# Draftsmen, Engineers...I need help identifying / translating this drawing symbol **URL:** \ **Category:** Factual Questions\ **Created:** [June 6, 2007, 12:36am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921 "2007-06-06T00:36:13Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![rainy](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@rainy](https://boards.straightdope.com/u/rainy)\ **Post date:** [June 6, 2007, 12:36am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/1 "2007-06-06T00:36:13Z")
Help. I’m doing some contract work translating some German produced blue prints for machined parts in order to get them quoted in the United States. An image of the call out is here [![](https://i196.photobucket.com/albums/aa56/rainyjames/quandry.jpg) ](https://i196.photobucket.com/albums/aa56/rainyjames/quandry.jpg) I believe the first third is a surface finish call-out the Ra1, 2 being measured in micrometers. To translate that to a more familiar format in the US it would be a 48 roughness (measured in micro-inches). Right? The other two thirds of that call out is completely new to me, I have no idea what it means. Can anyone explain this to me? Thanks -rainy ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [June 6, 2007, 2:09am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/2 "2007-06-06T02:09:05Z")
Off the top of my head . . . Surface finishes are not perfectly flat, they are in actualy wave like. I believe the second and third call outs refer to the upper and lower wave amplitude limits. Don’t have my Machinery’s Handbook at my side anymore these days so that’s the best I can guess right now. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 6, 2007, 2:25am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/3 "2007-06-06T02:25:56Z")
Not seeing the call out in context, I’m not sure exactly what the last two parts are. It’s possibly defining the surface is between a certain area for a machining process The triangle on the front of the first symbol means machining required. RA is in micrometers. Millionth. I’m pretty sure on this, that it isn’t in microns which is micro inches. RA is Roughness Average. RA does not give the lowest to highest range. This link does a basic explanation. > **[Quality 101: Surface Finish Measurement Basics](https://www.qualitymag.com/articles/84505-quality-101-surface-finish-measurement-basics)** > > Roughness is an important characteristic of MACHINED surfaces. This link is a .pdf that is more detailed. [http://www.rh.edu/~mccl4905/FWM/presentation2.pdf](http://www.rh.edu/~mccl4905/FWM/presentation2.pdf) This of course is help and not a definitive translation. Try some ANSI standards and symbols book, or whatever standard the print calls outs. I haven’t done this for over four years, but did for thirteen years. I don’t have access to my old reference books. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 6, 2007, 2:28am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/4 "2007-06-06T02:28:14Z")
[QUOTE=Harmonious Discord] RA is in micrometers. Millionth. I’m pretty sure on this, that it isn’t in microns which is micro inches. [/QUOTE] Um, what? A micron is a micrometer which is a millionth of a meter. ---
**Author:** ![rainy](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@rainy](https://boards.straightdope.com/u/rainy)\ **Post date:** [June 6, 2007, 2:45am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/5 "2007-06-06T02:45:51Z")
[QUOTE=Harmonious Discord] Not seeing the call out in context, I’m not sure exactly what the last two parts are. [/QUOTE] Yeah, sorry about that, I’m trying not to violate the non-disclosure agreement I signed with this company. What seems weird to me (but then again I know squat about specifying finishes) is that this string of symbols, occurs spaced just like in the linked image, free floating above the title block of the drawing. I thought surface finish call-outs usually pointed to the surface they referenced. ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [June 6, 2007, 2:57am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/6 "2007-06-06T02:57:17Z")
Free floating above the title block. That generally means that it is a general overall finish callout for all unspecified surfaces. Most likely close to an industry standard for that type of material. Can’t be too certain without knowing the application. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 6, 2007, 5:33am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/7 "2007-06-06T05:33:04Z")
[QUOTE=Q.E.D.] Um, what? A micron is a micrometer which is a millionth of a meter. [/QUOTE] RA is in micrometers. Micro is millionth of whatever unit your dividing. I’m pretty sure on this, that the RA isn’t in microns which is the same as saying micro inches. For Q.E.D. Like Si Amigo said it’s likely a general finish call out on any surface that has a finish requirement. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 6, 2007, 5:39am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/8 "2007-06-06T05:39:41Z")
I still made that sound stupid. A micron is metric., leave it at that. ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [June 6, 2007, 10:43am UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/9 "2007-06-06T10:43:47Z")
OK, I got up today and broke out the Machinery’s Handbook. The first value describes the wave distance from highest to lowest peaks. The other two seem to describe the exceptable range of amplitude off of the nominal. You will have to get a more precise answer from a German Machinist as I am only familier with ANSI standards and this format isn’t totally covered by any ANSI standard that I can find. ``` I can tell you that this finish is typical for die cast surfaces, boring, cold rolled surfaces and reaming. That is, it's better than a saw cut or sand cast surface but not super fine like lapping or polishing. ``` ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [June 6, 2007, 1:02pm UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/10 "2007-06-06T13:02:11Z")
The drawing should have the revision of the standard used for the drawing. You’ll then know what reference volume to use. ---
**Author:** ![rainy](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@rainy](https://boards.straightdope.com/u/rainy)\ **Post date:** [June 6, 2007, 1:28pm UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/11 "2007-06-06T13:28:06Z")
[QUOTE=Harmonious Discord] The drawing should have the revision of the standard used for the drawing. You’ll then know what reference volume to use. [/QUOTE] There is a note in the title block under “Surface / Partedge” labeled DIN ISO 1302 / 13715. I can’t turn up anything by googling that other than printed editions for sale. You’d think that kind of info would be available online. ☹ ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [June 6, 2007, 2:55pm UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/12 "2007-06-06T14:55:24Z")
[QUOTE=rainy] There is a note in the title block under “Surface / Partedge” labeled DIN ISO 1302 / 13715. [/quote] Well, I’m no machinist, but my initial impresion was that the second and third figures represented inside and outside corner specs – and ISO 13715 does cover edge specs, just as ISO 1302 covers surface finish. I only did a cursory Google, but I found several tutorials and summaries in English and German listed for each standard separately (I apologize if I’ve insulted your intelligence by suggesting that you may have googled them as a single spec, but I’ve see it a lot when looking up unfamiliar specs, esp in a foreign language) I don’t know if they provide the level of detail you desire. I didn’t see any complete copies of the complete ISO specs on the first page (100 results) ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [June 6, 2007, 3:19pm UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/13 "2007-06-06T15:19:47Z")
Now that I look at it on my PC instead of my blackberry it makes more sense. The second and third ones have nothing to do with surface finishes. They are obviously calling out edge and corner chamfer dimensional requirements. Basically all they are saying is break all sharp corners and edges. ---
**Author:** ![rainy](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@rainy](https://boards.straightdope.com/u/rainy)\ **Post date:** [June 11, 2007, 2:10pm UTC](https://boards.straightdope.com/t/draftsmen-engineers-i-need-help-identifying-translating-this-drawing-symbol/406921/14 "2007-06-11T14:10:59Z")
[QUOTE=Si Amigo] Now that I look at it on my PC instead of my blackberry it makes more sense. The second and third ones have nothing to do with surface finishes. They are obviously calling out edge and corner chamfer dimensional requirements. Basically all they are saying is break all sharp corners and edges. [/QUOTE] Yes that’s it. After having gotten the opportunity to talk with an engineer on the project this was verified. THanks everyone for the links and advice. -rainy