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Static electricity issue
#1
Hello. 

I use Viel S-5 belt grinder for sharpening. Recently I have been having problems with static electricity. It gets worse when using a Trizact belt or leather belt. Do you know any solutions?
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#2
I get a ton of static electricity with my Kally and various belts.  I can watch the sparks form in one of the gaps in between the mast clamp on my Kally Rest.  Pop, Pop, Pop.

When I accidentally touch the rest, it shocks me good!  I have no idea how to prevent it.  Maybe a grounding strap that connects the offending part to something?  

My only way to combat this, so far, is to touch the metal part with my forearm, which drains the charge without me really feeling it.  That seems to work.  But I don't always remember so.. pop!

In my serrated sharpening video you can see me yank my hand back as this happens.

Good luck.

Brian.
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#3
One possibly simple solution is to increase environmental humidity.  Very effective if you can do it.  I've noticed static charge is most noticeable during the winter when humidity levels are low.  Get a humidifier.

I'll show other solutions to permanently solve the problem at the end of this.

The part I don't understand is why a spinning belt builds up electrons.  Something is giving up electrons like rubbing wool against a balloon.  Wool gives up electrons that collect on the surface of the balloon causing the balloon surface to carry a negative charge.  In other words, electrons transferred from the wool to the balloon.

It appears that the back of the belt rubbing on the platen might be the source, like wool is to a balloon.

Looks like spraying the back of the belt with anti-static spray solves it.  If that works that is a really easy solution.

A grounded wrist strap is common when working with electronics.  Not so good around spinning equipment.  I'll post a link at the end of this where in the comments one guy uses a grounded ankle strap.  Seems like a pain in the butt to me.

Static charge from belt grinders is very well known.  If the charge is sufficient enough it can cause the operator to jerk and flail in an involuntary spasm and can actually be dangerous around machinery.  If you are flopping around like a fish on the beach when sharpening, it's probably best to resolve the issue.

Apparently the rotating belt is the source.  Electrons are transferred from the belt to the operator through the knife.  Like the surface of a balloon rubbed with wool, the operator becomes negatively charged with electrons like flies on, um... well you know.  When a grounded surface is touched, all those electrons move to the grounded surface.  And, they do it in a BIG hurry all at once.  POW!  ZAP!  A first hand demo of electricity 101.

Here are two links.  The first offers permanent solutions and an explanation of what's happening.  The second shows the principals involved.

In the following, read the comments too. Some info there.

http://dcknives.blogspot.com/p/static-di...inder.html

The following is a cool demo of what's happening.  It takes a while to load, so just let it finish.  Once loaded, drag the balloon and rub it over the sweater.  You can then move the balloon over to the wall.  A great visual demo of what's happening.

https://phet.colorado.edu/sims/html/ball...ty_en.html

If the anti-static spray thing works that's easy. 

Would wearing rubber or nitrile gloves work?  Both are insulators and would build up electrons like the surface of a balloon.  Nitrile gloves are very thin and I suspect you would still feel it when the charge is dissipated.  Thick rubber gloves would work, but who wants to wear them when sharpening.

Probably a permanent ant-static brush installed on the grinder is the best long term solution.  Hmm... accessory for the Kallyrest?  Or, get a humidifier.
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#4
(04-05-2020, 09:08 PM)grepper Wrote: One possibly simple solution is to increase environmental humidity.  Very effective if you can do it.  I've noticed static charge is most noticeable during the winter when humidity levels are low.  Get a humidifier.

I'll show other solutions to permanently solve the problem at the end of this.

The part I don't understand is why a spinning belt builds up electrons.  Something is giving up electrons like rubbing wool against a balloon.  Wool gives up electrons that collect on the surface of the balloon causing the balloon surface to carry a negative charge.  In other words, electrons transferred from the wool to the balloon.

It appears that the back of the belt rubbing on the platen might be the source, like wool is to a balloon.

Looks like spraying the back of the belt with anti-static spray solves it.  If that works that is a really easy solution.

A grounded wrist strap is common when working with electronics.  Not so good around spinning equipment.  I'll post a link at the end of this where in the comments one guy uses a grounded ankle strap.  Seems like a pain in the butt to me.

Static charge from belt grinders is very well known.  If the charge is sufficient enough it can cause the operator to jerk and flail in an involuntary spasm and can actually be dangerous around machinery.  If you are flopping around like a fish on the beach when sharpening, it's probably best to resolve the issue.

Apparently the rotating belt is the source.  Electrons are transferred from the belt to the operator through the knife.  Like the surface of a balloon rubbed with wool, the operator becomes negatively charged with electrons like flies on, um... well you know.  When a grounded surface is touched, all those electrons move to the grounded surface.  And, they do it in a BIG hurry all at once.  POW!  ZAP!  A first hand demo of electricity 101.

Here are two links.  The first offers permanent solutions and an explanation of what's happening.  The second shows the principals involved.

In the following, read the comments too.  Some info there.

http://dcknives.blogspot.com/p/static-di...inder.html

The following is a cool demo of what's happening.  It takes a while to load, so just let it finish.  Once loaded, drag the balloon and rub it over the sweater.  You can then move the balloon over to the wall.  A great visual demo of what's happening.

https://phet.colorado.edu/sims/html/ball...ty_en.html

If the anti-static spray thing works that's easy. 

Would wearing rubber or nitrile gloves work?  Both are insulators and would build up electrons like the surface of a balloon.  Nitrile gloves are very thin and I suspect you would still feel it when the charge is dissipated.  Thick rubber gloves would work, but who wants to wear them when sharpening.

Probably a permanent ant-static brush installed on the grinder is the best long term solution.  Hmm... accessory for the Kallyrest?  Or, get a humidifier.

Thank you grepper.

That's good idea Smile
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#5
Thank you Brian.
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#6
Interesting - AZ isn't exactly known for it's humidity rich atmosphere and I've never encountered this phenomenon with or without KallyRest attached.  That's a puzzler.
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#7
https://www.practicalmachinist.com/vb/ge...ks-174149/


Maybe it's the type of backing on the belt:

"a few pieces of wire dragging on the belt will help. Back when we had a wood shop 30 years ago and the belt backing was changed from cotten to polyester, static became a big problem. the polyester was then changed to polycotten IIRC, obviously every one had the same problem. When you are running a 20 hp 18 inch vertical sander that is a big problem. There was some spray the supplier gave us, but it was not practical for us to use, probably not effective after the first few minutes anyways."

I've been searching for static dissipation strip brushes but have yet to find any.  You know the type.  Like the brushes on a printer that rub against the paper. 

Anyway, it does not seem that hard to ground some little metal strips to from the machine to near the back of the belt.  Copper foil, etc. would work.

I get static here in Michigan in the winter but not the summer.  It is a bit of a head scratcher that you don't see it in AZ that normally runs negative RH in the summer.  Could you have grounded shoes?  Tennis shoes with rubber soles would exaggerate the problem.
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#8
They don't typically put roofs on buildings in Arizona, Grepper, so often I'm standing in a pool of water while grinding. Now that I think about it, maybe we should have roofs in Arizona. It does cloud up and sprinkle every 100 days or so.
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