Significant Figures applied to GD&T
Significant Figures applied to GD&T
(OP)
Thank you so much for your replys, it has really helped me.
Im new at all this forum stuff so Im sorry if I keep asking questions wrong.
The reason for the question of significant figures was because, I was asked was to find out what the term was for when you divide two numbers with different decimal places. You cant divide them with out adding a zero to make them have the same number of places, so whats that called when you cant do that...... It was found that what he was trying to find was the term "significant figures."
So, my boss, is trying to apply the law of significant figures to a deminsinal drawing using GD&T. But, can you use that law? Or, can you only use tolerance? and when you have different decimal places you add onto the tolerance.
Im new at all this forum stuff so Im sorry if I keep asking questions wrong.
The reason for the question of significant figures was because, I was asked was to find out what the term was for when you divide two numbers with different decimal places. You cant divide them with out adding a zero to make them have the same number of places, so whats that called when you cant do that...... It was found that what he was trying to find was the term "significant figures."
So, my boss, is trying to apply the law of significant figures to a deminsinal drawing using GD&T. But, can you use that law? Or, can you only use tolerance? and when you have different decimal places you add onto the tolerance.





RE: Significant Figures applied to GD&T
thread404-195481: significant figures thread1103-195484: significant figures
I think the answer to your question is no, but I’m still not really sure I understand correctly.
The number of decimal places has significance on most American Drawings as I detailed before. If you aren’t working to typical American Drawing standards the answer might be different.
At the end of the day if you are doing some kind of tolerance analysis you need to take into account the tolerance of each dimension.
So if you have the block tolerance I gave before and you have a stack of 1.3 + 1.200 the total worst case stack is = 2.5 +- .035
Does this answer your question?
What drawing standards are you working to, this may help with the answer.
KENAT, probably the least qualified checker you'll ever meet...
RE: Significant Figures applied to GD&T
i'm having trouble visualising what you're trying to do ... why would you need to divide two real numbers on a drawing ?
could you give us an example of the problem ?
RE: Significant Figures applied to GD&T
Thanks again
RE: Significant Figures applied to GD&T
RE: Significant Figures applied to GD&T
This is basically the opposite of dimensions on a drawing. Every nominal dimension on a drawing is exact because you are defining it by the drawing. If the drawing says 13.5mm, it means 13.50000000000000000000000000000..... Tolerances on the drawing, whether they are defined by the title block, GD&T, or called out explicitly on the dimension itself, express how far away from the theoretical exact value the actual fabricated part can be.
RE: Significant Figures applied to GD&T
RE: Significant Figures applied to GD&T
Significant figures are fairly well described here: http://en.wikipedia.org/wiki/Significant_figures Trust me, you don't want to use this method on drawings.
Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group