Slitting saw usage ?

When I worked for Texas Instruments I was checked with a static voltmeter without my lab coat and foot straps. I pegged the 20kV scale.

Living in Road Salt Alley is the bigger problem. I just finished painting the fender rust repair that I was welding on this morning, filling pinholes I found last last night with a strong light. This time instead of inlaying a flush patch I jammed a larger piece of 22 gauge steel behind the hole and lap welded it in, sandblasted, then filled to the template with Bondo Glass.

Supposedly my solar panels are within the TV antenna's Cone of Protection, but so is the metal chimney and I've heard a spark jump off the stove (now also grounded).

Even NASA admits uncertainty about lightning protection.

-jsw

[ ... ]

Have you looked at Greenlee Chassis Punches? Beware that there are two types of round ones (excluding the keyed, and D shaped and other specialties ones). The most common are "knockout punches" which make holes for the terminating threads of conduit and such, and are significantly larger than the nominal size. The others are for meters, pilot lights, rotary switches and such, and are pretty close to nominal size. If you find them at a hamfest, or a flea market, have a caliper with you to see what the size actually is. (Sometimes a knockout punch can be a size which will handle mounting a meter nicely, if you check the size first. (Kind of hard to make the hole smaller after using the wrong type/size of punch. :-) But they do make nice holes in aluminum and sheet steel up to reasonable gauges.

Most come with plain draw screws, but there are ball-bearing thrust bearings for heavier work. Use a ratchet wrench on the hex bolt head, and if you are working on a panel rather than the side of a box, clamp the punch end (which has two opposed flats) in the nearest milling vise.

There are specialty ones which are nice to have too, such as the keyed 15/32" (for toggle switch mounting so they won't turn), and the

5/8" and 1/2" D ones for fuse holders and the like.) I even have one for mounting the 25-pin DB-25 connectors for older RS-232 connectors.

Of course, for production, a turret punch with a set of dies for the special shapes is quicker to use. And for serious production there are CNC punches which make all kinds of rectangular holes as needed.

Enjoy, DoN.

Nice list there Don - I have a large collection myself, most are electronics level but not plug/socket level/switch level.

Rounds and squares. I have some from the 20/30's and 50/60's. Cans for the old ones and boxes for the newer ones.

The best kind have ball bearing bolts.

Martin

Nice summary. When I was an industrial electrician building custom test stations for GM I used a hydraulic Greenlee punch a lot to run conduit. into purchased JIC control boxes which don't have knockouts..

That company fabricated racks and non-liquidtight enclosures themselves and punched the holes on a Strippit. Later at Mitre I had a Rotex turret punch in my model shop.

At home I have Roper Whitney XX and #5 punches, step drills, the smaller sizes of Greenlee radio and conduit punches, and a boring head on the mill for everything else.

I wasn't impressed with the durability of the Greenlee RS-232 punch when used on 0.062" 6061. For home use I bought 0.050" 5052 which is easier on the punches and the 30" 3-in-1 sheet metal machine, and plenty strong for small portable enclosures. 0.031" is enough for meter boxes. I still use 0.062" to package Variacs and transformers and 0.093" for rack panels.

-jsw

I think the marketing guys sell on the "destroy voltage" numbers rather than the "running voltage" figures Engineering gives them, thinking it will entice more purchasers. Time was, marketing used to have the interests of the company in mind. Unfortunately, that time is long past. Now they think that higher sales numbers (even if they include all the free warranty replacements) are good.

My favorite LED flashlights use a Cree XM-L T6 bulb running 900LM (lumen) max, but Chiwanese vendors are calling them 2000, 2200, 2500,

5000, and 6000LM to grab sales. AFAIC, they're bright enough, have a zoom shroud, 3 brightness modes, flasher mode, and SOS mode, and cost only $5 on sale, so I'm happy.

Verily! Rheostat clutches? Arc chutes? Luckily, our control panels are smaller and less expensive nowadays. I imagine that amperages were slightly high in those boats. There were no figures quoted.

I'd like to have a new replacement copy or two of their battery banks, though.

What? You mean the brochures stating categorically that their device is lightning-safe up to several million volts @ several million amps have been lying to us?

Do you have a lightning arrestor at your breaker box?

The battery overcurrent relay was set between 12,000 and 14,000 Amps.

That manual describes the details that modern automation lets us ignore, unless you are the designer of the automation or are putting together a home solar system with batteries and a generator. Mine has the extra complication of both 12V and 24V inverters which requires floating some of the panels and being careful of cross connections.

A few month ago I posted a warning about the different types of automotive replacement circuit breakers, since Type 1 automatically reconnects after a timeout and Type 2 resets after power has cycled off. Only Type 3 stays open until you push the button.

And a shipyard crane to move them.

The operators had about 30 seconds to completely reconfigure the complex switchboard from running on Diesels and charging batteries to crash diving at full battery power. I need longer than that to change channels (antennas) on the TV.

-jsw

I haven't changed the house wiring, but I unplug a lot of things when I hear distant thunder or radar shows an approaching storm front. We rarely get isolated pop-up thunderstorms.

Lightning hit the pole in front of the house once, scaring the $#!+ out of the neighbor working near it. The only damage was to the old carbon arrestor in the phone network interface box. The electric meter and its box and drop are fairly new so I assume they are up to spec.

-jsw

I glossed over it, but didn't see much relevance. Looking again...

Yeah, I bet.

I don't recall seeing that. I use Type 3 exclusively. Button and lever.

Ayup.

That must have been fun, huh?

OK.

You assume with the people who gave us the Home Irradiator electronic meters and Time of Use fees? Um, OK. Not so much, here.

They can read it from the street but it isn't a networked Smart Meter.

After I returned from a CA trip to see family last March, I found that I wasn't sleeping normally. A couple days later, when I turned on the faucet for the front watering, I noticed a brand new natural gas regulator and electronic meter on the side of my house. After learning that it had a city-wide range, I built an L-shaped frame and tacked metal screen over it, then fastened it to the meter piping and brounded it to the gas pipe ground wire. It shields the house from the meter. Normal sleep resumed that night. Until then, I had been unsure of the concern over electric meter safety, but the shielded gas meter (much less powerful than the electronic meters from the electric utility companies) proved to me that they can and do affect human bodies in an unhealthy manner.

What cued me that something was hinky with the meter/reg replacement is that the girl told me that the batteries in the meters were due for replacement, yet the company spent (hundreds?) considerably more money on a new meter, new regulator, new valve, plus several hours labor rather than changing the battery.

Well then, case closed. You should start a religion.

BTW, there's a shit ton of radio waves floating around. Only way to stop them is to put the metal screen around your head. And don't forget to protect your friends who don't have access to Internet wisdom, or thumbs to make use of it.

LOL!

Single point grounds don't help much at cellular and WiFi frequencies. Even a gap in a large conductive surface, such as a warped cabinet door, can pass radiation.

-jsw

Would that slot antenna work with metal screen over the slot strip, or in place of the slot strip?

What can I say? It worked.

This led me to it.

When I had a nice HP vector network analyzer to test my concoctions sometimes they worked as planned and sometimes I learned another strange quirk of radio propagation. For instance a screen set up to block radio signals may unintentionally become an antenna to transmit them:

-jsw

They can read mine from anywhere in the country with an internet and the pass-code. My power company reads 3 of my meters that way. Keeps them off my place and fewer people. It aids the third party power companies who get the data and do it themselves or perhaps they get the main one to supply the data.

Martin

Now they can't turn off your utility. My water meter is like that - but the truck has to drive to the driveway to read three meters. Water meter is in the ground.

The electric meter is power line internet. I have IOP in my house,

500Mhz. Same as the wireless. Hard wire is 1G. Outside world tap is lower.

Mart> >