CNC mistakes...what's your worst? [Archive] - RCCrawler.com Bulletin Board

WRMorrison

03-24-2005, 05:09 PM

I just had a good one today. I was making some pretty small parts in the lathe (about 1" sticking out of the collet). After I set my G50's and ran a part, I decided to adjust the offset on the Z axis by .010". Evidently, the number pad on my control panel is a bit worn and it didn't read the first couple of keystrokes and input 1" instead... :shock: . Needless to say, the tool hit the collet, sparks flew and it grinded to a halt. A very expensive turning tool down the crapper. Luckily, the boss was in a good mood and said not to worry about it. Not really my fault, but I should have double-checked the screen to insure that the correct adjustments were made and read by the computer. Oh well. At least it wasn't a boring day as usual... :lol:

JasonInAugusta

03-24-2005, 05:31 PM

Worst CNC mistake?

Buying manual equipment. :lol:

Ace

03-24-2005, 07:05 PM

About 2 months ago I meant to jog down .001 but the jog was set at 1.000

Made a mess of my three jaw I was using to fixture parts.

a couple of weeks ago I busted 3 new carbide endmills in about an hour. 1st just broke cutting parts, not sure why. The other two were stupid mistakes on my part.

After the 3rd one I went upstairs and poured some scotch.

syco133

03-24-2005, 07:21 PM

Got one better than that one of the guys in my machine shop class left the big t chuck wrench in the lathe and turned it on and took off his thumb when it came back around.

WRMorrison

03-24-2005, 07:25 PM

Ace...ouch.

Try this one....

About 6 months ago, a former co-worker broke a 1.00"Ø carbide boring bar and then just said "oops". :lol:

Have you priced one of those lately?

Needless to emphasize (but I will anyway)... former

WRMorrison

03-24-2005, 07:27 PM

Got one better than that one of the guys in my machine shop class left the big t chuck wrench in the lathe and turned it on and took off his thumb when it came back around.

OFF?!

Damn!

syco133

03-24-2005, 07:34 PM

It was barley hanging on we tried to get it out with it attached but the lathe was locked up tight it bent the t handle and wouldnt budge.So we had to cut like one or two places to get it out it wasnt saveable anyway it was plum FLAT and MANGLED.He was happy just to be free from the lathe.My teacher also left it in one time chucked it all the way accross the shop thank god noone was in the way.

BENDER

03-24-2005, 07:40 PM

My teacher also left it in one time chucked it all the way accross the shop thank god noone was in the way.

:shock: :shock: :shock: That's just scary, I think you need to find a different school.

My worst is probably plowing a set of soft jaws with a 2 inch facemill, believe it or not the alum ripped every seat off the cutter. :shock:

Plays_with_Toys

03-24-2005, 09:09 PM

Holy nuts. Thats some scary stuff there. My biggest mistake was sending the wrong drawings for my TSC-10 chassis with the link mount holes 1/4 inch off each. I had to remachine all 50 units myself. "D'oh!" :shock:

RSI

03-25-2005, 07:39 AM

the biggest mistake ive ever done is had the speed up to high and broke a bit... not really that bad but i thought i share while we were on topic :lol:

Ace

03-25-2005, 12:49 PM

Running a "real" mill with 15 or more horsepower and silly fast rapids would be scary.

I have the advantage that if I'm having a bad day or I'm not focused I can just wait till I feel more in to it.

Doing it every day as your main job would be tough.

PinchFlat

03-25-2005, 04:49 PM

After the 3rd one I went upstairs and poured some scotch.

Ace likes scotch... Scotchy, scotchy, scotch.

JohnRobHolmes

04-25-2005, 10:07 PM

my biggest mistake was cancelling the order for my mill two months ago....

