How to call out this surface finish

[bawest47232]

We have parts that have been made for years by one supplier but now, we are getting the parts made by another supplier. WE have trouble interpreting and agreeing on what the current surface finish call out is. See attached.

The parts are supposed to have an intentional roughness (100-150 Rq) in a crisscross pattern. This was done by grinding.

So, my understanding of the current callout would be a .100-.150" step every .030" But if I understand this correctly, it doesn't specify that there should be about .150" between the crisscrossing cuts.

What would be the correct callout, or is there even a callout that would specify a .150" spacing (peak to peak) crisscross pattern that varies .100-.15 steps between peaks?

Does the question even make sense?

http://files.engineering.com/getfil...-6de6-48ec-a427-453cb631b82b&file=surface.JPG

 

[KENAT]

I think your units are off aren't they, unless noted otherwise surface roughness on 'inch' drawings is micro inches per ASME B1.1 or what have you isn't it?

https://en.wikipedia.org/wiki/Surface_finish

Do you really have a knurled surface?

http://www.eng-tips.com/viewthread.cfm?qid=173397

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[dgallup]

Your .030 is the cutoff length. You need to trace across 7 times this length, discard the first and last, and measure the interior 5. There is nothing in the spec that gives a spacing value. That would take another symbol with Sm parameter (mean spacing of profile irregularities).

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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.

 

[powerhound]

I sure hope you don't think that .002 flatness tolerance with 4X controls the coplanarity of those surfaces. Maybe via tribal knowledge but not legally per ASME Y14.5.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech

 

[bawest47232]

sorry, I meant a .001" to .0015" step about 1/8" apart.

 

[dgallup]

You are still off by a factor of 10 on your height and I have no idea where you came up with '1/8" apart'.

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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.

 

[powerhound]

What do you mean by "step"? Also, if this is in accordance with ASME Y14.36M then shouldn't the Rq value be under the radical? I thought the only thing that goes in that spot is an Ra value.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech