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Goofs & Blunders You Should Avoid.

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mmcmdl

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Never take your eyes off a 750 lb driveshaft , 15 ft in the air held on with two 1/2" taper pins only . Although we had 3 straps holding onto such shaft , when your pins snap , gravity has a way of shifting the load ( right onto my left hand ) . I had my hand on the edge of the scissor lift and bent down to get the taper pin remover when they sheared . Got me a trip to the ER this past Tuesday , and an invitation into the woodshed for a safety talk . :cautious:
 

Downunder Bob

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Never take your eyes off a 750 lb driveshaft , 15 ft in the air held on with two 1/2" taper pins only . Although we had 3 straps holding onto such shaft , when your pins snap , gravity has a way of shifting the load ( right onto my left hand ) . I had my hand on the edge of the scissor lift and bent down to get the taper pin remover when they sheared . Got me a trip to the ER this past Tuesday , and an invitation into the woodshed for a safety talk . :cautious:
Yes definitely ouch, would some lessons on rigging come in handy.
 

David S

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Not sure if this has been mentioned yet. When I machine long tapers on my 618 with the compound, I lock the carriage x travel. I always worry that I may forget and engage the power long feed for another operation. So for the only time that I place anything on the bed, I lay the locking wrench across the ways as a reminder.

David
 

Mach89

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Not sure if this has been mentioned yet. When I machine long tapers on my 618 with the compound, I lock the carriage x travel. I always worry that I may forget and engage the power long feed for another operation. So for the only time that I place anything on the bed, I lay the locking wrench across the ways as a reminder.

David
Smart thinking. It's amazing how something so simple can save you from a lot of problems later.

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Screen Guy

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George, I never have been able to figure why someone would flip a switch even when there is a tag on it. Thinking back on working on that organ, I think that I left the plug in was because I would have to crawl under a piece of furniture to get to the plug-in. But I learned my lesson and that was why I built that control box.
A friend of mine told me a story about his father-in-law. He was a pilot for what I believe a B26 and he was selected to take some officers to some meeting in Europe. Behind the pilot was a jumpseat and a second luey was in it. He saw and reached up and pulled this switch. Suddenly everything including the engines shut off. The pilot calmly reached back turn it back on and had his copilot help him restart the engines. Just before takeoff on the return trip, The general handed him his 45 and told him he had his permission to shot anyone who tried that again. The flight back was uneventful.
 

Screen Guy

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Ok, I'll try again. In the late '70's I did a student overseas thing in Bogata and lived with a local family. When the lights failed in the bathroom, I could no longer shave. I was the only one of shaving age, so I took it upon myself to fix the switch, successfully navigating a local hardware store in broken Spanish. I instructed the maid and the lady of the house in Spanish and English REPEATEDLY no to turn the power back on til I came down from the bath. The maid of course turned the power back on as soon as I was out of sight. I don't know what voltage they use in South America, but it felt excessive to say the least.
 

Screen Guy

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I had the exact same experience. I never found any missile either. Fortunately, my comprehensive covered most of the bill.

The guy that came out to replace the glass told me that the tempered glass windows were extremely susceptible to scratches, as he was gingerly scraping off the sticker on the new glass. A tiny scratch could make the the window spontaneously shatter. He told me that there were a lot of replacements in hot weather due to the glass heating and the stress building to the point of shattering. The glass is designed to break into tiny pieces with square edges to help prevent injuries.

When I was in high school, I used to make an oddity called a Prince Rupert's Drop. It is made by heating glass to the melting point and allowing a drop to fall into into cold water, resulting in a teardrop shaped piece. Because the resultant stresses from the sudden cooling and shrinking were so well balanced, you could hit the drop with a hammer withou breaking it but if you snapped the thin tail of the drop off, it would shatter into dust.
I can confirm the tempered glass story as a flat glass worker. The slightest knick at the edge and it disintegrates. On occasion tempered glass breaks spontaneously due to stresses set up when the glass was heat treated. Seen it once or twice.
 

jpfabricator

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I opened my brand new 1/4" center cutting carbide endmill, chucked it up in the mill, and proceed to break it off with the rapid traverse on the power feed. Less than 5 minutes from bringing it through the door, to throwing it in the trash. WHOOO HOOOO!

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savarin

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Always ensure the chuck jaws are engaged in the spiral.
Very quickly I set up a half inch wide cut off of a large plastic pipe and used the three jaw to expand outwards on the inside of the pipe so I could true the face.
OK, nice and tight, start to cut and zoom, bang!
two of the jaws flew across the room, they had expanded enough to pop out the spiral but the plastic ring kept them in place so I hadnt noticed.
Luckily I was not in the line of flight.
 

JPigg55

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The cost of being lazy and not paying attention.
I was machining a Tee shaped mounting bracket the other day for a small stepper motor.
As a final step, I was attempting to make a larger, shallower countersink hole to facilitate a small taper around the shaft bushing instead of a bigger through hole. I opted to use my mill since the piece was already set up there. Long story short, I went too deep and got into my vice jaws. Ouch !!!!
Luckily, it didn't do too much damage and I was able to smooth off the small boogered up area with a file. Lesson learned.
 

