ISO dimensioning

[seahag1961]

What is the ISO standard for calling out holes? I have a new boss, and he likes symbols for everything. My old boss didn't care too much. I used to dimension holes this way:

4x M3X0.5, 5 DP
PREHOLE 6.5 DP, C0.3

My new boss says ISO standard uses symbols for depth, and countersink and diameter for the chamfer.

Is he correct

 

[drawoh]

seahag1961,

Check out forum1103.

From what I have seen of the ISO specification, I strongly prefer ASME Y14.5M-1994. The symbols are very similar.

JHG

 

[CorBlimeyLimey]

seahag1961 ... which software are you using? The ISO callouts may be dimension options within the program.

 

[KENAT]

Don't have the relevant ISO. However figure C3 in ASME Y14.5M-1994 shows ASME/ISO equivalents.

It says the Counterbore, Countersink and Depth symbols are 'proposed' for ISO. So in 1994 I guess they weren't yet in the ISO, not sure about now.

I will say this, according to ISO you don't normally show the pitch for standard 'course' pitch. So M3x0.5 is normally just M3.

Also I'm not entirely sure what you're saying in the second part of the callout. Is this meant to be the lead in? Countersinks are usually given by diameter and angle, even in Iso as I recall.



KENAT, probably the least qualified checker you'll ever meet...

 

[CoryPad]

According to ISO 5845 Technical drawings -- Simplified representation of the assembly of parts with fasteners -- Part 1: General principles and ISO 6410-3 Technical drawings -- Screw threads and threaded parts -- Part 3: Simplified representation, threaded holes are noted with text, not symbols.

Examples:

M6 x 20/[φ]4,8 x 24

Which means a hole with ISO metric thread, 6 mm major diameter, 20 mm thread depth, initial hole diameter was 4.8 mm, and total hole depth is 24 mm.

As stated by KENAT, pitch is not always specified (although it doesn't hurt, and is not discouraged).

There are symbols for countersinks, whether holes are drilled in a workshop and fitted on site, or drilled and fitted on site, etc.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[KENAT]

First half looks familiar Cory.

I don't remember doing the second half like that in UK but maybe I've been americanized now!

KENAT, probably the least qualified checker you'll ever meet...

 

[seahag1961]

Thanks everyone. The software I am using is Solidworks, but they have parameters for all standards of drafting. I work for a Japanese company and they like to see the pitch call out on machining drawings. On a customer drawing it would just say "M3". I just wanted to prove my boss wrong.

 

[seahag1961]

Kenat,

Yes, the second part of the above call out is for the drilled prehole depth. This must be a Japanese thing too. The US and Japan can't agree on anything. Japan uses JIP and the US uses ISO....can't we all just get along?

 

[seahag1961]

I meant JIS.

 

[KENAT]

US actually uses ASME standards mostly, not ISO.

No everyone can't just get along, cause ISO sucks in some areas;-)

Per American, and in fact as I recal, UK convention you don't put the tap drill info on the drawing as that's specifying a process etc.

I guess the japanese like it.

Hmm, which is the more dominant engineering force...

KENAT, probably the least qualified checker you'll ever meet...

 

[seahag1961]

Kenat,
I know the US uses ASME, I was referring to the Japanese owned company I work for in the US.

As for the dominate engineering force....I say it's the one who holds all the cards and signs my paycheck!

 

[fcsuper]

Does the japanese standard actually insist on the drill being included in the thread callout? This would seem odd to me. It might be worth the investment to get an english version of the JIS that applies to dimensioning and tolerancing. Though, it really comes down to who's signing your check.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[Tmoose]

"Per American, and in fact as I recal, UK convention you don't put the tap drill info on the drawing as that's specifying a process etc."

In an application where I was forced to really care about the thread strength I might specify a percent of thread, which would define the tap drill within limits.

Some thread inserts (Keensert) are installed in a hole tapped to a standard screw thread, but a larger than std tap drill absolutely must be used.

 

[KENAT]

Trouble is, you can't really inspect what the tap drill size was once the thread is made.

So generally you want to define what thread form you need to end up with.

KENAT, probably the least qualified checker you'll ever meet...