×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Dual dimensioning units - surface roughness
3

Dual dimensioning units - surface roughness

Dual dimensioning units - surface roughness

(OP)
I've been asked to convert a couple of drawings to dual dimensioning units. This is easy to do with our CAD system for linear dimensions and geometric tolerances. Change on drawing configuration option and it's done. However, that has no effect on surface roughness symbols. I've never seen a dual dimensioned surface roughness symbol. Our symbols just have a text string for the roughness. Is it acceptable to do this:

50[1,2]

for the micro-inch[micron] values?

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Dual dimensioning units - surface roughness

I have never seen surface texture with mixed units, they are usually either in µM or µIN.

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

RE: Dual dimensioning units - surface roughness

Roughness symbol can be troublesome as it is, without dual units.
Would you consider placing conversion table somewhere near titleblock?
Naturally, the note should be provided saying something like “SURFACE ROUGHNESS IN MICROINCHES, FOR MICROMETERS CONVERSION SEE TABLE 2”

RE: Dual dimensioning units - surface roughness

dgallup,

One of the many arguments against dual dimensions traditionally is that the conversions might be wrong. It sounds like this is still true.

--
JHG

RE: Dual dimensioning units - surface roughness

(OP)
Believe me, I'm as anti dual dimensions as anyone, but when it has to be done it has to be done. The CAD system automatically takes care of most of it very well. It is just these surface finish tolerances that remain. ISO 1302-1978 (obsolete) recommends using roughness grade numbers to avoid misinterpretation of numerical values but since no one here is familiar with their use that would only add confusion in my opinion. I think I will add a table to each drawing, there are only 2 or 3 values on each drawing.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Dual dimensioning units - surface roughness

Here is another interesting idea: To think of it, even obsolete symbology may be used, if you clearly explain what you are trying to achieve. Please check the following link:
http://content2.smcetech.com/pdf/Supplier_QA_Manua...
This is remarkable document, created to ”level the field” for the suppliers, and make sure all of them will interpret company drawings in the same way.
The surface roughness chapter starts on the bottom of Page 18.
I am not saying this is the only way to do it, just an example. smile

RE: Dual dimensioning units - surface roughness

(OP)
We have a similar document that explicitly states every drawing standard we use and any special symbols, etc. It does not say anything about units as we have drawings in both inch and metric. I'm not about to start using obsolete symbols!

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Dual dimensioning units - surface roughness

Quote (dgallup)

I've been asked to convert a couple of drawings to dual dimensioning units. This is easy to do with our CAD system for linear dimensions and geometric tolerances. Change on drawing configuration option and it's done. However, that has no effect on surface roughness symbols. I've never seen a dual dimensioned surface roughness symbol. Our symbols just have a text string for the roughness. Is it acceptable to do this:
50[1,2]
for the micro-inch[micron] values?

I have been working with drawings using such convention. As long as there is a clear explanation on the drawing area or in a document referenced on the drawing as to what is what, I see no issues with that.

Correct conversion of dual dimensions is a different story.

RE: Dual dimensioning units - surface roughness

Two things I would not do:
1. Dual dimensions on surface roughness
2. Use vendors incapable of unit conversion

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources