Roughness tolerance h7

[bargeld]

Hi fellas,
I have some trouble with value over roughness symbol. The value is expressed as h7 or H7. It looks like on attached image. Anyone of You knows
which class describes it or how to translate it to Rz?

 

[prex]

If this is on the outer diameter of a shaft, could it be an (incorrect) indication of an ISO tolerance?

prex
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[bargeld]

This value also describes others surfaces e.g. face next to tolerated outer diameter.

 

[dgallup]

I've got quite a collection of surface texture documents and I can't find anything that looks like that. H7 should be an ISO hole size tolerance for a sliding fit. I've never seen any implied surface texture to go with an H7 hole and certainly it would not apply to a face. There is an ISO system for surface roughness with a number like that but it's an "N" series. N7 equates to 63 microinches Ra or 1.6 microns Ra.

Does the drawing have a definition of H7 somewhere else like in the general notes? Sometimes when a surface texture is used over and over on a drawing they will use an abbreviated symbol in all the locations and then explain the symbol in a note.

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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.

 

[juergenwt]

The symbol points to a surface that was altered by a material removing process. No additional notations are required. H7 is the tolerance for a hole. h7 is the tolerance for a shaft. They are not part of a symbol specifying a surface condition. You can be sure that the draftsman or engineer responsible for the drawing has limited knowledge on how to use that symbol. I think what he/she is trying to tell you is that a dim. marked H7 or h7 has that surface condition. Showing the symbol under those conditions is false since a H7/h7 tolerance can not be achieved without the removal of material (turning, grinding, honing, reaming etc.}
If the long line on the right side of the triangle had another horizontal line on top than additional information could be listed (surf. roughness, grinding allowance etc.)
Scroll down.

http://www.hexagondesign.net/images/pdf/surface_roughness_jigar_talati.pdf

 

[bargeld]

Thanks everyone for the replies.
dgallup There is note about roughness tolerance for other dimensions (removal of the material is not permitted) and additional symbols used in the drawing: Ra1,6 and Ra3,2. Nothing else.