new grinder a hair raising experience

[snj8198]

Hey gang, I got a new 1"x30" belt grinder from Harbor Freight for sharpening knives. It's giving me static shocks. The shocks can be related similarly to static from dragging feet on the carpet. I can get a little shock with one pass of a knife or a relatively big shock after 5 passes.

What can a guy do for this? Do I need to ground the grinder or myself some how?

Thanks!

Shocked Steve

[Deer_hunter_088]

never heard of this before, could be a faulty grinder?

[truckster]

If the sander is grounded, it's static building up on the workpiece. Does it happen if the workpiece is in contact with the table? If not, you might try a jumper from the workpiece to the grinder.

[snj8198]

I pulled the motor inspection cover off. The sander does use a three prong plug and the green wire is grounded to the motor housing. Other than that there is no other grounding system being used. The sander has rubber feet and the 3 belt rollers are all plastic. I'm not sure where to go with this. Grounding each knife to the sander body doesn't seem practical but something has to give. There is an adjustable metal backing plate behind the belt where I contact the belt with a knife. If I touch that metal backer with the knife tip after every single pass there is a very light little shock discharge. But if I try to avoid contacting the knife to metal for 6 or so passes then touch it the static build up is enough to darn right hurt.

I read online that a guy can run ground wires from the ground post on the motor body to the drive rollers to collect the static build up but the model has plastic rollers.

[walker]

Yep, just static. It happens more in the winter due to drier air. When the humidity goes up it doesn't seem to be a problem.

['63GENIII]

Hey Steve, Id try running a set of jumper cables from a metal part of the grinder (housing or stand) to a water pipe, electrical pipe or even a gas pipe as an experiment to see if you still get the same static build up. If the belt is moving fairly fast, it can build a charge just running. Give it a try. I could be wrong but air passing over a fixed surface can tend to build a static charge. If the belt is moving fast enough, it could be moving enough air to make some static.

[fear_nothing]

Pardon the minor thread de-railment. Quick Harbor Freight story. Had a cheap 12 dollar drill stashed away in tool cabinet. With the majority of tools engaged in another project I needed a drill. Plugged it in, put a bit in it, hand tighted it and it promptly started on fire. My hand tightening it was too much torque for it.

[Willie Makeit]

it has nothing to do with the brand, and everything to do with physics. it's static electricity generated from the paper-backed belts rubbing at high speed against the metal frame of the sander (think of dragging your feet in socks across carpet then touching your little brother/sister's ear ). ANY belt sander will do this if it is not equipped with some type of grounding mechanism that runs from the equipment to the user. In the industry it's called an ESD (electro static discharge) mechanism. It provides a grounding path between the source of the static charge (the equipment) and the source of the ground (the user)

https://www.amazon.com/StarTech-com-.../dp/B0002QKMEG

[100%Chevy]

Yep,you need to add a ground jumper to bleed the static off.
Did Ya'll know that in earlier years(my 57 Chevy for one)GM put a spring and cup on the end of the spindle in the front hub to bleed off the static generated by the rotation of the hub/bearings?
Was to stop noise in the radio.
Mike.

[snj8198]

oooooh jumper cables!

Thanks for the link Willie. I had no idea such a critter existed but it makes sense based on what truckster and walker said. My luck I wont pay attention to the strap and and get it and myself wadded up in this sander. Then ill be starting another thread about bad sander experiences. Could I just bolt a long jumper wire to the sander and alligator clip it to myself... somewhere? Anywhere??

[mongocanfly]

At work we have high speed transfer lines that build enough static to put you on your knees..to eliminate the mind blowing shocks we use what is called static string..its abouf 1/16" string with metal fibers woven into it..if you can find some it should help..and we have to wear esd shoes.That might help to

[midniteblues]

How about a pair of big ole clumsy rubber gloves to handle those keen edges.

Then a pair of rubber tites for when the gloves don't work.

What will really help with the clean up then is a nice rubber floor mat.

Sorry, I'm no help.

[snj8198]

What will really help with the clean up then is a nice rubber floor mat.

ya! i thought about this blues but since my rubber soled shoes didn't work i dis-guarded the idea. Maybe I need to head to HF for a shop set of rubber work matts. Thanks!

I got through all the kitchen knives, pocket, hunting, and shop knives. Sharper than heck! But my figures are kinda sensitive now and for some reason every static shock made my pants around my calves jump.

Regardless, I used 500 grit as my course belt, 800, then a leather strop. I got mirror image edges and they are shave able sharp! Wish I had this for butchery season last fall.

[midniteblues]

That was just a idea.

This is what i do on my hunting knives.
I only carry 2 when i'm out.
A folding buck and a fixed soild both are surgical stainless steel blades.

Usually during the summer I go over them if needed.
Useing progressively finer paper on a very hard flat block Up to 600 grit. Then I run them on the buffer.(careful here)

There is usually a very minuet burr left by buffing that a lightly oiled strop takes care of.

This makes a dangerously sharp edge that can be brought rite back with a few licks on the strop.