Attaching Geometric Tolerance frame to a surface? 2

[Pevac]

Hi all,

I am just starting with learning GD&T and do not have a real understanding of it yet, but I have a drawing which I would like to put some simple GD&T frames onto to show the parallelism of some surfaces.

Q. Is it acceptable to have the frame's leader pointing to a surface from a view that is oblique to the surface, or is it necessary to create a section view to be able to attach to this surface?

 

[ringman]

Pevac,

If you are using Y1`4.5, you should as a minimum get a copy of the standard and study it. Others in your working group will need to develop a understanding of it too. There is a lot more to it that most likely will not be resolved with
discussion in this forum.

 

[Pevac]

The trouble is that the type of parts we make (plastic, injection moulded, non-dimensionally critical) and the procedures that are set in place for the manufacture of the parts that we design will make developing an understanding of the standard really painful.

I will take your advice onboard, however can someone help me out with this particular problem at hand?

 

[Heckler]

Pevac,

IAW ASME Y14.5M-1994 section 3.5 Feature Control Frame Placement - The fearure control frame is related to the considered feature by one of the following methods and as depicted in Fig 3-25.

(a) locating the frame below or attached to a leader-directed callout or dimension pertaining to the feature.

(b) running a leader from the frame to the feature

(c) attaching a side or an end of the frame to an extension line from the feature, provided it is a plane surface.

(d) attaching a side or an end of the frame to an extension of the dimension line pertaining to a feature of size.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NIVIDA Quadro FX 1400
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_`\(,_
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"Coming together is a beginning, staying together is progress, and working together is success." - Henry Ford

 

[Pevac]

Thanks Heckler, but as this all relates to how you define a feature I am still uncertain.

My dillema is that I do not have a view which shows my feature (surface) as an edge and all examples that I have come accross have a GD&T frame attached to the edge representing a surface.

My interpretation of the the above (under (b) running a leader from the frame to the feature would be such that it is ok to terminate the leader onto the actual surface, rather then an edge representing the surface from an orthogonal view.)

 

[Heckler]

Pevac,

I would have to admit that would be a little unorthodox but if that's the only view then sobeit. As long as you get your point across with the vender. You would be better off getting some training in applying GD&T. We do injection molded plastic parts along with actual mold design and we apply GD&T to our designs. We have both onshore and offshore manufacuturing houses for our parts. Our problem is getting colour consistancy with translucent PC

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NIVIDA Quadro FX 1400
o
_`\(,_
(_)/ (_)

"Coming together is a beginning, staying together is progress, and working together is success." - Henry Ford

 

[Pevac]

Thanks, that's what I wanted to know. I'll stick with the orthodox way, even if I have to make some more sectional views.

The trouble is that this particular part is mostly out of surfaces that have no relation to front/side/top views - or each other, so my drawing is getting cluttered with sections and auxillary views. I was hoping that this would be an approach that is used elsewhere, just to avoid another view.

As for the training... I'll pick a day when the boss is in a good mood and see how I go

Thanks Heckler... here's a star!

 

[ringman]

Pevac,

It might be well if you invited your boss to attend the class with you and others in your working group.

Does your drawing callout Y14.5 in the notes? out

 

[Pevac]

Ringman,

We are part of an international group, but of very small companies, which makes it somewhat difficult. We all collaborate with our designs, and all of our injection moulded components are manufactured "in-house" which is actually not in the same country (countries) where the design is done.

The drawings do not call out any standard and each company has its own practices from way back when they were on their own.

It keeps my day interesting I will see if I can push through the implementation of a standard. Any pointers? Would you recommend this Y14.5 standard? Where can I obtain it and how much does it cost?

 

[ringman]

Y14.5 is the only GD and T Standard for interpretation that I am familiar with. Unless everyone using it is onboard, it is of little value.

This forum is primarily geared to respond to questions that relate to it. (IMHO)

 

[MechNorth]

Hi Pevac, and welcome to the wonderful world of GD&T! I've been studying GD&T for the last 5 or so years, and recently certified as GD&T Professional - Senior Level (GDTP-S) for ASME Y14.5M-1994.

To Ringman's last comment, unfortunately there are many GD&T standards out there. A while back (1960's?) the Canadian, British, Australian, ANSI and US MilSpec recognized critical consistencies between their individual standards and developed jointly the ANSI Y14.5 standard. ASME took over the ANSI Y14.5 standard in 1982(?) and metricized it for the 1994 release (hence the "M" in Y14.5M-1994). ASME is based in physical reality rather than numerical / computational theory.

Now consider the ISO (International Standards Organization) GD&T system which Europe has "officially" adopted. It is significantly the same, but with critical differences on how datums and such can be defined. Too big a topic to get into here, but as I understand it, ASME Y14.5M-1994 outsold the ISO equivalents in Europe for the last couple of years, so it's growing over there too. While ASME has a few relevant standards to cover all of the GD&T fields, ISO sells individual documents for each section, which results in a major cost.

There is also the Japanese Industrial Technology (JIT) version of GD&T...I don't know much about that system, but it makes my friends in the auto parts industries go pretty much nuts.

I was involved in a significant project to implement GD&T into a group of 3 business units in 3 countries. First, we had to fight a "customized" version of GD&T which was used by another couple of our business units, and consisted of elements of ISO, ASME, and some home-grown stuff. It was confusing to say the least, and impossible to apply or defend in practice. Our triad selected and defended ASME Y14.5M-1994 largely due to some major counselling/coaching from a training supplier. We managed to convert all of the other (5) business units based on the merit of the standard. The "trick" was to anticipate what problems / objections would arise, then get the designers to understand before overwhelming management with such a radical change.

You can get the Y14.5M standard online from ASME using this link

http://members.asme.org/catalog/CategoryView.cfm?Category=CS&Designator=Y14

It's $135 USD.

Once you start reading it, you'll quickly understand that you,too, may need some good coaching. I can give good references for that.

Good luck & stay the course...it's worth it.

 

[Pevac]

Thanks MechNorth for your post.

Very informative, interesting and useful! Keep it up.

All the best,
Ivan

 

[wgchere]

First, we had to fight a "customized" version of GD&T which was used by another couple of our business units, and consisted of elements of ISO, ASME, and some home-grown stuff.

Had to take a nitroglycerine pill after that one! Weak heart and all...

 

[ringman]

wgchere,

Sounds a little like MISSION IMPOSSIBLE to me.

Glad you survived. :>)

 

[MechNorth]

Had a great team working with me. Converted a couple of key allies from the Dark Side (other units) early on, and they "saw the light". The rest was training, haggling and arm wrestling...and lots of antacids.
tks guys

Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development

 

[dingy2]

Wow - I would strongly suggest that you get a lot of training in GD & T complying the ASME Y24.5M - 94. This is such a complex subject that applying some "simple" stuff could get your company in a lot of trouble.

DD