A shocking cabinet....

[bullfrog123]

Ok... I've had enough of this blast cabinet shocking my gut or arms. Cannot figure out why I get a shock when I blast. No matter what media I use. Without a shop vac hooked up it builds static. Tried tonite to "ground" the cabinet to the shop itself... no go, still buzzed my belly.

How do you deal with this????? Cabinet is Cumminns tool junk yard run of the mill HF clone, but still should not matter the brand. The shock is similar to static charge from your shoes and touching a metal object, or person but blasts me every 5 seconds or so. WTF??????

 

[930dreamer]

I wonder if a static/ground mat would help?

 

[bullfrog123]

I have two rubber/foam pads stacked up on the floor to isolate me from the concrete. Even had this same cabinet sitting a huge OSB floor and no difference.

 

[930dreamer]

I have two rubber/foam pads stacked up on the floor to isolate me from the concrete. Even had this same cabinet sitting a huge OSB floor and no difference.

It sounds like the grounding wiring you added isn't going a good job. It's grounding through you still.

 

[A**holes Garage]

our cabinet at work used to do that, can't remember the fix right now..

 

[tomshep]

Try attaching a section of chain to the cabinet box and let it hang on the floor and see if that helps.

That is a trick used for painting cars to help with static charge.

Tom

 

[Garage5.9]

oops didn't read.

 

[Alchymist]

How did you ground it "to the shop itself"? Did you run a ground wire to the center screw on a nearby receptacle?

 

[bullfrog123]

How did you ground it "to the shop itself"? Did you run a ground wire to the center screw on a nearby receptacle?

3rd pic... was a crude fast test... gator clip from a cabinet bolt to a self tapper screw holding the tin to the metal frame of the shop.

 

[Boiler]

If it is only static, why not try grounding it to yourself? That way there is never a buildup of static to discharge. Akin to someone working on the interior of a computer wearing a static discharge bracelet which clips to the frame of the computer.

It doesn't help with the why, but it should stop the shocks.

 

[bullfrog123]

If it is only static, why not try grounding it to yourself? That way there is never a buildup of static to discharge. Akin to someone working on the interior of a computer wearing a static discharge bracelet which clips to the frame of the computer.

It doesn't help with the why, but it should stop the shocks.

I tried that too... leaned up against the cabinet while blasting but still got a shock every couple seconds. Seems no matter what I do it has a charge for some dam reason.

 

[engineer2]

When you are sandblasting, the media strips electrons off the part you are blasting and also the gun to some extent. The probem is worse during lower humidity.

Since the media doesn't conduct much electricity, it holds the charge. Ground the gun to the cabinet by using a wire along the hose. Ground the part to the cabinet. A steel mesh "floor" above the media hopper will help since the part will be grounded through it.

BTW, don't sandblast a bunch of parts that are in a plastic cup or bucket. You will be knocked on your *** when you touch them.

 

[TWX]

To ground you to the cabinet use an ESD ankle strap. They don't get in your way that way.

You might need to make sure that paint isn't blocking grounding from metal area to metal area. That could theoretically reduce the effectiveness.

 

[hh76]

When you are sandblasting, the media strips electrons off the part you are blasting and also the gun to some extent. The probem is worse during lower humidity.

Since the media doesn't conduct much electricity, it holds the charge. Ground the gun to the cabinet by using a wire along the hose. Ground the part to the cabinet. A steel mesh "floor" above the media hopper will help since the part will be grounded through it.

BTW, don't sandblast a bunch of parts that are in a plastic cup or bucket. You will be knocked on your *** when you touch them.

this seems about right. You aren't being shocked from static moving from the cabinet to ground, you are being shocked from static going from the gun to the cabinet. When you lean against the cabinet with the gun in hand, you give it a path.

 

[Agent1320]

This happens on alot of blasters. I've been shocked thousands of times using the blaster at the refinery I do contract work for. The fix I found was to wrap some solid copper wire around the nozzle, zip tie it along the hose, and wrap the other end of the wire around the expanded metal 'floor' of the blaster, then another from the cabinet 'floor' to a bolt on the cabinet frame or leg.

With the blaster at my shop, I had some zaps on occasion, so I used one of those static discharge wristbands with an alligator clip on a wire. I got it from the computer store for like $4. I just wrap the velcro end around my elbow and clip it to one of the screws that holds the gloves to the cabinet. Seems to work fine.

 

[OccupantRJ]

Ground cabinet to known good ground.
Lean your belly against the cabinet, and HOLD it there.
Blasting plastic will often zap you anyway.
Use a stranded wire ground from the blaster handle to the cabinet.
Humidity will affect getting zapped.
Wear tin foil hat. (just kidding)

 

[bullfrog123]

Thanks for the replies fellas!!!!!!!
Will try some different grounding ways and see what works best.

