Translate into GD and T language: How? Which is the best way?
Translate into GD and T language: How? Which is the best way?
(OP)
Design intent: to control Ø.160/.156 hole location relative to the 1-1/16 hex.
What we don't want end up having is a part with the hole positioned near the corners of the hex-see sketch-
No control to center hole or to Ø1.11/1.09 hole is needed.
I have 3 options to "translate" in GD and T language the above design intent.
Which one do you think is the one (if any) we should/can use? Are there any differences between these 3 options or they are producing similar results and have identical meanings.
Option #2 is to made to be able to have a functional gage built to verify the requirement. Can we achieve the design intent by using a functional gage? I understood Boundary note is optional.
What else do you think is missing from this drawing to get the design intent? In other words, how the part could look like if we have these options depicted on the drawing?
Do you think can be a better way—less complicated in GD&T language—to get the right parts?
Thank you
What we don't want end up having is a part with the hole positioned near the corners of the hex-see sketch-
No control to center hole or to Ø1.11/1.09 hole is needed.
I have 3 options to "translate" in GD and T language the above design intent.
Which one do you think is the one (if any) we should/can use? Are there any differences between these 3 options or they are producing similar results and have identical meanings.
Option #2 is to made to be able to have a functional gage built to verify the requirement. Can we achieve the design intent by using a functional gage? I understood Boundary note is optional.
What else do you think is missing from this drawing to get the design intent? In other words, how the part could look like if we have these options depicted on the drawing?
Do you think can be a better way—less complicated in GD&T language—to get the right parts?
Thank you





RE: Translate into GD and T language: How? Which is the best way?
When you say no control to OD is needed, you do want the flats on the part don't you?
In my opinion you are abusing "all around" if you do not actually define the profile all around.
Frank
RE: Translate into GD and T language: How? Which is the best way?
Frank
RE: Translate into GD and T language: How? Which is the best way?
We are using ASME Y14.5-1994. The center hole is there, but you easy "pretend" is not there. Just ignore it so to say:)
And yes, I do want the flats (hex) on the part to be there.
If I remove "all around" circle is it better, means less confusing?
Thank you again
RE: Translate into GD and T language: How? Which is the best way?
First of all, none of the options controls hole to the hex, they all control hex to the hole.
- For option #1, I do not think you may have the same datum references repeated in the lower segment of profile composite FCF. It gives you nothing.
- In order to make option #2 legal, you need to have basic dimension for diameter 1.09-1.11 and for hex.
- Option #3: Bigger tolerance value cannot be specified in lower segment of feature control frame.
RE: Translate into GD and T language: How? Which is the best way?
Let me rephrase it: we would like to control the relative position between the hole and the hex.
Option #1: by having the lower segment the intent was to control the rotation of the hex to the datum reference frame. If this was achieved or not, that could be true, but that was the intention.
Option #2: if I have basic on Ø1.11/1.09 do I need to have it also --this diameter- as a datum and reference it on the DRF? I have 3x 1.063-already basic-- to control the hex. Maybe just to remove 1-1/16 hex note would be okay?
Option #3. Here I am confused. Why the size and form, could not be bigger than the location+orientation? Or Am I missing something? Profile .010 with no datum will control size and form.
profile .005 with A and B at MMB control location and orientation.
Am I right?
Thank you
RE: Translate into GD and T language: How? Which is the best way?
Drop the [B] datum,
Control everything in relation to [A],
Let "simultaneous requirement" do the job.
RE: Translate into GD and T language: How? Which is the best way?
If you want the flats to be there on the OD, then, you do care somewhat and you must decide how much you need to be there and that will help you determine the tolerance.
What he is saying is you can't do it with profile as shown in option 3. Option 2 does what you want for the flats holding them tighter in location than the basic form. Basically, like the ISO coaxial.
Frank
RE: Translate into GD and T language: How? Which is the best way?
RE: Translate into GD and T language: How? Which is the best way?
The all around symbol can be used on hex (polygon) surface, the all around symbol extends the profile tolerance zone to apply to all sides of the hex (polygon), one application example is on the hex head cap screws.
SeasonLee
RE: Translate into GD and T language: How? Which is the best way?
SeasonLee
RE: Translate into GD and T language: How? Which is the best way?
How I have it now, the profile of the hex is not clearly defined? Just asking.
If no, what am I missing?
Thank you
RE: Translate into GD and T language: How? Which is the best way?
