Why I HATE GD&T...

[@athanasiuschekouras1344]

Great video. The thing you really nailed is the lack of training at all levels. The example you used had numerous GD&T errors. Lack of Datum qualification, lack of Basic dimensions, mixed use of GD&T and standard tolerances. Clearly the design team needs training badly.

[@devindecater]

As a machinist - please do not make 100 page drawings. That is insanity. Eliminate unnecessary views, dimension cleanly, use thinner lines and slimmer fonts which are legible at 8.5x11. GD&T properly applied makes our job easier and clarifies questions. GD&T improperly applied will drive the cost of Manufacturing your part through the roof. Tread carefully.

[@SR-ml4dn]

The majority of mechanical engineer don't get the essence. I've seen so much woodo and hot air about GD&T and be prepaired for IOT 4.0. I started working with GD&T for more that twenty-five years ago and it was ASME that was first movers. First you must ask yourself why was the geometric tolerance system not suitable any more ? 1. CNC machines was starting to be commonly used in shops and that gives the opportunities to design more complicated surfaces, that geometric tolerance system could not cover. 2. GD&T is very much designed for CNC machines how they operate with the freedom of incremental or absolute fixed datum. 3. GD&T makes your drawing simpler. Old Schooled example is several holes along a x-axis was drawn with individual line to each hole from the datum, if you have 50 holes the drawing will end up in a messy line circus. With the GD&T it was aloud to use incremental distance from hole to hole. 4. GD&T makes your parts cheaper, because the tolerances can be set less precise. I order to understand that you have to realize the most commonly assembly of parts are ROUND bolt/taps fitting in a ROUND hole. The geometric tolerance system works in terms of cartesians coordinate system meaning it's best suited for squared BOLTS/TAP fitting in SQUARED holes. This is not very common to have SQUARED holes and bolts. GD&T describe tolerances in terms of circles. If you place a square inside a circle you can see that the tolerance diameter is lager and therefor cheaper parts. 5 The list goes on about why GD&T is genius, but also complicated to check the tolerances. I also just hated the system in the beginning and you have to learn the machinist some basics otherwise they just produce what they think is good for you.

[@timmallard5360]

Yes yes and yes. I have the same thoughts and you knocked it out of park with that description 👍

[@pb68slab18]

When my company went ISO-9002-AS, GD&T was mandatory. They sent us old guys to a local community college to learn the basics. We've been working with +/- for 40yrs or more. Those of us who didn't fall asleep were ready to quit the trade. It's more geared towards CNC and CMM. Does not relate well to the PROTOTYPE & DEVELOPMENT SHOP, where we use manual machines with DROs or maybe a Proto-trak. We take a few engineering students every 6mos as interns. It's amazing they don't even know basic mechanical drafting. Never saw a drafting table, T-square, templates, instruments. I don't think they ever saw a PENCIL before!

[@Blobby_Hill]

You probably think carburetors are better than efi

[@SR-ml4dn]

You are so right, GD&T add most value to the company when having CNC machines also a little when using DRO.

[@passiveaggressivenegotiato8087]

They'll scoff at the mentioning of mechanical drafting, but what is missing from their design methods is Orthographic Projection. This is why their assemblies have so many misalignments. That and they don't design in assembly mode. They are missing concepts that mechanical drafting didn't allow one to mis, or they'd get to do something else pretty quick.

[@joegamble5233]

efi, f*** not one gd*t sh*tbag bozo has ever run a cmm, it might take 2 hr to inspect 1 hole that the dude needed to be +/-2 thou but t.p. 2 thou is really +/-0.00002 if the damn plate is thick enough, meanwhile it would have been fine if the damn hole was 0.02" somewhere else as long as the bearing fit inside pretty ok. the issue is experience. the issue, is experience.... gdat is fine, if the engineer knows..... dude, t.p. 0.015. please!!!!

[@pb68slab18]

@@Blobby_Hill Yes! I took the EFI off my Harley and replaced it with a Carb. HD no longer supports that EFI system (Magnetti-Marelli), which was bad from the get-go! (Italian electronics!). I can rebuild any carb, and they let ya know they need attention well before they quit. EFI just quits!

[@hoffybeefe]

GD&T? Are you kidding me? i'm flat out getting drawings WITHOUT GD&T done even remotely properly... let a lone WITH GD&T!! To many views on a drawing you say.. just put more on there you say?! Far to many drawings i see have that as the problem. Way to many views that are redundant and completely unneeded..... AND with no usable dimensions on most of them! I"m dead sick of "CAD Engineers" spitting out CAD software names like as if it makes them more qualified by simply saying application names every 5 minutes to make themselves more "engineery" or smart or something... and yet they do a drawing of a rectangular plate with 4 holes and miss 75% of the god damn dimension required to define the damn thing!! Oh but have they got 4 orthographic views and a pretty shaded isometric pictorial! /end rant

[@athanasiuschekouras1344]

Agreed, the current training fails to get to the fundamental principles, so the classes stumble around in details.

[@beachboardfan9544]

Great vid! More of this guy and this content!!!

