Grizzly stirling engine plan symbols

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averagelemur

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Hello,

I am new to this forum and just purchased a lathe. I am looking to make one of the Grizzly stirling engine kits from their plans and don't understand a symbol that seems to appear on a few pages of drawings.

Can anyone explain to me what the upside-down check mark symbol around the octagon is supposed to indicate?

Thanks very much!

Symbol Meaning.jpg
 

TonyM

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The basic sign is for surface finish. That particular one means do not remove material on this surface.
 

TonyM

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The drawing says brass rod so I don't know why it's there. 0.8 μm may be the standard finish for brass round. Maybe it's just in case you are not using 6mm bar. Putting that particular tolerance looks overkill as it is just a connecting rod but then I don't know what purpose the part actually serves.
 

Mechanicboy

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And you need Rubert Surface Roughness Comparator Set if you want, but cheap?.. $261
Surface roughness tester.jpg
 

Richard Hed

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And you need Rubert Surface Roughness Comparator Set if you want, but cheap?.. $261 View attachment 116713
I have one of these I bought many years ago a fellow machinist sold me in a bundle of tools. I have never used it, other than to look at it an wonder. It's nice to know about and occassionally I look at it just to know approximations.
 

Mechanicboy

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I have one of these I bought many years ago a fellow machinist sold me in a bundle of tools. I have never used it, other than to look at it an wonder. It's nice to know about and occassionally I look at it just to know approximations.
The roughness surface tester are to check the product under mass production due cost of production time, not for home model engineering.
 

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