Appendix B4 ASME Y14.5M-1994 Fixed Fastener Positional Tolerance Calc. 5

[KENAT]

Linked below is a spreadsheet I’ve set up for calculating positional tolerances.

Typically I wouldn’t expect to need to fill in the top portion but if copy is needed for records etc then I thought it may come in useful.

Please feel free to use it and/or to give constructive criticism.

If members think it would be worth it I’ll put it as part of a FAQ.


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

 

[KENAT]

tunalover, the spreadsheet just uses the calculations from the standard. If you think they are too simple then I suggest you contact the ASME 14.5 committee to ask for a change at the next revision.

Much of the time pencil & paper or maybe just mental arithmetic will be more than adequate. I have a learning disability which makes mental arithmetic a bit more challenging for me so on a bad day this spreadsheet (not fully populated) helps me out. Also sometimes I’m required to present my calculations in which case again this printout attached to the relevant drawing can be of use.

This spreadsheet was also developed to try and assist interns with Tolerancing.

It’s not the be all and end all but just something I believe is useful in some situations.


KENAT,

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

http://eng-tips.com/market.cfm?

 

[dgallup]

Pencil and paper, how quaint. Do you scan it to save with all the other design data?

I don't do anything on paper anymore. If it is not saved in the project files it doesn't exist.

 

[Tunalover]

dgallup-
Either the hole pattern is designed to fit or not is clear from the drawing and the calculation does not need saving once the drawing is released. It sounds like you spend a lot of time with excessive documenting when designing is time better spent.

Tunalover

 

[vc66]

Tunalover-

You don't document the calculations you use in your designs?

Scary.

V

 

[KENAT]

tunalover, whether the hole pattern is designed to fit is not usually clear from one drawing, you have to look at both mating parts and do some simple math. Something most people around here are incapable of.

Anyway, if you don't like it don't use it, it you have any ideas for improving it's usefulness I'm open to suggestions. However, decrying it as useless, when I've already had people here use it and find it beneficial, doesn't do much for me.

KENAT,

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

http://eng-tips.com/market.cfm?

 

[JLang17]

KENAT,

In the section where you have the X Tolerance Range, Y Tolerance Range and the Equivalent Positional Diameter, I noticed your equation doesn't multiply by 2. In a book I have, it says to multiply by 2 to get the Equivalent Positional Diameter...

When I follow the equation in the book, I get exactly double what your spreadsheet gives me.

Books equation is SQRT(X^2 + Y^2)X2

 

[KENAT]

I use the term 'tolerance range' meaning the value from max to min not the deviation from the 'nominal'.

So if the tolerance is +-.005, then tolerance range is .010.

See example 3 on the updated 4 September version.

KENAT,

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

http://eng-tips.com/market.cfm?

 

[JLang17]

Ah, right, the book doesn't use the full range, just half. Thanks, the spreadsheet will come in handy.

 

[Michael854]

tunalover,

I agree that hand calculations are necessary to any responsible engineering decision...but, I suck at penmanship...I do my hand calculations in excel.

In looking at Kenat's spreadsheet...I think it is a good double-check instrument...but to rely on it?...I see that as turning engineers who should be "chef's"...into short order cooks.

I think Kenat's spreadsheet is missing a few assumptions which should be documented to be complete...I can't speak for Kenat, but I bet he has those in his own project notes..and I bet he could explain them if challenged...I'll bet you a nickel he doesn't just hand off the sheet and run...and I'd bet you another nickel he has not included them in the spreadsheet so the spreadsheet could be readable.

The biggest problem I see...is in Kenat's later thought that many engineers do not understand how to use the mathematics to describe the system...and without such spreadsheets...are they seem very willing to guess.

I'm usually given only a stack of drawing to checks. So, I see Kenat's sheet as an improvement...Even if we assume no improvement to drawing quality...I think I would still be able to easier see where an engineer made an error...and save me time.

My thought is that a few simple notes on another worksheet in the same workbook could accompany Kenat's sheet.

That would be a drawing checker's utopia.

Didn't we learn in school..."Show your work?"

Michael
GDTP-S0470
"Drawing checker who ain't ever seen Utopia"

 

[KENAT]

Michael854 please feel free to make any suggestions of what assumptions etc you believe should be noted. The spreadsheet is intended to be used in companion with ASME Y14.5M-1994 Appendix B, not completely by itself.

KENAT,

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

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[fcsuper]

KENAT,

Would you mind me adding your spreadsheet to sw.fcsuper.com?


Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[KENAT]

No, go ahead.

Be aware there is a glitch in the conditional formatting, at least on the version I released at work. One of the cells (can't remember which) indicated interferance if the result is actually a line fit. I couldn't work out what was going on.

KENAT,

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

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[fcsuper]

KENET,

I'll just add a disclaimer like I do to my own works. If you know which field it is, can you give me a version with it highlighted to point it out?

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[KENAT]

I can't remember, I'm not sure if it happened all the time.

KENAT,

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

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[fcsuper]

I'll be tacking this on to the first sheet:

"Warning: The information and formulae within the spreadsheet are based on tertiary sources, original research, particular assumptions and calculations. Some information or results may be incorrect. This spreadsheet, its information, and its calculations should only be used as a general reference. Always verify results. Use at your own risk!"

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group