How to lower drafting/drawing errors 6

[jkdrummer]

We produce mechanical drawings for ground support tooling in aerospace. The number of drawing changes due to either a drawing engineering error or drafting errors has to be reduced as per our leaders.

We are a large company and have standards, checkers, designers and engineers doing it all together. The errors range from wrong heat-treatment specs, parts list errors, to missing dimensions. Our drawings do not require GD&T so it's not rocket science. Most of these errors are found by the fabricators and then we issue a drawing revision. And we get tracked on the quantity of errors and the number of drawings being scheduled and revised. The checkers are naturally the ones to blame, but they work hard and that's all they do all day.

Has anyone else had this task to reduce these error numbers with success?

 

[dgallup]

CAD has made the situation worse, not better.

All any unskilled operator need do is pull the trigger on the "Dimension Shotgun" tool and BLAM! There are dimensions everywhere.

If you are using a system that has a "Dimension Shotgun" tool it's not a real design system. It's just an electronic etch-a-sketch. Dimensions and geometric tolerances should come from the feature dimensions that define the model. The engineer that created the model does need to think about the dimensioning scheme and care about the finished drawing. Done properly there is not a single dimension created in the drawing package, it all comes from the model. This captures the design intent & makes sure there are only sufficient dimensions to properly constrain the geometry. And if the model is correct the BOM has to be correct.

Anybody who can't produce a vastly better drawing with CAD tools than a board either has bad tools or does not know how to use them. Not necessarily at the first release but after a half dozen revisions the board drawing probably needs to be thrown away and restarted from scratch, the CAD drawing automatically redraws every view CORRECTLY. I've worked with old board drawings of complex assemblies that only bore a faint resemblance to the actual product because nobody wanted to take the time to redraw all those components the had only changed "just a little". It was impossible to determine it there was clearance, interference, etc.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[ajack1]

I agree with everything dgallup says above.

As for improving quality well there are many obvious ways, better systems, better training, better personal and the correct work load, in my experience people who have too little to do are more careless with their work than people who are kept busy but still given enough time to complete the tasks.

Out side the box slightly, have you tried making it competitive? At one company I used to work for they had big problems trying to keep “cells” clean and tidy and tried various things, the one that worked best was marking them and offering a prize for the best kept. It was never a great amount but it became a matter of pride to have the bragging rights and things improved immeasurably. Either a stick or carrot can work or even both.

I know how competitive I can become on the golf course when playing for a pint, not that the price of a pint matters a jot to me.

 

[CheckerHater]

Jkdrummer,
Apparently your company has everything in place.
I wonder, did your company ever send somebody to training and have your company ever rewarded somebody for good work?

 

[Vimalmechs]

jkdrummer,

Your designers & draft persons considering realistic situations during CAD ??.. repeating parts for all the locations, proper fit dimensions during Modelling stage itself ??.. Proper dimensional scheme for the manufacturing drawing during part modelling itself ??.. Accessing the dim's for the drawings from the model without adding the drawing dim's (This itself reduces the large number of dims missing issues) ??? .. "DFX" checks based on personal experiences and reference database ???..

 

[duk748]

hello - great conversation here & help - our company it seems is one of the above mentioned companies that relies on a cad system to make perfect
drawings % designs along w/ the no-checker mentallity - i am an old school guy & alot of what i have seen here is like your company recently -
our drawings have become worse in using a 3-d cad package as to when we were using a 2-d cad package - the young guns rely soley on cad to do everything
for them & what it tells them they believe - case in point a flatness datum on a round shaft?? - that drawing even made it thru inspection!!
it has become very frustrating for me to sit here & watch this go on & since i am not in a position to make changes or when i do
the upper level people have the say in the end (which goes against my opinion) - i have even had upper level people tell me that
the ge drafting manual was wrong - (not to say it can't be, but very un-likely)- i believe we need to clean house here, start paying good money for qualified people
& not keep getting the "under the bridge people" to work for us - thank you for letting me rant this early in the mourning!

 

[CheckerHater]

Duk748 brings out the issue of leadership – something we all knew deep inside, that “fish stinks from the head”.
“We have standards, checkers, designers and engineers doing it all together” – what’s missing then? Someone to point all of that in right direction. Send “the young guns” to learn something. GE manual may be occasionally wrong, but it is better than nothing. And yes, start paying good money for qualified people!
It is virtually impossible to implement changes without strong support from “upper level people”, providing they are interesting in something beside “savings”. It looks like smaller privately-owned companies where bosses still remember being machinists and drafters themselves have better chances. Large corps run by penny-pinchers… not so much.
So good luck to jkdrummer

 

[ewh]

duk748's post reflects my experiences to a great degree. It is difficult to overcome the frustrations of herding cats, as talented as they may be. Sometimes product has to get out the door, standards be damned. What can you do when wrong practices have been followed not only because "that's the way we've always done it", but also because the way they've always done it has been encoded into company standards (even though Y14.5 is proffessed to be the driving standard), and getting those corrected or justified seems to threaten some of the people that have been here the longest? New employees just starting out creating drawings are forced to follow these company "standards", and are developing some bad habits because of them. Longer term employees seem to not know any better.
I just shake my head and continue to fight the good fight. I do enjoy my job, I just have to keep things in perspective.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[TenPenny]

"We also have issues with people on a lower payscale finding errors in the work of people paid more."

That sounds like a failure in management, no matter what the issue is. If someone is offended by a lower-paid person finding an error, they need to be shown the door.

 

[drawoh]

Here is a fun post in the SolidWorks forum...

thread559-340725

--
JHG

 

[TheTick]

Good checkers don't make good drawings. Good drafters do.

