View Full Version : Static shock from belt grinder?

03-05-2011, 09:29 PM
At home I have one of those little cheap Delta 1" belt grinders. Every time I fire it up it builds up a hell of a static charge. I you don't constantly keep discharging it, pretty soon your going to pi$$ down one leg. How can I stop this? And no I don't mean pi$$ing down my leg, just the static build up. At work I have a Baldor and it never does this. Have any of you run across this?

Scotty Moore

03-05-2011, 09:43 PM
Where does the charge accumulate? What you have is essentially a Van der Graaf generator. Somewhere the belt is stripping off electrons and depositing them somewhere else. I suspect the issue is plastic rollers/plastic components. If you can figure out where the charge accumulates, replace that component with a metal one and then ground it. If it has a three prong plug, then you can just ground it to the metal frame/base of the machine.

The Baldor doesn't have this problem because it has metal rollers and the belt is probably supported by a metal strip. All of these components are electrically tied to the frame which is grounded.

03-05-2011, 09:56 PM
I'm going over to the shop tommorow, and I'll take note of the wheels on the Baldor. I know the bottom drive wheel is some sort of plastic, but I think the small top wheel just might be metal. I just never paid any particular attention to them. You may very well be on the right track. If that looks like the issue, making an aluminum wheel for the Delta shouldn't be any problem.


03-05-2011, 10:01 PM
I'm not sure why your Delta machine has that problem. My stationary belt sander is an old one with a cast iron body and wooden roller wheels , and never generates any static charge that I notice. It even sits on a wooden table, and is powered by a V belt from a 2 prong plug motor. However, I would think that grounding the machine frame to a metal stand, or to a piece of steel sitting on a concrete floor would stop the static discharge through you. Are you sure you aren't actually feeling an electrical leak from the machine motor , which is for some reason not discharging through the grounded conductor?

03-05-2011, 10:09 PM
I had one of those little belt sanders,all three wheels are plastic and it's a nylon backed belt going roundy round on them,so ya,perfect static generator.

Mine only built up static when the humidity was low.

03-05-2011, 10:09 PM

This is a pretty common problem with belt grinders. Easiest fix is to just let some metal tinsel drag across the back of the belt to drain the charge to a ground.

When I worked for Minnesota mining and Manufacturing we had such an arrangement on all the high speed slitters. Polyester back and cloth back abrasives would build a heck of a charge as it was being run through all the flexer rollers. It would be enough to knock you on your backside. So we used copper tinsel to dissipate the charge. It only took once to teach an operator to make sure the tinsel was in contact with the back.


03-05-2011, 10:27 PM
Take a closes dryer softner pad and rub it over the back of the belt while it is running. That will help if the problem is static. Be sure that it is static and not leakage. My switch went bad on the drill press and it started giving that tingling feeling. I have become very oriented to putting frame grounds to a driven ground.

03-05-2011, 11:04 PM
I don't feel like it's leakage from the system, but that said, I also don't know how to determine if it is or isn't. This machine has done it since the day it was new.

Today I was grinding out a small casting about 2" x 2" x 3" and had to keep tapping the casting against the corner of the table every 5-6 seconds to discharge the build up. If I didn't it would build up to the point it would arc across to get me. It was a very effective reminder.

Thanks again,

J Tiers
03-05-2011, 11:27 PM
I have the same type 1" Delta belt-disk grinder, and same issue.

Stuff setting on the table does not get a static blast...... it's grounded. it's only when you are free-handing a part up in the non-backed part that it happens.

As for teh grounding..... the belt has a backing plate at table height, which does NOT discharge anything.... the belts are pretty decent insulators front-to-back.

Might need tinsel or points held just off the FRONT surface of the belt at a pulley.

03-05-2011, 11:41 PM

I've got a 2 inch Kalamazoo that throws a blue arc off of it, that is reminiscent of the high frequency start from my TIG welder. :eek:

Baldor motor and a rubberized drive wheel - not sure what the upper roller is made from. Will have to check that. All I know is when I get within 1-2 inches of the belt, it lights my fire. :mad:

Pray tell.... where does one find copper tinsel???

