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GD&T professional development resources

thunderskunk

Cast Iron
Joined
Nov 13, 2018
Location
Middle-of-nowhere
Hey guys,

Where do ya go when you want to be a metrology expert?

Every CMM dealership offers a one week class or something, but what’s the next step up? A fella I work with is an absolute wiz with PC-DMIS and I’ve learned tons from him. I have a lot of tools at my disposal to play around with general GD&T, but I don’t see much in the name of formal education. Hell there’s not even an elective in engineering courses, or at least I haven’t seen looking up in course descriptions. Or I’m just not looking up the right buzz words; I’d love to be proven wrong.

Where did you guys go? Was it mostly on the job? Or do you just read Y14.5 and call it a day?

Thanks
 
For me OJT, 15 years in drafting. 5 of that as lead checker. I've been working that past 4-5 years as a CMM programmer slash metrologist. Yes, its even more fun, figuring out how GD&T actually works.
I believe there are two Universities that have a Metrology program. One of the Carolina Unis and one in Cali.
 
Buy a book(s). I'd recommend a couple to you but I am in ISO land, not familiar with ASME, at least not enough to recommend any reading material to anyone.

Also go and make an account at CMMGuys Forum - Powered by vBulletin. It's nice to have some discussion about the topic here I guess, but so few participate. That forum is a much better resource.
 
Buy a book(s). I'd recommend a couple to you but I am in ISO land, not familiar with ASME, at least not enough to recommend any reading material to anyone.

Also go and make an account at CMMGuys Forum - Powered by vBulletin. It's nice to have some discussion about the topic here I guess, but so few participate. That forum is a much better resource.

I tried registering; haven’t seen a confirmation email and it won’t let me bug the admins until I’m confirmed. Looks like a good forum though.
 
Hell there’s not even an elective in engineering courses, or at least I haven’t seen looking up in course descriptions. Or I’m just not looking up the right buzz words; I’d love to be proven wrong.

Where did you guys go? Was it mostly on the job? Or do you just read Y14.5 and call it a day?

Thanks

In my case, it was the evening CAD/CAM and Metrology courses at the local community college; could be taken stand-alone, or as part of the engineering program.
 
It can be a complete minefield.
I've worked with a lot of prints where the guy drawing them didn't really understand what he was "splashing on there".

OP - books for #1.
Perhaps there's some youtube vids - IDK.
PM me and i'll send you what I have.
:cheers:

Yeah, I know. I was told I did 2699 releases in a year. I was lead checker. Just has a casting drawing the other day. Machining data and casting data on the same view. People who have never machined a part in their life think they know it all. Yeah, been there.
 
Lead inspector and I took GD&T class at local community college, mainly for documentation purposes for our ISO/AS cert but hoping to hone our knowledge along the way. What a joke that was. Story was the guy that normally taught the class abruptly retired a couple weeks prior. The guy they replaced him with was a CIVIL engineer who had never made anything in his life. Basically he read the book and regurgitated it back to the class as a lecture (through a Turkish accent and a horrific stutter) and I guess hoped none of the 19yo ME students would be any the wiser. Long story short we spent the next 16 weeks trying to steer the poor SOB in the right direction and they found someone else the next year.

ASME themselves has a certification exam and pre-covid had some in person training events around the country. I've looked into it a couple times but never pulled the trigger so I can't speak in any further detail.
 
I hate to say this, but if you actually read Y14.5 cover to cover you are miles ahead of 95% of people using GD&T in the field who didn't read to the end of a pocket guide.
We tend to push our new engineers through an online course, but it's just the basics. I inquired about their advanced course last year and was informed that half the team had already take the in person version...so apparently not so advanced. I've also looked into the ASME course, but never taken it.
One of the engineers I work with supposedly took a full term course in Y14.5 at CalPoly at some point, but I don't know if any of that is available online.
The issue I often have with more junior people coming out of the CMM company courses is that they tend to come out with a good understanding of how to tell the CMM software to do things, but don't really understand what those things are. This becomes evident when they can't tell the difference between an illogical answer and a real one. Those with a bit more granite block time tend to do better, but maybe I'm being an old (I'm not) grouch at this point.
 
That’s just it though: I read Y14.5-1994, and I have questions. I don’t exactly get giddy about purchasing my own copy of either 2009 or 2018 given the price, and the company I work for full time is locked in on 1994 anyways.

I took a “LinkedIn Learning” course on GD&T since I posted this. It was awful. I started out believing what it was saying, then started catching things that didn’t quite make sense. It was straight up giving incorrect examples, and it was on pretty basic topics too. A good online course on the basics of metrology would be great, but that wasn’t it by a long shot.

I ordered that book; much cheaper on flea-bay.
 
Ignoring the fact that at least the 2009 release is (or at least used to be) very easy to find online, if you don't like the $230 price for the standard you really aren't going to like the price tags on any "formal education". Even the fully online courses where the only instructor interaction you get is an e-mail address are going to be in that ballpark.

