hole dimension tolerances on prints 2

[bearisle]

Might not be in the right forum....I am looking for a good way to put a blanket statement in my title block to cover HOLE dimension tolerances. I currently use linear dimension tolerances as follows:
x.x = +/- 0.1
x.xx = +/- 0.015
x.xxx = +/- 0.005

 

[drawoh]

bearisle,

Are you talking about the diameters of the holes, or positional tolerances?

How about...

UNLESS OTHERWISE SPECIFIED, ALL HOLES ARE...
DIAMETER: +.005/-0
POSITION: <DIA>.006 A B C

I am assuming that you are drilling the holes, and that you are using them for small screws, such as less then #10. Your datums are going to have to be A, B and C.

The advantage of standard tolerance notes is speed and convenience. The disadvantage of them is that they save me having to think about stuff that I really ought to have thought about. If I were doing a titleblock in my own drafting office, I would be tempted to _not_ do a tolerance note.

If someone wants to be lazy, they can add their own tolerance note as a note. At least they thought about it. I am getting tired of seeing weldment and sheet metal drawings set to three/two decimal places on English/metric drawings, indicated +/-.005/0.1 tolerances respectively.

JHG

 

[diamondjim]

The are some specs governing drilled hole
size tolerances. The H28 handbook gives
the tap drill sizes and the expected
high sizes for the different thread sizes
and assumes 3 times the diameter for depths.
I have seen a Navy spec for holes in steel.
You can get minus tolerances with aluminum.

 

[diamondjim]

Dia. Hole Tolerance
.0135 THRU .125 +.003/ -.001
.1260 THRU .25 +.005/ -.001
.2510 THRU .500 +.006/-.001
.5010 THRU .750 +.008/ -.001
.7510 THRU 1.000 +.010/ -.001
1 .001 THRU 2.000 +.012/ -.001
See the following and check out the
web searching on drilled hole tolerances.
This looks like a good approach.

http://websearch.cs.com/cs/boomfram...+hole+tolerances&clickedItemURN=http%3A%2F%2F

http://www.engineersedge.com%2Fdril...=http://www.engineersedge.com/drill_sizes.htm

 

[bearisle]

Thank you diamond! That is basically what I was looking for.