Use of Equal Space as a basic dimension

[ringman]

Are there users of the ASME Y14.5M who have had occasion to apply Equal Spaced to a holes located on a basic dimensioned diameter? I had thought that was an antiquated and retired term for dimensioning.

And if you have, did you put the block around it to indicate it as a 'basic locator'?

 

[KENAT]

This was discussed, kind of, a few months back - take a look.

My opinion would be to use 6X 60° (BASIC) or similar as generally shown in ASME Y14.5M-1994.

However, I don't think it explicitly contravenes the standard.

Back in the UK we said equispaced not equally spaced, sounds cleverer to me.

KENAT, probably the least qualified checker you'll ever meet...

 

[drawoh]

ringman,

The standard shows angle times quantity, over and over again.

I think this is in the same category as the TYP specification. The standard requires that you specify actual numbers. On CAD, I would think it would be easier to go 6X60deg, i.e. do it properly, than it would be to draw a box around a note, especially if you are not a touch typist.

JHG

 

[ringman]

I had rather expected a yes or no response with a possible follow up to the questions that I asked.

Sometimes communication, whether it be written, symbolic, or verbal is perplexing.

Has anyone used this method? And if so, was a block used around the EQLSP?

I am not in favor nor proposing that it be used but apparently is is being taught as acceptable by some.

 

[KENAT]

The main point of my post was to get you to look at thread1103-208563 although it may not explicitly answer your questions as you want them answered.

Q:

Are there users of the ASME Y14.5M who have had occasion to apply Equal Spaced to a holes located on a basic dimensioned diameter?

A: I have nut used equally spaced since working with ASME Y14.5M-1994, nor seen it used on drawings iaw this standard.

Discussion point:

I had thought that was an antiquated and retired term for dimensioning.

Comments: I agree it is arguably antiquated although I'm not sure it's been explicitly 'retired'.



KENAT, probably the least qualified checker you'll ever meet...

 

[ringman]

Kenat,

Thanks and I did not recall having seen that thread although I did post to it.

It concerns me that some instructors for the GD and T are promoting the use of Equal Spacing in conjunction with basic dimensions. It seems be confusing and misleading.

 

[CheckerRon]

Drawoh has got it right. Quantity X value in the box. I like, and have used the example in Figure 5-43 (page 141) when the quantity is such that it gives you a fractional value. This used to be done by "equally spaced" in ancient days. Works well on flange hole patterns for example.

 

[KENAT]

I hadn't noticed that example before Ron, thanks.

KENAT, probably the least qualified checker you'll ever meet...

 

[drawoh]

ringman,

Let us assume the drawing contains the note "INTERPRET DIMENSIONS AND TOLERANCES AS PER ASME Y14.5M-1994", and assume that the pitch circle has a note saying "EQSP" contained in a box.

If someone applied an angular dimension, and they replaced the angle with the text "EQSP" and they put a box around it, I would interpret it as a basic dimension. If I were the checker, I would reject the drawing of course.

If there were a boxed note next to the pitch circle dimension saying that holes are equally spaced, I would not know if the drafter was simply trying to draw attention to the note. This is very poor drafting practise.

You can apply a note to the drawing or view stating that all dimensions are basic unless specified otherwise. That way you can do the good old fashioned note ".375DIA HOLES THRU 6 PLCS ON AN 8.875 B.C.D.". Hopefully, everyone will know what B.C.D. means.

All of this is a lot more work than showing the pitch circle and one angle times the number of holes.

JHG

 

[CheckerRon]

Only englishmen, or guys like me that worked for an british engineering manager know what BCD is. I used to tick him off by refusing to use it, and saying it was totally redundant.

 

[drawoh]

CheckerRon,

Okay, hopefully somebody knows what BCD stands for. Perhaps even I do!

JHG

 

[ctopher]

I have used BCD for years. Then we had a female checker without any drawing experience, except folding them. She said to remove all reference to specs and anything that was abbreviated or looked like an ancronym! She eventually quit. I guess I gave too much of a hard time.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Apr 30, 2008)

 

[ringman]

What are the checks and balances for the people in position of teaching and selling Texts on GD and T who promote ideas that may be flawed and /or misleading. Especially to the novice users of GD and T. It makes it difficult for checkers to perform their jobs.

Anyone have thoughts?

 

[KENAT]

ringman,

As it's not covered by PE type issues I doubt there is anything. I suspect even if you have GDTPS or something and then teach something that's a load of @#$%$#%$# they aren't going to pull your accreditation, but I could be wrong. Just like I could probably write a book on English grammar with a bunch of nonsense and it's unlikely I'd face any legal or similar consequences.

".375DIA HOLES THRU 6 PLCS ON AN 8.875 B.C.D.". or you could dimension it the way the standard consistently shows.

As to BCD, this came up a while back and I don't think it's in ASME Y14.38 as a recognized abreviation. Pitch circle I think may be in there. As such I'd probably redline it if I saw it on a drawing that claimed to be ASME Y14.100 compliant, sorry any fans of it.

But now I'm sure most will agree I'm being pedantic.

KENAT, probably the least qualified checker you'll ever meet...

 

[powerhound]

I taught for about a year before I got my GDTP-T certification. The company I taught for didn't care if I had the cert when I first started but they did put me through a quasi-audition. I taught a day with the senior instructor in the class, to see if I even had an inkling of an idea of what GD&T was. Apparently that was good enough for them because they gave me classes to teach right after that.
The only classes I teach are fundamentals and it all comes straight from the standard. There's not a lot of room for individual interpretation in a fundamentals class. The issues that cause controversy on this board are not in the fundamentals course that I teach. Occasionally students will ask a question that causes deeper digging into the standard. At that point we will find an answer in the standard or if it's not directly addressed and extensions of principle don't apply, then it becomes a gray area like the ones we kick around on this board. The subject of this thread doesn't seem to be a gray area because it is directly addressed in the standard and the compliant way of doing it is clearly indicated.

Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[ringman]

Powerhound,

I also taught a class on basics years ago. I somehow get a little concerned when some of the 'Qualified Instructors' seemingly get a little off course and there is apparently no one to reign them in. This thread that I started is an example of that.

Any ideas as to a possible solution?

 

[CheckerRon]

My english boss (when doing piping and pressure vessels, thus many flanges) used BCD as "BOLT CIRCLE DIAMETER". As a stubborn American I took it as a Britishism and inherently redundant.

".375DIA HOLES THRU 6 PLCS ON AN 8.875 B.C.D.".

Assuming this quote to be a drawing note and applying ASME drawing standards to it, how many things do you see wrong with it?

 

[KENAT]

Ouch Ron, so am I inherantly redundant;-)!

Don't see B.C.D. in 14.38. For that matter don't see BCD.

They do have BC for bolt circle & DBC for Diameter Bolt Circle, so my memory was wrong.

They also hav PC for Pitch Circle and PD for Pitch Diameter and DP for Diametral Pitch.

EQLSP is Equally Spaced.

KENAT, probably the least qualified checker you'll ever meet...

 

[drawoh]

CheckerRon,

".375DIA HOLES THRU 6 PLCS ON AN 8.875 B.C.D." is an arrow pointed at a hole.

I prefer to see acronyms kept to a minimum because they limit understanding. BCD also means Binary Coded Decimal. The standard shows the pitch diameter and angle between holes shown explicitly, with a separate specification shown for the holes, with an attached positional tolerance. There is no need for any terminology, much less a mysterious acronym. The specification can be understood by someone who does not speak English.

In the presence of a note stating that all dimensions are basic unless specified otherwise, the above text minimally meets the requirements of ASME Y14.5M-1994. It is still poor practise, especially since the correct method is less work.

JHG

 

[btrueblood]

Ugh. The callout

".375DIA HOLES THRU 6 PLCS ON AN 8.875 B.C.D."

requires you (on the cad system I use) to manually input at least one of the numbers .375, 6, or 8.875. Dimensioning them individually ensures that if I change from 3/8 holes to 1/2, or add a 7th hole, or etc. etc., the drawing will likely update by itself rather than requiring my rather tattered brain cells to remember to do it.