Composite or 2 single segment FCF to control perpendicularity of hole 1

[KENAT]

I have a single hole in a part that has fairly loose location requirements but needs tighter perpendicularity refinement at MMC.

I've attatched a simplified (may be incomplete) sketch to try and illustrated my case.

Should it be a composite control or 2 single-segment FCF or maybe 2 completely separate FCF.

I Browsed 5.4 of ASME Y14.5M-1994 but it's focus is on patterns. I'm sure I've done this before but can't recall how.

If someone could point me in the right direction I'd appreciate it.

KENAT,

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[drawoh]

KENAT,

Why do you not use the perpendicularity symbol as per Figures 6-37, 6-38, 6-39, 6-41, and 6-42? Those last two figures show perpendicularity errors of zero at MMC.

JHG

 

[DesignBiz]

KENAT,

I am pretty sure that it is illegal to use composite tolerance for other than a "pattern".

You might want a looser location tolerance with a refining perpendicular control for the axis. However I am not so sure a projected tolerance zone is legal for the perendicular callout. It would seem to technically work the same way regarding perpendicularity of an axis.

DesignBiz

 

[DesignBiz]

Fig 6-38 does show projected tolerace used with perpendicularity to an axis.

DesignBiz

 

[KENAT]

Drawoh - Because I'm a dumb a$$.

Thanks, I originally was looking at perpendicularity but gave up before I reached figure 6-38 which shows almost exactly what I want, it has both MMC & projected tolerance zone (take a look at 6-38 DesignBiz, and at section 5.5 in the text).

Problem solved, thanks very much star for you.

KENAT,

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[KENAT]

Sorry DB, you posted while I was typing.

KENAT,

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[DesignBiz]

NP KENAT

DesignBiz

 

[ringster]

Kenat,

Looks sorta like a case of gross OK. (overkill)

For a reasonable assessment, one should know the interface. otherwise you are shooting blindly.

Not trying to be too harsh, but realistic.

 

[KENAT]

Ringster.

I know the interface, I have the drawings of the mating parts right here on my desk. I know that as currently dimensioned & toleranced it is causing problems.

My problem was that I'd forgotten/didn't know about applying perpendicularity at MMC with a projected tolerance zone. This was why I'd initially rejected using perpendicularity and was trying to use a position refinement, I only cared about the perpendicularity at/near MMC.

The sketch was to illustrate this specific issue. It is not exactly the same as the drawing I'm looking at. I'd hoped the "simplified (may be incomplete) sketch " covered this.

KENAT,

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[drawoh]

KENAT,

I find that the index and the table of contents of ASME Y14.5M-1994 are not very good. I found that stuff by searching backwards throught the chapter.

JHG

 

[KENAT]

Yeah, that doesn't help, I hope one of the improvements in the new version is a better index/table of contents.

I was searching forwards and gave up at figure 6-37 for some reason, having convinced myself it wouldn't work for me.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

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What is Engineering anyway: faq1088-1484