2020 POTD Thread Archive

hman said:
Just a note of caution ... True, induction motors don't have sparky brushes. But they do have a centrifugal switch, which opens during startup, and can cause a spark. All of us are thinking of your continued safety!
Click to expand...
I appreciate all the advance and consideration for my safety, i'm much more careful now then in my young years, but stuff happens. The turbine i showed is a 3 phase motor i'm pretty sure they have no switch inside, and i plan to be be controlling it from outside the pit. I personally don't drive petrol cars, only my little niva was petrol and on LPG but i'm changing it to diesel also, so my biggest concern is carbon dioxide. Im sure i'll need to fix an exhaust so i'll have to use my Mig welder that i use CO2 on, and i'll feel better if i can switch on ventilation so i can bread clean air after welding, i'll probably end up tunneling under the concrete to the edges of the garage and run hose or pipe to the outside.
 
by the way.... a common gas which is heavier than air is Argon. And almost all of us have an Argon tank in our shop. Yes...Argon can kill you. its an inert gas....but being heavier than air one must make sure it doesn't accumulate in a lower hold of a boat, cabin, or a pit. A leaking mig welder or regulator and the pit is definitely a recipe for an accident. I'd wire an exhaust fan hooked to the lights so its always running. IN MY OPINION. just can't be too careful. Propane also heavier than air.
 
Argon is a major component of our atmosphere, similar to nitrogen. Both are simple asphyxiants, which means they displace oxygen if released in a confined space. Cryogenic argon is heavier than air because it is cold; compressed argon is equal to air and will not stratify unless cooled from expansion as it escapes a tank. Simple asphyxiants are safe (in shop quantities) with adequate natural ventilation. Problem with oxygen displacement is you don't realize it until you hear White Rabbit in your head and hit the floor. It's a fate for industrial workers, not so much for home shops. For peace of mind, you can use a "snooper" which is a wash bottle filled with soapy water to leak check your setup whenever you open a gas fitting to change tanks or do maintenance.
 
@pontiac428 not to argue with your experience, but, according to Specific Gravity of gasses, the specific gravity of argon is 1.38 x that of air. Carbon dioxide is 1.52. This means both will settle to low spots. The specific gravity of gases is normally calculated with reference to air - and defined as the ratio of the density of the gas to the density of the air - at a specified temperature and pressure.
The Specific Gravity can be calculated as

SG = ρgas / ρair [3]

where
SG = specific gravity of gas
ρgas = density of gas [kg/m3]
ρair = density of air (normally at NTP - 1.204 [kg/m3])

NTP - Normal Temperature and Pressure - defined as 20oC (293.15 K, 68oF) and 1 atm ( 101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 30 in Hg, 760 torr)

With normal ventilation and non-leaking tanks there's no problem. Having tanks means some amount of leak monitoring. It's what you should do. Who wants a leak? It costs you money (and time). Soapy water works great for finding leaks as mentioned in your post.

Pits or enclosed areas need more than natural ventilation. The White Rabbit as you call it, can be deadly. Both argon and nitrogen can kill by asphyxiation, but argon, CO2, most volatile cleaning solvents, and refrigerants can also accumulate in low spots. The link above shows some common gasses and their specific gravities.

It's just another hazard to look out for, one of many, that we all face everyday. We don't stop work, but we should pay attention to the hazards and attempt to mitigate them best we can. My two cents.
 
Cut Some 1/4" Steel Plate With My Sawzall

IMG_1115 2.jpeg

I started a project today by making a 14" long cut in a piece of 1/4" mild steel plate. So, this was a test to see if my sawzall
would do the job, which as you can see, it did. The blade is a Diablo Steel Demon carbide blade made for metal up to
9/16" thick. I was a bit skeptical, but it worked OK, so I can recommend the blade.
 
Last edited:
Nogoingback said:
Cut Some 1/4" Steel Plate With My Sawzall

View attachment 341018

I started a project today by making a 14" long cut in a piece of 1/4" mild steel plate. So, this was a test to see if my sawzall
would do the job, which as you can see, it did. The blade was a Diablo Steel Demon carbide blade made for metal up to
9/16" thick. I was a bit skeptical, but it worked OK, so I can recommend the blade.
Click to expand...
That came out really well! How much was the blade?
I'll answer that ~ $10 for the 6", ~ $15 for the 9". That's pretty cheap.

Any special precautions? Hearing protection advised? I have some 1/4" stuff to cut that's just bigger than my HF 4x6 bandsaw can handle. How do you start the cut? At 8 TPI thats 2 teeth for 1/4". Is it grabby?
 
Well it took few days. We did found couple of bullet shells, from a AK47 probably, but we wore very lucky not a single stone, only sandy soil and clay. But the cat worked, and we started to work at 5 AM the guy keep digging till he reached the max depth on his machine but only on the side near the door, the other side we hit clay, so down we went with my hammer drill, pick and a shovel and we dealt with the clay by hand. That is unusual, the guys running diggers will get what they can with a machine and you deal with the rest. Perhaps he feel bad for dragging the job and me doing so many repairs on his machine. And he changed me only his cost for fuel and other expenses. I helped him load the machine and we said goodby, but few minutes later he got back on foot. It started to drizzle a bit as he was leaving and he chose to go from the back road which is dirt and he managed to slip off the road, near tip the truck and machine. I got down there i got in the truck, he in the mini digger and we plow a new road, made a real mess but got him on the road. What a journey just to dig a hole in my garage.
IMG_20201014_193459_1.jpgIMG_20201016_125459_1.jpgIMG_20201016_150712 (1).jpgIMG_20201016_172248 (1).jpgIMG_20201016_172321_1 (1).jpgIMG_20201017_113803.jpgIMG_20201017_113811.jpgIMG_20201016_141332_1.jpgIMG_20201016_141342_1.jpg
 
Glad you got it dug out, and then got him dug out, too!
 
Put the finishing touches (and paint) on my lifting arm. I added a band to the top which greatly reduces flex of the arm.

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The capacity of the arm is much greater than the capacity of the lift truck.

Robert
 
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