A request for information on your mill or lathe

[nova_robotics]

Static is odd, no doubt. Know I've related following observation about one particular belt sander. It would deliver low, continuous but obvious shocks to me while running it. 1" abrasive belt, direct drive, 110v, metal stand in substantial, professional toolroom. Meter tested operative ground conductor, plug and receptacle, zero regarding rubber mounted motor case, period. Cowhide gloves stopped it, a little open belt machine, so minimal risk.

I too had this exact issue with a cheap 1" belt sander. A shock every 5 seconds or so. If you look at the construction of most belt sanders, they are almost identical in construction to a Van De Graaff generator. A non-conductive belt that is driven between two (or more) different pulleys. Charge is picked up on the belt as it comes in to contact with one pulley, then as the belt travels away the voltage is increased through Van De Graaff voltage multiplication. Some fairly high voltage can be developed this way. So what I did was replace the nylon (?) pulleys with some nice aluminum crowned pulleys I turned down on my lathe. That grounds out the sandpaper just before it gets to the workpiece and your hand. Problem completely solved.

https://en.wikipedia.org/wiki/Van_de_Graaff_generator

Here's the belt sander with the aluminum pulleys, top and bottom. I left the original plastic tensioner pulley because it contacts the belt in a place that doesn't really matter. If you have a problem sander I definitely recommend this upgrade. Technically only the top pulley needed to be changed to achieve the desired effect, but some other things happened to that poor little sander that required some additional surgery.

Another shop; under strict ESD protocols, even pure mechanical assembly areas; gowns, wrist straps, shoe covers, bonnets. Every day entering the lab you'd already be suited up, step on the check plate, touch the contact (without, then with) wrist strap connected to ascertain conductivity. Everybody would get low readings; I could do it without the wrist strap, consistently. Due to sensitive product, wore one anyway.
The lab's responsible engineer, an Air Force officer watched me one day, amazed at the phenomena. "How is that possible...?" he said.
I quipped "Well sir, I'm not pole-ish, a positive attitude, drink only ground coffee." (dramatic pause) "and I know how to conduct myself!".
Uproar of the staff, best ever.

Nice. Well done, sir. I do a lot of electrical design work in my shop. I compulsively ground myself out on every available piece of metal as I'm working. I don't wear a grounding strap, but I have one hand on a grounded frame most of the time anyway. I'm basically ESD grounding OCD at this point.