[@buffalobill8]

sounds like your complaint isn't about GD&T but with the people that don't understand their trade. How many of these engineers, machinist and inspectors have even read the standard? Would you hire a lawyer that doesn't understand the law because it's too complicated?

[@pb68slab18]

Would you hire a mechanical engineer with no mechanical aptitude, hands-on experience or basic tradesman skills?

[@hoffybeefe]

"Would you hire a lawyer that doesn't understand the law because it's too complicated?" how are you going to know if a lawyer doesn't understand the law?

[@passiveaggressivenegotiato8087]

Many young engineers have weak cadcam skills, so they'll drop the ball on any type of tolerances. They screw up other notations as well. Middle engineering managers should ALWAYS witch-hunt their designs, and/or have in-house manufacturing engineering do it, w/ a reward system for finding errors (so they don't just associate level ass-suck around pretending away mistakes).

[@trexinvert]

4:41 Allow me to practice my knowledge of gd&t location tolerance(true position) and "redmark" this dim: 1. Let's start with just "conventional" dimensioning. a.) There is no hole diameter and no hole diameter tolerance b.) Worse, this is a "counterbored hole" there is no spec for large diameter and depth. No diameter for thru hole. c.) Where's the fkn, vertical dim? - - - - - - - - 2. Now, let's get into the GD&T true position tolerance screw up: a.) Where is the datum reference to "B" and "C" in the feature control box? b.) Where is the (mmc) symbol? Don't tell me that he "meant" RFS. That he "knows" the 2nd rule of Gd&T. Not. c.) Where are the [basic dimension] symbols for vertical and horizontal dim to the hole center? Also, the basic dims are "not tolerance".

[@He-Is-One-and-Only]

That's why mechanical engineering is failing people losing interest. 99% of the tools are closed source and it's annoying 😮😮😮😮

[@colonialroofingofnorthcaro441]

As a person who runs a small machine shop and looking to grow, what does the abbreviations that you're talkin about

[@tdg911]

Sounds just like computer programming.. Once you become comfortable with one language it evolves into another. Libraries become deprecated and new libraries implemented. It's a never ending cycle. Keep up with it or get left behind.

[@samualadams862]

I find it interesting you rant about misunderstanding of GD&T and your examples have errors. Comment below has details of errors.

[@samualadams862]

Counterbore Position Diametric 0.01 to A identifies the counterbore is coaxial to the through hole. While position in conjunction with Y14.5-2018 4.1(o) will help control perpendicularity, the primary function is still control of location. The perpendicular call out is a tolerance of orientation (Y14.5-2018 Section 9) and does not control location. Profile of Surface 0.1 to A and 10.00±0.10 The profile of surface is an equal bilateral tolerance, which would allow for ±0.05, not ±0.10. The profile of surface would allow for a floating tolerance zone of 0.10 that could move up and down within the 10.00±0.10 (9.90 to 10.10). Ambiguity Y14.5-2018 4.1(o) USO(Unless Otherwise Specified), all tolerances and datum features apply for full depth, length and width of the feature. Thus, the statement of ambiguity of linear measurement would not apply, as the entire centerline of the hole must be within the defined tolerance zone. Mandatory Appendix 1 Alternative Practices deals with different methods of tolerance stack used prior to the practice of Position and Profile tolerance methods.

[@darmat9009]

​@@samualadams862 You are completely wrong in your judgement. Counterbore position 0.01 to A does not identifies its coaxiality because A is not an axis of the through hole! Because A is a plane nominaly perpendicular to the counterbore axis - that specification only identifies perpendicularity so the author is right in the video The profile tolerance is not floating here because profile tolerance is by default fixing all degrees of freedom including not only orientation but also position +/- tolerances are unambiguous only for feature of size. The position of hole center from a plane is not a feature of size so it is ambiguous as the author said.

[@samualadams862]

@@darmat9009 I concede that I am by no means infallible, and I am always open to debate. I would, however, request if you wish to label my assertions “wrong”, you provide reference to back your statements. I have provided references to Y14.5-2018, for the purpose of allowing others to research my points. I would recommend you do the same. If you would like to debate this further, please do one of the following. Provide your references to back the assertions you’ve made, so I may review. Or, review my references and explain how my interpretation is incorrect.

[@joegamble5233]

+/-5 aint t.p.5. not one new guy engineer knows................... cylinder 3d, circle 2d, not one new guy engineer knows..

[@Taffer9876]

Maximum Material Condition

[@colonialroofingofnorthcaro441]

What does gd&t technically mean

[@nfitzsim]

Geometric dimensioning and tolerancing. This essentially means applying certain geometric zones to define where the part can and cannot be. And as said in the video, it’s a great tool if used properly but is frequently misused and/or misunderstood

[@lukeissobad]

Do you know what a drawing is for your parts? basically the dimensions and how to place them on the drawing so that it makes sense and you can convey the areas of importance. Think of it like a contract, client sends you the drawing with the tolerances and dimensions and its your requirement to meet or exceed those for you to complete your end of the deal and get paid.

[@willysnowman]

It is French for engineers arguing over make belief

[@Loprintz]

Hmmm.....Very "Ambiguous".