If you're looking for free, or nearly so, resources you might try eng-tips, or ask here.

Many of us don't have a copy of the 1994 standard handy, so it may help to paste in relevant sections, or accept the 2009 (or 2018) version of the answer.

My current employer runs on 2018. My last one is probably still on 2009. They finally made the switch to using 2009 on new drawings in 2016 or 2017 when I pointed out that none of the people arguing for sticking with 1994 had actually read the 1994 standard, nor could they explain the differences between 1994 and 2009, and our suppliers were all working in 2009.
 
Ignoring the fact that at least the 2009 release is (or at least used to be) very easy to find online, if you don't like the $230 price for the standard you really aren't going to like the price tags on any "formal education". Even the fully online courses where the only instructor interaction you get is an e-mail address are going to be in that ballpark.

If you're looking for free, or nearly so, resources you might try eng-tips, or ask here.

Many of us don't have a copy of the 1994 standard handy, so it may help to paste in relevant sections, or accept the 2009 (or 2018) version of the answer.

My current employer runs on 2018. My last one is probably still on 2009. They finally made the switch to using 2009 on new drawings in 2016 or 2017 when I pointed out that none of the people arguing for sticking with 1994 had actually read the 1994 standard, nor could they explain the differences between 1994 and 2009, and our suppliers were all working in 2009.

I do remember the 2009 one being out there in pdf, but it was super sketchy. My employer at the time was AS9100 and needed to buy it anyways, but I’ve since left and I haven’t looked too hard for the bootleg copy. On cost, it’s just harder to justify at home given my shop isn’t certified in anything. My day job is super school-friendly and pays for all sorts of stuff. They’d be a lot happier sending me to school rather than buying a standard they simply don’t use. You’re not wrong though.

I have the advantage that our suppliers are only working off our drawings. The only thing really stopping us from switching to 2018 is having to rev a few thousand prints to match.
 
I do remember the 2009 one being out there in pdf, but it was super sketchy. My employer at the time was AS9100 and needed to buy it anyways, but I’ve since left and I haven’t looked too hard for the bootleg copy. On cost, it’s just harder to justify at home given my shop isn’t certified in anything. My day job is super school-friendly and pays for all sorts of stuff. They’d be a lot happier sending me to school rather than buying a standard they simply don’t use. You’re not wrong though.

I have the advantage that our suppliers are only working off our drawings. The only thing really stopping us from switching to 2018 is having to rev a few thousand prints to match.

We didn't REV any historical drawings for the sake of doing so, I agree that would be a huge exercise. Additionally, many of them use concentricity, which was removed in the 2018 release*, so they wouldn't be compliant anyways. Our fix was to simply put the new standard on all new drawings going forward. Existing drawings could keep functioning as-is, and even if we put it in the drawing template that did not apply back to existing files. When revising drawings we left it to the engineer's discretion if they wanted to update it or not. While there were a few exceptions, most part numbers don't live more than 5-10 years, so the problem solves its self at some point even if it isn't update on revision. I've been told there are some cases where a part made interpreting the drawing per 1994 would work, and one interpreting per 2009 would not, but I've never actually come across one of these and they would probably need a very specific conversation with the manufacturer in any case.

*I have mixed opinions about this. IME the majority of the time it does not match the intent of what the engineer who placed the symbol wanted, and my high volume suppliers always wanted me to change it to TIR. They were all aware that TIR was always equal or more restrictive than concentricity, but that properly measuring concentricity is more difficult than TIR. That said, there are some times in hydraulic systems where you do actually want concentricity, and would rather not have the tighter TIR callout.
 
I ran into this exact issue, which is why I had a reinvested interest in the 2018 standard. The difference is it practically takes an act of Congress for us to obsolete a part. I actually had a guy compare a group of parts on a CMM that didn’t quite jive with our concentricity measurement. I think the experiment spurred more questions than I wanted to ask.
 
<snip>

That said, there are some times in hydraulic systems where you do actually want concentricity, and would rather not have the tighter TIR callout.

I worked in hydraulics and we completely avoided concentricity. Too hard to inspect. We used T.I.R.
 
I worked in hydraulics and we completely avoided concentricity. Too hard to inspect. We used T.I.R.

That’s what we did most of the time as well, with an occasional cylindricity call. The thing that bothers me is that it isn’t the same definition of what you need.
You can always gauge the concentricity as TIR, much like you can always choose a gauge pin that cuts off a portion of the tolerance band.

A better equivalent might be position. Position is usually used with a circular tolerance zone. Every now and then a square or other shape extending beyond that circle will still provide functional parts. If the supplier wants to be overly conservative and not use that extra area then so be it, but the standard carries a provision to allow it.

While I understand removing concentricity, it bothers me that there is no longer an easy way to allow the perfectly functional part that concentricity allowed, but TIR does not.

As a positive, asking “How do you feel about the changes to concentricity?” is a great way to fact check someone who insists they are using the latest version of the standard, but has never read it.
 








 
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