Hard milling threads with no hole

[Brian]

CNC brochure specs hasn't helped as "machines are so accurate nowadays".
Lack of apprenticeship also hasn't helped.

Maybe I'm just getting old and cranky, but I get the idea that what we often considered "common sense" isn't quite as common as it once was! I've been (unpleasantly!) surprised to learn that many folks think that making an accurate part "just" takes an "accurate machine"....no awareness of how many other factors all contribute (or not-ugh!) to the desired outcome.

It's like as the computers/software/etc. have become better (or more realistic-looking), we've lost sight of the bigger picture, or the context within which we all operate. The illusion is complete! The computer says it's so!

And don't get me started on DFM-related stuff, either! I'm gonna blame that on computers, too! (Full disclosure: there's absolutely no way I could do much of what I do every day, or stay in business, w/o this stuff-and I absolutely LOVE IT....and I bet everyone else here would say the same, but jeez folks-ya still gotta use your brain!).

I used to think that anybody who worked in this trade (I'll include mechanical engineers in this group, too) must just naturally be "mechanically inclined"-boy was I wrong! And it's not just the chicks who come up short, either-OMG.

Now that I've slandered everyone I'll go run some parts!

[Newbeeee™]

Maybe I'm just getting old and cranky

"why is this part so expensive"
Because it's designed that way....

Although it obviously could be crap methodology....to quote Jimmy at BarefootCNC "Don't be out machined!"

Yes, the trouble with common sense, is that it isn't very common

[RobertELee]

I had a Ø2.25" x 6 UN bolt pattern rejected the other day.
They checked in on a CMM using a 4mm ruby.
They told me the holes were out of round, out of position and not perpendicular to the face.
I'm guessing at least half the hits fell inside the threads yielding a bad hit or even shanking out.
I've been trying explain this to our CMM guy for 17 years now and he continues to insist his CMM inspections
are golden and accurate to eleventy billionths of an inch...

Has guy never heard of a Jo Plug?

[CNCAppsJames]

If the guys running your CMM's are not using a cylinder stylus to measure threaded holes (which is STILL bad)  they are just; "operators" at best definitely NOT  professionals.

#ChangeMyMind

[gcode]

Has guy never heard of a Jo Plug?

I have suggested these in the past.
The usual response is "we don't need no stinkin' Jo Plug. We have an app for that" 

also

I'm guessing a 2.25 x 6 UN Jo Plug would be custom order and more than a little pricey

Not to mention, screwing that thing in and out of 24 holes, inspecting each hole, one at a time, would be a whole lot more work than is reasonably expected of an inspector.

[JakeL]

Maybe I'm just getting old and cranky, but I get the idea that what we often considered "common sense" isn't quite as common as it once was! I've been (unpleasantly!) surprised to learn that many folks think that making an accurate part "just" takes an "accurate machine"....no awareness of how many other factors all contribute (or not-ugh!) to the desired outcome.

We had some MIT students do a tour of our facility a couple years ago. I was paired with one of our business guys, he answered the business questions, I got the manufacturing questions.

I answered a question (something about programming in MC) and one of the MIT students literally said "I thought the machine figured that out. Like you just give the machine a model and it makes it". Wasn't really sure how to respond to that one.

[gcode]

I thought the machine figured that out. Like you just give the machine a model and it makes it"

I believe this was the original intent of STEP files, a model, with all the data needed to manufacture
the part embedded in the file.

[SuperHoneyBadger]

one of the MIT students literally said "I thought the machine figured that out. Like you just give the machine a model and it makes it"

I know a few mechanical P. Eng guys, buddies of mine, and they all have zero clue about how parts are made, all grads from the last 5-10 years. Different schools, same answer when I asked how much they learn about design for manufacture in university, and the response was "they teach us a lot of calculus in our one manufacturing class, it's boring and I almost failed because I didn't care." and "Yea for sure, we visited a machine shop for a few hours one time in 3rd year, we got to push a big green button and the machine made a square". Also zero CAD instruction at any point, was the consensus. Not a single fucking hour of CAD instruction across 4 years of mechanical. The engineers that are coming up want office jobs where they stamp forms, they don't want to learn anything about design.

[JakeL]

I know a few mechanical P. Eng guys, buddies of mine, and they all have zero clue about how parts are made, all grads from the last 5-10 years. Different schools, same answer when I asked how much they learn about design for manufacture in university, and the response was "they teach us a lot of calculus in our one manufacturing class, it's boring and I almost failed because I didn't care." and "Yea for sure, we visited a machine shop for a few hours one time in 3rd year, we got to push a big green button and the machine made a square". Also zero CAD instruction at any point, was the consensus. Not a single fucking hour of CAD instruction across 4 years of mechanical. The engineers that are coming up want office jobs where they stamp forms, they don't want to learn anything about design.

One of my fiance's roommates in college was getting her mechanical engineering degree. They had a whole semester class on manufacturing. Worked a bunch with Solidworks and even got to do a couple little programs on some mills. She said most of her classmates didn't see the point and didn't care for the class 

[gcode]

One of my fiance's roommates in college was getting her mechanical engineering degree. They had a whole semester class on manufacturing. Worked a bunch with Solidworks and even got to do a couple little programs on some mills. She said most of her classmates didn't see the point and didn't care for the class 

I went to Colorado School of Mines in a past life (3 semesters, ran out of $$$ and motivation)

This was pre PC and CAD didn't even exist.
We had one class in industrial drawing that came with one workbook

It had hundreds of ISO and 3 view drawing of simple parts.

If it was an ISO drawing, our task was to create a Top/Front/Side sketch
If is was a Top/Front/Side sketch we drew an ISO

This was all done by hand in the workbook with no drawing aids, just a pencil
I really struggled in this class.... I could see in my mind what needed to be done
but my drawing/sketching skills were/are less than zero.

That class and my high school drafting classes really helped when I found myself working in machine shops
a few years later

[Brian]

I answered a question (something about programming in MC) and one of the MIT students literally said "I thought the machine figured that out. Like you just give the machine a model and it makes it". Wasn't really sure how to respond to that one.

It just boggles the mind, doesn't it? And remember that MIT isn't for dummies, either....

If it makes you feel any better, I've experienced the very same thing with one of my customers, a mechanical engineer with a degree in physics. I was gobsmacked! (Man, I love that word....gotta hand it to the Brits).

[Brian]

I believe this was the original intent of STEP files, a model, with all the data needed to manufacture
the part embedded in the file.

Was this STEP, or STEP-NC? (I thought it was the latter but wouldn't put money on it).

[Brian]

he said most of her classmates didn't see the point and didn't care for the class 

Again....another OMG moment for me! This would be like wanting to be a chef, going to school for it even, but you don't like to cook. How is this even possible?

I'm clearly too dumb to get this stuff....

[gcode]

And remember that MIT isn't for dummies, either....

I'm thinking a current student would not last a week in a remedial MIT class 30 or 40 years ago.

Words I remember from my professors were "rigor" and "discipline" and "due today means today!!"

I suspect those words are out of favor in today's MIT, replaced by LGBT and DEI and a host of other liberal buzzwords I can't remember.

[gcode]

Was this STEP, or STEP-NC? (I thought it was the latter but wouldn't put money on it).

STEP-NC sounds familiar, but then they realized whoever thought of Step_NC was smoking crack so now it's just step