The question is basically: can "all around" actually be used intermittently as is being done here? I feel it is a fundamental conflict of terminology; this is more a "6X" condition, IMHO.
Frank
RE: Translate into GD and T language: How? Which is the best way?
SeasonLee
RE: Translate into GD and T language: How? Which is the best way?
1. Regardless of your 3 options, if your concern was only to control profile of 6 flat portions of the hex and not whole outline of the part including cylindrical portions, then I would say your all around profile specification is illegal. It cannot be applied to the outline which is interrupted by anything. So either you remove all around symbol and add '6X' to profile callout or define diameter 1.09-1.11 as basic 1.10 and leave all around symbol as it is. (Is this what you asked for, Frank?)
2. As for your question about my comment on option #3, it is really geometrically impossible to have lower segment tolerance value bigger than for upper segment and gain something. Refer to para. 6.5.9.1 of Y14.5M-1994 clearly specifying that: "Lower segment[...] specifies smaller profile tolerance for the feature within the profile locating zone (form and orientation refinement)".
3. I am just wondering if switch on diameter dimension 1.09-1.11 to basic 1.10 will be enough to fully define true profile of the outline. I always try to visualize similar situations by imagining what will happen if I tried to draw this outline (with all dimension given and implied) in the sketcher of a CAD software. Would the sketch be fully constrained then? I do not have access to my CAD program right now, so cannot tell with 100% certainity, but I am afraid in this case it would not, since there is nothing on the print saying what are the basic lengths for flat or arc portions of the outline. As far as I see there is no tangency at points where flats and arcs meet, am I correct?
CH,
Your idea is not so crazy. The scheme you proposed basing on "simultaneous reuirements" concept makes sense, at least to me. For sure it is elegant and looks simplified to maximum on the print. For your sketch and in general, I am just thinking, how many inspectors will verify position and profile all around in one step, meaning in a way they should be verified? I would just be afraid that the concept leaves too much space for not grasping mutual locational relationship between the hole and the hex during measurements done by some not enough educated inspectors.
RE: Translate into GD and T language: How? Which is the best way?
Yes, Thank you.
I also agree with your other comments. My problem with the simultaneous requirement is really simply only that "they" (manufacturing and inspection) generally object when I play the game that way. If the rules can't be used in practice what good are they to me?
Frank
RE: Translate into GD and T language: How? Which is the best way?
I checked in my CAD program what I had mentioned in point 3 of my last post. Please have a look to attached pdf. You will see what my point was.
http://fi
Hope this helps.
RE: Translate into GD and T language: How? Which is the best way?
We had a discussion in our company, if documents should be sufficient for the complete stranger to do the job (and our shop is spoiled rotten). I quoted old standard from the times when standards actually said something rather than referencing each other:
"Engineering drawings... shall provide engineering definition sufficiently complete to enable competent manufacturer to produce and maintain quality control of item(s)..."
The key is "competent manufacturer", not the "bum from the street". We finally agreed that manufacturer has to carry some part of the weight.
Several manufacturers don't understand Rule 1 to begin with.
RE: Translate into GD and T language: How? Which is the best way?
I understand, I am only trying to show that I am not opposed to it in concept, I am attempting to convince pmarc and others I am not really such a bad guy. In practice it seems to fall short, IMHO, I suspect the ISO made the other choice for that reason.
My interest, in this area, has always been in communization and harmonization of both of the standards to make it easier on us all, preparing for the lowest common denominator, or worst case, is standard practice for most other areas of engineering training. Therefore, I see it as only being consistent with the general engineering philosophy. Again, I suspect the ISO does too.
Frank
RE: Translate into GD and T language: How? Which is the best way?
Never said nor even thought you were a bad guy
I really appreciate all the efforts you put into ISO vs. ASME battlefield in this forum.
RE: Translate into GD and T language: How? Which is the best way?
Thanks, I find my time spent here, very valuable to me, due to the people like you.
Frank
RE: Translate into GD and T language: How? Which is the best way?
To answer to your earlier post:
- there as no tangency at points where flats and arc meet, you are right about this.
- nothing on the print is saying what are the basic lengths for the flat or arc portions, you are right on this either, but the question is do we need these basic flats or arc portions dimensioned? If I specify the hex size 1-1/16, shoudn't be understood that the flats are equal = same length, and the angle between them is 120°-- all 6 angles--
I don't think we need that dimension p7 on your sketch (p7=0.34) for the sketch to be fully defined. At least in my CAD software I don't need it---of course with the above assumptions- equal flat lengths and 120°, defined IMHO by the HEX note-
Thank you
RE: Translate into GD and T language: How? Which is the best way?