 

[ewh]

Good checkers make good drafters.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[truckandbus]

"We also have issues with people on a lower payscale finding errors in the work of people paid more."

That sounds like a failure in management, no matter what the issue is. If someone is offended by a lower-paid person finding an error, they need to be shown the door.

It is actually the opposite problem - the lower paid people resent having to find errors in the work of higher paid engineers

 

[Manifolddesigner]

My $.02
I have a degree in mechantronic engineering. But I consider myself a mechanical engineer w/ a good foundation in electronics.
Graduated in 07 w/ a lot of projects under my belt and my own business making sand cast intake manifolds and patterns.
I never took a drafting class. It wasn't required. I took the first solidworks class the university offered and they took it as credit for the autocad class.
I managed to get a job as a contractor (MCAD) for a large consumer electronics company. I worked w/ some other contractors that were awesome, the older guys were former military supplier engineers. Great and taught me so much. After working there for a year? more?
I snuck into a GD&T class that they had an outside presenter offering (technically I wasn't eligible to take because I was a contractor, not an employee)

THIS 2 DAY CLASS WAS LIFE CHANGING. It just totally changed the way I think about the design itself.
WHY ISN'T THIS TAUGHT IN SCHOOL? MANDITORY??? You guys are bashing the younger, cheap guys...but the #$^% just isn't taught in school. So teach the j@#$%^! Pay for classes for you employees. Sooner rather than later. Yes your bloody contractors too!
I'd trust a new kid, green around the gills that had just taken his class over an old block tolerance guy.
I'll shameless plug the guy from GEOTOL. I didn't pay for it, I can only imagine he's expensive. It was the best presentation of any kind on any topic I've ever been a part of. I'm trying to organize any of my classmates to get together and pay for a group class together.
I believe with the right training so many things would change. Parts would go together the first time, they'd be cheaper to make, etc. etc. Preaching to the choir, I know.

Now I'm working at a company where GD&T is a bad word. Seriously I was told to 'take all that crap off' and just block tolerance everything. EWWEEEEEE. I tell them I can't, I have to redesign some things because the tolerance loop won't work. I get this glazed over look...I honestly don't think that anyone here in our dept (half dozen experienced ME's) know what a tolerance loop is.
We have no checkers. Technically 2 of the bosses are supposed to check every drawing. (yeah right, we automatically just put their initials on the drawing when we start)
I started here in December and when it came time to do my first drafting, I asked around, looking for someone to go over my drawings to tell me how to fit into the corporate standard. My boss finally assigned one guy to check them. I got one guy (an Austrian raised on ISO and DIN standards) to give me a glazed over look (doesn't understand GD&T or tolerance loops) and say 'cool, ship em'.'
a month later after the shop kicks back the drawings w/ the GD&T on em' because 'YOU CAN'T HAVE A ZERO POSITION TOLERANCE'. (actually a 0M - sloppy loose tolerances) the boss looks at em and takes a red pen to em' that looks like he slit his wrist on the thing.
(His corrections were all corporate style or in some cases just wrong or stupid - remove the note that says dimensions apply after coating, that's gonna make it too hard to make)

So frustrating.


To answer the question du jour. My current strategy for checking drawings is four times.
Usually I'm not releasing one part, but several all at once.
I get each drawing done until I think it's done.
Then go back to the first one (in cad)
check it.
If I find one error, I go through all.
Then again. Usually one error.
Export the PDF's. Things look different in PDF's than in CAD.
Check em'.
Then I print them out.
Looks so much different.
Then I after that I just get embarrassed when they're fubar.
J

 

[ewh]

'YOU CAN'T HAVE A ZERO POSITION TOLERANCE'

Not true, depending on the modifier used.

Being an ace at GD&T is only part of the battle. Basic drafting skills - creating drawings that are clear, complete, concise, easy to read and subject to only one interpretation is another part, one not covered by Y14.5 alone.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[KENAT]

Plus on the training front, it's one thing that it isn't covers on most university courses as far as I can tell.

It's another thing that some of the people making drawings seem to make no real attempt to learn how to do it properly off of their own initiative or to improve their drawings out of pride for their work.

I didn't get taught it at university, and have never had a formal training class. I have been fortunate enough to have my prints looked over by some pretty good guys at certain points in my career. I was encouraged to improve in part by the ribbing of the guy checking my early drawings, and in part just by my desire to get through checking with no red on my drawing (not sure it ever happened to this day;-)). However, a big part with GD&T was I took a job where it was required so figured I better learn it and did so in large part on my own time.

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[duk748]

hello again - glad to see this topic is still active - kenat has really made a great point - i too worked for a major tire company in the late 70's right out of high school -
i too had some wonderful people that were willing to teach me the industry standards & take me out of the green pasture - but i also had a thirst to learn my trade & work myself up to
being the best that i could be - that is the real problem today - most (and not all )in our group would rather manage then do any work - as before if the software tells them it is right then
it is right to them but not the "right" way of doing things - no one here wants to think & our management is simular to manifolddesigner's post - we too were told to remove any gd&t when i
1st got here & i refused - some people to this day here at my company still cannot do tolerance stackup & that is a shame - i am a standards guy it was just the way i was taught &
recently i was told by our vp that "do not use the word standards" "we have no standards here" - go figure

 

[duk748]

sorry for the 2nd reply - just read the sw post from above - my vp just told me a few weeks ago that i was not to feel that my drawings were "better" then anyone else in the group -
that is why some of our customers are avoiding us like the plague now because the rest of the groups drawings are better then mine