Only a Machinist Would Notice

My life is like the kids magazine highlight which has those pictures with the caption what’s wrong with this picture? First being a mechanic my job is looking for things that are not right. Starting my hobbies long ago in woodworking of all sorts when I walk into a room I’m looking at the trim work all the seams and joints etc. Noting how the doors open and close pretty much everything carpentry. Then I get into metalworking and find myself looking at toolI got marks and paths. Trying to Figure out how they held it or steps involved.
To answer the op’s Question it’s a trait. It’s what interests you, what catches your eye. Did anyone answer the question on the purpose for multi start threads?
 
Well we looked at it from many angles but it turns out to be just a fashion statement.
 
Reason for multi start thread. Have a long lead (nut advances a long way in one turn) while at the same time having small threads with a shallow depth.
Example. a 20 tpi 4 start thread has a lead of 1/5 inches or .2 inches per turn.
You could get that with a 5 tpi thread. But the 5 tpi thread is much deeper from crest to root. You could never cut one on a thin walled tube.
Multistart allows threads in thin walled parts AND fast lead. QED.
 
Here's a messy experience with milk jugs.
This goes back about (20+) years, not sure if then they were made out of HDPE or not.
Changed the oil in the car using quarts, and I poured the used into a milk jug to take it for recycle.
Had it sitting in an old teflon frying pan, it got a bit messy so I didn't bother to wipe it down and just left in the pan for awhile.
It sat for a spell and when I went out into the garage one day I had oil all over the floor.
Something, somehow had reacted between the teflon, the oil dripage, and the jug. The bottom was deteriorated.
 
Had a similar thing with a gallon of HCL (36 % muriatic acid) the jug was in the garage in the corner and one of the HDPE seams had a tiny split in it. Only discovered it when I started noticing rust on some of my good tools. Lost a cheap Starrett mic. I store acids outside now. :)
-M
 
middle.road said:
Here's a messy experience with milk jugs.
This goes back about (20+) years, not sure if then they were made out of HDPE or not.
Changed the oil in the car using quarts, and I poured the used into a milk jug to take it for recycle.
Had it sitting in an old teflon frying pan, it got a bit messy so I didn't bother to wipe it down and just left in the pan for awhile.
It sat for a spell and when I went out into the garage one day I had oil all over the floor.
Something, somehow had reacted between the teflon, the oil dripage, and the jug. The bottom was deteriorated.
Click to expand...
That happened to me too. The jug was near my car so when I saw the pool of oil under the car I thought "Oh #@$*. After finding the true culprit all I could feel was relieved that it was not from the car.. Seems the four "corners" of the milk jug bottom are extremely thin and the weakest point.
 
middle.road said:
Here's a messy experience with milk jugs.
This goes back about (20+) years, not sure if then they were made out of HDPE or not.
Changed the oil in the car using quarts, and I poured the used into a milk jug to take it for recycle.
Had it sitting in an old teflon frying pan, it got a bit messy so I didn't bother to wipe it down and just left in the pan for awhile.
It sat for a spell and when I went out into the garage one day I had oil all over the floor.
Something, somehow had reacted between the teflon, the oil dripage, and the jug. The bottom was deteriorated.
Click to expand...
Some of the constituents of used motor oil are acidic or capable of reacting to become acidic. Weakly acidic but given time they will work their way through many plastics and even some metal. It is like canned tomatoes, you would hardly think of them as being an acid but they will eat through a can that isn't lined in a matter of weeks to months.
 
markba633csi said:
Had a similar thing with a gallon of HCL (36 % muriatic acid) the jug was in the garage in the corner and one of the HDPE seams had a tiny split in it. Only discovered it when I started noticing rust on some of my good tools. Lost a cheap Starrett mic. I store acids outside now. :)
-M
Click to expand...
Anything and everything that says 'Acid' on the label I store in the Garden/Mower shed.
Years ago I was working in SoCal at a company that had a fantastic in house machine shop and tool room.
The shop manager instructed the poor clean up kid to mix up some muriatic acid and clean the floor over in the storage area where some oil/lube had leaked all over the floor.
The dude took the jug and poured it directly on the floor. Had to evacuate the building and air the place out.
Every piece of machinery from the CNCs to Manuals to the inspection area to tools in toolboxes was ruined.
Unbelievable the amount of rust that coated everything.
 
Surprisingly tho, HCL is great for removing rust- you just need to make sure to neutralize it afterwards with an alkali
I've noticed they don't sell 36% stuff anymore, here you can only get 30, but it's still pretty strong and fumes
 
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