True position callout question - dia modifier?

[neurosis]

We have an old print here from around 1973. It has a true position call-out with a 'dia' modifier on it. I've never seen this before and am not exactly sure what it means. Typically I'll see a 'max material cond' call-out or similar.  Any old timers know what this means?

[kccadcam]

You have .0025 true position no matter the hole size.

[neurosis]

LOL.. Ok.. this is just me be being a dumb dumb.  I'm used to seeing it called out like this

with any modifiers after the dimension. The diameter symbol is always there. but before the tolerance.

Our QC guy seems to think that we have max material condition on this part unless otherwise specified due to the age of the print.

I'm going to have to do some digging.

[mkd]

I think they wrote the dia insted of the Ø symbol because MS windows hadnt figured out the ALT 0216 keystroke to get it on the print.

[crazy^millman]

I believe there was an older standard that MAX material was implied unless otherwise stated with regardless of feature size. Then it flipped to unless max material is called out regardless of features size is the controlling aspect. Maybe around 1994 is when that change occurred. What does the customer say and what will they accept? What they will accept it what I would follow.

[neurosis]

I believe there was an older standard that MAX material was implied unless otherwise stated with regardless of feature size. Then it flipped to unless max material is called out regardless of features size is the controlling aspect. Maybe around 1994 is when that change occurred. What does the customer say and what will they accept? What they will accept it what I would follow.

I'm going to have the owner contact the customer tomorrow. I think that this is a 'max material condition implied' situation but we want to make sure. 

I'm looking for older documentation on GD&T. I think that we've found this before and it said exactly what you're saying here. 

[neurosis]

I believe there was an older standard that MAX material was implied unless otherwise stated with regardless of feature size.

In case you're interested.

[crazy^millman]

In case you're interested.

Thank you I thought I remembered that being the case.

[Brian]

Hi everybody:

I realize that Neurosis's question has been answered, but this reminded me of a similar issue some time ago, and I stumbled onto these guys (https://www.gdandtbasics.com/) when I was unable to decode something after referring to my trusty drafting book....

https://www.gdandtbasics.com/

Cheers, Brian

[Brian]

....and I know this wasn't the intent of GD&T, but am I the only one that sees a drawing larded up with a bunch of GD&T stuff and thinks "hmm....this part looks like it ought to cost more"? LOL

And I *love* it when folks use a true position callout, and then omit one or more datum references....hmm, do you want me to guess?

[crazy^millman]

....and I know this wasn't the intent of GD&T, but am I the only one that sees a drawing larded up with a bunch of GD&T stuff and thinks "hmm....this part looks like it ought to cost more"? LOL

And I *love* it when folks use a true position callout, and then omit one or more datum references....hmm, do you want me to guess?

You would love to see some of the printed stuff I have seen lately. They are calling out .000 true position with max material on a /-.0002" diameter back to printed features that they had printed to size with no material to clean up. I said great I want a full receiving inspection report on each printed part before we get started running them on the machine. I am not going to create a nightmare for the machinist trying to set these parts up. The normal we have a PHD or this that or the other and am I crazy to even dare question any of this. I said no problem get someone else to help you and since these are supposed to be going to the moon per NASA requirements for Flight and deep space components aren't you suppose to do that anyway as part of the validation process for submitting them? Uh what are you talking about? Please check with your compliance person and get back to me. We will get this answered right now. Compliance person agrees with me and they concede to get receiving inspection for the machine shop from the print shop. They had primary datum on a diameter that had +/-.01 tolerance that was .03 out of round. The secondary datum was .1 out of tolerance and the tertiary feature was so far out that they were considering changing it. Not on one of these, but on 8 different parts that had been printed out of Titanium. Now here we are 3 months later and they will be machined out of billet.

[neurosis]

They are calling out .000 true position with max material on a /-.0002" diameter back to printed features that they had printed to size with no material to clean up.

We run a job very similar.  0 true position but the hole tolerance is +.001 -.000   We don't have a temperature controlled shop so we have to keep track of the coolant temp while running these. The locations can change between the shop floor and QC. 

Our shop isn't set up for jobs like that. 

We tried to farm these out to a local company (wont mention any names) and they totally flubbed the job.  The plan was to have a shop more tailored to this type of work do the job for us, but after the first shop failed, nobody else would quote it. 

We haven't scrapped any parts - ehem - due to the hole locations.   

[Brian]

The normal we have a PHD or this that or the other and am I crazy to even dare question any of this. I said no problem get someone else to help you

Remember everybody....PhD stand for "piled higher and deeper." All kidding aside, I continue to be amazed at these sorts of things. It really feels like as the tools (s/w, machine tools, etc) have gotten better and more capable, the human factor has regressed! It's as if the technology is making us dumber....

[CNCAppsJames]

Was gonna pipe in... that era, with no modifier MMC was assumed. Sometime in the 90's IIRC they changed it to RFS if no modifier.

Carry on.

[Brian]

Sometime in the 90's IIRC they changed it to RFS if no modifier.

The next revision to the standard needs to include "FFS"....which obviously means "for f***s sake"