BultacoJim

04-25-2005, 10:59 PM

my biggest mistake was cancelling the order for my mill two months ago....
That’s because you really want the one that has the Servo-motors for CNC already installed. :lol: :lol:

rcconcept

05-01-2005, 11:09 PM

I was working a place that did custom plastis parts & I had like 300 peices to mill flat.I shimmed the peice so wound`t come loose but my boss didn`t like my idea of taking to passes to finish each peice & I sheepishly said I`ve tried to snugg it up but the peices pops out to easily.Well my bosses says I`ll so how you just need to wiggle the small flat peice of aluminium in place.Well he fires up the mill & while the bite spinning to make shure that the everything cleared hes starts pushing/tapping the small flat peice of aluminium with a peice of round stock or what ever we had on hand.Then all of the sudden I hear **TWING** & I all I could see was this sliver flash.The cutting bite caught the small flat peice of aluminium & pulled it right outta the vice & shot if a cross the shop.Nobody was hurt but the cutting bite & the peice of aluminium were toast

4XADICT

05-13-2005, 11:27 AM

Not realy my mistake, but I got the a** chewing anyway. I was running a Fanuc milling center with an 8 tool turret and about half way thru a 10min cycle it switched to the third tool and went into rapid traverse on the Z axis and tried to drive the tool thru the bed. Broken tool, tool holder, fixture, and spindle. It ejected most of the tool holder which bounced off the window right in front of me, thankfully it was enclosed. Machine was down for almost a week.

broncotxt

06-01-2005, 07:12 PM

Couple of days ago i was making some steering links and i left the T wrench in the lathe but luckliy it flew out and no damage was done. It scared the s*%@ out of me though :shock:

Rockinrockcrawler

06-01-2005, 09:10 PM

Well i've never done any cnc machineing but i'd have to say the worst one i've seen is my uncles missing bit of thumb. But i think he actually did that on a lathe.

BENDER

06-02-2005, 12:37 AM

Couple of days ago i was making some steering links and i left the T wrench in the lathe but luckliy it flew out and no damage was done. It scared the s*%@ out of me though :shock:

I'm sure you won't forget again. :-P

NEVER leave the T-handle in the chuck!! ;-)

stampede_dude

06-02-2005, 10:49 AM

i did the smae thing with my drill press except dumbazz me stuck it in there just to se what itwould do...not only did it scareme, it almost tookm thumb off:lol:

ILoveRCRockCrawlin

06-02-2005, 04:05 PM

haha i cant leave the wrench in the chuck cause its spring loaded so if you let go it will come out.

well my dumbest mistake was when i tried drilling a whole in a peice of metal and i thought its just gunna take a min so i didnt secure it down and just held it with my hand. next thing i know i have a slice in my hand wide enough to fit a nickle in it and probably 1/4 inch deep

ILoveRCRockCrawlin

06-02-2005, 04:06 PM

You right there are just a dumbass!

Why didn't you put it in, and go get a friend to turn it on, while your 20 ft away? :lol:
i like that one im gunna have to try that one

RampageFSJ

06-03-2005, 08:14 AM

I`ve never had an accident in the machine shop, or welding. But I`ll share a couple from welding at school. First, some really inexperienced guy in my class tried to use the grinding wheel and got his thumb caught in it :shock: . Luckily, he was wearing his welding gloves and it only mangled the glove and minorly injured his thumb. Then, in another class, a friend of mine was using the wire wheel on a piece of metal and it got pulled out of his hand, bounced off of the wall in front of him, and hit him right next to his eye, just past his safety glasses. Left a 2 inch cut and he had to get stitches. Now he says that he doesn`t even feel that spot and he laughs about it. Finally, another one of my friends, a year or so ago had the same thing happen to him but the metal went down and hit his leg and lets just say about 4 inches off of the mark an he would have been castrated :shock: .

ILoveRCRockCrawlin

06-03-2005, 06:56 PM

an he would have been castrated :shock: .

ouch

Train Of Thought

06-10-2005, 09:52 PM

One time, at band camp, I stuck a T wrench in my puss.

bigbomber

06-13-2005, 05:33 PM

did u forget it in there too?

well in welding class a guy was grinding down a 1/4" piece of metal and got his thumb stuck in there. it was nasty all bloody and stuff, all the teacher did was duct tape it till he could get to the nurse. and this happand to two more people. the only thing that happend to me was welding and then sparks jump down my gloves or burn holes in my shoes. peace, BB

ILoveRCRockCrawlin

06-24-2005, 09:23 PM

mine EVERY THING and gotting in to this hobbie
that has nothing do do with fabricating mistakes.

syco133

06-24-2005, 10:59 PM

Worst thing that happened to me personaly was getting hot chips in my shoe that hurts like a bi well you know.

