Don't you just love CNC?

[Sleazey]

I've been a professional computer programmer for almost 40 years. Here are a few comments I have made, or heard, dealing with computers. They apply to CNC as well.

Computers allow us to make mistakes faster and with less effort than ever before.

Modern computers allow us to make mistakes the ancients could only dream of.

It would take 10,000 mathematicians working 8 hours a day for a thousand years to make the same number of mistakes a computer can make in 1 second.

These modern multi-core super high speed processors have taught me patience.

Computers provide us with the ability to create disasters far beyond that which the unaided intellect will ever achieve.

Wasting time is the single human activity most improved by computers.

Hours of computation are no substitute for a few seconds of thought.

 

[jpeter]

It's all fun and games until the tool slips out of the spring collet.

 

[steamer]

on the wall of my Fortran classroom

I really hate this machine!
I wish that they would sell it!

It never does just what I want!

But only what I tell it.........

 

[steamboatmodel]

Well it happens i wish i had a picture of the kurt vise someone plowed the cutting head right into it.

On a Haas mill it shows work offset position for x,y, and z but because it uses tool length offset to guage where the part is in relation to the cutter you never need to change that z unless you have a special setup.

With that being said one of the hotshot students that really didnt know what he was doing changed that z coordinate to the parts zero BIG MISTAKE.

Now the machine thinks that zero is about 5 inches lower than it should be and all of his tool length offsets were set before he changed that z coordinate. So the machine starts changes to 1.25 inch flat endmill carbide mind you and then proceeds to move over to the part and plow at rapid through an inch of 7075 aluminum and about .125 into the brand new vise.

Ruined everything the whole machined had to be realigned and serviced the vise was toast and that piece of aluminum was beyond repair. Worst part is none of that belonged to the student so about 3k later everything is fixed and back to spec. What grinds my gear is he didn't shell out a dime nor did he show any concern that it left the machine out of commission for 3months. I got dicked out of what it cost to fix the machine because i was no longer able to mill my paintball gun trigger frames nor any of the other parts i made and had sold already. So a simple ignorant mistake cost me a fortune even though i was completley uninvolved in the destruction when it took place.

Lesson learned never allow a student to work without supervision. He claimed he didn't know how it could have happened and his program was written proper. No one was able to place any blame until i showed up and had them look at the offset settings and it became blatantly obvious what happened and who was to blame. Not the instructor but the STUDENT who didn't listen to the numerous statement made by the professor to leave work offset z alone.

The instructor is acutally my father whos been in the Machining industry for about 45+ yrs and about 30 of those spent teaching other how to machine. He has bundles of experience and while sometimes i surprise him with something new 9 out of 10 times he makes it clear how much more knowledge and experience he really has.

It sounds to me like the instructor needs to sharpen up how he runs his course. What is your position at this school? Back when I was learning it was forbidden to use school equipment to make anything for profit.
Regards,
Gerald.

 

[jpeter]

There is a difference between high schools and commercial machine shops. In industry consumate professionals use million dollar machines to make thousands of dollars parts. In schools rank beginners are incouraged to use 40 year old beater equipment to make junk parts. They both are going to catch hell when they make a mistake. Who pays for school mistakes? Tuition pays and the teacher does the repair after hours. In industry the maintanence department does the fix'n and the machinist goes on to another machine. The consummer pays. That's the way of it. Mistakes are gonna be made.

 

[Ken I]

I supply and maintain robot systems generally in the $100-500k price range.

I haven't written NC G codes in a long while but do a lot of robot programming - make a mistake - particularly with jump and call commands and all hell can break loose.

Its just a dumb machine - tell it to bang its head on the wall and it does just that.

But then I check everything in slow mode first - so in spite of a number of small collisions over the years (been playing with these critters for nearly 30 years) - no real harm done.

Can't say the same thing for the customers though - I recently studied the maintenance costs to my customers and discovered (as I suspected) that just over half the breakdowns and damage were caused by operational error (shot themselves in the foot) only 25% was genuine breakdowns and the ballance was doing things for the customer he should have been able to do himself.

The lesson - check carefully before hitting the big switch.

Ken

 

[Admiral_dk]

We don't even have to go all the way to CNC according to a German electronic magazine from 1988.
According to them (a joke), CAD / CAM means :
Computer Am Dienstag / Chaos Am Mittwock ~ Computer on a Tuesday > Chaos on Wednesday.

 

[Ken I]

CAD = Computer Assisted Disaster

Close cousin to the Radar Assisted Collision.