I wish I had been there for that discussion.
The standard has been clear on this issue for a long time, so anyone who is "trained" should know this. They all have been trained.
The problem may be, as you said, spoiled manufacturing, expecting to be spoon fed. I suspect the real issue is the image of perfection; no manufacturing person wants to be held to perfection, I don't want to either. I certainly never achieve it.
Frank
RE: Translate into GD and T language: How? Which is the best way?
My sketch was prepared also by assuming that:
- flat lengths were equal,
- arc length were equal,
- all angles were equal,
- everything was centered at the XOY origin,
- no tangency was at the points where flats and arc meet.
Maybe a 3rd opinion is needed?
RE: Translate into GD and T language: How? Which is the best way?
We might need "arbitration" here:):).
I just double check my sketch again. Looks like on mine I don't need that p7 dimension. And more than that on my sketch the p7 dimension is .28289 and not .34 as in yours. What's going on here?
Let's rephrase my assumptions ---beside the ones we already agreed upon, see above--
I've used 1.063 flat-to-flat hex dimension, Ø1.10 (radius .55) diameter (OD). That's all I need to make the sketch fully defined.
More than that the flat length for the "uncut" hex is 1.063* SQRT(3)/3 = .6137234
Now, if the flat hex is "cut" by the Ø1.10 diameter (.550 radius) the flat hex become .28289 (and this last dimension can be calculated also: A^2+B^2=C^2, so no additional constrained is needed)
RE: Translate into GD and T language: How? Which is the best way?
Frank
RE: Translate into GD and T language: How? Which is the best way?
I also strongly agree on the slippery slope you mentioned. In this case it just seems we already lost that battle in the real world that I work in day to day.
Frank
RE: Translate into GD and T language: How? Which is the best way?
This is why I feel bitter every time I see sales pitch about GD&T being "universally accepted".
But enough about that. Let's go back to our hex.
If you have G. Henzold's book handy, check out Fig.20.65 thru Fig.20.69 and Fig.20.93.
Lot of interesting ideas
RE: Translate into GD and T language: How? Which is the best way?
Excellent, I would love to discuss with you the selling of GD&T vs. its use in the real world, I do feel that it is a contributing problem with the standard and that it has lead to some of the differences in ASME & ISO's approach, that is just my opinion, of course.
Frank
RE: Translate into GD and T language: How? Which is the best way?
I am waiting for that new book to appear on amazon and I plan to snap it right up. I want to get it from someone I know how to deal with.
Frank
RE: Translate into GD and T language: How? Which is the best way?
The value p7=0.34 is completely accidental. It could be 0.1 as well if I draged one of the end points of bottom horizontal flat more towards y axis. Then the lengths of all 6 arcs would increase. I just put this p7 dimension to show that the dimension is missing, not to show its exact value.
I must say I don't get what you mean by saying "the flat length for the uncut hex is...". Could you show it somehow on my sketch?
And of course I would love to see another opinion(s) on this.
RE: Translate into GD and T language: How? Which is the best way?
If you are using 1.063 flat-to-flat dimension on the hex and 1.10 diameter, then the flat length cannot be any other dimension than .28289
For the uncut hex I mean: Let's say you have a hex with 1.063 flat-to-flat dimension. Do you agree than the flat length cannot be other than .6137?
Now if you put Ø1.10 (radius .55) in play the flat length became .28289 (and only this length)
RE: Translate into GD and T language: How? Which is the best way?
Sketches are attached.
RE: Translate into GD and T language: How? Which is the best way?
RE: Translate into GD and T language: How? Which is the best way?
The sketches were not needed as I analized my sketch once again and indeed it seems that no length of flat (p7 dimension) is needed. I must have not defined one relationship originally. Thanks for being persistent enough to convince me.
Coming back to your original print, I would just add for clarity (as thin extension lines) those pieces of circle which are not part of true profile and associate basic dia. 1.10 dimension with the circle, for clarity. Thanks again.
RE: Translate into GD and T language: How? Which is the best way?
I agree. I will add basic dimension on Ø1.10
And for this thread history:
I will scrap option #1 (from the original sketch at the begining of this post)--no value added,
keep option#2 as is, with all around symbol there.
On option #3 I will flip-flop the tolerance values (.005 versus .010).
And now, the remaining options (#2 and #3) preserve the design intent and provide similar results.
Thank you for you help