CustomCrawler

06-25-2005, 06:33 PM

Its not a CNC mistake, by my live center 'exploded' when turning a part throwing the bearing and nose a couple of feet.

4X4XFAR

07-06-2005, 12:39 PM

Ive never had and major accidents, just a few destroyed tools, but I have a few I've witnessed.

The first one was back in school when a female student was using a lathe with her long hair out :shock: , lets just say that I never wanna see that happen again (scalped)!

The second was when I did my apprenticeship and the electricians were learning how to use the lathe's, one of them did the chuck's fasteners up the wrong way and the bloody thing went flying out of the work shop at over 800 RPM, lucky no one was in it's path!

Plays_with_Toys

07-06-2005, 12:44 PM

This isn't the thread you wanna read right before signing up for a shop class... :lol: I'll be taking a mill/lathe class in spring. Hopefully I can keep my head on straight.

Artstu

07-06-2005, 06:55 PM

by the sounds of things dont worry about ur head being on straight just keep it on :shock:

CrawlinNoob

09-05-2005, 01:24 AM

i entered a minus number for my tool length offset instead of a possitive and knocked the tomb stone off a makino horizontal..i went home after that

bill_jr

11-02-2005, 03:33 AM

Ever put a new 4" grinding wheel in a angle grinder and forget to tighten the hold down bolt? Well, when the wheel flies off at about a zillion rpm's, it will do a serious burn out and take off never to be seen again.

Kamikaze

11-07-2005, 02:12 PM

I was running a six tool program in an exell 3 axis and when it was suposed to change from a long 1 inch carbide endmill it stuck and I stoped to get it unstuck and when I turned it back on it stayed with that tool instead of switching to a very short ufo cutter and BANG!!! it drove itself at 100 inches a minute into my custom vise jaws that I spent the beter part of three days making for that part. Anyway that's not as bad as this guy that hit the wrong rapid lever on our 72" horizontal lathe and riped the 3 inch boring bar off of the head.

WRMorrison

11-08-2005, 05:32 PM

I never thought I'd see this thread again... :lol:

Not much to report lately except for a few broken taps and such. The new guy keeps whacking the tailstock with the turret, keeping the Daewoo service guy busy... :lol:

My most recent was a couple months ago. I was running about 5 different parts (a couple of operations each) on 4 separate tombstones. On the one I just set up, I spent a day checking and double checking everything. I ran the program through single block through most of the tooling, thought everything was fine, switched it back over to rapid and block delete, and WHAM! Drove a #6 center drill about 4 inches deep into cast aluminum. Used the same H value for two different tools...oops. :shock: :lol:

Smooth sailing ever since....so far............................

SavageMachinist

11-08-2005, 07:37 PM

My worst machining mistake I ever made was becoming a machinist.

BENDER

11-08-2005, 07:47 PM

My worst machining mistake I ever made was becoming one.

That's some funny **** right there!! :lol:

TMXONR

11-27-2005, 11:00 AM

My worst machining mistake isn't very bad. When I was in high school I was in an enginering class and we were machining little name plates. I was using a very tiny bit to make the part. There was one really annoying kid who wanted to man the emergency stop, and he wasn't paying attention, I yelled for him to hit the stop button, and the tool stoped about 1mm from the vice. Other than that I have launched many small parts across the shop when grinding parts for my crawler, and i have burned my feet and legs many times when welding.

skipstr71

11-27-2005, 11:14 AM

Cool thread.. Well mine isnt that horrible but I went in to the shop on a saturday to do some of my projects. I run the waterjet machine and so I was cutting some stuff.. Well I thought I was done for the day so I took off... only to come in on monday and I had left the water pump running which sprung a leak, flooding not only the shop I work at but the whole building.. 5 units down still had an inch of standing water... A dimentioning lab got the worst.. I had a big sit down with the boss and still to this day have the name "water boy" becasue of that day..

mike5721947

11-29-2005, 09:37 PM

Got one better than that one of the guys in my machine shop class left the big t chuck wrench in the lathe and turned it on and took off his thumb when it came back around.