RandyWilson

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Learned this one last night. When installing hardware on new cabinets, and the new looking box of bits you found in the FiL's collection just doesn't want to cut, might want to check the packaging and see if you inadvertently grabbed a box of left-handed bits...
 

David S

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First time ever for this hobbyist. I was side milling a fairly small part held in the vice on two parallels. I taped the part down onto the parallels while tightening the vise. The part being milled was outside the vise jaws. Long story short one parallel managed to slip forward and crash the end mill. Parallel survived, milling cutter not so much.

I took a piece of shipping steel banding and bent it into a U to hold the parallels tight against the jaws and also made sure the part was seated firmly on both parallels.

David
 

darkzero

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There were some comments above about removing swarf.
Here's a shot of the acid brush I use to remove swarf and apply cutting oil to the work area:
View attachment 141751

The milling cutter grabbed it, pulled it thru and spit it out the other side.
I am so glad it wasn't my fingers.

I still use it.....keeping it as a reminder......

-brino
Sorry for quoting an older post, I was away during that time.

Funny! Reminds me of Randy Richard on YT. In one of his videos he shows it in action!

Pretty funny! I'll have to try that sometime!

http://www.hobby-machinist.com/threads/milling-machine-aka-automatic-brush-roller.32385/
 

coolidge

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When running a CNC machine turns your feeds down to 10% on the first part when proofing a new program. This guy in our shop, running a lathe the size of a mini van with a 3 foot chuck and a 6 inch thick boring bar, chucked up a 30 inch cast iron brake drum, hit the green button and let her fly at 100% speed. It knocked the brake drum out of the chuck, it blew the door off the lathe and landed out on the shop floor BOOM. Our shop foreman ran down there and chewed that guy's ass for like 20 minutes. lol
 

Charles Spencer

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When doing an utterly simple calculation it pays to still think about it and double check. I was making an arbor for a 7/8" plain mill cutter. Near as I can recall the old brain figured something like this:

"hmm, 7/8"? Let's see, 3/4" = 0.750 so 7/8" = 0.875"

So I then proceeded to turn it down to 0.750". A simple double check would have prevented it.

Fortunately it was only for 1/2" in length and I had left ample length on my cut off bar stock to fix it.
 

westerner

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Teleportation-- After test driving the truck I just put a new ring and pinion gearset in, I bent down under the truck to feel how hot the diff housing was. As I crawled under , my left hand closed around the "remote start" feature on the keyfob! In only a handful of nanoseconds, I was on my feet, several yards away!
 

dlane

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Whoops, ain't no warning label on that thing, there every else
 

kvt

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Wait a min, Isn't there supposed to be a safety in there some where so it will not do that.
 

brino

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Wait a min, Isn't there supposed to be a safety in there some where so it will not do that.
The "safety" is usually a switch that detects if the hood is open. In this case I suspect he was checking under the vehicle with the hood closed.
....or it could be that the switch got stuck down (open)....like mine did!

-brino
 

westerner

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There are actually several safetys that must be satisfied before the vehicle will start- trans in park, doors and hood closed. They all worked fine! No safety available for a careless mechanic crawling around under the rig! Another teleportation I have achieved- I had stuffed myself under the dash of a Mack dump truck to repair some wiring. Not an easy fit. The floor of the cab is 5 feet off the ground, the seat and pedals and shifter take up ALOT of room. Repair finished, just gotta shrink the tube over the repair. When the heat melted a nylon air line with 120 psi in it, I was certain I had awakened a rattle snake VERY CLOSE BY. I was NOT very close by, the very next thing I knew! I have no recollection of the trip.
 

kvt

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Wait till the car tried to run over you. they bring in a car from the school that had a fire under the hood. Had to replace the wiring harness under dash, and hood, Carb, distributor and other things. Last thing under the hood was to drop the distributor in, So put the starter bump button on and got all set up, Bumped the engine a little to get the distributor to set down, Well, had not put the steering column back in place yet, When it dropped, It started, in drive at about 1500 rpm, I went up and over, the fender, the car planted about 2 foot into the wooden work bench and cabinets. Boss was not happy.
 

Wreck™Wreck

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Remember where to set the spindle speed gearbox settings, 2 weeks ago when turning the OD of a 9 1/4" SS round at 260 RPM's or 613 FPM, (a bit fast but it worked) I put the spindle out of gear to measure the first pass diameter, this machine has an electric spindle brake which will not allow you to rotate the chuck by hand when in gear. The diameter was well within the desired range, put it back in gear (the wrong one) and started the spindle and feed and it went to 750 RPM's and the tool fed about 1/16" into the work before I could hit the feed hold button.

This caused the expected results, many sparks were created and the insert edge was toasted, 1700 FPM at .012" feed per revolution will do that.

Note to self, low range is to the left, high range is to the right on this machine.
 

mcostello

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Know a Guy that left a 400lb mold in a SMT still chocked up with a overhead crane. Crane did not get pulled down, the mold blew the door off on its way out. Many expensive parts and hours to fix that. Around 5-600 rpm. Pucker factor was off the scale on that one. No one hurt or fired.
 
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