03-06-2011, 03:52 AM
I have the 2" Kalamazoo -zoo - too, and man it's a shocker sometimes. Scares the daylights of me. I've wondered about some sort of makeshift ground strap on my wrist, but haven't tried it yet. Tinsel sounds like a plan if it can be found, or made.

03-06-2011, 08:45 AM
Take a clothes dryer fabric softener pad and rub it on the back of the sanding belt with it running. If it doesn’t work tell me and I will have learned something. If it does work then you have learned something.

03-06-2011, 08:58 AM
I have a 1" Kalamazoo with a Baldor motor. The drive wheel is plastic and the top wheel and platen are metal. It also has a 3 wire cord so it's grounded. I have never been bit off it yet and I've used it in all kinds of weather, high and low humidity and have ground parts without having them touch the base, in fact I've never given it a thought about getting bit. To start I would try a different brand belt, I think my belts are made by Sait.


03-06-2011, 09:50 AM
Get belts with a cotton backing, not the plastic film type.

03-06-2011, 10:50 AM
I have two hard drive magnets mounted in the sparks path and that does a good job of catching the ferrous dust.

And the grinder fur will always be 'kissing' the belt and take away the charge.

(Plastic wheels is the cause)

03-06-2011, 11:11 AM
You don't even need a belt sander to make a Van De Graff generator.

When I was working in the County fleet shop, our facility was in a pre-fab metal building. The boss started whining about the insulation inside getting dirty. After several attempts to wash & scrub the aluminum faced batting, I came upon the idea of vacuuming it, with our rather large shop vac.

The shop vac was a "top-of-the-line" Home Depot unit with a 4 horsepower motor, and a stainless steel tub. We fitted the brush end of the vac with a 10 foot long piece of schedule 40 PVC pipe and hooked the hose to the machine.
Once in operation, it could reach almost to the top of the insulation batting and did a wonderful job of removing the dust and soot (among other things) from the walls. To perform the vacuuming task, I recruited a porter and one of the jail trustees to push the vac while the porter vacuumed the walls. The storage canister would be full by the time they got half-way across one wall, in the shop. As many of you know, we're in the high desert here, and humidity is seldom very high.

Things went well for the first wall, then, after emptying the canister, they were going along the wall when the jail trustee dropped like somebody pole-axed him. We ran over and revived him, and soon discovered the PVC pipe, plastic vacuum cleaner hose and the stainless steel canister, pulling large amounts of dust & grit off the wall had produced a large (and powerful) Van De Graff static generator. Yes, it was stripping electrons off the wall and depositing them in the stainless canister. Our unlucky jail trustee had accidently touched the metal part of the handle while they were vacuuming, and got himself knocked senseless. Of course, the boss immediately blamed the shop vac, threw it in the truck and returned it to Home Depot claiming it was "defective". It was only after the trustee got knocked silly for the third time before I realized what we had....Especially since the vacuum was unplugged when he got floored the third time. A simple fix was devised with a small two foot length of chain bolted to the canister dangling on the ground...

Frank K
03-06-2011, 03:26 PM

I've got a 2 inch Kalamazoo that throws a blue arc off of it, that is reminiscent of the high frequency start from my TIG welder. :eek:

Baldor motor and a rubberized drive wheel - not sure what the upper roller is made from. Will have to check that. All I know is when I get within 1-2 inches of the belt, it lights my fire. :mad:

Pray tell.... where does one find copper tinsel???

I have the same one. Spray the back of the belt with anti-static spray that's sold for use on women's dresses. One shot lasts for a couple of weeks. Smells nice too.

John Garner
03-06-2011, 03:49 PM
Static discharge has lit up my eyes many a time when I was using a belt or disc grinder, but only -- as J. Tiers pointed out earlier -- when the workpiece was handheld. Eventually I learned that keeping one of my little fingers, wrists, or arms in contact with the grinder table / rest was pretty easy to do and kept the arcs-and-sparks at bay.

J Tiers
03-06-2011, 10:45 PM
Thanks, John Garner...... You gave me an idea.

Working in electronics, I am very familiar with static wrist straps and cables to ground...... using one at the sander would do the job. Odd that I never thought of it until you made that point.

They have breakaway snaps on the cords, so getting pulled-in would be unlikely.