Couple of days ago i was making some steering links and i left the T wrench in the lathe but luckliy it flew out and no damage was done. It scared the s*%@ out of me though :shock:

and thats why the first rule my metal shop teacher said was to not leave the chuck key in the machine.

worse i had was when i was facing a peice of 1 3/4" steel stock on a lathe and bumped the left/right crank (sorry i cant remember the correct terminology.) and took a nice 1/16" gouge out of the peice. (so i had to completely remake the peice.)

but the worse i had on a CNC machine was in grade 8 tech when the teacher and i set the depth of cut too deep and cut the peice almost in half.

but if you really want to know what freaked me out the most in metal class was when the power saw (power hack saw/bandsaw) blade got caught in the 1/8" sheet of steel i was cutting. (jammed the blade and bent the blade a bit.)

blue devil toyota

12-16-2005, 02:59 PM

culhan9

12-17-2005, 09:21 AM

Back in High school I was trying to pull my stock out of the 3 jaw and I was pulling and pulling, I should have loosened it more but it finally came out and what you know the cutting tool did some custom puncture work on my thumb! Dont know how far in that beyatch went but the blood and pain pretty much sucked. Rookie mistake!

JasonInAugusta

12-17-2005, 09:32 AM

Man...old thread.

I'm glad I've never seen any of this crap happen.

I guess I can thank my old High School Industrial Arts teacher, Mr. Covington, for all the hard lessons he taught us.

If he was giving a demonstration on how to do something and he caught you standing say...behind a table saw, joiner, etc, he'd sling the board back off the table and hit whoever happened to be standing in the wrong spot.

He didn't seem to care how hard or where he'd hit us, he knew he was teaching us a lesson. Bleeding because of it? Go bandage yourself and get your *** back over here and stand in a safer spot. :lol:

He was a hardass when it came to safety...still is.

Hard to imagine that today he's still crackin' kids with lumber, but he is! :lol:

JohnRobHolmes

12-17-2005, 12:41 PM

I had a few hardass shop teachers myself, and most were missing digits. If you dont pay attention, you will get injured.

Cloak

01-10-2006, 08:10 PM

He was a hardass when it came to safety...still is.

Hard to imagine that today he's still crackin' kids with lumber, but he is! :lol:

Interesting that. I was just talking to my dad about his school. He went to the school for the blind down in souther NM. They had this one shop teacher that would do tons of things with the blind and visually impaired. He never once had an accident with any of those kids because he taught them very well about shop safety. Shortly after my dad left the school, that teacher left the school. My understanding is they had more accidents that following year than since the school opened up.

They closed down the shop and turned it into a storage room shortly thereafter.

turbo_bird

03-08-2006, 10:19 PM

Kind of bringing this one back from the dead again.
My boss just told me about a friend of his that works in a local machine shop. One of the guys was turning a piece of 2" round steel and had it sticking out about 4 or 5 feet past the end of the headstock. Buddy was standing near the headstock when something happened to make the steel bend and it came around and broke his arm. It was mangled pretty good.
I've had some painful lessons that might give a bit of a laugh too. In highschool I was drilling something in the drill press with a 3/4" bit and didn't have it clamped down good enough, when it came around it tore the pad off my left thumb. That would have been about 8 years ago and most of that thumb print is missing. Another one I learned is not to wear a watch while welding. Got some slag between the watch back and my wrist, I couldn't get that watch off fast enough.
Kristian

Frakk

03-09-2006, 05:43 AM

the worst mistake ive made so far is that i didnt tighten a 1/2 endmill only by hand in a smaller CNC Mill. About half way through it dropped, but the end of the taper was still in the spindle so it didnt just fall out, it was still spinning loose and the machine still moving. Fortunately I stopped it before things went flying and learned my lesson :D