Checking an expensive part on the CMM. I made a quick program because it was urgent. "Proved" out the program for moves and such. Ran the same part multiple times. CMM reports a large deviation on a critical diameter along a taper and everyone was scratching their heads trying to figure out what went wrong. Management almost conceded to scrap that part. I was asked to re run it again just to make sure and I find a point out of place on my cone construction. It just took 1 apple to run the bunch. Point was accidently taken in a tiny grease hole and I didn't foresee. I used paste and pattern and didn't think twice about it. I re-ran the part and the diameter is nominal, $40k part passed. I'm a genius and an idiot.
It happens. I have spent too much time trying to figure out a similar issue in the past. Now the first thing I look for is points grossly out of place.
Don't beat yourself up. Consider it a learning experience.
At least you got it all figured out. I think the key is not necessarily to avoid making any mistakes. Mistakes happen. The key is to find and fix mistakes before they become problems. You did that, so I think you won the situation.
Easily one of the most concerning parts about this job. In most cases we are correct. The data we provide is usually sound and can be used to make corrections or changes that yield positive results. One mistake can cause so much confusion and concern because typically the data isn't wrong.
My biggest fear is to screw up something HUGE. Complacency is what I'm afraid of. And due to my fear of it I live with anxiety. And because of my anxiety I double check and triple check my work before I send it on. However we have all had that "Need Data NOW!" situation. That's the one that bites the hardest.
Glad you found the issue before it went any further. Well done.
Not too many years ago (about 10) I missed an email in a string of about 15-20 emails back n forth between our QE and the SQE on a GD&T callout. That missed email was worth about $150k in parts not meeting the "last change" on the drawing. I was sweating bricks and made myself sick over it for about a month and I dreaded walking into work every day, I told the boss I was leaving over it and he wanted to know why it bothered me so much that it would get to this. I was miserable and he told not to worry about it.... He did tell me that the customer SQE had accepted a deviation on those parts a couple days earlier because even though they didn't meet the intent of the drawing they still functioned perfectly.
It happens more than most want to admit. Take it as a lesson and learn from it
louisd Working in the medical for the last 16 years has proven to see exactly how idiotic this line of thought is. I truly believe they are over engineering and creating tolerances that are directly responsible for the escalating cost of health care here in the US. Tolerances that have been cut from +/-.015mm to +/-.005mm is ridiculous and add s to the cost. Is our body going to feel a 0.5mm difference in the form of a medial condyle on a knee replacement? Or a 0.25mm shift in the hip socket? When they cut the "AP box" for a knee replacement are they that accurate with the bone saw?
The only bad mistakes are the ones where you don't learn from and, unfortunately, the bigger the mistake the more you learn.
Case in point (not related to inspection), I sell and change race tires for motorcycles on the side. My first weekend doing it I was changing a tire and the bead of the tire got caught on the valve stem. I thought the tire was just being difficult so I just forced it around (didn't see that it was caught on the stem)... snapping the valve stem so I (my company) had to pay for a new valve stem for the customer. I learned exactly where the valve stem needs to be on the machine before I start changing the tire and I make sure every wheel goes on the machine with the valve stem in the same location so it does not happen again. It was a mistake that cost us some money and I had to swallow my pride and tell the customer that I screwed up. Bet your a$$ that won't happen to me ever again because I take the extra few seconds every time to make sure it is located properly. It was a mistake but I learned what to do so it will never happen to me again.
