, etc. and no, none of that helped. However, when I start getting zapped (I work with the with the work rest installed which zaps my knuckles that are resting on it) I wet the knuckles of my glove that is resting on it or just smooth some water on the rest and it seems to get rid of the problem. Not sure how this will help you, but it seems to dump whatever static I'm holding.
 
You could go to Radio Shack and get one of the PC Grounding wrist straps... or just make your own. Just something that's small and metal and lay it on spot that's grounded near the grinder and attach a small thin piece of wire to it like the real thin picture hanging wire... Attach a small flat smooth piece of metal to the other end and tuck it inside the waist band of your pants. When you are grinding make sure to lay the loose end on the ground, then as you walk away the loose end will fall off the table and come with you. Make it just long enough that it dangles around your ankle.

Shouldn't be that hard of a gizmo for you guys to make, it should be cheap and out of the way and you shouldn't really notice it being there or in the way. Depending on the shop layout could be to either side or even behind you to ground out.

Make sense???

DM
 
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