"Equally Spaced"
"Equally Spaced"
(OP)
I am currently reviewing drawings drawn to 14.5-1973. I am finding the "Equally Spaced" used quite often to call out holes around a Basic circle. We are having a discussion over how the positional tolerance applies. Does the "Equally Spaced" get treated as a Basic callout and the positional tolerance apply on the circle after the equally spaced math is done? Or does the tolerance in the title block apply to the "Equally Spaced" and then the positional tolerance only applies to the holes location on the pattern circle?
Thanks,
Anthony
Thanks,
Anthony





RE: "Equally Spaced"
I would treat treat is as a basic dim and apply the positional tolerance from there.
RE: "Equally Spaced"
Believe it if you need it or leave it if you dare. - Robert Hunter
RE: "Equally Spaced"
Thanks,
Anthony
RE: "Equally Spaced"
Believe it if you need it or leave it if you dare. - Robert Hunter
RE: "Equally Spaced"
A possible way to figure it out, does the positional FCF show a diameter symbol for the tolerance zone? If so I think the equally spaced would have to be basic for the tolerance to make sense.
However, I don't have a copy of, or familiarity with the 1973 version (I wasn't born yet). There are a couple of regular posters here who probably did work to it, they may know.
I don't believe the current version, ASME Y14.5M-1994 addresses "equally spaced" (or equispaced as we used to say in the UK). The examples appear to show 6X 60° (basic) or equivalent. I don't see it listed in appendix C either.
KENAT, probably the least qualified checker you'll ever meet...
RE: "Equally Spaced"
Here in the USA it is OK to call out equally spaced, except use "EQ SP". I have not seen anything that says you can't use it.
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog
RE: "Equally Spaced"
My opinion is that the "eually spaced" has to be basic to make sense. Using his math 119.5 would NOT be "equally spaced". He then argued after applying the .004 diameter tolerance zone that they wouldn't be equally spaced. I told him he was taking on the whole definition of BASIC with that statement!
RE: "Equally Spaced"
KENAT, probably the least qualified checker you'll ever meet...
RE: "Equally Spaced"
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog
RE: "Equally Spaced"
I'm young & inexperienced so can you be sure I'm right
KENAT, probably the least qualified checker you'll ever meet...
RE: "Equally Spaced"
RE: "Equally Spaced"
Now for a post over on "How to Improve Myself to Get Ahead in My Work" or "Overcoming Obstacles Getting My Work Done" on how to break this to your more experienced co-worker
KENAT, probably the least qualified checker you'll ever meet...
RE: "Equally Spaced"
WhitmireGT, the expert, nailed it and stopped my search.
As to "Is equally spaced a valid callout in ASME Y14.5?" No, but it was in ANSI Y14.5-1973.
RE: "Equally Spaced"
I thinketh the old timer has a basic misunderstanding. To my knowledge, it has NEVER been permissible to mix basic and +/- dimensions in a callout.
RE: "Equally Spaced"
Back in the 1966, 1973 Y14.5 days there was a lot of mixing of basic and ± dimensions, and it was a disaster when trying to do tolerance stacks to check assemblies, especially with already released (and often built) parts.
I worked a lot of MRB then and verifying the acceptability of discrepant parts made to such drawings was an education in tolerancing.
RE: "Equally Spaced"
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06/08
ctopher's home (updated 10-07-07)
RE: "Equally Spaced"
RE: "Equally Spaced"
It sounds as if some of y'all will keep using EQ SPC on drawings per Y14.5-1994. I got a different read on this subject after looking thru all the posts. In my mind the confusion is avoided by specifically calling out the pattern with a basic dimension (e.g. "8X 30 deg."), and since the latest Y14.5 does not specifically deal with "EQ SPC", it should be avoided on new drawings. I agree with the interpretation that EQ SPC should be considered a basic dimension for position-controlled features, but if the argument could be avoided by being specific, I'll opt to avoid it.
RE: "Equally Spaced"
RE: "Equally Spaced"
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06/08
ctopher's home (updated 10-07-07)
RE: "Equally Spaced"
I agree with btrue, (I think I said as much in a previous thread on the topic) don't use 'Equally Spaced', dimension it per the examples in 14.5.
While 'Equally Spaced' may not be explicitly forbidden/wrong, it can be confusing, hence this thread.
KENAT, probably the least qualified checker you'll ever meet...
RE: "Equally Spaced"
RE: "Equally Spaced"
RE: "Equally Spaced"
Believe it if you need it or leave it if you dare. - Robert Hunter
RE: "Equally Spaced"
You're correct.
(I'm done for this afternoon, not feeling well)
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06/08
ctopher's home (updated 10-07-07)
RE: "Equally Spaced"
David