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spec for machining tolerances

spec for machining tolerances

spec for machining tolerances

(OP)
I'm looking for a spec for standard machining tolerances for different processes.

I found ANSI b4.1, but it looks as though it is only dealing with cylindrical fits (even though I see other websites using it as a reference for positional tolerances).

So is ANSI B4.1 the best out there, or is there something better.


I should note that the only reason this came up is because I'm getting something machined that is larger (12x30x1.75") than what I usually get made. Typically I would just slap .005 everywhere, but I don't feel like that scales well when I have 2 holes 28" apart.

All help is good help.

Chris Loughnane - Product Design

http://www.pdnotebook.com
http://www.twitter.com/DesignNotebook
 

RE: spec for machining tolerances

Check the Machinist Handbook and the Machining Data Handbook

RE: spec for machining tolerances

There are many factors that affect this.  Best is to talk to your vendor.

Similar questions come up every now and then, Ctopher & I have both pasted links to sites with useful information before now.

Someone will probably suggest looking at ISO2768, I'm not a fan of it but to get some idea of achievable tolerances may be of use.

12*30*1.75 inch isn't that big, if done in a single set up +-.005 should be readily achievable but...

Do you need it?

Specify the loosest tolerances you can get away with based on Function, then make sure those are within process capability.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

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