A request for information on your mill or lathe

[Frank S]

Now that you mention it my 2x48 belt sander gives me a small shock sometimes. I try to avoid touching the frame while grinding but, the shock is sometimes even felt through the work piece when I make and break contact with the rest. I thought it could be a bad ground but after checking I couldn't find any problems. Gloves are such a pain to even remember where a pair are, insulated plier does the trick for small items. There is no way I would have ever correlated a belt sander with the Van de' Graff, but now at least a possible direction for a solution has been made available. Thanks to all for the tip.

[Carnel]

Hi Rick,
"These are the lowest readings I've seen so far. I'm guessing that your machines are new enough to have ball bearings and not babbitted bearings."

As far as I know it are tapered roller bearings. So a relatively large contact area.

Harry

[nova_robotics]

Now that you mention it my 2x48 belt sander gives me a small shock sometimes. I try to avoid touching the frame while grinding but, the shock is sometimes even felt through the work piece when I make and break contact with the rest. I thought it could be a bad ground but after checking I couldn't find any problems. Gloves are such a pain to even remember where a pair are, insulated plier does the trick for small items. There is no way I would have ever correlated a belt sander with the Van de' Graff, but now at least a possible direction for a solution has been made available. Thanks to all for the tip.

No probs. Just make a single metal pulley and put it at the top. That way it grounds out the belt before it has a chance to shoot little zaps into your fingers. Maybe replace the slider/platen thing that holds the sandpaper against your workpiece with a metal one? There are probably a few different ways to prevent charge from building up on the belt.

But really when you think about it, we're intentionally CAUSING the thing we've spent the whole thread trying to avoid. You are now grounding out your belt through a bearing. I've been using the crap out of mine for years like this and haven't had to replace a bearing yet. I'm sure it's accelerating bearing wear, but those bearings are easily changed and only a few dollars. A mill spindle bearing is a different situation.

[Toolmaker51]

This site is always a blast, great minds tackling issues of any kind, with real-world solutions. Points out things we tolerate, without pause to suss out a remedy that might be just a few minutes effort. Amid the negatives the web brings, this makes up for it.

OK! Now, about this supply chain issue...

[Frank S]

No probs. Just make a single metal pulley and put it at the top. That way it grounds out the belt before it has a chance to shoot little zaps into your fingers. Maybe replace the slider/platen thing that holds the sandpaper against your workpiece with a metal one? There are probably a few different ways to prevent charge from building up on the belt.

But really when you think about it, we're intentionally CAUSING the thing we've spent the whole thread trying to avoid. You are now grounding out your belt through a bearing. I've been using the crap out of mine for years like this and haven't had to replace a bearing yet. I'm sure it's accelerating bearing wear, but those bearings are easily changed and only a few dollars. A mill spindle bearing is a different situation.

I may have to try other solutions the platen is metal and the top roller is aluminum. Since it mostly happens when the back of my hand or along my fore arm happens to touch the grinder / belt sander housing but only under certain conditions like on the rare higher humidity days something that goes against my belief of it having to do with static electricity alone. I am more inclined to believe what I am experiencing is possibly a dust trail either in the motor itself or in the wiring to the switch. I am thinking the humidity and if it is dust is possibly acting like an impedance capacitor in some way which discharges to my touch. Does any of that make sense?

[tonyfoale]

I would like to learn the electrical resistance between the spindle and the machine's body of people's mills and lathes

Rick

By body of the machine I assume that you mean to the table of a mill and not to the fixed framework. The table is two moving slides away from the body.

[rgsparber]

By body of the machine I assume that you mean to the table of a mill and not to the fixed framework. The table is two moving slides away from the body.

Tony,

I think you will find that the resistance between table and frame is less than 0.1 ohms.

Rick