[ESander]

Hi all,

New to the forum, but have used the site/others' responses frequently and it has been a ton of help. However, I do have a question to pose because there has been debate with colleagues and I would like some input from the machining world at large:

We have been presented with a drawing for a part from a customer which gives a cylindricity callout of .07mm per 1 meter with no overall cylindricity. We machine everything in inches. The direct conversion is: .0027"/3.28 ft. The part to be machined is approximately 17" long. The question is this: With no overall cylindricity given, do I have a total of .0027" for this part since the part length falls within the 3.28 ft? OR is it necessary to convert the .0027" to a per inch callout and multiply by the overall length of 17" (which comes out to be .0008")?? Depending on which is technically correct, the cylindricity callout is either .0027" or .0008"; pretty big difference.

Any input from you guys is greatly appreciated,

Ed

[bostosh]

We made parts for years without this GD&T stuff.
The management came around with this "new" stuff and after studying, nothing i did changed.

This is for inspection not machining.
Just make parts within tolerance +/- or better,

[ESander]

First: Snarky or smart-ass replies are not appreciated. I am trying to gain a better understanding of machining/QC so don't respond at all if it is not constructive.
Second: This doesn't answer my question. Even if this is strictly for inspection, inspection/QC will need to interpret these callouts. Depending on how the callout is read, the part will be bad or good. Again, if you only want to reminisce about the glory days before GD&T, please don't respond.

We made parts for years without this GD&T stuff.
The management came around with this "new" stuff and after studying, nothing i did changed.

This is for inspection not machining.
Just make parts within tolerance +/- or better,

[bostosh]

Please educate me then............. Really !

As machinist, (during the last century)
we /I could Jig Bore and Jig Grind to .0001 X,Y position and .0001 diameter.
( Precision tooling for production molds )
On machines made in the 1940's or earlier. DeVlieg SIP Moore Wotan
I did not have a reason to understand GDT i just made parts like always .