what is the tolerance of the dimension?

4 comments

Rate

elegantessay Associate Join Date: Aug 2008 Posts: 34	what is the tolerance of the dimension? 09/01/2008 4:20 AM
	there is a sand casting part as the attaching image. one surface will be machined and the other surface will kept unmachined. what is the not stated tolerance of the dimension connecting one side to the other side? can i use the standard ISO 2768 to calculate the tolerance? thanks
	Register to Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

These comments received enough positive votes to make them "good answers".

markar Power-User Join Date: Mar 2007 Location: Nothing sucks more than that moment during an argument when you realize you're wrong. Posts: 301 Good Answers: 22	#1 Re: what is the tolerance of the dimension? 09/01/2008 10:47 AM
	As a dimensional inspector this is near and dear to my heart! Typically a properly defined drawing should leave nothing to chance, *guess work, that's why we use them.* I say "typically" because it seems each customer can and will have their own flavor if you will by where they interpret things like the ANSI standards for drawings, dimensioning and CAD models to suit their business practices. Some lay it out clearly to avoid confusion and get the work done, some make you hunt for definitions and it seems some actually like to play games to test your knowledge experience. Enough of that, look for "catch-all call-outs" like Unless Otherwise Specified or possibly a customer specification manual that will cover it. Lastly call the customer for clarification, with every one trying to do the work of 3 people, the data may have been left off. Function dictates tolerance, don't guess and put the monkey on you back, make the designer provide it. __________________ You never know when it will strike, but there comes a moment when you know that you just aren't going to do anything productive for the rest of the day.
	Register to Reply Good Answer (Score 2)

Anonymous Poster	#2 Re: what is the tolerance of the dimension? 09/02/2008 1:46 AM
	By definition ISO 2768 applies to dimensions of parts that are produced by metal removal or parts that are formed from sheet metal. As per the same standard, in cases of dimensions between finished and unfinished surfaces in cast parts, where also ISO 8062 applies, you must determine the tolerance by both 2768 and 8062 and apply the largest. I expect that the 8062 tolerance will be the largest, so this is what you should use for D. Best of luck
	Register to Reply

elegantessay Associate Join Date: Aug 2008 Posts: 34	#4 In reply to #2 Re: what is the tolerance of the dimension? 09/02/2008 10:27 AM
	my colleague told me that two different tolerance values could be got respectively according to the two different standards, and the bigger value will be the tolerance. he said the designer didn't specially give the dimension a tolerance, on the other hand, one of the two sides is kept unmachined. so it is clear that the dimension is less important, and so the tolerance should not be checked. what my collleauge said is very similar to what you said.
	Register to Reply

MOBI Guru Join Date: Aug 2007 Location: Australia Posts: 1630 Good Answers: 20	#3 Re: what is the tolerance of the dimension? 09/02/2008 6:35 AM
	This is another method of showing machining allowance and surface finish. The 3 tells you that you have a 3mm machining allowance all round, that your surface is to be machined on a lathe with a surface finish of Rz 3,1. The diameter of 25mm will probably be covered by the general drawing tolerance. __________________ TO BE. or NOT TO BE. That is the question!! The Bard
	Register to Reply

These comments received enough positive votes to make them "good answers".

Copy to Clipboard

Anonymous Poster (1); elegantessay (1); markar (1); MOBI (1)

	Got Something to Say?
	Ask a Question Start a Discussion

	Search this Forum
	Quality Assurance / Control: Go

	Aerospace
	BioMech & BioMed
	Chemical & Material Science
	Civil Engineering
	Communications & Electronics
	Education and Engineering Careers
	Electrical Engineering
	General Discussion
	Instrumentation
	Manufacturing
	Mechanical Engineering
	New Technologies & Research
	Software & Programming
	Sustainable Engineering
	Transportation

	Site Directories
	Forum Directory Blog Directory User Group Directory RSS Feeds CR4 Rules of Conduct CR4 FAQ Site Glossary Who's Online (116 right now) Show Members