I figured that since the building is all steel construction that the ground wire from the cabinet to the bolt on the shop would be more than enough to ground it. Guess not, will try inside the cabinet tricks next.

 

[Charles (in GA)]

I have the same problem with my TP Tools blast cabinet. I have a good electrical ground, so I took a piece of #14 THHN (I even used green ) and ran it straight to the steel building structure (good bare metal) and still get when I get my nose too close to the cabinet, or sometimes from the retaining ring for the gloves to my arm, even through a jacket in the winter. Its caused by the air and media traveling thru the hose and gun, but I'm yet to find a fix for it.

Charles

 

[mathil]

Mine zaps me from the glove mount screws to whatever is nearest. I usually just bear it, it makes sure I'm awake when I spend long nights in the shop.

 

[Falcon67]

From my electronics mfg days - IIRC, our static dissipation tables and wrist straps used a 1 or 10 meg resistor in the strap cord between the operator and the table to bleed off the charge. A regular grounding wire didn't do so much. But that memory is approaching 20 years so take with a millivolt of salt.

http://www.allaboutcircuits.com/vol_3/chpt_9/1.html
See ESD Damage Prevention for some ideas

 

[MoonRise]

From my electronics mfg days - IIRC, our static dissipation tables and wrist straps used a 1 or 10 meg resistor in the strap cord between the operator and the table to bleed off the charge. A regular grounding wire didn't do so much. But that memory is approaching 20 years so take with a millivolt of salt.

http://www.allaboutcircuits.com/vol_3/chpt_9/1.html
See ESD Damage Prevention for some ideas

The resistor/resistance in the static dissipation straps/tables is there to keep you from getting fried from a short circuit. It also limits the static current flow so the accumulated static charge 'bleeds' down and doesn't leave in a Zap!

Ground the gun, the cabinet (and the mesh parts tray as well), and you (via the simple ESD strap, with the built-in resistance) to a known 'good' ground. No static build-up, no zap.

And yes, the cause of the zap/static is the air and the media flowing through the gun/nozzle. Media impact on parts is (usually) not really a (major) factor.

 

[1948]

i always thought this was my imagination! or sand going through the gloves, now it all makes sense!

 

[Modern Jess]

I've been shocked many times while using a blasting cabinet (which was properly grounded). I found that I would get shocked most often while holding the part free (with the integrated gloves, of course) rather than putting the part down on the metal grill inside the cabinet. As long as I keep the part touching the metal grill, the shocks are just about nonexistent.

 

[NUTTSGT]

So now after readin gthis thread, I'll probably start getting shocked. Thanks for jinxing me guys.

 

[bullfrog123]

So now after readin gthis thread, I'll probably start getting shocked. Thanks for jinxing me guys.

Your welcome

LOL.... my daughter was using it tonite and complaining of being "shot"... told her it was my subtle way of shock therapy...... not sure she got the joke or thought I was really serious....

 

[mjb]

I found that I would get shocked most often while holding the part free (with the integrated gloves, of course) rather than putting the part down on the metal grill inside the cabinet.

Before I started doing this, I got shocked all the time. Can't remember the last time I got zapped blasting.

The belt grinder is a different story.

 

[Greatbear]

It's not the cabinet accumulating a static charge, it's YOU.

The problem comes from the media moving through the plastic pick-up hose then through the isolated metal gun. You've essentially made a pneumatic Van der Graaf generator, and you are holding the business end of it. The fix is easy, you need to attach a wire from the cabinet gun to the shell of the cabinet itself, and make sure the cabinet itself is grounded (it appears you've done the latter). The wire does not have to be thick, it can even be bare. I used a bare copper stranded wire wrapped around the pickup hose. Since the ends of the hose connect to the metal parts of the gun and cabinet, I just folded the wire over into the hose and pushed the hose back onto the fittings, the wire makes decent contact. Bingo, greatly reduced static zaps!

Note that I said greatly reduced. You can still build up a charge on the gloves if you hold a small item in your hand while blasting, and a large amount of media hits the glove, but it is not with the same intensity or frequency as without the grounding wire, by far. Also, since you have what appears to be a new cabinet, the static problem will eventually disappear as you use the cabinet. All the rust and metal bits blasted off will eventually adhere to the gloves, the hoses and everything else, this builds a conductive layer that prevents static from building.

 

[buening]

The guys stating it's the gun building up the static is spot on. You need a ground wire attached to the gun. Been there, done that, and got the Tshirt!

 

[countryroad82]

So now after readin gthis thread, I'll probably start getting shocked. Thanks for jinxing me guys.

Yeah I was thinking the same thing myself!!! Never have had a problem with my cabinet or others' shocking me but I have a feeling that is about to change!!!