Implied tollerances

Really for any kind of machining the print has to *explicitly* reference a tolerance for *every* dimension. This is often done as a call-out at the bottom, which says, +/- such-and-such for a dimension of so-many decimal places. Often dimensions which are toleranced differently (read, most often, "tighter") are indicated on the print, right at the dimension.

But the call-out note on the print serves the purpose of putting an explicit tolerance on every single dimension number on the print, even if there are no special individually dimensioned values present, and the values chosen by the designer are vital to making the part function correctly for its intended use, and are not the same for each job in general.

This point was explained to me, in great patient detail by a superb mechanical designer, the late Bill Goss. Who also introduced me to the

MIL-TFP-41

specification.

Thanks, Bill for all your imparted wisdom. I hope some of it stuck.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Most standard drawing formats (either the old, old vellum or the File/New/Drawing screens have a 'standard' implied tolerance block that might look something like

x.xxxx +/- .0001 x.xxx +/- .005 x.xx +/- .01

or something like that, depending on your particular drafting room and shop practices. Special tolerances for fits or large pieces are specified separately in the normal way.

Obviously, you don't need this if you're just drawing for yourself, but if the drawing is part of a contact or purchase order, it really should everything specified one way or another. Imagine two inspectors, one from the buyer and one from the seller, trying to decide whether a part is good or not. "I thought"s and assertion of "Industry standards" just don't cut it when the money is on the table.

If you didn't tolerance your 2.000 bore separately, you'd have to accept

hth, Fred "Old Enough To Have Worked In A Drafting Room" Klingener

AW Yess. :-) Havent seen that spec for a long time. ...lew...

Implied tolerance can be stated as "the understood statement done in my best Spanglish" - understood by the husband of the woman I was speaking to in the last bar I was in tonight in Honduras - REALLY! Ken.

What is the title for Mil-TFP-41? Is it publicly available?

Stephen R.

Gardner

Set the hook! You got one!

Make It Like The Friendly (or some other "f" word) Plan

Publicly available. Yup!

Stands for

Make It Like - The F___ing Plan - For Once !

Cheers Trevor Jones

Classic...

I will definitely use that one at work.... I was told directly by some of our shop techs that they don't usually read the notes on our drawings (usually only at crunch time).

Thanks,

Stephen R.

Print

I was instructed that the word was "print" actually.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Hey Jack,

SACOTKAM plus RRRROLFLMAO . I too was unfamiliar with that Mil Spec designati>>

We used to use MIL-TFD-41. I don't know if that was an earlier or later version.

Dick

I think that it was an earlier version of MIL-TFD-C4 (Make It Like The F*** Drawing Calls For) HTH

We use Print for the name of what was sent to the shop but I guess Drawing is just as good. Our "drawings" were "archived" in the drafting dept. ...lew...

Damn, I think that spec has gone around here about as often as the Henway thing. Glad you enjoyed it.

But SACOTKAM? That's a new one to me.

SNIP

OK. Breakfast is over:

Snot And Coffee On The Keyboard And Monitor.

Brian