Goofs & Blunders You Should Avoid.

samthedog said:
  • Never assume a capacitor is discharged. I nearly rode the lightning into the next life with this one
All goofs above were learned by yours truly either directly or indirectly.
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I once knew a guy who thought it was great fun to toss a fully charged capacitor to "the new guy" to catch.
I never saw the retribution but I always assumed that at least one person had a meeting with this yahoo after work and off company property.

Looking back as some of the practical jokes that we played; none seem funny.
 
george wilson said:
I was in a hurry,and did 2 things wrong: 1; use paper in the SMOOTH jaws. 2; grind a vertical flat on the cutting edges of the 1/2" drill so it wouldn't suck up the brass when it broke through. This is GOOD,GOLDEN advice when you are drilling Plexiglass,too. It will shatter when the drill breaks through. Take this advice and save yourself lots of money when drilling a sheet of plexiglass!! Grinding a vertical edge on the drill causes it to scrape rather than cut. It doesn't seem to make the drill less effective when using a drill press. Might hurt when pushing an electric drill by hand. Keep the edges sharp.
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George,

I'm having a mind freeze on this vertical flat idea. Can you post a sketch or photo?
 
A charged capacitor can stop your heart. Horsing around like that by ignorant clowns can have tragic results. Air hoses can blow up your intestines and kill you,too. That's why the safety models with the holes drilled through their sides are made. You know exactly where some idiot is going to jam an air hose.

I don't have a picture of the drill. The cutting edge of drills is a wedge shape made by the angle of the bottom edges of the drill,and the angle where the spiral flute meets the cutting edge. Just grind the spiral flute into a vertical angle where the spiral flute meets the cutting edge. That way the drill scrapes instead of cutting as it drills. It's not complicated. You only need to grind a 1/32" tall vertical spot on the drill for this to work.

Google "How to grind a drill bit for drilling in brass". There are several sites to go to for pictures and demos.
 
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Speaking of capacitors, I remember an incident in HS Physics class where a Wimhurst generator was being used to demonstrate static electricity principles. A Leyden jar (an early form of capacitor) was sitting on the counter and I absentmindedly picked it up and brought the ball terminal up in the vicinity of my lip. It was charged to something more than 50KV and the lesson was learned. To add insult to injury, I touched the ball with a finger and again learned a lesson that even though you discharge a capacitor, there is usually a residual charge left.

Ever since then, I discharge capacitors not once but twice before handling.
 
Reeltor said:
I'm having a mind freeze on this vertical flat idea. Can you post a sketch or photo?
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When I was growing up, we called that a "titanium rake". Its a flat ground on the twisted face of the drill, parallel the axis. No. I dont' have a picture, either. As George said, it makes the drill scrape instead of cut, like drawing a knife sideways across a piece of wood.
 
A note about 'chip breakers' and long chips.

When I had my first 'real' job as a machinist, well machinist's helper was the title. We made punches and dies for mass production in a small shop. So tool steel was the norm for turning and milling. I don't know what I was turning in the machine, I didn't know one metal from the other at that time...come to think of it if I ever did I've forgotten most of it...the cut produced a long continuous chip. Very ductile material. I wasn't thinking about breaking the chip and let it go where it wanted. It wanted to wrap around the levers and knobs on the apron of the carriage.

When my cut was nearing the end, very close to the chuck I might add, I reached down to disengage the feed. Well as things go the chuck chose that moment to grab the chip, catching my finger in a 'loop' of the chip and snatching my hand up from the lever. It caught my finger and sliced it to the bone, had it been an eighth of an inch lower it would have taken part of the finger at the joint. That was forty two years ago and my right hand index finger is still numb and it aches like the dickens on cold days. Could put it all down to ignorance on my part or blame the machinist for not keeping an eye on the helper but I know I have no one to blame but me. When working with machine tools we all need to be aware of what is going on at all times.

Point is, break the chip if it doesn't break on its own.
 
When using a vertical band saw to cut aluminum, don't push where the blade will come through. I put a screw driver slot in my left thumb many years ago. The scar's still there, a line connecting the two corners of my thumb nail. The skin inside it is ultra sensitive, like the nerves grew back with a vengeance.

I was cutting up some scraps to make pads for the jaws of a vise.
 
savarin said:
dont listen for the gas at the tig nozzle when you have a high frequency start.
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Happened to me a couple times, not in the ears but on fingers.

Pressed the pedal to feel the gas flow..
We have different tig welders at work, plus my own at home wich is ''lift arc''. Only one of these machines is high frequency so having done lots of welding with the other machines I kinda forgot this particular one was HF.

For those not familiar with the high frequency thing here's a short definition from the millerweld website:

the current must heat the tungsten so it becomes a better emitter of electrons; at that point, the arc can jump from the tungsten to the work piece. One traditional option for solving DC arc starting problems, and the standard method for improving AC arc starts, involves superimposing a high frequency (HF) current over the welding current. Basically, the HF current forms a path for the welding current to follow and so the arc can be established.

- See more at: https://www.millerwelds.com/resourc...a-tig-welding-machine-qa#sthash.WO8QKFyp.dpuf
 
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